essay on green hydrogen

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Green hydrogen can be stored in a liquid form. Wolfgang Kumm/picture-alliance/dpa/AP Images

Green Hydrogen: Could It Be Key to a Carbon-Free Economy?

Green hydrogen, which uses renewable energy to produce hydrogen from water, is taking off around the globe. Its boosters say the fuel could play an important role in decarbonizing hard-to-electrify sectors of the economy, such as long-haul trucking, aviation, and heavy manufacturing.

By Jim Robbins • November 5, 2020

Saudi Arabia is constructing a futuristic city in the desert on the Red Sea called Neom. The $500 billion city — complete with flying taxis and robotic domestic help — is being built from scratch and will be home to a million people. And what energy product will be used both to power this city and sell to the world? Not oil. The Saudis are going big on something called green hydrogen — a carbon-free fuel made from water by using renewably produced electricity to split hydrogen molecules from oxygen molecules.

This summer, a large U.S. gas company, Air Products & Chemicals, announced that as part of Neom it has been building a green hydrogen plant in Saudi Arabia for the last four years. The plant is powered by 4 gigawatts from wind and solar projects that sprawl across the desert. It claims to be the world’s largest green hydrogen project — and more Saudi plants are on the drawing board.

Green hydrogen? The Saudis aren’t alone in believing it’s the next big thing in the energy future. While the fuel is barely on the radar in the United States, around the world a green hydrogen rush is underway, and many companies, investors, governments, and environmentalists believe it is an energy source that could help end the reign of fossil fuels and slow the world’s warming trajectory.

“It is very promising,” said Rachel Fakhry, an energy analyst for the Natural Resources Defense Council. Experts like Fakhry say that while wind and solar energy can provide the electricity to power homes and electric cars, green hydrogen could be an ideal power source for energy-intensive industries like concrete and steel manufacturing, as well as parts of the transportation sector that are more difficult to electrify. “The last 15 percent of the economy is hard to clean up — aviation, shipping, manufacturing, long-distance trucking,” Fakhry said in an interview. “Green hydrogen can do that.”

Germany has allocated the largest share of its clean energy stimulus funds to green hydrogen.

Europe, which has an economy that is saddled with high energy prices and is heavily dependent on Russian natural gas, is embracing green hydrogen by providing funding for construction of electrolysis plants and other hydrogen infrastructure. Germany has allocated the largest share of its clean energy stimulus funds to green hydrogen. “It is the missing part of the puzzle to a fully decarbonized economy,” the European Commission wrote in a July strategy document.

Hydrogen’s potential as a fuel source has been touted for decades, but the technology has never gotten off the ground on a sizeable scale — and with good reason, according to skeptics. They argue that widespread adoption of green hydrogen technologies has faced serious obstacles, most notably that hydrogen fuels need renewable energy to be green, which will require a massive expansion of renewable generation to power the electrolysis plants that split water into hydrogen and oxygen. Green hydrogen is also hard to store and transport without a pipeline. And right now in some places, such as the U.S., hydrogen is a lot more expensive than other fuels such as natural gas.

While it has advantages, says Michael Liebreich, a Bloomberg New Energy Finance analyst in the United Kingdom and a green hydrogen skeptic, “it displays an equally impressive list of disadvantages.”

“It does not occur in nature so it requires energy to separate,” Liebreich wrote in a pair of recent essays for BloombergNEF. “Its storage requires compression to 700 times atmospheric pressure, refrigeration to 253 degrees Celsius… It carries one quarter the energy per unit volume of natural gas… It can embrittle metal; it escapes through the tiniest leaks and yes, it really is explosive.”

In spite of these problems, Liebreich wrote, green hydrogen still “holds a vice-like grip over the imaginations of techno-optimists.”

Green hydrogen is produced using renewable energy, making it a CO2-free source of fuel. SGN

Ben Gallagher, an energy analyst at Wood McKenzie who studies green hydrogen, said the fuel is so new that its future remains unclear. “No one has any true idea what is going on here,” he said. “It’s speculation at this point. Right now it’s difficult to view this as the new oil. However, it could make up an important part of the overall fuel mix.”

Hydrogen is the most abundant chemical in the universe. Two atoms of hydrogen paired with an atom of oxygen creates water. Alone, though, hydrogen is an odorless and tasteless gas, and highly combustible. Hydrogen derived from methane — usually from natural gas, but also coal and biomass — was pioneered in World War II by Germany, which has no petroleum deposits. But CO2 is emitted in manufacturing hydrogen from methane and so it’s not climate friendly; hydrogen manufactured this way is known as gray hydrogen.

Green is the new kid on the hydrogen block, and because it’s manufactured with renewable energy, it’s CO2-free. Moreover, using renewable energy to create the fuel can help solve the problem of intermittency that plagues wind and solar power, and so it is essentially efficient storage. When demand for renewables is low, during the spring and fall, excess electricity can be used to power the electrolysis that is needed to split hydrogen and oxygen molecules. Then the hydrogen can be stored or sent down a pipeline.

Such advantages are fueling growing interest in global green hydrogen. Across Europe, the Middle East, and Asia, more countries and companies are embracing this high-quality fuel. The U.S. lags behind because other forms of energy, such as natural gas, are much cheaper, but several new projects are getting underway, including a green hydrogen power plant in Utah that will replace two aging coal-fired plants and produce electricity for southern California.

The Middle East, with the world’s cheapest wind and solar power, is angling to be a major player in green hydrogen.

In Japan, a new green hydrogen plant, one of the world’s largest, just opened near Fukishima — an intentionally symbolic location given the plant’s proximity to the site of the 2011 nuclear disaster. It will be used to power fuel cells, both in vehicles and at stationary sites. An energy consortium in Australia just announced plans to build a project called the Asian Renewable Energy Hub in Pilbara that would use 1,743 large wind turbines and 30 square miles of solar panels to run a 26-gigawatt electrolysis factory that would create green hydrogen to send to Singapore.

As Europe intensifies its decarbonization drive, it, too, is betting big on the fuel. The European Union just drafted a strategy for a large-scale green hydrogen expansion, though it hasn’t been officially adopted yet. But in its $550-billion clean energy plan, the EU is including funds for new green hydrogen electrolyzers and transport and storage technology for the fuel. “Large-scale deployment of clean hydrogen at a fast pace is key for the EU to achieve its high climate ambitions,” the European Commission wrote.

The Middle East, which has the world’s cheapest wind and solar power, is angling to be a major player in green hydrogen. “Saudi Arabia has ridiculously low-cost renewable power,” said Thomas Koch Blank, leader of the Rocky Mountain Institute’s Breakthrough Technology Program. “The sun is shining pretty reliably every day and the wind is blowing pretty reliably every night. It’s hard to beat.”

BloombergNEF estimates that to generate enough green hydrogen to meet a quarter of the world’s energy needs would take more electricity than the world generates now from all sources and an investment of $11 trillion in production and storage. That’s why the focus for now is on the 15 percent of the economy with energy needs not easily supplied by wind and solar power, such as heavy manufacturing, long-distance trucking, and fuel for cargo ships and aircraft.

The Fukushima Hydrogen Energy Research Field (FH2R), a green hydrogen facility that can generate as much as 1,200 normal meter cubed (Nm3) of hydrogen per hour, opened in Japan in March. Toshiba ESS

The energy density of green hydrogen is three times that of jet fuel, making it a promising zero-emissions technology for aircraft. But Airbus, the European airplane manufacturer, recently released a statement saying that significant problems need to be overcome, including safely storing hydrogen on aircraft, the lack of a hydrogen infrastructure at airports, and cost. Experts say that new technologies will be needed to solve these problems. Nevertheless, Airbus believes green hydrogen will play an important role in decarbonizing air transport.

“Cost-competitive green hydrogen and cross-industry partnerships will be mandatory to bring zero-emission flying to reality,” said Glen Llewellyn, vice president of Zero Emission Aircraft for Airbus. Hydrogen-powered aircraft could be flying by 2035, he said.

In the U.S., where energy prices are low, green hydrogen costs about three times as much as natural gas, though that price doesn’t factor in the environmental damage caused by fossil fuels. The price of green hydrogen is falling, however. In 10 years, green hydrogen is expected to be comparable in cost to natural gas in the United States.

A major driver of green hydrogen development in the U.S. is California’s aggressive push toward a carbon-neutral future. The Los Angeles Department of Water and Power, for example, is helping fund the construction of the green hydrogen-fueled power plant in Utah. It’s scheduled to go online in 2025.

A company called SGH2 recently announced it would build a large facility to produce green hydrogen in southern California. Instead of using electrolysis, though, it will use waste gasification, which heats many types of waste to high temperatures that reduce them to their molecular compounds. Those molecules then bind with hydrogen, and SGH2 claims it can make green hydrogen more cheaply than using electrolysis.

California officials see green hydrogen as an alternative to fossil fuels for diesel vehicles.

California officials also see green hydrogen as an alternative to fossil fuels for diesel vehicles. The state passed a Low Carbon Fuel Standard in 2009 to promote electric vehicles and hydrogen vehicles. Last month, a group of heavy-duty vehicle and energy industry officials formed the Western States Hydrogen Alliance to press for rapid deployment of hydrogen fuel cell technology and infrastructure to replace diesel trucks, buses, locomotives, and aircraft.

“Hydrogen fuel cells will power the future of zero-emission mobility in these heavy-duty, hard-to-electrify sectors,” said Roxana Bekemohammadi, executive director of the Western States Hydrogen Alliance. “That fact is indisputable. This new alliance exists to ensure government and industry can work efficiently together to accelerate the coming of this revolution.”

Earlier this year, the U.S. Department of Energy announced a $100 million investment to help develop large, affordable electrolyzers and to create new fuel cell technologies for long-haul trucks.

In Australia, the University of New South Wales, in partnership with a global engineering firm, GHD, has created a home-based system called LAVO that uses solar energy to generate and store green hydrogen in home systems. The hydrogen is converted back into electricity as needed.

All these developments, says Blank of the Rocky Mountain Instiute, are “really good news. Green hydrogen has high potential to address many of the things that keep people awake at night because the climate change problem seems unsolvable.”

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Article Contents

Introduction, 1 overview of green hydrogen production, 2 energy transition with green hydrogen, 3 the perspective of green hydrogen energy, 4 conclusions, acknowledgements, conflict of interest statement, data availability, green hydrogen energy production: current status and potential.

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Ali O M Maka, Mubbashar Mehmood, Green hydrogen energy production: current status and potential, Clean Energy , Volume 8, Issue 2, April 2024, Pages 1–7, https://doi.org/10.1093/ce/zkae012

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The technique of producing hydrogen by utilizing green and renewable energy sources is called green hydrogen production. Therefore, by implementing this technique, hydrogen will become a sustainable and clean energy source by lowering greenhouse gas emissions and reducing our reliance on fossil fuels. The key benefit of producing green hydrogen by utilizing green energy is that no harmful pollutants or greenhouse gases are directly released throughout the process. Hence, to guarantee all of the environmental advantages, it is crucial to consider the entire hydrogen supply chain, involving storage, transportation and end users. Hydrogen is a promising clean energy source and targets plan pathways towards decarbonization and net-zero emissions by 2050. This paper has highlighted the techniques for generating green hydrogen that are needed for a clean environment and sustainable energy solutions. Moreover, it summarizes an overview, outlook and energy transient of green hydrogen production. Consequently, its perspective provides new insights and research directions in order to accelerate the development and identify the potential of green hydrogen production.

Nowadays, the technology of renewable-energy-powered green hydrogen production is one method that is increasingly being regarded as an approach to lower emissions of greenhouse gases (GHGs) and environmental pollution in the transition towards worldwide decarbonization [ 1 , 2 ]. However, there is a societal realization that fossil fuels are not zero-carbon, which leads to significant thinking about alternative solutions.

The global energy system ought to drastically change from one mostly reliant on fossil fuels to one that is effective and sustainable with low carbon emissions to meet the goals of the Paris Agreement. Accordingly, >90% is the required global CO 2 emission decrease and the projected direct contribution of renewable energy to the necessary emission decrease is 41% [ 3 , 4 ]. Hydrogen (H 2 ) is a cost-effective, environmentally friendly alternative for energy consumption/storage [ 5 , 6 ]. In addition, it can contribute to making a low-carbon society a reality and largely boost the share of hydrogen [ 7 ].

Hydrogen technologies have been considered an approach to strengthening various economic sectors since the COVID-19 pandemic. The potential of hydrogen is currently the subject of an important consensus, partly due to an increased ambitious climate policy [ 8 , 9 ]. In addition, hydrogen can be used in fuel cell technology in the power generation sector and many other sectors, such as industry, transport and residential applications, which reflects its potential for decarbonization [ 10–12 ].

Several initiatives and projects worldwide are rapidly rising, reflecting the outstanding political and commercial momentum that the development of hydrogen as a zero-carbon fuel is undergoing. The growing boost is caused by the decreasing cost of hydrogen produced by renewable energy sources, or ‘green hydrogen’, and the urgent need to reduce GHG emissions [ 3 , 13 ]. However, green hydrogen is expected to increase in prominence over the next few decades and attain high commercial viability [ 13 , 14 ]. Producing hydrogen can be done using coal, methane, bioenergy and even solar energy; however, green hydrogen production is one of the pathways [ 15 , 16 ].

Numerous countries consider hydrogen the next-generation energy management response, and they increasingly support adopting hydrogen technology intended to create a decarbonized economy. Therefore, many strategies and plans for developing and implementing hydrogen have been made [ 17 ].

By 2050, according to Anouti et al. [ 18 ], there could be 530 million tonnes (Mt) of demand globally for green hydrogen, or hydrogen produced with fewer carbon dioxide emissions. Consequently, it would displace ~10.4 billion barrels of oil, which is equivalent to ~37% of the pre-pandemic world oil production [ 18 , 19 ]. Based on its forecast, the worldwide market for green hydrogen exports may be worth $300 billion annually by 2050, creating ~400 000 jobs in the hydrogen and renewable-energy industries [ 18 ].

Based on the technique used to produce hydrogen, the energy source used and its effects on the environment, hydrogen is categorized into various colour shades, including blue, grey, brown, black and green [ 20 ]. Using the steam-reforming/auto-thermal reforming method, grey hydrogen is extracted from natural gas but CO 2 is emitted into the atmosphere as a by-product. When the steam-reforming method converts natural gas into hydrogen and the CO 2 emissions from the process are captured, this is known as blue hydrogen. The most prevalent type of hydrogen used today is brown hydrogen, mainly produced via the gasification of hydrocarbon-rich fuel, in which CO 2 is released into the atmosphere as a by-product. However, green hydrogen is produced by water electrolysis, which is powered by renewable energy resources [ 18 , 21 , 22 ].

Green hydrogen is already competitive in regions with all the appropriate conditions [ 15 ] and will play a significant role in achieving sustainable development goals (SDGs) for the UN 2030, based on the agenda for sustainable development adopted wholly by UN Member States. The specified section of SDG 7 depends on ‘Affordable and Clean Energy’ [ 23 , 24 ]. For this reason, many efforts have been made to attain this goal globally in recent years.

Therefore, continuing on from those issues mentioned above in the introduction, in this paper, we analyse green hydrogen production technologies and investigate several aspects of the significance of the growth of the green hydrogen economy (GEE). The key objective of this study is to highlight the potential and progress of green hydrogen production and its significance in meeting energy needs. The paper is organized as follows. Section 1 summarizes the introduction, Section 2 presents an analysis of the energy transition with green hydrogen, Section 3 details a general overview of green hydrogen production, Section 4 specifics the perspective of green hydrogen energy production and Section 5 summarizes the conclusions and recommendations for future work.

There are several uses for hydrogen, including energy storage, power generation, industrial production and fuel for fuel cell vehicles. Hence, hydrogen production from green energy sources is essential to meet sustainable energy targets (SETs) as the globe attempts to move to a low-carbon economy.

Green hydrogen production requires large amounts of renewable energy and water resources. Thus, areas with an abundance of renewable energy resources, as well as accessibility to water sources, have been determined to be optimal for producing huge amounts of green hydrogen. However, to allow green hydrogen to be more economically viable than fossil fuels, advances in technology and cost reductions must be made.

In order to achieve the target for the expansion of green hydrogen production and utilization, details ought to be established at the level of the authorities. They can facilitate adoption, on the one hand, by increasing manufacturing capacity and guaranteeing an ongoing renewable energy source and, on the other, by increasing the need for green hydrogen alongside its derivatives and developing a system for storing and transporting hydrogen [ 25 ].

This paper performed a literature review to screen >100 papers related to Google Scholar/Web of Science to consider precisely green energy production by filtering the information in a large number of literature papers in science databases. Figs 1 and 2 illustrate the visualized literature network diagrams; hence, searching for keywords in science databases maps the intensity of relations/strengths among items. The analysis, which determined the research relationships of networks for visualization and exploration, utilized the VOSviewer. The categorical evaluation relies on the occurrence and frequency of keywords in related publications. The red cluster (lower left) represents initial development words trend links, the blue cluster (upper center) represents the second stage of development and the green cluster (lower right) links the green hydrogen words. Fig. 1 displays and signifies the mapping of the intensity of relations among words. In recent years, more research has focused on developing green hydrogen production from 2016 to 2023. Fig. 2 elucidates the keywords of scientific mapping and field trends. The blue cluster (lower left) represents the trend of research development from 2016 to 2019 and the bright maroon cluster (upper right) represents the trend of research development from 2020 to 2023.

Characterizes scientific mapping and relations between words

Characterizes keywords of scientific mapping and developing field trends from 2016 to 2023

The technology of green hydrogen can play a vital role in energy storage. Electrolysis can be utilized for producing hydrogen by using a surplus of renewable energy produced when demand is low. Whenever required, hydrogen can be used directly in various applications or stored and subsequently turned back into power using fuel cells. Hydrogen can be stored in different ways, either in the form of liquid, gaseous fuel or solid state; thus, the storage method is determined based on the consumption approach or export. In addition to resources such as solar and wind, this makes it possible to integrate renewable energy into the grid. This may lower the overall cost of the hydrogen yield.

Long-haul transportation, chemicals, and iron and steel are only a few industries that can benefit from the decarbonization of clean hydrogen produced using renewables, fossil fuels, nuclear energy or carbon capture. These industries have had difficulty in reducing their emissions. Vehicles fuelled by hydrogen would enhance the security of energy and the quality of air. Although it is one of the few alternative energy sources that can store energy for days, weeks or months, hydrogen can facilitate the incorporation of various renewable energies into the electrical grid.

Hydrogen storage technology, either underground or surface storage, gives more effectiveness and is more reliable to utilize; also, storage on a large scale has advantages in terms of energy demand and flexibility of the energy system [ 26 ]. The important consideration of storing hydrogen efficiently and safely is vital for many applications, such as industrial processes and transportation.

The transition towards green hydrogen will create new job opportunities in several sectors, including manufacturing, fuel cells, infrastructure, and operation and maintenance of electrolysers. Moreover, the development of the green hydrogen sector has the potential to promote economic growth, produce income through exports, bring in investments and drive scientific breakthroughs in the field.

Green hydrogen technological progress is the focus of ongoing studies and developments. Hence, this encompasses enhancing the effectiveness of electrolysis procedures, making affordable fuel cells, investigating cutting-edge materials for hydrogen storage and raising the overall efficacy of hydrogen systems. The range of applications for green hydrogen will grow due to technological improvements that will lower costs, boost effectiveness and expand their usage. State-of-the-art electrolyser devices and their development are based on decreasing the cost of manufacturing, enhancing efficiency and increasing the role played by electrolysis in the global hydrogen economy.

However, before worldwide commerce in hydrogen becomes a feasible, affordable option on a large scale, numerous milestones must be accomplished. The key is a techno–economic analysis used to investigate the circumstances required for such a trade to be profitable. The scenarios are for predicting the hydrogen trade outlook towards 2050 in which hydrogen production and costs of transportation are accessible. The trade of hydrogen is expected to develop in local markets to a great extent.

Based on a global plan through a ‘pathway toward decarbonization and net-zero emissions via 2050’ in the 1.5°C scenario, ~55% of the hydrogen traded globally by 2050 will be transported through a pipeline. The vast majority of the hydrogen network would rely on already-built natural gas pipelines that can be converted to transport pure hydrogen, greatly lowering the cost of transportation [ 27 , 28 ]. Hence, if we examine the economic and technological production capability of green hydrogen globally over various scenarios, we can evaluate the prognosis for the global hydrogen trade in 2030 and 2050 [ 27 ].

Progress and optimization of the hydrogen supply chain are important for comprehending the potential of hydrogen as a sustainable and clean energy carrier. Moreover, socio-economic aspects through providing a labour market can extend to the supply chain by deploying/installing renewable-energy devices. Thus, as technology and infrastructure continue to develop, the hydrogen supply chain is anticipated to play a substantial role in the shift to a low-carbon energy system.

Further outlook of green hydrogen to extend knowledge to include outreach approaches incorporating hydrogen-related topics into the curriculum might include online sources, community workshops and collaborations with educational institutions.

Accordingly, many factors have led numerous countries to endorse adopting green hydrogen technology projects. These aim to create a decarbonized economy and reduce GHG emissions, considering hydrogen as an alternative for sustainable energy management. Table 1 summarizes the breakdown of recently announced ongoing investment projects in green hydrogen production.

List of large green hydrogen planned/ongoing projects

Achieving the 1.5°C scenario includes a commercially viable form of large-scale production of hydrogen and commerce. The electricity needed for the production of hydrogen should be adequate and not take away from the electricity needed for other vital and more productive purposes. Thus, this leads to increased scale and acceleration of renewable-energy development at the core of the transition to green hydrogen.

Green hydrogen has the potential to play a crucial role in the development of a cleaner and more sustainable energy future as costs decrease, technology improves and supportive policies are put in place [ 34 ]. Fig. 3 depicts a potential pathway for producing hydrogen from green energy resources. An environmentally friendly renewable-energy supply, so-called biogas, is produced whenever organic matter, including food scraps and animal waste, breaks down. The biomass gasification of organic materials or agricultural waste can be gasified in a controlled environment to harvest a mixture of hydrogen. The biogas produced may be used to generate energy, heat houses and fuel motor vehicles.

Potential pathway for producing hydrogen from green energy

Electrolysis is a procedure that uses electrolysers to separate water into hydrogen and oxygen, utilizing electricity produced by renewable sources such as solar technology, including photovoltaic (PV) and concentrating solar power (CSP), wind or hydropower. The hydrogen produced can then be used for numerous purposes, such as fuel cells or industrial processes, or it can be stored. The basic production of hydrogen via electrolysis using electricity to split molecules in water into hydrogen and oxygen is given by:

It is important to mention that another method—the so-called photoelectrochemical (PEC) hydrogen production technique—depends on the use of solar radiation to drive the water-splitting process directly; PEC cells transform solar energy into hydrogen [ 35 , 36 ]. Although this technology is still in its infancy, it indicates promise for producing hydrogen sustainably and effectively [ 35 ].

Owing to their capability for photosynthetic oxygen production, algae have been recommended as a potential resource for the production of green hydrogen. Some types of algae can also produce ‘hydrogen gas as a by-product of their metabolism’ under certain conditions. Green hydrogen production from algae is based on the biohydrogen production technique, which is a subject of interest and ongoing study [ 37 , 38 ]; however, it is not commonly used in industrial practice yet [ 39–41 ].

Electrolysers ought to function at a higher usage rate to reduce the expenses of producing hydrogen, although this is incompatible with the curtailed supply of restricted energy [ 42 ]. Several research publications suggested the idea of using direct seawater electrolysis to produce hydrogen and oxygen [ 43–45 ].

The shift towards clean energy using green hydrogen necessitates collaboration among industries, governments, communities and research institutions. It offers a chance to increase sustainable growth, diversify sources of energy and decrease emissions of GHGs [ 14 ]. Table 2 details the world’s green hydrogen production capacity (in EJ) and potential by region distributed on continents. The top high potential was in sub-Saharan Africa, at ~28.6%, followed by the Middle East and North Africa, at ~21.3%. Then, the following other regions across the continent are listed.

Breakdown of the potential of global green hydrogen production by region [ 46 ]

Green hydrogen, from an economic perspective, represents a large economic opportunity. It includes the potential to promote the growth of new industries, the creation of employment opportunities and economic expansion. Thus, countries with abundant renewable energy resources can use green hydrogen generation to export energy, diversify their economy and lower their dependency on fossil fuels.

The production of hydrogen can assist in reducing curtailed systems that use a significant amount of variable energy from renewable sources [ 42 ]. Herein, green hydrogen is considered a technological development catalyst from a technical development perspective. Technology advances in the field are anticipated to result from research and development initiatives to increase electrolysis efficiency, lower costs and create improved materials and methods. This perspective highlights the innovative potential and development of green hydrogen technology.

Moreover, green hydrogen is considered an essential catalyst of the energy shift from the perspective of that transition. Subsequently, clean energy sources such as wind and solar power provide a method of integrating and balancing energy from renewable sources. Green hydrogen may increase the shares of clean energy sources in the energy system by offering grid flexibility and long-term energy storage.

It is clear that the movement towards the global transition is accelerating based on the energy transition policies and carbon-neutrality targets of different nations [ 47 ]. The investments in green hydrogen projects are progressing and taking place globally, including the USA, Germany, Austria, Saudi Arabia and China, to name a few. These countries have taken a step forward towards implementing large-scale projects of green hydrogen [ 15 , 42 ].

Energy from hydrogen can be utilized in numerous fields encompassing industry, electricity, construction, transportation, etc. [ 47 ]. Fig. 4 elucidates the schematic flow of perspectives on green hydrogen production. The demand for green hydrogen has recently evolved since more recent sources have become the latest insights on its current status and projections. The need for green hydrogen is anticipated to increase over the coming years as green technologies develop and the urgency to battle climate change grows. The demand is also needed for environmental aspects of climate change mitigation, decarbonization, technological developments and policy support.

Green hydrogen production perspectives

A study reported that hydrogen has a significant potential role in supporting the globe in meeting decarbonization goals/net-zero emissions by 2050 and limiting the global warming phenomenon to 1.5°C because it can reduce ~80 GT (gigatonnes) of CO 2 emissions by 2050 [ 48 ].

The potential of green hydrogen relies on geographic location and abundant natural resources. Hence, water, solar energy, wind and hydro-energy and organic materials are available. The development in infrastructure enables the widespread implementation of green hydrogen and important infrastructure progress is required. It comprises establishing hydrogen refuelling and building electrolysis plants, storage systems, etc.

Furthermore, investment projects would be viable in desert areas, where large projects might be constructed using solar PV and CSP to generate electricity. Subsequently, electricity can be used to produce enough hydrogen for the local market and export the surplus. Hence, these will help economic development in countries with great potential for solar radiation intensity over the years.

The economies of scale enabled via a developing global market for clean energy sources and green hydrogen will continue to drive down overall expenses [ 29 ]. However, the most economical way to use green financing will be to focus on helping the initial phases of the expansion of green hydrogen generation during a period when the investment takes place [ 49 ]. The investment cost is the main aspect to be considered while designing a hydrogen plant. Therefore, a core desired feature is low-levelized energy costs from renewable energy resources and electrolysers. These will make the project more feasible, efficient and cheap for the production of green hydrogen. The environmental impact of green hydrogen production is a key tool for attaining global climate goals—the potential to guarantee a more sustainable and environmentally friendly future for our planet.

This paper summarizes the outline of green hydrogen, its contribution and its potential towards net-zero emissions. Hence, its viewpoint provides new insights to accelerate the expansion of green hydrogen production projects. In order to accelerate the implementation of green hydrogen, scholars, industries and governments worldwide will contribute to the research and development of the technology. It is considered a feasible option for lowering emissions of GHGs, encouraging energy independence and helping in shifting to a low-carbon, environmentally friendly energy system.

There has been development of hydrogen technology that has significantly progressed to meet energy needs. Therefore, green hydrogen yield, which depends on renewable energy resources, has recently become a more attractive option due to decreased expenditure. Thus, it has the potential to mitigate environmental issues, promote economic expansion and contribute to the transition of the entire world to sustainable and clean energy systems. To adequately realize the potential of green hydrogen, challenges, including lower expenses, development of infrastructure and industrial scale, remain important factors.

A worldwide market for green hydrogen could emerge, enabling assignees with abundant renewable resources to export surplus electricity in the form of hydrogen. Therefore, this could assist countries in switching to a more sustainable energy mix and decrease their dependence on fossil fuel imports. Future work includes developing/deep analysis of a cost-effective, high-efficiency electrolyser device that will decrease the overall cost of green hydrogen yield.

Many grateful thanks go to the Libyan Authority for Research Science and Technology, and many thanks go to the staff in the Libyan Centre for Research and Development of Saharian Communities. Also, thanks to the anonymous reviewers for their constructive comments in improving this paper.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data sharing does not apply to this perspective paper, as no new data sets were created during this research.

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Green Hydrogen: An Introduction

• First Online: 21 May 2024

Cite this chapter

• M. R. Nouni 6 &
• Joydev Manna 7  

Part of the book series: Energy, Environment, and Sustainability ((ENENSU))

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In the present energy scenario with growing environmental and climate change concerns and increasing focus on energy security, global interest in low carbon hydrogen is increasing. In an energy system focussing on accelerated deployment of renewable energy systems, the role of hydrogen for balancing it is being increasingly recognised. Hydrogen for industrial use is traditionally produced from fossil fuels such as natural gas and coal, but cleaner hydrogen can be produced from renewable energy sources. Hydrogen is a colourless gas, but many colours have been associated with it depending on the energy sources used for its production and CO 2 emissions associated with it. The definition of green hydrogen is evolving, but hydrogen produced using renewable energy sources is generally considered as green. Presently, most of the hydrogen produced globally is grey as it is derived from fossil fuels without carbon capture. Hydrogen as a versatile energy vector finds several applications in industry, buildings, power, and transport sectors. Moreover, it can also be transformed into derivatives like ammonia, methanol etc. which are used as feedstocks for producing several industrial products and can also be used as green fuels, if produced from green hydrogen. Besides, substituting grey hydrogen used by the industry, green hydrogen can decarbonise many hard to abate industrial processes. However, there are several challenges associated with economically producing green hydrogen and its large-scale utilisation. This chapter discusses the above aspects of hydrogen energy in general and green hydrogen in particular in detail.

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Nouni, M.R., Manna, J. (2024). Green Hydrogen: An Introduction. In: Singh, P., Agarwal, A.K., Thakur, A., Sinha, R.K. (eds) Challenges and Opportunities in Green Hydrogen Production. Energy, Environment, and Sustainability. Springer, Singapore. https://doi.org/10.1007/978-981-97-1339-4_2

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Integration of renewable-energy-based green hydrogen into the energy future.

1. Introduction

• Electricity Generation: Green hydrogen can be used as a clean fuel source in power plants, where it is converted into electricity through fuel cells.
• Transportation: Green hydrogen is suitable as a fuel for vehicles, including automobiles, buses, trains, and trucks. It can be stored in fuel tanks and converted into electricity within the vehicle using fuel cells.
• Industrial Applications: Industries that require hydrogen as a fuel or raw material, such as fertilizer, chemical, and glass manufacturing, can benefit from the use of green hydrogen.
• Aviation: Green hydrogen shows promise as a fuel for aircraft, particularly in hybrid aircraft that utilize a combination of batteries and fuel cells to convert it into electricity.
• Cost: The production of green hydrogen using renewable electricity is currently more expensive compared to other hydrogen production methods. This is primarily due to the costs associated with water analysis, hydrogen storage, and the establishment of renewable energy infrastructure networks.
• Infrastructure: The widespread adoption of green hydrogen requires the development of a new infrastructure for its storage, distribution, and utilization across various applications. Building this infrastructure entails significant investment.
• Efficiency: Fuel cells used for converting hydrogen into electricity are less efficient compared to alternative energy conversion mechanisms. As a result, larger amounts of hydrogen consumption are necessary to generate the same quantity of electricity.
• Safety: The utilization of green hydrogen demands stringent safety measures for storage, transportation, and usage. Specialized techniques are necessary to prevent hydrogen leakage and ensure careful handling.
• Water Analysis Techniques: New technologies with improved efficiency and lower costs are being developed for water analysis, making green hydrogen production more cost competitive.
• Hydrogen Storage Techniques: Advances are being made in the development of storage technologies that offer high efficiency and low costs, such as hydrogen storage through hydride salts.
• Fuel Cells: Ongoing advancements in fuel cell technology aim to enhance efficiency and reduce costs, making the use of green hydrogen more effective for electricity generation and vehicle operation.
• Infrastructure: Investments are being made to establish a new infrastructure for the distribution and utilization of green hydrogen, including renewable energy networks and integration with existing natural gas networks.
• Safety Control: Innovative technologies are being developed to enhance safety measures in the storage, transportation, and utilization of green hydrogen, thereby improving the overall user experience.
• Hydrothermal Gasification: Clean coal technology utilizing hydrothermal gasification to convert coal into hydrogen gas. This hydrogen can then be used as a clean fuel, powering fuel cells to generate electricity.
• High-Temperature Fuel Cells: High-temperature fuel cells making use of the heat generated from used hydrogen fuel to produce electricity, thereby improving fuel efficiency and reducing emissions.
• Energy Storage Systems: Energy storage systems involving the use of batteries to store energy derived from the conversion of hydrogen to electricity. This stored energy can be utilized later to generate electricity as needed.
• Solid Film Fuel Cells: Ultra-clean fuel cells employing solid film technology to efficiently convert hydrogen into electricity while maintaining low emissions.
• Waste-to-Hydrogen Technologies: Waste treatment technologies can be utilized to produce green hydrogen. Organic waste can be converted into hydrogen gas through processes such as biodegradation or pyrolysis.
• Environmental Benefits: Green hydrogen is a clean fuel that does not produce harmful emissions, contributing to environmental health and improved air quality.
• Renewable and Sustainable: Green hydrogen can be produced using renewable energy sources like solar and wind energy, making it a sustainable option for meeting various energy needs.
• High Energy Conversion Efficiency: Green hydrogen is highly efficient at energy conversion. It can be used in fuel cells to generate electricity more efficiently compared to traditional fuels.
• Easy Storage and Transportation: Green hydrogen can be easily stored and transported through existing natural gas networks, making it suitable for use in industries and vehicles.
• High Production Costs: The production of green hydrogen entails high costs, including the expense of producing solar or wind energy and analyzing water to obtain hydrogen.
• Infrastructure Requirements: The use of green hydrogen necessitates the development of infrastructure for storage and transportation. This requires significant investments and ongoing development efforts.
• Safety Concerns: Green hydrogen can be dangerous if mishandled or if there is a leakage. Proper handling and adherence to safety procedures are essential.
• Technological Development: The utilization of green hydrogen relies on advanced technologies for storage, transportation, and usage. Developing these technologies and making them commercially viable requires time and effort.
• Highlighting the Importance of Green Hydrogen: The manuscript aims to emphasize the significance of green hydrogen as a key solution in achieving a sustainable energy future. It will shed light on its unique characteristics, including its ability to be produced through renewable energy sources and its potential to decarbonize various sectors.
• Examining the Integration of Renewable Energy Sources: The manuscript will delve into the integration of renewable energy sources, such as solar and wind power, in the production of green hydrogen. It will explore the technological advancements, challenges, and opportunities associated with this integration process.
• Assessing the Environmental and Economic Benefits: The manuscript will evaluate the environmental benefits of green hydrogen, including its contribution to reducing greenhouse gas emissions and mitigating climate change. Furthermore, it will analyze the economic opportunities and market potential associated with the widespread adoption of green hydrogen technologies.
• Exploring Applications and Sectoral Integration: The manuscript will explore the diverse range of applications for green hydrogen across various sectors, such as transportation, industry, and power generation. It will examine how green hydrogen can be effectively integrated into existing energy systems, fostering a sustainable and resilient energy future.
• Identifying Policy, Regulatory, and Technological Implications: The manuscript will discuss the policy frameworks, regulatory mechanisms, and technological advancements required to facilitate the widespread adoption of green hydrogen. It will address the challenges and opportunities associated with scaling up production, storage, and distribution infrastructure.

2. Green Hydrogen Energy Policy Review Methodology

2.1. methodology, 2.2. methods of hydrogen production, 3. results of water electrolysis, 3.1. chemical equation, 3.2. electrolysis techniques.

• Alkaline Electrolysis: Alkaline electrolysis is a well-established and widely used method for producing hydrogen through water electrolysis. In this method, a solution of potassium or sodium hydroxide serves as the electrolyte, and the electrodes are typically made of nickel or nickel-plated materials. Alkaline electrolysis operates at relatively high temperatures (60–90 °C) and pressures (1–30 bar). It is commonly employed in large-scale industrial applications due to its relatively low cost and high efficiency. However, the corrosive nature of the electrolyte can lead to electrode degradation over time, limiting its use.
• Polymer Electrolyte Membrane (PEM) Electrolysis: PEM electrolysis is a more advanced method of hydrogen production through water electrolysis. It utilizes a solid polymer electrolyte membrane to separate the anode and cathode compartments, and platinum-based catalysts are employed on both sides of the membrane to facilitate the electrochemical reactions. PEM electrolysis operates at lower temperatures (30–80 °C) and pressures (1–10 bar) compared to alkaline electrolysis. It offers higher efficiency and faster response times. PEM electrolysis is particularly suitable for small-scale applications like fuel cell vehicles or portable power systems due to its compact size and low maintenance requirements.
• Solid Oxide Electrolysis: Solid oxide electrolysis is a relatively new and still-developing method for hydrogen production through water electrolysis. It employs a solid oxide electrolyte to separate the anode and cathode compartments, with a high-temperature ceramic material serving as the electrode. Solid oxide electrolysis operates at high temperatures (600–1000 °C), enabling higher efficiency and faster reaction rates. However, maintaining the high temperature requires significant energy input. Solid oxide electrolysis is still in the experimental stage, but holds potential for offering high efficiency and scalability for large-scale industrial applications.

3.3. Electrolysis Performance Calculation

• Electrolysis Efficiency Calculation: One crucial calculation is determining the efficiency of the electrolysis, which measures the ratio of the energy required to produce a specific quantity of hydrogen to the energy contained within that hydrogen. The efficiency of electrolysis can be computed using the following equation:

3.4. Green Hydrogen Optimization Techniques

• Techno-Economic Analysis (TEA): Techno-economic analysis (TEA) is a method used to evaluate the economic feasibility of a technology or process, taking into account both technical and economic factors. TEA can be used to optimize the design and operation of green hydrogen production systems, to minimize costs and maximize profitability. For example, TEA can be used to evaluate different electrolysis technologies, renewable energy sources, and hydrogen storage options, and to determine the optimal size and configuration of the production system [ 31 , 32 ].
• Life Cycle Assessment (LCA): Life cycle assessment (LCA) is a method used to evaluate the environmental impacts of a product or process throughout its entire life cycle, from raw material extraction to end-of-life disposal. LCA can be used to optimize the design and operation of green hydrogen production systems, to minimize environmental impacts and maximize sustainability. For example, LCA can be used to evaluate the greenhouse gas emissions, water use, and other environmental impacts of different electrolysis technologies, renewable energy sources, and hydrogen storage options [ 33 , 34 ].
• Supply chain optimization: Supply chain optimization is a method used to optimize the production and distribution of a product, taking into account factors such as cost, efficiency, and environmental impacts. Supply chain optimization can be used to optimize the design and operation of green hydrogen production systems, to minimize costs and minimize environmental impacts. For example, supply chain optimization can be used to determine the optimal location of the production facility, the optimal transportation routes and modes, and the optimal distribution network [ 35 , 36 ].
• Control system optimization: Control system optimization is a method used to optimize the control and operation of a process or system, taking into account factors such as efficiency, safety, and reliability. Control system optimization can be used to optimize the design and operation of green hydrogen production systems, to maximize efficiency and minimize costs. For example, control system optimization can be used to optimize the operation of the electrolysis and hydrogen storage system, to minimize energy consumption and maximize hydrogen production [ 37 ].

3.5. Green Hydrogen Production Estimation until 2050

• Europe: The European Union has set a target of producing 40 GW of green hydrogen by 2030, and 10 million tonnes of renewable hydrogen by 2030. According to a report by the Hydrogen Council, Europe could produce up to 800 TWh of hydrogen per year by 2050, with a potential market size of up to EUR 630 billion per year.
• China: China has set a target of producing 5 million tonnes of hydrogen per year by 2025, with a focus on green hydrogen produced from renewable energy sources. According to a report by the International Energy Agency (IEA), China could produce up to 60 million tonnes of hydrogen per year by 2050, with a potential market size of up to USD 150 billion per year.
• United States: The United States has set a target of producing 5 GW of hydrogen by 2030, with a focus on green hydrogen produced from renewable energy sources. According to a report by the Hydrogen Council, the United States could produce up to 25% of the world’s hydrogen demand by 2050, with a potential market size of up to USD 140 billion per year.
• Japan: Japan has set a target of producing 300,000 tonnes of hydrogen per year by 2030, with a focus on green hydrogen produced from renewable energy sources. According to a report by the Hydrogen Council, Japan could produce up to 20% of the world’s hydrogen demand by 2050, with a potential market size of up to USD 80 billion per year.
• Australia: Australia has set a target of producing hydrogen at a cost of less than AUD 2 per kilogram by 2030, with a focus on green hydrogen produced from renewable energy sources. According to a report by the Australian Renewable Energy Agency (ARENA), Australia could produce up to 10% of the world’s hydrogen demand by 2050, with a potential market size of up to AUD11 billion per year.

4. Leading Countries in This Field

4.1. summary of the current production and utilization of green hydrogen, 4.1.1. countries.

• Germany: Germany aims to become a global leader in hydrogen technologies. It has set a target of producing 5 gigawatts (GW) of electrolytic hydrogen by 2030 and 10 GW by 2040. The country is investing in research, infrastructure, and projects to support the production and utilization of green hydrogen across various sectors.
• Australia: Australia has significant potential for green hydrogen production due to its abundant renewable energy resources. The country aims to become a major exporter of green hydrogen and has several projects underway. The Australian government has set a target of producing hydrogen at less than AUD 2 per kilogram by 2030, making it cost-competitive with other energy sources.
• Japan: Japan is a major consumer of hydrogen and has ambitious goals for hydrogen utilization. The country aims to have 800,000 fuel cell vehicles and 5.3 million residential fuel cells in operation by 2030. Japan is also investing in hydrogen infrastructure, including hydrogen refueling stations and hydrogen-powered trains.
• Netherlands: The Netherlands has set a target to have 500 megawatts (MW) of electrolyze capacity by 2025 and 3–4 GW by 2030. The country is focusing on developing hydrogen clusters, integrating hydrogen into industrial processes, and establishing hydrogen infrastructure for transport and energy storage.
• United States: The United States is actively promoting the production and utilization of green hydrogen. The Department of Energy has launched the Hydrogen Shot initiative, aiming to reduce the cost of clean hydrogen by 80% to USD 1 per kilogram by 2030. The country has several projects and pilot plants for green hydrogen production, particularly in regions with abundant renewable energy resources like California and the Gulf Coast.
• Chile: Chile has vast renewable energy potential, particularly in solar and wind power. The country aims to become a leading exporter of green hydrogen. It plans to install 5 GW of electrolyze capacity by 2025, and aims to produce the cheapest green hydrogen in the world. Chile is also developing hydrogen-production facilities and exploring export opportunities to countries like Japan, South Korea, and Europe.
• Saudi Arabia: Saudi Arabia, known for its abundant solar resources, is investing in green hydrogen production. The country aims to become a major global player in the green hydrogen market and has plans to develop projects totaling over 4 GW of electrolyze capacity. Saudi Arabia intends to leverage its existing infrastructure and expertise in the energy sector to produce, store, and export green hydrogen.
• South Korea: South Korea has a strong focus on green hydrogen as part of its energy transition strategy. The country aims to produce 5.26 million tons of hydrogen per year by 2040, with a significant portion coming from renewable sources. South Korea is also promoting the use of hydrogen in transportation, industry, and power generation, and is investing in research and development to advance hydrogen technologies.
• India: - Green Hydrogen Production: India has been focusing on renewable energy deployment and has set a target of 450 GW of renewable energy capacity by 2030. This commitment to renewables provides a strong foundation for green hydrogen production. The government has launched the National Hydrogen Mission, aiming to scale up hydrogen production and promote its use in various sectors. - Transportation Sector: India is exploring the use of green hydrogen in transportation. The government has plans to develop hydrogen fueling infrastructure and promote the adoption of hydrogen-powered vehicles. Initiatives include the development of hydrogen-powered buses, cars, and two-wheelers, as well as the establishment of hydrogen refueling stations. - Industrial Applications: Industries in India, such as steel, cement, and chemicals, are exploring the utilization of green hydrogen to decarbonize their operations. Green hydrogen can be used as a reducing agent or heat source, replacing fossil fuels in industrial processes. This transition can significantly reduce greenhouse gas emissions in these sectors.
• Canada: - Abundant Renewable Resources: Canada possesses vast renewable energy resources, including hydro, wind, and solar power. These resources can be harnessed to produce green hydrogen through electrolysis. Several projects are underway to develop large-scale electrolysis facilities powered by renewable energy, enabling the production of green hydrogen. - Export Potential: Canada aims to leverage its green hydrogen production capacity for domestic use as well as for export. The country has the advantage of being well positioned to supply green hydrogen to international markets, including the United States and Europe. The export of green hydrogen can contribute to Canada’s economic growth and support global decarbonization efforts. - Industry Transition: The Canadian government is working with industries such as steel, mining, and oil sands to explore the integration of green hydrogen in their operations. This includes using green hydrogen as a reducing agent in steelmaking, replacing carbon-intensive processes. The adoption of green hydrogen in these industries can help reduce their carbon footprint and support the country’s climate goals.
• China: - Hydrogen Economy Plans: China has set ambitious targets to become a global leader in the hydrogen economy. The country aims to expand its hydrogen production capacity, with a focus on both blue and green hydrogen. China has plans to develop large-scale hydrogen production projects, including coal gasification with carbon capture and storage (CCS), as well as renewable-energy-powered electrolysis facilities. - Transportation and Mobility: China is exploring the use of hydrogen fuel cells and hydrogen combustion technologies in transportation. The country has been investing in the development of hydrogen-powered buses, trucks, and even trains. The goal is to reduce emissions in the transportation sector and promote the adoption of hydrogen-powered vehicles. - Industrial Applications: China is exploring the utilization of hydrogen in various industries, including steel, chemicals, and refining. Green hydrogen can be used as a reducing agent or feedstock in these sectors, replacing fossil fuels and reducing carbon emissions. China’s focus on hydrogen in industries aligns with its broader efforts to achieve carbon neutrality.
• Russian Federation: - Natural Gas Resources: The Russian Federation has abundant natural gas reserves, which can be used as a feedstock for hydrogen production. The country is exploring the production of blue hydrogen by reforming natural gas with carbon capture and storage (CCS) technologies. This approach can reduce the carbon footprint of hydrogen production in the country. - Industrial Applications: Russia is exploring the utilization of hydrogen in industries such as steel and chemicals. Hydrogen can be used as a reducing agent in steelmaking, replacing coal or coke. The use of hydrogen in these industries can help reduce greenhouse gas emissions and support Russia’s climate goals. - Research and Development: Russia is actively involved in the research and development of advanced electrolysis technologies for green hydrogen production. This includes exploring high-temperature electrolysis and solid oxide electrolysis cells (SOEC), which can enhance the efficiency and cost effectiveness of hydrogen production.
• South Africa: - Renewable Energy Potential: South Africa has significant renewable energy resources, including solar and wind power. The country is exploring the production of green hydrogen through electrolysis powered by renewable energy sources. This can enable the utilization of renewable energy surpluses and support the transition to a low-carbon economy. - Industrial Decarbonization: South Africa is exploring the use of green hydrogen in industries such as mining and steel. By replacing fossil fuels with green hydrogen, these industries can reduce their carbon emissions and contribute to sustainable development. The use of green hydrogen as a reducing agent in steelmaking, for example, can help decarbonize the steel industry. - Power Generation and Energy Storage: South Africa is investigating the use of green hydrogen for power generation and energy storage. Hydrogen can be used in fuel cells to generate electricity, providing clean and reliable power. Additionally, excess renewable energy can be used to produce hydrogen, which can then be stored and converted back to electricity when needed, supporting grid stability and energy storage.

4.1.2. Industries

• Transportation: The transportation sector is increasingly adopting green hydrogen as a zero-emission fuel. Fuel cell electric vehicles (FCEVs) powered by hydrogen are being developed and deployed by automakers such as Toyota, Hyundai, and BMW. There are also initiatives to use hydrogen for heavy-duty vehicles, buses, and trains.
• Power Generation: Green hydrogen can be used in power plants to generate electricity with zero carbon emissions. Hydrogen can be combusted directly in gas turbines or used in fuel cells to produce electricity. Several countries are exploring the use of hydrogen in their power generation mix to decarbonize the electricity sector.
• Industrial Applications: Industries such as steel, chemicals, and refineries are exploring the use of green hydrogen to decarbonize their processes. Hydrogen can be used as a feedstock, a reducing agent, or a source of heat in various industrial applications. Pilot projects and collaborations are underway to integrate hydrogen into industrial processes and reduce carbon emissions.
• Energy Storage: Green hydrogen can be stored and used as a form of energy storage, helping to balance intermittent renewable energy sources. Excess renewable energy can be used to produce hydrogen through electrolysis, which can then be stored and converted back to electricity or other forms of energy when needed.
• Refining and Petrochemicals: The refining and petrochemical industries are exploring the use of green hydrogen to reduce carbon emissions. Hydrogen can be used as a cleaner alternative to fossil fuels in various refining processes, such as desulfurization and hydrocracking. The transition to green hydrogen in these industries can help decarbonize their operations and reduce their environmental footprint.
• Aviation: The aviation industry is investigating the use of green hydrogen as a sustainable fuel for aircraft. Hydrogen-powered aircraft, either through combustion or fuel cells, have the potential to significantly reduce greenhouse gas emissions compared to traditional jet fuels. Several companies and research institutions are working on developing hydrogen-powered aircraft and infrastructure.
• Residential Heating: Green hydrogen can be used for residential heating applications, replacing natural gas or other carbon-intensive fuels. Hydrogen boilers and fuel cells can provide heat and hot water with zero carbon emissions. Pilot projects are underway in various countries to explore the feasibility and effectiveness of using hydrogen for residential heating.
• Energy Export: Countries with abundant renewable energy resources, such as Australia and Chile, are exploring the export of green hydrogen to international markets. Green hydrogen can be transported as a commodity in the form of compressed or liquefied hydrogen, enabling countries to share their renewable energy potential with regions that have limited renewable resources.
• Energy Storage and Grid Balancing: Green hydrogen can play a crucial role in energy storage and grid balancing. Excess renewable energy can be used to produce hydrogen through electrolysis during periods of low demand. The hydrogen can be stored and then converted back to electricity through fuel cells or combustion when demand exceeds supply, helping to stabilize the grid and ensure a reliable energy supply.

4.2. Green Hydrogen Production Using Renewable Energy

4.3. green hydrogen application in different industries, 4.4. key aspects of the benefits of green hydrogen production and utilization, 5. innovative methods of producing and using green hydrogen.

• Power-to-Gas (P2G): P2G technology allows for the conversion of excess renewable energy into hydrogen. When the supply of renewable energy exceeds the demand, the surplus electricity is used to power electrolyzes, which split water into hydrogen and oxygen. The produced hydrogen can be stored and used later when renewable energy generation is low or as a clean fuel for transportation, heating, or industrial processes.
• Biomass Conversion: Biomass can be converted into hydrogen through gasification or pyrolysis processes. Gasification involves heating biomass in a controlled environment to produce a synthesis gas (syngas) consisting of hydrogen, carbon monoxide, and other gases. The syngas can then be further processed to extract hydrogen. Pyrolysis, on the other hand, involves heating biomass in the absence of oxygen, which produces bio-oil, syngas, and char. Hydrogen can be extracted from the syngas component.
• Photo Electrochemical (PEC) Water Splitting: PEC water splitting utilizes specialized semiconductor materials to directly convert solar energy into hydrogen. These materials are capable of absorbing sunlight and initiating the water-splitting reaction within the cell, generating hydrogen and oxygen. PEC technology offers the potential for efficient and direct solar-driven hydrogen production, eliminating the need for external electricity sources.
• Hydrogen Fuel Cells: Hydrogen fuel cells are devices that generate electricity through an electrochemical reaction between hydrogen and oxygen. Hydrogen is supplied to the anode and oxygen (usually from the air) is supplied to the cathode of the fuel cell. The reaction produces electricity, heat, and water as byproducts. Fuel cells are a versatile technology that can be used in various applications, including transportation (e.g., fuel cell vehicles) and stationary power generation for buildings or remote off-grid locations.

6. Green Hydrogen Challenges, Recommendations, Expectations and Observations

6.1. challenges.

• Hydrogen Energy Loss: Implementation of green hydrogen is associated with a loss of about 30% of its energy content due to hydrogen liquefaction. This means that each unit of hydrogen produced equals only 70% of the available energy.
• Storage of Liquid Hydrogen (LH2): Storing liquid hydrogen is challenging due to the low storage temperature required (−253 °C under 1 bar) and the need for an effective isolation system.
• Hydrogen Safety: Because of hydrogen’s flammability and potential for dilution of oxygen, hydrogen can pose a threat to human safety.
• High energy density: Hydrogen has a wide combustible limit range, low boiling point, low temperature, rate, content and flash rate. In addition, the heating value of hydrogen (LHV) is as low as 120 MJ/kg, which is three times the heating value of heavy fuel oil. This high energy density must be handled carefully to avoid accidents.
• Technical Challenges: Green hydrogen technology faces technical difficulties associated with high temperature and high pressure, which makes its storage difficult.
• Cost: The cost of hydrogen gas must be reduced to be competitive. Achieving a cost of USD 2 per kilogram is a competitive goal.
• Electricity Demand: The production and application of green hydrogen requires a large amount of electricity. To support these applications, renewable energy production such as offshore wind and solar energy must be increased.
• Offshore Wind Capacity: support is needed for such an application. Therefore, in the next 30 years, and every year, offshore wind energy should be developed more than in the last 20 years.
• Infrastructure: The establishment of a comprehensive infrastructure for the production, storage, transportation, and distribution of green hydrogen is a significant challenge. It requires the development of hydrogen production facilities, hydrogen refueling stations, and pipelines or other means of transporting hydrogen to end-users.
• Scaling Up Production: Scaling up the production of green hydrogen to meet the demand for various sectors such as transportation, industry, and power generation poses a challenge. Currently, the production of green hydrogen is limited, and significant investments and advancements are required to increase production capacity.
• Electrolysis Technology: The primary method for producing green hydrogen is through electrolysis, which involves using electricity to split water molecules into hydrogen and oxygen. The efficiency and cost effectiveness of electrolysis technology need further improvements to make green hydrogen more commercially viable.
• Availability of Renewable Energy: The production of green hydrogen relies on a consistent and abundant supply of renewable energy sources such as wind and solar power. However, the intermittent nature of these energy sources poses challenges in ensuring a continuous and reliable supply of electricity for hydrogen production.
• International collaboration: The implementation of green hydrogen requires international collaboration and cooperation due to the global nature of the energy transition. Harmonizing standards, sharing best practices, and establishing cross-border infrastructure are essential for the widespread adoption of green hydrogen.
• Regulatory Rramework: Developing a supportive regulatory framework is crucial for the successful deployment of green hydrogen. This includes policies and incentives that promote investment in green hydrogen projects, facilitate research and development, and address safety and environmental concerns.
• Public awareness and acceptance: Promoting public awareness and acceptance of green hydrogen is vital. Educating the public about the benefits and potential of green hydrogen, addressing safety concerns, and fostering a positive perception of hydrogen as a clean energy source are important for its widespread adoption.

6.2. Recommendations

• Consider Hydrogen as Part of Energy Transition Efforts: It is true that green hydrogen can be a sustainable solution in the long run. There should be a focus by the government and the private sector on supporting the green hydrogen market and promoting its use in various sectors such as transportation, industry and energy.
• Focusing on Green Hydrogen as a Long-Term Supply Option: It is clear that producing green hydrogen based on renewable energy is a sustainable option in the long term. Governments and companies should focus on developing these technologies, enhancing their availability and reducing their production costs to make green hydrogen more competitive.
• Comprehensive integration: It is true that the various aspects of integration in the hydrogen value chain deserve special attention. From production to distribution, storage and use, the integration of all these processes must be enhanced to achieve maximum efficiency and environmental benefits.
• Ensure Efficient Supply and Use of Hydrogen: Appropriate technology and infrastructure must be developed to deal with storage and transportation losses and achieve the highest efficiency in hydrogen use. Advanced and innovative storage and transportation technology can contribute to this goal. Therefore, joint action between governments, companies and the international community must continue to promote the use of clean hydrogen and achieve a sustainable energy transition.
• Japan: Japan is considered one of the leading countries in the field of green hydrogen. Japan aims to achieve a hydrogen-based society by 2050, and is investing in developing the technology and infrastructure needed to produce and use green hydrogen.
• Germany: Germany is making ambitious plans to promote green hydrogen as part of its energy strategy. The German government is promoting the production and sustainable use of green hydrogen in sectors such as transport and industry.
• The Netherlands: The Netherlands seeks to become one of the leading countries in the production of green hydrogen. The Netherlands is investing in green hydrogen projects and working to provide the necessary infrastructure to promote the use of green hydrogen in transport and industry.
• South Korea: South Korea is one of the leading countries in the field of green hydrogen. South Korea is investing in developing technology related to green hydrogen and aims to increase its use in transportation and industry. These countries are making significant investments in developing technology and infrastructure related to green hydrogen, and are expected to continue to make significant progress in this field in the coming years.

6.3. Expectations

• Industries such as the iron and steel industry and the chemical industry can benefit from using clean hydrogen to decarbonize production processes and reduce emissions. Pure hydrogen can be used as a reducing agent in the steel industry, and it can also be used as an energy source in other high-temperature industrial applications.
• In the transportation sector, clean hydrogen can be used in fuel cells or internal combustion engines to power vehicles. Pure hydrogen is considered a supplement to electric vehicles in the field of long-distance charging.
• Hydrogen can play an important role in the energy system as energy storage and resilience services. Hydrogen can be produced from excess electricity generated from renewable sources, and stored for use in periods of excess demand [ 70 ].
• Hydrogen can also be injected into the existing natural gas transmission and distribution network as a potential alternative to reducing carbon emissions in building gas consumption [ 71 ]. However, it should be noted that these prospects and potential uses of clean hydrogen are dependent on technology development, availability of adequate infrastructure, and costs of production and use [ 72 ].

6.4. Observations

• Potential and Benefits: Green hydrogen has the potential to play a crucial role in integrating renewable energy sources into the energy future. It offers a versatile and carbon-neutral energy carrier that can be produced using renewable electricity. The integration of green hydrogen can help address the intermittency and storage challenges associated with renewables, thereby enabling a more reliable and resilient energy system.
• Environmental Impact: Green hydrogen production offers a sustainable alternative to conventional hydrogen production methods, which often rely on fossil fuels. By utilizing renewable energy sources, green hydrogen can significantly reduce greenhouse gas emissions, air pollution, and dependence on finite fossil fuel resources.
• Technological Advancements: Ongoing research and development efforts are focused on improving the efficiency and cost effectiveness of green hydrogen production, storage, and utilization technologies. Advancements in electrolysis technology, catalysts, and infrastructure development are key areas of progress that will further enhance the viability of green hydrogen as a mainstream energy solution.
• Infrastructure Requirements: The widespread adoption of green hydrogen would necessitate the development of a robust infrastructure, including hydrogen production facilities, storage systems, and distribution networks. Collaboration among governments, industries, and research institutions is essential to facilitate the necessary investments and infrastructure planning.
• Economic Viability: While the costs of green hydrogen production have been decreasing, further efforts are needed to make it economically competitive with conventional energy sources. Technological advancements, economies of scale, and supportive policies can contribute to reducing the costs and enhancing the economic feasibility of green hydrogen.
• Policy and Regulatory Support: Governments play a pivotal role in creating a favorable environment for the growth of green hydrogen. Supportive policies, such as financial incentives, research funding, and carbon pricing mechanisms, can accelerate the deployment of green hydrogen technologies and stimulate market demand.
• Collaboration and Knowledge Sharing: Collaboration among stakeholders, including researchers, policymakers, industries, and communities, is vital for the successful integration of green hydrogen into the energy future. Sharing knowledge, best practices, and lessons learned from pilot projects and real-world deployments can facilitate the widespread adoption of green hydrogen technologies.
• Scalability and Deployment: As green hydrogen technologies continue to develop, it is essential to assess their scalability and deployment potential. Scaling up production, storage, and distribution infrastructure to meet increasing demand will require careful planning and coordination among stakeholders. Identifying suitable locations for large-scale green hydrogen projects and optimizing supply chains will be critical for successful deployment.
• Energy Transition Synergies: Green hydrogen can contribute to the broader energy transition by integrating with other renewable energy technologies and systems. For example, coupling green hydrogen production with wind or solar farms can help balance electricity supply and demand, maximize renewable energy utilization, and provide additional revenue streams for renewable energy project developers.
• Technological Challenges: Despite advancements, there are still technological challenges that need to be addressed. For instance, improving the efficiency of electrolysis processes, reducing the cost of catalyst materials, and enhancing hydrogen storage methods are areas that require ongoing research and development efforts. Innovations in these areas can further enhance the viability and competitiveness of green hydrogen.
• International Collaboration: Given the global nature of climate change and energy transition, international collaboration is crucial. Sharing best practices, research findings, and collaborating on joint projects can accelerate the development and deployment of green hydrogen technologies. International agreements and partnerships can also facilitate cross-border trade and cooperation, driving the growth of a global green hydrogen market.
• Social and Economic Implications: The transition to a green hydrogen-based energy system will have social and economic implications. It has the potential to create new job opportunities, particularly in industries related to green hydrogen production, infrastructure development, and hydrogen-based applications. However, it is important to ensure a just transition, providing support for affected communities and workers in fossil fuel-dependent industries.
• Public Awareness and Acceptance: Public awareness and acceptance of green hydrogen will play a crucial role in its successful integration. Educating the public about the benefits, potential applications, and environmental impacts of green hydrogen can foster support and drive consumer demand. Transparent communication about safety measures and addressing any misconceptions can also instill confidence among stakeholders.
• Life Cycle Assessment: Conducting a comprehensive life cycle assessment of green hydrogen is essential to evaluate its overall environmental impact. This assessment should consider the entire life cycle, including the production, distribution, and utilization stages, to determine its carbon footprint and potential environmental benefits compared to conventional energy sources.
• Electrolysis with Renewable Energy Sources: One of the most economical methods of green hydrogen production is through electrolysis powered by renewable energy sources such as solar, wind, or hydroelectric power. By utilizing abundant and low-cost renewable energy, electrolysis can produce green hydrogen with minimal carbon emissions. This method can be properly utilized by strategically locating electrolysis facilities near renewable energy generation sites, optimizing the use of excess renewable energy during off-peak hours, and implementing grid-balancing strategies.
• Biomass Gasification: Biomass gasification is another cost-effective method for green hydrogen production. Biomass feedstocks, such as agricultural residues or dedicated energy crops, can be gasified to produce a syngas, which is then converted into hydrogen through various processes. This method offers the advantage of utilizing organic waste materials and providing an additional revenue stream for the agricultural sector. Proper utilization involves establishing biomass supply chains, optimizing gasification technologies, and ensuring sustainable sourcing practices.

7. Conclusions

Author contributions, data availability statement, conflicts of interest.

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Marouani, I.; Guesmi, T.; Alshammari, B.M.; Alqunun, K.; Alzamil, A.; Alturki, M.; Hadj Abdallah, H. Integration of Renewable-Energy-Based Green Hydrogen into the Energy Future. Processes 2023 , 11 , 2685. https://doi.org/10.3390/pr11092685

Marouani I, Guesmi T, Alshammari BM, Alqunun K, Alzamil A, Alturki M, Hadj Abdallah H. Integration of Renewable-Energy-Based Green Hydrogen into the Energy Future. Processes . 2023; 11(9):2685. https://doi.org/10.3390/pr11092685

Marouani, Ismail, Tawfik Guesmi, Badr M. Alshammari, Khalid Alqunun, Ahmed Alzamil, Mansoor Alturki, and Hsan Hadj Abdallah. 2023. "Integration of Renewable-Energy-Based Green Hydrogen into the Energy Future" Processes 11, no. 9: 2685. https://doi.org/10.3390/pr11092685

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• Published: 08 September 2022

Probabilistic feasibility space of scaling up green hydrogen supply

• Adrian Odenweller   ORCID: orcid.org/0000-0002-1123-8124 1 , 2 ,
• Falko Ueckerdt   ORCID: orcid.org/0000-0001-5585-030X 1 ,
• Gregory F. Nemet   ORCID: orcid.org/0000-0001-7859-4580 3 ,
• Miha Jensterle   ORCID: orcid.org/0000-0001-6701-9572 4 &
• Gunnar Luderer   ORCID: orcid.org/0000-0002-9057-6155 1 , 2  

Nature Energy volume  7 ,  pages 854–865 ( 2022 ) Cite this article

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• Energy modelling
• Energy supply and demand
• Hydrogen energy

Green hydrogen and derived electrofuels are attractive replacements for fossil fuels in applications where direct electrification is infeasible. While this makes them crucial for climate neutrality, rapidly scaling up supply is critical and challenging. Here we show that even if electrolysis capacity grows as fast as wind and solar power have done, green hydrogen supply will remain scarce in the short term and uncertain in the long term. Despite initial exponential growth, green hydrogen likely (≥75%) supplies <1% of final energy until 2030 in the European Union and 2035 globally. By 2040, a breakthrough to higher shares is more likely, but large uncertainties prevail with an interquartile range of 3.2–11.2% (EU) and 0.7–3.3% (globally). Both short-term scarcity and long-term uncertainty impede investment in hydrogen end uses and infrastructure, reducing green hydrogen’s potential and jeopardizing climate targets. However, historic analogues suggest that emergency-like policy measures could foster substantially higher growth rates, expediting the breakthrough and increasing the likelihood of future hydrogen availability.

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Green hydrogen, defined as hydrogen produced from renewable electricity via electrolysis, and derived e-fuels 1 are critical components of the energy transition 2 , enabling emissions reductions in sectors where direct electrification is infeasible 3 , 4 and avoiding sustainability concerns associated with biofuels 5 . These features, plus its versatility, have spurred a recent surge of enthusiasm 6 , policy targets 7 , 8 and investments 3 . Furthermore, in response to the current energy crisis, an accelerated market introduction of hydrogen is considered a key option to decrease Europe’s reliance on fossil fuel imports 8 . Hydrogen therefore plays a central role in facilitating many net zero emissions scenarios 9 , 10 and government plans 7 . Of all ways to produce hydrogen, green hydrogen offers the lowest life-cycle emissions 11 and likely lowest long-term mitigation costs 12 , making it most suitable for climate neutrality.

While much of the debate and research around hydrogen has revolved around demand-related questions of suitable applications, markets and sectors 1 , the question of supply availability is equally critical. Hydrogen is very valuable for achieving increasingly pressing and legally binding emissions reduction targets 13 , 14 as it can provide diverse energy services, ranging from energy storage and long-distance transportation to industry feedstocks 3 . Due to the substantial size of these hard-to-abate sectors and because virtually all hydrogen production today is fossil 3 , 4 , ramping up green hydrogen supply is urgent 15 . Growing awareness that scalability is a critical success factor for climate mitigation technologies has stimulated recent research to apply insights about the pattern 16 , 17 and pace 18 , 19 , 20 of energy technology diffusion to specific feasibility analyses 21 , 22 , 23 of ramping up renewable 24 , 25 , 26 , 27 , 28 , 29 and phasing-out fossil technologies 22 , 30 , 31 fast enough. However, so far no study has analysed possible expansion pathways of green hydrogen from electrolysis, a technology in its infancy that needs to experience rapid innovation and deployment to unleash its potential for climate change mitigation 15 .

Electrolysers are a centrepiece of future green hydrogen supply chains, and their deployment is thus an indicator of the systemic challenges of concurrently ramping up additional renewable energy capacity, transport infrastructure and hydrogen end-use applications. In addition, the ramp up of electrolysers is a key bottleneck in itself. Starting at an estimated 600 MW globally in 2021 (Fig. 1 ) (ref. 32 ) in mostly small and individually manufactured plants (<10 MW), global capacity needs to grow 6,000–8,000-fold from 2021 to 2050 to meet climate neutrality scenarios compatible with the Paris Agreement 9 , 10 . This dwarfs the simultaneously required tenfold increase of renewable power 9 , 10 , which is readily available and cost competitive 33 , 34 . While electrolysis project announcements indicate an exponential build-up of momentum in the upcoming years with triple-digit annual growth rates, 80% of additional capacity announced to come online by 2023 is not yet backed by a final investment decision (FID) (Fig. 1c,d ). It thus remains unclear how many electrolysis projects will materialize in the short term and whether overall capacity can expand fast enough to meet mid- to long-term hydrogen demands.

a , c , Projects in the European Union by country ( a ) and by project development status ( c ). b , d , Global projects by aggregated region ( b ) and project development status ( d ). Each panel is split into two parts, showing data from 2000–2023 in the main left-hand part and 2023–2030 in the smaller right-hand part with a separate axis. Projects without a specified starting date are omitted, which affects 21 GW in the European Union and 127 GW globally. In a and b , decommissioned projects have been subtracted. Data from ref. 32 .

Here we analyse the potential deployment of electrolysis capacity for green hydrogen production by combining an S-shaped logistic technology diffusion model 17 with a probabilistic parameterization based on data from established successful energy technologies: wind and solar power 35 , 36 , 37 . Despite such high growth rates, we find strong evidence of short-term scarcity and long-term uncertainty of green hydrogen supply. This bears a high risk of a substantial gap between likely supply and potential demand, threatening the outlook of green hydrogen for urgent climate change mitigation. In contrast, if electrolysis capacity were to grow at unconventional growth rates, which some non-energy technologies have experienced under special circumstances in the past, it could quickly overcome supply scarcity and secure future green hydrogen availability.

Three uncertain parameters that define the feasibility space

In a finite market, technology adoption starts exponentially but gradually flattens out to follow an S-shaped curve as it approaches saturation (Fig. 2 ). The theory behind this logistic functional form originates from Roger’s (1962) conception of technology adoption, initiating with a small group of early adopters comfortable with an unfamiliar technology and then proceeding with a much larger group of adopters with lower willingness to pay who wait for lower costs and reliable performance 17 . This notion has been developed by transition theory scholars, for whom the defining characteristic of early adopters is the role of niche markets where unproven technology finds initial markets 38 , 39 , 40 .

In order, these parameters are the initial capacity (1), the emergence growth rate (2) and the demand pull, for which we distinguish magnitude (3.1) and anticipation (3.2). The small filled black circles indicate historical electrolysis capacity (illustrated by the shaded area), while the large open black circles indicate electrolysis deployment targets, which are set by policy ambitions or project announcements and define the demand pull magnitude (Table 1 ). The demand pull is indicated by the grey dotted line and is defined as a piecewise linear function between the deployment targets. The vertical green arrows indicate the pulling effect of the demand pull on the example path. Anticipation brings the demand pull forward in time, indicated by the horizontal apricot-coloured arrows, which eventually increases the total demand pull as indicated by the vertical light green arrows. The inset shows a close-up view of the formative phase, where the error bars indicate the uncertainty of future operational electrolysis capacity. The error bars are a simplified illustration of the probabilistic definition of the ‘initial’ electrolysis capacity in Fig. 3a,b and show the full range of uncertainty. The minimum of the error bars is defined by the cumulative sum of projects that are already operational or under construction. The maximum of the error bars follows from the probabilistic definition and approximately matches the cumulative sum of all projects, including those that are uncertain due to their development status (Fig. 3a,b provides the parameterization and Methods provide the mathematical definition). The solid line indicates a single example path. The probabilistic feasibility space follows from the propagation of the uncertain parameters using a Monte Carlo simulation approach.

The resulting technology diffusion pathway follows three distinct phases. In the formative phase, policy-backed demonstration projects face technical uncertainty and high costs during the proverbial valley of death 41 , leading to slow and unsteady growth 42 . In the growth phase, increasing returns to scale 43 and cost-decreasing learning effects 44 accelerate market adoption. After reaching the maximum rate of expansion, growth starts to slow down as a result of technological, economic and social constraints 17 . This marks the beginning of the saturation phase when the final market level is approached. This trajectory characterizes all stages of the technology adoption process and is mathematically described by the three-parameter logistic function (Methods). Considering the electrolysis market ramp up, the three parameters—initial capacity (timing), emergence growth rate (steepness) and saturation (asymptote)—relating to these three stages are all uncertain and independent.

First, the initial capacity is an uncertain parameter as it depends on the possibly strong yet uncertain momentum in the upcoming years, which could propel electrolysis capacity from the formative phase to the beginning of the growth phase and therefore must be included in the analysis. Beyond the evidently speculative nature of projects pending an FID, there are further mutually opposing uncertainties. On the one hand, even projects that have secured an FID may fall behind schedule. On the other hand, data gaps due to additional future projects or missing projects might introduce downward biases. Striking a balance between including near-term momentum and excluding uncertain long-term announcements, we focus on the year 2023 as the ‘initial year’, as we do not expect any potential new projects to proceed from announcement to operation in less than two years. Figure 3a,b shows the probability distributions of the initial capacity in 2023, which spans the full range of project announcements, centred around an expected value of realizing 30% of projects in the feasibility study category 45 and assuming that all projects under construction are built in time (Methods).

a , b , Initial capacity distributions in the European Union ( a ) and globally ( b ). The horizontal bars correspond to the 2023 bar in Fig. 1c,d , where decommissioned projects have been subtracted from operational projects. c , d , Emergence growth rate distributions in the European Union ( c ) and globally ( d ) based on wind (blue dotted lines) and solar PV (orange dotted lines) in the interval 1995–2010 with fastest relative growth. The vertical dotted lines indicate the fitted exponential growth rates of each seven-year window within the interval 1995–2010 (Extended Data Fig. 1 ), for wind and solar PV capacity data in the European Union ( c ) and globally ( d ).

Second, the growth rate is an inherently uncertain function of policy support 46 , technological characteristics 47 and possible cost reductions 44 , of which the latter are notoriously difficult to predict 48 . As the annual growth rate gradually decreases due to market saturation, we parameterize the emergence growth rate 26 , which is the maximum annual growth rate that is realized after the formative phase, related to the steepness parameter in the logistic function (Methods). Unlike previous research, which constructed feasibility spaces by looking at historical precedents of the same technology in different regions 28 , 31 , we instead turn to historical precedents of different technologies in the same region. This comparison is necessary because, as long as green hydrogen is uncompetitive 44 , historical growth rates are primarily proxies of past policy support and not necessarily indicative of future potential. In this way, we also abstract from a more granular analysis of factors that influence the pace of technology diffusion to construct different scenarios. In the conventional growth scenario, we compare electrolysis with wind and solar power, the historically fastest-growing energy technologies, which now comprise nearly 10% of global electricity generation 49 , during their periods of fastest relative growth, 1995–2010 (Extended Data Fig. 1 ). Figure 3c,d shows the corresponding distributions, revealing that solar power grew faster than wind during all seven-year intervals, both in the European Union and globally. The distributions are robust to the interval length (Extended Data Fig. 2 ). Extended Data Table 1 compiles drivers and challenges for higher and for lower hydrogen growth rates compared with wind and solar power, such that we carefully conclude that wind and solar PV are a valid initial proxy to derive rough estimates of green hydrogen ramp up and availability. Later, in the unconventional growth scenario, we compare these growth rates to a broader set of predominantly non-energy technologies.

Third, the final market volume is uncertain as the outcome of the competition among different climate change mitigation technologies remains undecided in many end-use applications 50 . In these applications, hydrogen constitutes a new energy carrier, which implies that not just its supply, but also its demand and infrastructure have to be ramped up in parallel. In contrast, wind and solar power produced an economic good with existing demand and pre-installed infrastructure, namely electricity. We capture the just-emerging hydrogen market by a steadily increasing demand pull and distinguish between its magnitude and anticipation (Fig. 2 ). We opt for a simple piecewise linear demand pull function, parameterized on policy targets and announcements in the short- to mid-term and on demand from climate neutrality scenarios in the long term (Methods). The demand pull therefore comprises all factors that increase market opportunities through policies, regulation and improved competitiveness 51 , 52 .

The propagation of the uncertain initial capacity and emergence growth rate (Fig. 3 ) defines a probabilistic feasibility space under the condition of an increasing policy-backed demand pull that spurs investment and mitigates financial risks. Table 1 summarizes the key model parameters for the electrolysis market ramp up in the European Union and globally.

Reconciling different approaches to long-term projections

Our model steers a middle course between two approaches in the recent literature that have analysed growth trajectories of wind and solar power but arrived at different conclusions regarding their outlook. The first approach relies on fitting growth models with the asymptote as a free parameter that is estimated from historical data if possible 24 , 28 . Studies differ in their interpretation of the asymptote as the final market volume 24 or as a non-indicative parameter that may be surpassed again later in the diffusion 28 . While including the asymptote as a free parameter often yields a good fit to data, it comes at the expense of high sensitivity to random fluctuations in the last few data points 53 and to the type of growth model used 28 . A slowdown, which might in hindsight turn out to be just a temporary artefact, for example due to discontinuous policy 54 or economic crises 55 (for example, Extended Data Fig. 1a ), could be misinterpreted as terminal saturation if the asymptote is taken at face value. In that case, this approach risks constraining future conditions to policy-driven historical deployment, which can negatively bias the long-term outlook.

In contrast, the second approach in the literature applies an ex ante target towards which wind and solar power diffuse from their historical trajectory 26 , 27 . While this enables an inter-decadal feasibility analysis under the presupposition that a stated market volume will be attained, it implicitly assumes an existing market with sufficient demand that technologies can penetrate. This may not be the case for hydrogen because demand-side transformations and infrastructure requirements mean it cannot immediately tap into new markets that are just emerging. In our approach, these coordination challenges are summarized by the steadily increasing demand pull that contributes to reconciling the debate on long-term projections of energy technologies, especially for hydrogen, but potentially also for wind and solar power.

Modelling green hydrogen growth using a logistic model that is driven, but also constrained, by an increasing demand pull leads to an asymmetric S-shaped adoption curve, which approaches the asymptote more gradually than the standard symmetric logistic function. While a similar shape may also be described by the Gompertz model (used in ref. 28 ) as another special case of the generalized logistic function (comparison in Extended Data Fig. 3 and Methods), our model allows for a more precise control of the increasing market volumes, which can be informed by additional information about policy targets, improving cost competitiveness and scenario results.

Electrolysis capacity using growth rates from wind and solar

Figure 4 shows the probabilistic feasibility space of electrolysis capacity in the European Union and globally using a distribution of growth rates assembled from the historical growth of wind and solar power and applying demand pull anticipation of five years (sensitivity analysis in Extended Data Fig. 4 ). Three key insights emerge.

a , In the European Union. b , Globally. The colour shade indicates the yearly probability density that results from the uncertainty propagation of the initial capacity in 2023 and the emergence growth rate. Grey lines indicate random example pathways, illustrating the vast range of plausible outcomes under growth rates similar to wind and solar power. The vertical diagram on the right-hand side shows the probability density at the intersection year 2038 in the European Union ( a ) and 2045 globally ( b ). The results reveal short-term scarcity, with little electrolysis capacity until 2030 in the European Union and 2035 globally, and substantial long-term uncertainty, with a wide range of possible electrolysis capacity until 2050. The zoom panels show the probabilistic feasibility space until 2030, demonstrating that short-term deployment targets are out of reach under growth rates similar to wind and solar power.

First, in the upcoming one to two decades, in the first half of the growth phase, electrolysis capacity is likely to remain relatively small compared with both intermediate and final targets and to total energy demand. Green hydrogen will thus remain scarce, leading to a large gap between likely supply and potential demand. Another gap exists between likely supply and project announcements (Extended Data Fig. 5 ). In the European Union, neither the 2024 target of 6 GW nor the 2030 target of 100 GW are within reach under conventional growth rates as both fall outside the distribution. The global target of 254 GW by 2030, which ensues from ambitious project announcements 32 (Fig. 1d ) plus planned EU imports 8 , also lies far beyond the 95th percentile, illustrating the short-term challenges of ramping up green hydrogen production within the European Union and globally.

Second, a breakthrough to high capacities is possible, but both timing and magnitude are subject to large uncertainties. The results reveal a threshold above which the probability distribution flips towards larger values and then follows the linear demand pull with a few years of delay. For the European Union, this occurs around 2038 and globally around 2045, which approximately coincides with the years of largest annual electrolysis capacity additions in the midst of the growth phase. This tipping behaviour is a property of the probability space, which combines the information of the pathway ensemble and is thus more relevant to decisionmakers than individual pathways, which are more continuous and span a larger range. The interquartile range (IQR) of probabilistic electrolysis capacity in 2040 is 94–330 GW in the European Union (246–1121 GW globally) and 412–497 GW in the European Union (1,873–3,434 GW globally) in 2050, marking the saturation phase. Substantial uncertainty thus prevails for several decades, especially globally.

Third, the propagation of uncertainties not only leads to a tipping point but also to a pronounced bimodal distribution near the tipping point, which has adverse consequences for risk management. This pattern is a direct outcome of the superposition of many S-shaped diffusion curves and occurs despite input parameters that follow a well-defined normal distribution with a clear maximum (Fig. 3 ). This is because, for most of the period, the logistic curve produces low and later high capacities (small annual additions); because of high growth rates, the transition phase occurs quickly (large annual additions), and thus the probability of being at an intermediate capacity is low. Using the Gompertz model (Extended Data Fig. 3 ), the distribution does not turn visibly bimodal until 2050 but is instead very wide and flat, implying a similarly large risk of the supply–demand gap.

Both short-term scarcity and mid- to long-term uncertainty are robust to the type of growth model used and create challenges for policymakers, system planners, industry and consumers. Relying on the large-scale availability of green hydrogen could lead to expensive path dependencies or even fossil lock-ins 56 if supply expansion falls short of expectations. Accounting for these risks probably discourages investments in hydrogen supply, infrastructure and end-use technologies, thus exacerbating short-term scarcity and mid- to long-term uncertainty. In addition, scarce and uncertain supply complicates and delays required end-use transformation and infrastructure investments. As a consequence, green hydrogen could fail to realize its potential.

There are good arguments both in favour and against the hypothesis that electrolysis could grow even faster than wind and solar power did (Extended Data Table 1 ).

Emergency deployment with growth beyond wind and solar

To explore what might be possible with special dedication, coordination and funding, we now parameterize our electrolysis diffusion model with unconventionally high growth rates that have been achieved under specific circumstances in the past (Fig. 5 ). These include mostly non-energy products in situations of wartime mobilization (for example, US aircraft or liberty ships in World War II), of massive public investments and central coordination (for example, nuclear power in France or high-speed rail in China) or of market-driven deployment of highly modular information technology innovations with low coordination requirements (for example, internet hosts or smartphones).

a , Growth pathways of 11 exemplary technologies in different regions from 1938 until today, normalized to their respective maximum level measured in different units (Methods). The horizontal dotted line indicates the respective maximum value of each technology pathway, normalized to 1. b , Distribution of emergence growth rates in the unconventional growth case, obtained from fitting logistic curves to the technology pathways in a . The vertical dashed lines indicate the corresponding emergence growth rate of each numbered technology in a . The shaded bars indicate the histogram of the random sample as in Fig. 3c,d . c , d , Probabilistic feasibility spaces under unconventional growth rates for the European Union ( c ) and globally ( d ). The results demonstrate that the ramp up is accelerated substantially compared with the conventional growth case, overcoming short-term scarcity and reducing long-term uncertainty. COVID vaccinations are a case of extremely fast adoption and hence had to be excluded from the distribution.

Figure 5a shows the normalized historical trajectories of these technologies. To cover the full spectrum of associated growth rates, we fit logistic curves and extract the respective annual emergence growth rates. The resulting distribution of unconventional growth rates has a mean value of 126% per year, substantially larger than in the conventional growth case (Table 1 ) and stretches beyond 300% per year (Fig. 5b ). Within the analysed data, only US production during World War II achieved growth rates above 100% per year—except for the number of COVID-19 vaccinations, which far surpass all other technologies such that we exclude it as an outlier with very different circumstances and product characteristics.

For green hydrogen, reaching such unconventionally high growth rates requires policies and regulation to urgently secure business cases by creating, or even guaranteeing, revenue streams through public co-financing or direct investments. If policymakers decide for subsidies, such as co-financing of capital expenditures (CAPEX) or operating expenditures (OPEX), the funding of these programmes would need to reflect the envisaged scale of the hydrogen market ramp up. There are plans for such instruments, for example, in the European Union, which are yet to be specified and implemented. These comprise carbon contracts for differences, which subsidize additional OPEX of operating industrial processes with green hydrogen (for example, primary steel via direct reduction) or CAPEX subsidies as part of the European Union’s ‘Important Projects of Common European Interest’ 8 . In addition, emergency policies should provide security and coordination along the whole value chain. As hydrogen requires new infrastructure, and as most hydrogen applications are not yet competitive and no hydrogen market exists, policymakers and regulatory agencies should support the coordinated ramp up of demand, supply and infrastructure together with relevant industry stakeholders. Because hydrogen infrastructure and trade will partly be international, this involves international cooperation.

The resulting probabilistic feasibility spaces show that unconventional growth rates substantially mitigate the issues of short-term scarcity and mid- to long-term uncertainty (Fig. 5c,d , sensitivity analysis in Extended Data Fig. 6 ). In both regions, European Union and global, green hydrogen immediately enters the growth phase, leading to a probability distribution that already tips around 2030 after which the demand pull acts as the main constraint. In 2030 an even more pronounced bimodal distribution emerges from the simulations, which however also subsides more quickly thereafter. After 2035, the demand pull, median and 95th percentile are separated only by a very small margin, effectively closing the gap between supply and demand with a high probability. While smaller than before, the 90% confidence interval still indicates a substantial spread as small growth rates cannot be ruled out. However, towards 2050, the spread swiftly decreases for the 80% confidence interval, indicating a high probability of mid- to long-term availability.

The differences between conventional growth (such as wind and solar power) and unconventional growth (emergency-like deployment) become even more apparent in the direct comparison of Fig. 6 . In the conventional growth case, the breakthrough year, defined as the year of largest annual capacity additions, in the median occurs around 2040 in the European Union and 2045 globally. However, this is again subject to substantial uncertainty with an IQR of 2036–2045 in the European Union and 2043–2049 globally. In contrast, unconventional growth hastens the median breakthrough to before 2035 in both regions, even though uncertainty remains with an IQR of 2029–2036 in the European Union and 2030–2037 globally.

a , b , Breakthrough year distribution in the European Union ( a ) and globally ( b ). The breakthrough year is defined as the year of largest annual capacity additions. The vertical black dotted lines indicate the intersection years 2030 and 2040 shown in c – f . c – f , Electrolysis capacity distribution in 2030 and 2040 in the European Union ( c , d ) and globally ( e , f ). The left axis shows electrolysis capacity (in GW), while the secondary right axis shows the approximate final energy share this capacity could supply domestically (in percent) given total final energy consumption of scenarios that reach net zero emissions by 2050 (Methods). The horizontal blue and red dashed lines indicate the median of the corresponding distribution.

These marked differences in the breakthrough year are also reflected in the electrolysis capacity distributions (Fig. 6c–f and Extended Data Fig. 7 ). In the conventional growth case, it is likely (≥75%) that in 2030 less than 1% of final energy in the European Union (less than 0.2% globally) can be supplied with domestic green hydrogen. Under unconventional growth, supply in 2030 spans a wide IQR of 0.8–4.5% in the European Union (0.3–2.1% globally). This also increases the probability of achieving the EU 2030 target of 100 GW to 49%, as opposed to 0.2% under conventional growth. However, even under unconventional growth rates, ramping up global electrolysis capacity to 850 GW by 2030 as required by the International Energy Agency (IEA) Net-Zero Emissions by 2050 Scenario (NZE) 9 is unlikely (18% probability), which is also a result of the limited demand pull at that time (compared with Extended Data Fig. 6f ).

In the long run, by 2040, large uncertainties dominate in the conventional growth case, illustrated by an IQR of 3.2–11.2% in the European Union (0.7–3.3% globally), which stands in stark contrast to the narrow 11.7–12.9% in the European Union (6.6–7.8% globally) under unconventional growth. The global probability distribution under conventional growth in 2040 is skewed to low capacities, while it is wide and slightly bimodal in the European Union. Under unconventional growth, by 2040 the probability distribution is focused at the upper end of the range in both regions and primarily determined by the demand pull.

Despite strong momentum and enthusiasm around green hydrogen, the market ramp up of electrolysis is a decisive bottleneck on the pathway to climate neutrality. There is also substantial uncertainty about the role and potential of green hydrogen for achieving climate goals: while 1.5 °C-compatible pathways presented by the IEA and the International Renewable Energy Agency (IRENA) foresee a rapid scale up of green hydrogen, it only plays a limited role in most integrated assessment model (IAM) scenarios surveyed by the Intergovernmental Panel on Climate Change (IPCC) (Extended Data Fig. 8 ). We show that despite exponentially increasing project announcements for the upcoming years, green hydrogen probably (≥75%) remains scarce (<1% of final energy demand) until 2030 in the European Union and until 2035 globally if electrolysis capacity grows similarly to wind and solar power, which have been the biggest success stories of the energy transition so far. This can be explained by the nature of exponential expansion, which includes a flat beginning such that even high annual growth rates take time to translate into noteworthy market shares. However, once the breakthrough occurs, it may happen quickly—as was the case for solar power.

For the electrolysis market ramp up, however, the timing of this breakthrough in terms of largest annual capacity additions is uncertain but unlikely (≤25%) to occur before 2036 in the European Union and 2043 globally. We show that the propagation of inevitable uncertainties associated with both near-term deployment and feasible growth rates leads to uncertain availability of green hydrogen in the mid- to long-term, which implies a substantial risk of a long-term gap between likely supply and potential demand. It is important to note that the probability distributions presented here are conditional on continuous policy support assumed as part of the demand pull. Even under such policies, uncertainties prevail for decades.

In addition, future short-term scarcity and long-term uncertainty of electrolysis capacity might create additional barriers to electrolysis deployment already today. First, short-term scarcity creates problems due to the threefold coordination challenge of ramping up hydrogen supply, demand and infrastructure simultaneously, which has been described as a ‘three-sided chicken-and-egg problem’ 57 . The lack of sufficient hydrogen volumes delays both the end-use transformation and required infrastructure developments such as the repurposing of existing gas pipelines. Second, long-term uncertainty might deter investors, who could choose to wait for the market to consolidate and for costs to drop (second-mover advantage) 58 . From a policy perspective, relying on the large-scale availability of green hydrogen is therefore a risky bet that, if hydrogen abundance and affordability fail to materialize, may lead to a fossil lock-in due to remaining fossil fuel infrastructure and end-use equipment. As a consequence, under conventional growth such as wind and solar power, uncertainties may translate into risks that discourage policymakers and investors such that green hydrogen might fall short of its potential and thus endanger climate targets.

By contrast, policymakers and industry could minimize these risks by fostering rapid investments into green hydrogen supply chains that enable unconventionally high growth rates of electrolysis. In this way, the feasibility space would broaden beyond what has been experienced for energy analogues such as wind and solar. This could break the vicious cycle of uncertain supply, insufficient demand and incomplete infrastructure and turn it into a positive feedback mechanism. Short-term scarcity and long-term uncertainty are two sides of the same coin and could be resolved together. Policies that kick start a rapid deployment of gigawatt-scale electrolysers in the upcoming few years could help to unlock substantial innovation and scaling effects, prompting industries to switch from manual to automated production and thus driving down costs, which would secure expectations and further accelerate growth.

Such unconventional growth could not only allow green hydrogen to meet demand in sectors inaccessible to direct electrification, but in conjunction with expanding renewable electricity, it could keep the window open to reaching a broader and more prominent role of hydrogen in a climate-neutral energy system. However, policymakers should be aware that there remains a risk of overestimating green hydrogen’s potential. While it will be possible to expand the use cases of hydrogen if supply surpasses expectations, in the opposite case, if supply falls short of expectations, it might simply be too late to switch to alternatives. Under these asymmetrically distributed risks, policymakers face a twofold problem. On the one hand, they need to accelerate the development of green hydrogen throughout the entire supply chain to foster unconventional growth; on the other hand, they need to safeguard against the inevitable risk of limited availability. Policymakers, therefore, need to strike a sensible balance between providing regulatory certainty to spur green hydrogen investment while maintaining a realistic judgement on its long-term prospects and fostering available and more efficient alternatives such as direct electrification and energy efficiency. Future research should further develop probabilistic decision frameworks 59 that help enable urgent technological deployment, while navigating the uncertain feasibility space and associated risks.

Approach and key input data

We conduct an uncertainty analysis of the market ramp up and further expansion of electrolysis capacity in the European Union and globally, using a stochastic adaptation of the logistic technology diffusion model. The model accounts for inevitable uncertainties of two main parameters: the initial electrolysis capacity in 2023 and the annual growth rate, which we parameterize using up-to-date electrolyser capacity data from built, planned and announced projects and from empirical data on the growth of successful technologies from the past. We capture the nonlinear propagation of these uncertainties within the logistic diffusion model by a Monte Carlo simulation approach. We further assume a steadily increasing electrolysis demand pull driven by continuous policy support and expanding competitiveness of hydrogen applications (Fig. 2 ). This approach enables us to derive probability distributions of electrolysis capacity deployment over time, which we then interpret as a probabilistic feasibility space of scaling up green hydrogen supply. By design and by necessity, the results do not represent absolute probabilities but conditional probabilities that are contingent on the assumed demand pull from policies and markets.

Our analysis relies on global electrolysis projects from the IEA Hydrogen Projects Database 32 , complemented by our own market research, which we use to parameterize the initial capacity distribution, depending on the project status as explained below.

To parameterize the growth rate distribution, we draw on data of historical analogues and distinguish two cases. In the conventional growth case, we assume that electrolysis grows as fast as wind and solar power have during their period of fastest relative growth from 1995–2010 (Fig. 3 ). In the unconventional growth case, we explore the electrolysis market ramp up under historical growth rates of a wide set of primarily non-energy technologies that grew even faster than wind and solar power (Fig. 5 ).

For the demand pull (from policies, regulation and markets) that drives the technology diffusion, we parameterize its magnitude in time and its anticipation by investors. For the European Union, in the short term, the magnitude is parameterized to the political 2024 target of 6 GW, while the 2030 target of 100 GW follows from the REPowerEU Plan 8 , which foresees the domestic production of 10 Mt of renewable hydrogen, approximately equivalent to 100 GW electrolysis capacity. The long-term demand pull is set to 500 GW by 2050 as mentioned in the EU Hydrogen Strategy 7 . Globally, the short-term demand pull magnitude of 254 GW follows from cumulative project announcements of 154 GW by 2030 plus an additional 10 Mt of renewable hydrogen the European Union recently announced it plans to import 8 , equivalent to 100 GW of electrolysis capacity. In the long run, we use scenario data of the IEA NZE scenario, which is 3,600 GW globally by 2050 9 . The demand pull anticipation states by how many years these targets, associated policies and hydrogen competitiveness are anticipated by potential investors, which thus constitutes a measure of both regulatory certainty and investor foresight. Our default assumption is five years, while we conduct sensitivity analyses for zero years, ten years and a hypothetical case of full anticipation of the long-term market size (Extended Data Fig. 4 and Extended Data Fig. 6 ).

Data handling

We use the IEA Hydrogen Projects Database, which lists 984 global hydrogen projects, of which 886 are based on electrolysis. The database includes the project’s development status, technology characteristics, designated end-use applications and, most importantly, size as electrical capacity in MW for electrolysis projects. In addition, to ensure the model’s initial capacity in 2023 is accurately parameterized, we review all projects with an announced starting year in 2022 or 2023 and an announced size of at least 50 MW. This applies to 49 projects, which we track and include in the GitHub repository (below). Electrolysis projects with a ‘DEMO’ development status are allocated to the ‘Operational’ and ‘Decommissioned’ status, depending on whether they are still in operation. The IEA Hydrogen Projects Database also contains several entries for confidential projects between 2000–2020. We distribute these projects to all regions in proportion to the share of total capacity from other non-confidential projects within that time window and equally over time.

For the conventional growth case, we use data of installed wind and solar capacity from the BP Statistical Review of World Energy 2021 60 . Solar capacity is available from 1997 onwards in the European Union and from 1996 globally. Wind capacity is available from 1997 in the European Union and from 1995 globally. We fit exponential models to this data in sliding seven-year intervals until 2010, which we use to parameterize the emergence growth rate distribution. This corresponds to the period in which both technologies grew the fastest (Extended Data Fig. 1 ). The distribution is robust to the choice of the slice length (Extended Data Fig. 2 ). The emergence growth rate is related to the steepness parameter in the logistic function (below) and describes the growth rate that is approximately attained in the emergence phase of the technology diffusion when the asymptote is not yet constraining.

Truncated normal distributions

The stochastic uncertainty analysis rests on a Monte Carlo-based simulation approach to randomly sample from probability distributions that reflect the underlying parametric uncertainty. We use normal distributions with lower truncation for both the initial capacity in 2023 and the emergence growth rate.

For the initial capacity distribution, we define the lower truncation a by the capacity of all projects that are already operational or under construction and due to start production in 2023. Given the truncation interval \(\left[ {a,\infty } \right]\) , we thus need to determine the pre-truncation parameters μ (mean) and σ (standard deviation). This leaves two degrees of freedom for which we impose two conditions. First, we set the post-truncation expected value to the capacity that is equivalent to realizing 30% of feasibility study projects, \(C_{0.3\mathrm{FS}}\) . Given ϕ as the probability density function and Φ as the cumulative density function of the normal distribution, the first condition is related to the expected value and reads:

Second, we assign a 15% probability to the option that only those projects that are already backed by an FID, with capacity \(C_\mathrm{FID}\) , are built. Following the truncated cumulative distribution function, the second condition is:

The two equations ( 1 ) and ( 2 ) form a system of nonlinear equations that we solve numerically to obtain μ and σ . Jointly with the lower truncation value a , this defines the truncated distribution (Fig. 3a,b ).

For the emergence growth rate distribution, we first calculate the mean and standard deviation of the seven-year growth rates of wind and solar power in the European Union and globally. Subsequently, we apply a lower truncation of 15% per year, which thus constitutes the lower boundary of the electrolysis market ramp up (Fig. 3c,d ).

Adapted logistic technology diffusion model

To account for the threefold coordination challenge of concurrently ramping up green hydrogen supply, demand and infrastructure, we propose an adaptation of the standard logistic technology diffusion model by including a steadily increasing demand pull that replaces the fixed final market volume. This accounts for the observation that the market for green hydrogen is just emerging, which stands in contrast to energy technologies such as wind and solar power that were able to tap into the existing electricity market (main text). We deliberately do not model market shares but instead directly describe the growing market volume because the emerging green hydrogen market is not well described by a substitution of technology shares.

The standard logistic function for the electrolysis capacity \(C\left( t \right)\) reads

where \(C_\mathrm{max}\) is the asymptote, k is the growth constant, t 0 is the inflection point and e is Euler’s number of approximately 2.718. This is the solution of the logistic differential equation

under the condition that \(C\left( {t_0} \right) = C_\mathrm{max}/2\) . Our model idea rests on an adaptation of this differential equation. We turn \(C_\mathrm{max}\) into a time-dependent demand pull \(C_\mathrm{max}(t)\) and discretize the differential equation, which yields

where t denotes time in yearly units and \(b = \mathrm{e}^k - 1\) is the annual growth rate. In the Monte Carlo simulation, we independently draw a sample ( N  = 10,000) for both the initial capacity \(C_{2023}\) and the annual growth rate b and subsequently feed both into the diffusion equation ( 5 ). To improve numerical accuracy, we use a quarterly time resolution in the model with a quarterly growth rate of \(b_q = \left( {1 + b} \right)^{1/4} - 1\) . Further increasing the temporal resolution did not noticeably affect results.

Comparison with Gompertz model

The default logistic function is a special symmetric case of the generalized logistic function

with v as an additional parameter, where the logistic function follows for \(\nu = 1\) . Another prominent special case of the generalized logistic function is the so-called Gompertz model, which follows as the limiting case for \(\nu \to 0\) and may be written as

or in differential form as

where ln is the natural logarithm and which discretized translates into

Compared with the default logistic function, the Gompertz function is asymmetric and approaches the asymptote much more gradually. Our adaptation of the logistic model with a steadily increasing demand pull results in a similar shape, yet one that can be controlled and parameterized more directly using additional information on policy targets and scenario results. Thus, the Gompertz model already includes an asymmetric damping term, so that we use it only with a constant asymptote, \(C_\mathrm{max} = \mathrm{const}\) . Calculating the Gompertz model together with a non-constant demand pull would introduce an undesirable superposition of different damping effects.

In contrast to the logistic model in equation ( 5 ), the Gompertz model in equation ( 9 ) does not simplify for \(C_t \ll C_{t,\mathrm{max}}\) so that b cannot be interpreted as the emergence growth rate. Instead, we parameterize the Gompertz model such that the initial seven-year growth from 2023–2030 matches the emergence growth rate (Extended Data Fig. 3 ). This is in line with our definition of the emergence growth rate for which we fitted exponential models in moving seven-year windows.

Emergency deployment

To extend the probabilistic feasibility space of electrolysis capacity to emergency deployment, we use a wide dataset of primarily non-energy technologies to parameterize a distribution of unconventional growth rates. This encompasses technologies on both the regional and global level, measured in different units, which we normalize by the respective maximum value. All technologies represent stock variables; apart from nuclear power in France and dry shale gas in the United States, which are yearly flow variables. In contrast to the conventional growth case, where we used exponential growth rates of wind and solar power to parameterize the emergence growth rate distribution, for the unconventional growth case we fit logistic models (equation ( 3 )), because many technologies have already passed through the entire S-curve (Fig. 5a ). After converting the growth constant k to the annual growth rate b , via \(b = \mathrm{e}^k - 1\) , we re-parameterize the distribution of emergence growth rates (Fig. 5b ), draw another sample ( N  = 10,000) and run the Monte Carlo simulation again to obtain the probabilistic feasibility space of Fig. 5c,d .

Final energy shares

We translate electrolysis capacity into corresponding shares of final energy demand that can be supplied under this capacity. This requires assumptions on the electrolysis efficiency and further processing steps, its full-load hours and final energy demand.

We assume an overall efficiency of 60%, which results from a 60–81% efficiency of electrolyser systems 61 and additional losses due to further processing of some hydrogen into e-fuels 1 and losses incurred during transportation, storage and conversion 3 . Please note that we report shares of hydrogen on the level of final energy, not useful energy. This excludes the efficiency of the end-use application (for example a fuel cell), which would further reduce the overall efficiency. Final energy is easier to measure and hence regularly reported by energy system models and frequently taken up by policymakers.

Additionally, we assume that electrolysis runs at 5,000 full-load hours, equivalent to a capacity factor of 57%. Such full-load hours could be realized, for example, by hybrid solar–wind power plants in several world regions 62 . Furthermore, this assumption is in harmony with the range of 3,000–6,000 full-load hours regarded as cost-minimizing using grid electricity 61 . In reality, higher full-load hours would reduce the demand pull for electrolysis capacity as the same hydrogen volume could be produced by fewer electrolysers. While this could slow down the growth of electrolysers, it would not impact the final energy share of hydrogen. On the other hand, higher full-load hours would reduce costs and therefore increase the competitiveness of green hydrogen, spurring investment and growth.

Final energy demand over time is obtained from scenarios that reach climate neutrality by 2050. For the European Union, due to the lack of published official modelling results beyond 2030, we use scenarios results of the INNOPATHS project, a recent European Union-specific model intercomparison study 63 . Specifically, we calculate the median of a total of nine scenarios, which originate from three different models (ETM-UCL, PRIMES, REMIND-EU) under three different transformation narratives (New Players 1.5, Incumbents 1.5, Efficiency 1.5). As the results are only available for the EU28, not EU27, and all British Isles (the United Kingdom and the Republic of Ireland) are aggregated into one region (UKI), we approximate the EU27 final energy demand by subtracting the UKI values from the EU28 values. This leads to a slight underestimation of the EU27 value because only the United Kingdom has left the European Union. However, as Ireland’s final energy demand accounts for only around 1% of that of the EU27, the error is negligible compared with the modelling uncertainty. Global final energy demand is given by the IEA NZE scenario 9 (variable ‘total final consumption’) and linearly interpolated if necessary (for 2025, 2035, 2045 in Extended Data Fig. 7 ).

Comparison with other energy modelling scenarios

In Extended Data Fig. 8 , we also provide a comparison of our technology diffusion model results with integrated assessment model scenarios and single data points of policy targets, project announcements and further studies. If hydrogen volumes instead of electrolysis capacities are reported, we calculate the corresponding electrolysis capacity using an efficiency of 70% (assuming no additional losses due to transport and further processing) and 5,000 full-load hours.

For the European Union, we include climate mitigation scenarios from the recently published IPCC AR6 Scenario Explorer and Database, version 1.0 (categories C1, C2 and C3, equivalent to limiting warming to 2 °C with a probability of >67%) (ref. 64 ), approximating the European Union with the ‘Europe’ region from the R10 regions dataset and from the INNOPATHS project (scenarios New Players 1.5, Incumbents 1.5, Efficiency 1.5) (ref. 63 ), again approximating EU27 values by subtracting UKI from EU28 (above). Data from the IPCC SR1.5 is not available for Europe. As an additional point of comparison, we include 2030 and 2050 data points from a roadmap of the industry association Hydrogen Europe 65 , using the ‘ambitious’ scenario under the assumption that all hydrogen is produced via electrolysis.

Globally, we include climate mitigation scenarios from the IPCC SR1.5 Scenario Explorer, version 2.0 (categories Below 1.5 C, 1.5 C low overshoot, 1.5 C high overshoot and Lower 2 C) and the IPCC AR6, version 1.0 (categories C1, C2 and C3, equivalent to limiting warming to 2 °C with a probability of >67%) (refs. 64 , 66 ). In addition, we show the IEA NZE scenario 9 , the IRENA 1.5 °C scenario 10 and the ‘green only’ scenario of the Hydrogen Council 67 , a global hydrogen industry association.

Limitations

We focus on the upscaling of electrolysis capacity. However, there are other elements in the supply chain of green hydrogen that could also constitute critical bottlenecks. Of particular concern is the upscaling of technologies to capture atmospheric carbon 68 , especially direct air capture 29 , for the synthesis of climate-neutral e-fuels, which was out the scope of this article.

The capacity data of wind and solar power does not include very early upscaling before 1995. To parameterize the growth rate distribution, we are therefore limited to the interval 1995–2010, after which growth starts to slow down again. The power of prediction could possibly be improved by including a longer dataset. However, we view 1995–2010 as a valid interval to explore the feasibility space of green hydrogen under the assumption that the growth rates observed for wind and solar power in this 15-year time period can be sustained at least as long for electrolysis.

The calculation of final energy shares in the European Union leaves out imports from other world regions, which could become substantial in the longer term. An analysis of hydrogen trade was outside the scope of this article, and final energy shares must be interpreted accordingly.

All stated probability distributions are contingent on the demand pull, which assumes continuous policy support, in particular in the next decade, and an expanding competitiveness of hydrogen due to cost reductions and direct and indirect carbon pricing. While we regard this as a necessary assumption because green hydrogen is still at the very beginning of the market diffusion, future research could examine appropriate policy instruments that are capable of realizing this demand. This limitation is related to the observation that limited competitiveness of green hydrogen could also reduce the demand pull, which was however outside the scope of this analysis. Another inevitable caveat of our approach is that we need to provide an exogenous long-term demand pull as an input parameter, thereby enforcing and simultaneously constraining the market ramp up. Further energy system research is required to improve the estimates of the long-term demand for electrolysis capacity.

Finally, we deliberately do not include an analysis of fossil hydrogen, which can be available earlier than green hydrogen as steam reforming of natural gas is an established technology (grey hydrogen). Combining steam reforming with carbon capture gives ‘blue’ hydrogen with reduced emissions. Fossil hydrogen could play at least a bridging role, which would enable an early ramp up of hydrogen infrastructure and end-use transformation towards hydrogen. However, there are concerns about the life-cycle emissions of blue hydrogen 11 and new fossil lock-ins 69 , 70 , which could, in turn, slow down the expansion of lower-emission green hydrogen. In addition, blue and grey hydrogen face competitiveness challenges aggravated by high current natural gas prices 12 , which are anticipated to persist at least for a couple of years in the European Union, such that grey and blue hydrogen would also require policy support. Further research is required to analyse the balance between taking transitionary steps and fostering the mid- to long-term availability of green hydrogen.

Data availability

All data are publicly available. We use data from the IEA Hydrogen Projects Database 32 for electrolysis project capacity, complemented by our own market research and provided in the GitHub repository. Data on wind and solar power capacity is taken from the BP Statistical Review of World Energy 2021 60 . Data sources for the unconventional growth case are listed in the GitHub repository and include, among others, refs. 71 , 72 , 73 , 74 , 75 . Final energy scenario data is taken from the IEA NZE 9 on the global level and from the INNOPATHS project 63 for the European Union. Scenario data from the IPCC SR1.5 and IPCC AR6 are available from the respective scenario explorers 64 , 66 .

Code availability

The R model code, including all input data apart from the IPCC scenarios (for Extended Data Fig. 8 ), is available on GitHub: https://github.com/aodenweller/green-h2-upscaling/ . Pre-run simulation results to reproduce all figures are available on Zenodo: https://zenodo.org/record/6567669#.Yuf_5-zMJ3k .

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Acknowledgements

We gratefully acknowledge funding from the Kopernikus-Ariadne project (FKZ 03SFK5A; A.O., F.U., M.J., G.L.) and the INTEGRATE project (FKZ: 01LP1928A; F.U., G.L.) by the German Federal Ministry of Education and Research and the German Federal Environmental Foundation (Deutsche Bundesstiftung Umwelt; A.O.). We thank J.M. Bermudez for comments and R. Rodrigues for providing final energy scenario data.

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Adrian Odenweller, Falko Ueckerdt & Gunnar Luderer

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Contributions

F.U. and G.L. suggested the research question. A.O. and F.U. jointly conceived and designed the study in consultation with G.F.N. and G.L. A.O. implemented the model and created the visualizations. A.O. and F.U. interpreted the results. A.O. wrote the manuscript with contributions from G.F.N., M.J. and G.L. A.O. and M.J. verified and updated relevant electrolysis project announcements. A.O. collected data for the unconventional growth case.

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Extended data

Extended data fig. 1 historical capacities and exponential growth rates of solar and wind power..

a, Solar power in the EU, b, Solar power globally, c, Wind power in the EU, d, Wind power globally. The zoom panel displays the period of fastest growth until 2010, from which we estimate exponential growth rates in 7-year slices. The percentage values indicate the corresponding growth rate for the subsequent 7-year period. These growth rates define the emergence growth rate distributions in Fig. 3c-d . To illustrate the idea of our adapted logistic technology diffusion model, we also calculate the implicit demand-pull from 2011-2020 (dotted line, 5-year rolling mean) that replicates the historically observed capacities based on the average emergence growth rate taken from the 1995-2010 interval (see Eq. 5 ). The approximately linear shape of the implicit demand pull demonstrates that this is a well-founded assumption, which we therefore also apply to the analysis of electrolysis capacity upscaling.

Extended Data Fig. 2 Emergence growth rate distributions in the conventional growth case under varying interval lengths.

a, in the EU, b, globally. The distributions are robust to the length of the time slice (of wind and solar power) that underlies the estimate of the exponential growth rate. We therefore use the intermediate 7-year slice length, which also corresponds to the 2023-2030 time window that is of particular concern for 2030 policy targets as the model starts in 2023.

Extended Data Fig. 3 Comparison between the adapted logistic model and the Gompertz model.

a,b, Comparison of the logistic model with increasing demand pull and the Gompertz model with full demand pull for the mean parameter specification of the initial capacity in 2023 and the emergence growth rate, for the EU (a) and globally (b). The Gompertz model is parameterised so that the growth within the initial 7-year period from 2023-2030 corresponds to the emergence growth rate, which is in line with the parameterisation of the conventional growth case (see Methods). c,d, Probabilistic feasibility space of the adapted logistic model for the EU (c) and globally (d). These panels are a copy of Fig. 4 and included here only for comparison. e,f, Probabilistic feasibility space of the Gompertz model, leading to a much earlier damping of the market ramp up than in c-d. This implies a substantially reduced long-term availability and illustrates the broad methodological difficulties of long-term projections. Nevertheless, our two main conclusions are robust as the Gompertz model also reveals short-term scarcity and long-term uncertainty of green hydrogen supply. While both models lead to an asymmetric adoption curve that approaches the asymptote more gradually than the default logistic function, our adapted logistic technology diffusion model allows for a more precise control of the increasing market volume that can be informed by additional information about policy targets and scenario results.

Extended Data Fig. 4 Sensitivity analysis of probabilistic feasibility spaces for the conventional growth case under varying demand pull anticipation levels.

a,c,e, EU with no anticipation, 10 years anticipation, and a hypothetical case of full anticipation of the long-term market size, respectively. b,d,f, globally. Both short-term scarcity and long-term uncertainty are robust to the level of demand pull anticipation. However, in the long-term capacity deployment is higher under full anticipation of the demand pull (that is the default logistic function), especially in the EU, which has higher growth rates than globally.

Extended Data Fig. 5 Comparison of conventional growth percentiles with project announcements until 2030 for validation.

a, in the EU. b, globally. Both panels show the conventional growth case (like wind and solar) with five years demand pull anticipation, similar to Fig. 4 . In both regions, cumulative project announcements surpass the median of the diffusion model results at all times. This is in line with the observation that the vast majority of announcements are fundamentally uncertain as they are not backed by a final investment decision yet. The comparison between the results of our probabilistic technology diffusion model and the cumulative project announcements demonstrates the plausibility of our modelling approach.

Extended Data Fig. 6 Sensitivity analysis of probabilistic feasibility spaces for the unconventional growth case under varying demand pull anticipation levels.

a,c,e, EU with no anticipation, 10 years anticipation, and a hypothetical case of full anticipation of the long-term market size, respectively. b,d,f, globally. In both regions, short-term scarcity can be overcome to an even greater extent under full anticipation of the demand-pull. Notably, under unconventional growth rates and full demand pull anticipation, short-term uncertainty results as indicated by the marginal distributions in 2030. As the probabilistic feasibility space is primarily determined by the demand pull after 2030 in both regions, under full demand pull anticipation the saturation market volume is reached already around 2035 with a high probability in both regions.

Extended Data Fig. 7 Probability distribution of electrolysis capacity in 5-year time steps between 2025-2050.

a,b,e,f,i,j, in the EU, c,d,g,h,k,l, globally. This diagram is an extension of Fig. 6c-d with additional years (2025, 2035, 2045, 2050). The left axis shows electrolysis capacity in GW, the right axis the corresponding final energy share that can be supplied with this capacity. In 2025, green hydrogen supply is minimal in terms of the final energy share in both regions and largely irrespective of the growth rate. In 2035, unconventional growth rates enable a final energy share that is almost 4 times larger than under conventional growth rates in the EU, and more than 10 times larger globally. In 2045, and even more so in 2050, the demand pull acts as the main constraint such that the differences between conventional and unconventional growth rates become smaller again.

Extended Data Fig. 8 Comparison of our probabilistic diffusion model results with IAM climate mitigation scenarios, targets, and further studies.

In both the EU and globally, IAM scenarios tend to use (far) less green hydrogen than envisaged by policy targets or other studies such as by Hydrogen Europe, the Hydrogen Council, the IEA, or IRENA. This is especially true for the global IPCC SR1.5 scenarios, which contain hardly any hydrogen produced via electrolysis. Most of all, this comparison demonstrates that the awareness of hydrogen’s critical importance for climate change mitigation and potential for technological learning is just emerging and already acknowledged by the IEA and IRENA. However, this awareness has not yet penetrated into the IAM community, even though electrolysis capacity deployment levels in climate mitigation scenarios have increased from the IPCC SR1.5 to the IPCC AR6 globally, as well as from the IPCC AR6 to the more recent EU-focused INNOPATHS scenarios. We believe that our analysis can help to parameterise plausible expansion pathways of green hydrogen for climate change mitigation scenarios in IAMs. Note that in the long run the technology diffusion pathways are asymptotically constrained by the exogenously assumed final market volume (see Table 1 ). The long-run capacity levels achieved in reality may exceed this level. The box plots show the median (50% quantile) as the centre, the 25% and 75% quantile as the bounds of box, and the whiskers as the minima and maxima of the full data set. Data sources: refs. 9 , 10 , 63 , 64 , 65 , 66 , 67 .

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Odenweller, A., Ueckerdt, F., Nemet, G.F. et al. Probabilistic feasibility space of scaling up green hydrogen supply. Nat Energy 7 , 854–865 (2022). https://doi.org/10.1038/s41560-022-01097-4

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6 minute read

What is green hydrogen, and how can it be used to build a healthier planet?

Nearly everyone has heard of hydrogen at some point in their life. It is, after all, the very first element on the periodic table. Today, hydrogen is often mentioned alongside technologies that are rapidly evolving to meet the pressing demand for cleaner, more sustainable energy.

2023-06-19T16:47+02:00

While there is no silver bullet for climate change, it’s certainly possible for hydrogen to be a big part of the solution for reducing greenhouse gas (GHG) emissions and shrinking our carbon footprint. In this context, we most often hear about “green hydrogen.” But what, exactly, is green hydrogen?

Let’s take one step back and find out how hydrogen is used, and why it’s an important part of building a healthier planet. 

Hydrogen basics, from grey to green

Hydrogen is one of the most basic building blocks of the world around us. It easily combines with other elements and molecules (to form, for example, water), and with those combinations, countless things can be made — including energy. Using hydrogen in the process of storing energy is appealing because hydrogen provides an alternative to coal and oil. And when hydrogen is used for energy production, water and heat are the only by-products.

In addition, hydrogen can be used as a reactive agent — for example, to refine petroleum products by breaking down heavy molecules and removing impurities. In fact, this is the main use for hydrogen today. However, other markets, such as transportation (where hydrogen is used in fuel cells), are growing rapidly, demonstrating both the versatility of hydrogen and the need for further research and development. 

“Decarbonizing existing hydrogen production by replacing grey (i.e. fossil) hydrogen with renewable hydrogen — which is essential for industries ranging from steel production to transportation — is an important means to cut industry emissions,” says  Outi Ervasti,  Vice President, Renewable Hydrogen at Neste. “Many of hydrogen’s current applications are very challenging to decarbonize, and can’t be solved directly with electrification. Instead, electrification must work hand-in-hand with green hydrogen.”

Green, grey and blue hydrogen

Currently, around 95% of all hydrogen is produced from fossil fuels. Hydrogen from natural gas (usually produced using a process called steam methane reforming) is called  grey hydrogen , and it has two main drawbacks:

Natural gas is a non-renewable raw material.

Production of grey hydrogen causes significant carbon dioxide (CO 2 ) emissions.

One way to make grey hydrogen production more sustainable is to use carbon capture technology to prevent the resulting CO 2   emissions from reaching the atmosphere and contributing to climate change. When carbon capture is integrated with the production of hydrogen from natural gas, we call it  blue hydrogen .

Through a process called electrolysis, however, which involves using renewable electricity to split water molecules into hydrogen and oxygen, it is possible to produce hydrogen in a way that does not require natural gas and creates no direct CO 2  emissions. Since this process only requires water and renewable electricity, we refer to it as renewable hydrogen, or  green hydrogen .

Green hydrogen acts as a renewable, scalable, and versatile raw material for processes such as manufacturing steel, cement, fertilizers, fuels, and other chemical products. In transportation especially, green hydrogen has the potential to significantly reduce GHG emissions in the next decade. 

It is important to note that producing hydrogen requires substantial energy inputs, and an emphasis should be placed on ensuring the availability of renewable electricity when investing in green hydrogen production.

Green hydrogen = low-emission and renewable

Blue hydrogen = low-emission and fossil-based

Grey hydrogen = higher-emission and fossil-based

Legislative support — how crucial is it?

A strong awareness of climate change is an important driver of the hydrogen economy. The  EU’s current hydrogen strategy  calls for increasing development of hydrogen infrastructure and markets, and aims to make hydrogen a central part of the energy system. The goals were set to at least one million tons (6 GW) of green hydrogen by 2024 and at least 10 million tons (40 GW) by 2030. These significant goals set for green hydrogen production and the improved financing opportunities have accelerated the development of many hydrogen-related projects. However, legislators continue to play a crucial role. 

“Both the supply and demand for green hydrogen currently need to be clearly regulated to form a solid framework on which  investment decisions can be made,” points out Ervasti. 

“Support for supply can come through investment incentives, while demand can be supported through mandates for the use of renewable fuels, as well as by ensuring that the cost of carbon emissions is reflected in fossil fuel pricing.”

In addition, it is important for electrical grids, pipelines and storage, and other infrastructure elements to be developed and maintained to meet the needs of the industry. Permitting processes also have to become quick and transparent. Ultimately, making a positive business case for green hydrogen and ensuring it can be deployed at scale requires government and industry to collaborate closely.

Neste is leaning into green hydrogen and leading the way

In Finland,  Neste  is already the largest producer and user of hydrogen, and is working on green hydrogen projects to decrease the  carbon footprint  of its refineries and to offer its customers high-quality fuels with even lower emissions than before.

In alignment with the company’s ambition to reach  carbon-neutral  production by 2035, Neste is working on a  120 MW electrolyzer  project to produce green hydrogen at its refinery in Porvoo, Finland. The company has now begun the basic engineering phase of the project, and with an investment decision on track to be made in 2024, green hydrogen production could start as soon as 2026.

In Rotterdam, Neste is setting up a  demonstration unit for green hydrogen production  -  the world’s first multi-megawatt electrolyzer based on the innovative SOEC (solid oxide electrolysis cell) technology that is integrated into industrial production. 

In the short term, Neste plans to use green hydrogen to provide more sustainable support for its refinery processes. However, in the longer term, the company plans to use hydrogen as a raw material for e-fuels, further supporting the company’s climate and sustainability goals.

With many companies undertaking similar efforts around the world, essential partnerships and collaborations are emerging to facilitate the successful development and deployment of green hydrogen at scale. 

The transition to a green hydrogen economy is just getting started, and the path to large-scale adoption of renewable hydrogen needs pioneers to lead the way. Focus on renewable hydrogen is an essential part of  Neste’s strategy  as well as its goal to reach carbon-neutral production by 2035. 

As Ervasti notes: “The opportunities for green hydrogen are vast, as are the challenges. With  innovation  in our DNA at Neste, this is precisely the kind of work we are passionate about.”

By taking action now, as well as continuing investment and development, the company aims to be a major contributor to this emerging and promising opportunity to reduce emissions — both its own and those of its customers — while bringing new solutions to the table and building a healthier planet for all.

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Vestas Ventures Makes First Investment With Stake in Wooden Tower Start-Up

Vestas launches world’s largest turbines as 'big 3' competition ramps up, bp, rwe and enbw win big in uk offshore wind leasing round, so, what exactly is green hydrogen.

For a colorless gas, hydrogen gets described in very colorful terms. A new GTM series helps explain the weird and wonderful world of clean energy.

Contributing Writer

That product is renewable or "green" hydrogen. And while it's not a central concern today for those companies (Enel, EDP, BayWa and others) or industry groups (SolarPower Europe and WindEurope), all see green hydrogen playing a vital role in achieving deep decarbonization of the energy system.

Interest in green hydrogen is skyrocketing  among major oil and gas firms. Europe is planning to make hydrogen a big part of its trillion-dollar Green Deal package , with an EU-wide green hydrogen strategy expected to be published in July. 

“We cannot electrify everything,” said WindEurope CEO Giles Dickson. “Some industrial processes and heavy transport will have to run on gas. And renewable hydrogen is the best gas. It is completely clean. It will be affordable with renewables being so cheap now.”

What is green hydrogen? An intro to the hydrogen color palette

For a colorless gas, hydrogen gets referred to in very colorful terms.

According to the nomenclature used by market research firm  Wood Mackenzie , most of the gas that is already widely used as an industrial chemical is either brown, if it's made through the gasification of coal or lignite; or gray, if it is made through steam methane reformation, which typically uses natural gas as the feedstock. Neither of these processes is exactly carbon-friendly.

A purportedly cleaner option is known as blue hydrogen, where the gas is produced by steam methane reformation but the emissions are curtailed using carbon capture and storage. This process could roughly halve the amount of carbon produced, but it's still far from emissions-free.

Green hydrogen, in contrast, could almost eliminate emissions by using renewable energy — increasingly abundant and often generated at less-than-ideal times — to power the electrolysis of water.

A more recent addition to the hydrogen-production palette is turquoise. This is produced by breaking methane down into hydrogen and solid carbon using a process called pyrolysis. Turquoise hydrogen might seem relatively low in terms of emissions because the carbon can either be buried or used for industrial processes such as steelmaking or battery manufacturing, so it doesn’t escape into the atmosphere.

However, recent research shows turquoise hydrogen is actually likely to be no more carbon-free than the blue variety, owing to emissions from the natural-gas supplies and process heat required.

How do you make green hydrogen?

With electrolysis, all you need to produce large amounts of hydrogen is water, a big electrolyzer and plentiful supplies of electricity.

If the electricity comes from renewable sources such as wind, solar or hydro, then the hydrogen is effectively green; the only carbon emissions are from those embodied in the generation infrastructure.

The challenge right now is that big electrolyzers are in short supply, and plentiful supplies of renewable electricity still come at a significant price. 

Compared to more established production processes, electrolysis is very expensive, so the market for electrolyzers has been small.

And while renewable energy production is now sizable enough to cause duck curves in California and grid problems in Germany, overproduction is a relatively recent development. Most energy markets still have a need for plenty of renewables just to serve the grid.  

How do you store and use this stuff?

Theoretically, there are lots of useful things you can do with green hydrogen. You can add it to natural gas and burn it in thermal power or district heating plants. You can use it as a precursor for other energy carriers, from ammonia to synthetic hydrocarbons, or to directly power fuel cells in cars and ships, for example.

To start with, you can use it simply to replace the industrial hydrogen that gets made every year from natural gas and which amounts to around 10 million metric tons in the U.S. alone.

The main problem with satisfying all these potential markets is in getting green hydrogen to where it is needed. Storing and transporting the highly flammable gas is not easy; it takes up a lot of space and has a habit of making steel pipes and welds brittle and prone to failure.

Because of this, the bulk transport of hydrogen will require dedicated pipelines, which would be costly to build, pressurizing the gas, or cooling it to a liquid. Those last two processes are energy-intensive and would further dent green hydrogen’s already underwhelming round-trip efficiency (see below).

Why is green hydrogen suddenly such a big deal?

One of the paths to near-total decarbonization is electrifying the whole energy system and using clean renewable power. But electrifying the entire energy system would be difficult, or at least much more expensive than combining renewable generation with low-carbon fuels. Green hydrogen is one of several potential low-carbon fuels that could take the place of today’s fossil hydrocarbons.

Admittedly, hydrogen is far from ideal as a fuel. Its low density makes it hard to store and move around. And its flammability can be a problem, as a Norwegian hydrogen filling station blast highlighted in June 2019.

But other low-carbon fuels have problems too, not least of which is cost. And since most of them require the production of green hydrogen as a precursor, why not just stick with the original product?

Proponents point out that hydrogen is already widely used by industry, so technical problems relating to storage and transport are not likely to be insurmountable. Plus, the gas is potentially very versatile, with possible applications in areas ranging from heating and long-term energy storage to transportation.

The opportunity for green hydrogen to be applied across a wide range of sectors means there is a correspondingly large number of companies that could benefit from a burgeoning hydrogen fuel economy. Of these, perhaps the most significant are the oil and gas firms that are increasingly facing calls to cut back on fossil fuel production.

Several oil majors are among the players jostling for pole position in green hydrogen development. Shell Nederland, for example, confirmed in May that it had joined forces with energy company Eneco to bid for capacity in the latest Dutch offshore wind tender so that it could create a record-breaking hydrogen cluster in the Netherlands. Days later, BP’s solar developer Lightsource BP revealed that it was mulling the development of an Australian green hydrogen plant powered by 1.5 gigawatts of wind and solar capacity.

Big Oil’s interest in green hydrogen could be critical in getting the fuel through to commercial viability. Cutting the cost of green hydrogen production will require massive investment and massive scale, something the oil majors are uniquely positioned to provide.

How much does green hydrogen cost to make?

Green hydrogen is still expensive to produce today. In a report published last year (using data from 2018), the International Energy Agency  put the cost of green hydrogen at $3 to $7.50 per kilo, compared to $0.90 to $3.20 for production using steam methane reformation.

Cutting the cost of electrolyzers will be critical to reducing the price of green hydrogen, but that will take time and scale. Electrolyzer costs could fall by half by 2040, from around $840 per kilowatt of capacity today, the  IEA said  last year.

The business case for green hydrogen requires very large amounts of cheap renewable electricity because a fair amount is lost in electrolysis. Electrolyzer efficiencies range from around 60 percent to 80 percent, according to Shell . The efficiency challenge is exacerbated by the fact that many applications may require green hydrogen to power a fuel cell, leading to further losses.

Some observers have theorized that green hydrogen production might mop up excess renewable energy capacity from big production centers, like Europe's offshore wind farms. Given the still-high cost of electrolyzers, though, it's questionable whether green hydrogen project developers would be willing to let their electrolyzers sit idle until renewable energy prices drop below a certain level.

More likely, as is already being considered by Lightsource BP and Shell, developers will build green hydrogen production plants with dedicated renewable energy generation assets in high-resource locations.

How much green hydrogen is being produced?

Not much, in the grand scheme of things. Green hydrogen currently accounts for less than 1 percent of total annual hydrogen production, according to Wood Mackenzie.

But WoodMac forecasts output booming in the coming years. The pipeline of green hydrogen electrolyzer projects  nearly tripled in the five months leading up to April 2020, to 8.2 gigawatts. The surge was mainly driven by an increase in large-scale electrolyzer deployments, with 17 projects scheduled to have 100 megawatts or more of capacity.

And it's not simply the case that more projects are getting developed. By 2027, the average size of electrolyzer systems will likely exceed 600 megawatts, WoodMac says.

Who is leading the development of green hydrogen?

Green hydrogen seems to be on everyone’s mind at the moment, with at least 10 countries looking to the gas for future energy security and possible exports. The latest nation to jump on the bandwagon is Portugal, which in May unveiled a national hydrogen strategy said to be worth €7 billion ($7.7 billion) up to 2030. 

Alongside oil and gas firms, renewable developers see green hydrogen as an emerging market, with offshore wind leader Ørsted last month trumpeting the first major project to exclusively target the transport sector .

Beyond such big names, a host of smaller companies is hoping to grab a slice of the growing green hydrogen pie. Companies such as ITM Power might not be that well known today, but if green hydrogen lives up to a fraction of its promise, it could one day be huge.

And what about hydrogen vehicles?

Ah, yes. The eye-catching Toyota Mirai helped fuel early hopes that hydrogen fuel-cell vehicles might vie with electric cars to take over from the internal combustion engine. But as the EV market has boomed, the prospect of hydrogen being a serious contender has faded from view, at least in the passenger vehicle segment.

There are roughly 7,600 hydrogen fuel-cell cars on U.S. roads today, compared to more than 326,400 plug-in electrics that were sold in the U.S. last year alone.

That said, pundits still expect hydrogen to play a role in decarbonizing some vehicle segments, with forklifts and heavy-duty trucks among those most likely to benefit.

Further reading from Wood Mackenzie, The Future for Green Hydrogen

• electrify everything
• green hydrogen
• hydrogen fuel cells
• offshore wind

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Green hydrogen: Fuel of the Future

• Recently, the Indian Minister of Petroleum and Natural Gas advocated at the World Economic Forum (WEF) in Davos, Switzerland that India will emerge as the leader of green hydrogen .
• Background: This came almost a month after Oil India Limited (OIL) commissioned India’s first 99.99% pure green hydrogen plant in eastern Assam’s Jorhat .
• Minister’s stand: It will be done by taking advantage of the current energy crisis across the globe. 

Green Hydrogen

• Hydrogen is the lightest, simplest and most abundant member of the family of chemical elements in the universe. 
• The ‘green’ depends on how the electricity is generated to obtain the hydrogen, which does not emit greenhouse gas when burned.
• Production: Green hydrogen is produced through electrolysis using renewable sources of energy such as solar, wind or hydel power.
• It was in keeping with the goal of making the country ready for the pilot-scale production of hydrogen and its use in various applications
• Research and development efforts are ongoing for a reduction in the cost of production, storage and the transportation of hydrogen.
• Powered by a 500 KW solar plant, the green hydrogen unit has an installed capacity to produce 10 kg of hydrogen per day and scale it up to 30 kg per day.
• A specialised blender has also been installed for blending green hydrogen produced from the unit with the natural gas supplied by the Assam Gas Corporation Limited and supplying the blended gas to the Jorhat area for domestic and industrial use.
• OIL has engaged experts from the Indian Institute of Technology-Guwahati to assess the impact of the blended gas on the existing facility.
• Grey hydrogen is generated through fossil fuels such as coal and gas and currently accounts for 95% of the total production in South Asia. 
• Blue hydrogen , too, is produced using electricity generated by burning fossil fuels but with technologies to prevent the carbon released in the process from entering the atmosphere.

Image Courtesy: WEF  

Advantages of Green Hydrogen as a fuel

• Stored for a long period: The intermittent nature of renewable energy, especially wind, leads to grid instability. Green hydrogen can be stored for long periods of time. The stored hydrogen can be used to produce electricity using fuel cells. 
• Grid stability: In a fuel cell, a device that converts the energy of a chemical into electricity, hydrogen gas reacts with oxygen to produce electricity and water vapour. Hydrogen, thus, can act as an energy storage device and contribute to grid stability. 
• Monetary benefits: Experts say the oxygen, produced as a by-product (8 kg of oxygen is produced per 1 kg of hydrogen), can also be monetised by using it for industrial and medical applications or for enriching the environment. 
• Flexible carrier: Hydrogen is a flexible energy carrier and can be used for many energy applications like the integration of renewables and transportation. 
• Fewer emissions: It is produced using RE and electrolysis to split water and is distinct from grey hydrogen, which is produced from methane and releases greenhouse gases. 
• The byproduct is also environmentally friendly: Energy can be extracted from hydrogen through combustion or through fuel cells, which emit only water as a by-product.
• Global dominance increasing: Several countries in Europe and North America are experimenting with mixing green hydrogen with PNG. For instance, in the UK, power utilities are blending hydrogen into pipelines to fuel power plants, industrial applications and to serve homes. The mixing is around 15-20% in some networks. Besides, there are various pilot projects on hydrogen blending with PNG being tested in countries like the Netherlands, Germany, France, Australia, South Korea and Japan.

Disadvantages

• On the pipeline front, hydrogen embrittlement can weaken metal or polyethylene pipes and increase leakage risks, particularly in high-pressure pipes”.
• Brittle: Hydrogen embrittlement is a situation when the metal (pipeline) becomes brittle due to the diffusion of hydrogen into the material. The extent of embrittlement depends on the amount of hydrogen and the material’s microstructure. 

Why is India pursuing green hydrogen?

• It is a legally binding international treaty on climate change with the goal of limiting global warming to below 2°C compared to pre-industrial levels. 
• At the 2021 Conference of Parties in Glasgow , India reiterated its commitment to move from a fossil and import-dependent economy to a net-zero economy by 2070 . 
• India’s average annual energy import bill is more than $100 billion.
• The increased consumption of fossil fuel has made the country a high carbon dioxide (CO2) emitter , accounting for nearly 7% of the global CO2 burden. 
• In order to become energy independent by 204 7, the government stressed the need to introduce green hydrogen as an alternative fuel that can make India the global hub and a major exporter of hydrogen.
• It will benefit India’s transportation sector (which contributes 1/3 of India’s greenhouse-gas emissions), iron and steel and chemical sectors.
• Hydrogen energy can provide impetus to India’s aim to decarbonise by 2050 and attain 175 GW of renewable energy capacity by 2022.
• The energy in 2.2 pounds (1 kilogram) of hydrogen gas contains about the same as the energy in 1 gallon (6.2 pounds, 2.8 kilograms) of gasoline.

• Renewable developers see green hydrogen as an emerging market and some have targeted the transport sector, although electric vehicles have begun to catch the imagination of consumers today.
• Policymakers need to take a holistic approach to plan and analyse the best model suited to adopt green hydrogen as a primary fuel.

Source : TH

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Green Hydrogen and Carbon-Neutral Future

• 07 Jan 2023
• GS Paper - 2
• Government Policies & Interventions
• GS Paper - 3
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• Growth & Development
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This article is based on “A green promise: On the National Green Hydrogen mission” which was published in The Hindu on 06/01/2023. It talks about National Green Hydrogen mission and related challenges.

For Prelims: Green hydrogen, Renewable energy, Greenhouse gas emissions, Chemical industry, Steel industry, Fossil fuels, Nationally Determined Contribution (NDC) Targets, Paris Climate Agreement, Electrolysis.

For Mains: Significance of Green Hydrogen, Challenges Related to Green Hydrogen in India.

In India, there is growing interest in green hydrogen , which is hydrogen produced using renewable energy sources. Green hydrogen has the potential to significantly reduce greenhouse gas emissions , as it does not produce any carbon dioxide when burned. This makes it a particularly attractive option for India, which is committed to reducing its carbon footprint and mitigating the impacts of climate change.

The use of green hydrogen in India is still in the early stages, and there are several challenges that need to be addressed in order to scale up its production and use. These include the high cost of production, the lack of infrastructure for the distribution and storage of hydrogen, and the need to develop suitable technologies for its use in different applications.

Despite these challenges, the potential for green hydrogen in India is significant. It has the potential to play a key role in the country's energy mix, helping to reduce reliance on fossil fuels and contribute to a cleaner, more sustainable energy system. With the right policies and investments, green hydrogen could become a major part of India's energy future.

What is Green Hydrogen?

• Green hydrogen is a type of hydrogen that is produced through the electrolysis of water using renewable energy sources such as solar or wind power.
• The electrolysis process splits water into hydrogen and oxygen, and the hydrogen produced can be used as a clean and renewable fuel.
• Chemical industry: Manufacturing ammonia and fertilisers.
• Petrochemical industry : Production of petroleum products.
• Furthermore, it is starting to be used in the steel industry, a sector which is under considerable pressure in Europe because of its polluting effect.

What is the Significance of Green Hydrogen?

• Under the Paris Climate Agreement, India pledged to reduce the emission intensity of its economy by 33-35% from 2005 levels by 2030. Green hydrogen can drive India’s transition to clean energy, combat climate change.
• In terms of mobility, for long distance mobilizations for either urban freight movement within cities and states or for passengers, Green Hydrogen can be used in railways, large ships, buses or trucks, etc.
• Reducing Import Dependence: It will reduce India’s import dependency on fossil fuels . The localisation of electrolyser production and the development of green hydrogen projects can create a new green technologies market in India worth USD 18-20 billion and thousands of jobs.

What are the Challenges Related to Green Hydrogen?

• This is because the process of electrolysis , which is used to produce green hydrogen, requires a large amount of electricity, and the cost of renewable electricity is still relatively high in India.
• This includes a lack of hydrogen refuelling stations and pipelines for transporting hydrogen.
• This is due to a lack of awareness and understanding of green hydrogen among the general public, as well as a lack of incentives for businesses to switch to this technology.
• For transportation fuel cells, hydrogen must be cost-competitive with conventional fuels and technologies on a per-mile basis.

What Should be the Way Forward?

• This can be done through the expansion of renewable energy sources such as solar and wind power.
• Developing Hydrogen Infrastructure : There is a need to develop infrastructure for the production, storage, and distribution of green hydrogen to make this technology more accessible. This includes building hydrogen refuelling stations and pipelines for transporting hydrogen.
• Implement Regulatory Incentives: The government can play a key role in promoting the adoption of green hydrogen by implementing regulatory incentives, such as tax credits and subsidies , to encourage the production and use of this technology.
• This can be done through public awareness campaigns and educational initiatives.

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HØST PtX Esbjerg Project, Denmark

The HØST PtX Esbjerg Project is a hydrogen and ammonia plant being planned to be developed in Esbjerg, Denmark.

Project Type

Hydrogen and Ammonia Plant

Esbjerg, Denmark

More than €2bn

Expected Start of Construction

Expected start of full operations, electrolyser capacity.

Copenhagen Infrastructure Partners (CIP), Arla, Danish Crown, DLG, A.P. Møller Mærsk, and DFDS

The scheme was conceived as a gigawatt-scale Power-to-X project (PtX) to support energy transition in the country.

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PtX, a term primarily used in Denmark, refers to the technologies leveraged to produce fuels, chemicals and materials using hydrogen via electrolysis.

The project is in the CI Energy Transition Fund I managed by Danish fund management company Copenhagen Infrastructure Partners (CIP). Other partners are Arla, Danish Crown, DLG, A.P. Møller Mærsk, and DFDS.

Plans to build a hydrogen and ammonia plant began in 2021 with due diligence, surveys, regulatory processes and project clarification.

In September 2023, the local plan and the strategic environmental assessment (SEA) for the area secured municipality and the Ministry of Environment of Denmark approval.

The Final Investment Decision (FID) on the HØST PtX Esbjerg Project is slated to be taken in 2025. Full operations are expected to start in 2028/29.

The development of the PtX project will entail an investment of more than €2bn. Once complete, it would become one of the largest PtX facilities in Europe contributing to an annual reduction of 1.5 million tonnes of emissions.

HØST PtX Esbjerg Location

The HØST PtX Esbjerg Project will be developed on the west coast of Denmark in the Måde Industrial Area. The site is located close to the Port of Esbjerg, a seaport city on the Jutland peninsula in southwest Denmark.

The The Port of Esbjerg is the largest base port in Europe for transporting offshore wind turbines. The port provides access to Hamburg and Rotterdam ports, ensuring expeditious delivery in Europe.

Overall, the project site covers a total area of approximately 30 hectares (ha).

HØST PtX Esbjerg Project Details

The HØST PtX Esbjerg Project will use a 1GW electrolyser to produce green hydrogen , which can be then converted to ammonia.

The project will be powered by renewable electricity from wind and solar energy sources. The plant is expected to consume around 6,000GWh of power annually.

According to the plan, HØST PtX Esbjerg will produce approximately 100,000 tonnes of green hydrogen which will be delivered to the future hydrogen grid of Denmark.

The produced green hydrogen will be either sold directly to the market or it will be converted into green ammonia.

The plant will use the conventional Haber-Bosch Process under which nitrogen reacts with hydrogen in the presence of a catalyst under high pressure and temperature to produce ammonia.

It would be capable of producing up to 600,000 tonnes, which can be used as a feedstock to produce fertilisers and green fuel for the maritime industry.

The project will have operational flexibility and will adapt to the available power supply from renewable sources. The heat generated in producing green hydrogen and ammonia will be used to supply heat to 15,000 households in the Esbjerg or Varde area.

The construction phase of the plant will be completed in two to three years.

Additionally, the plant will create a total of 100-150 permanent employment opportunities.

Benefits of the Hydrogen and Ammonia Plant

The hydrogen production process at the plant will be completely carbon dioxide free, while the 600,000 tonnes of green ammonia could be used to produce 1.5 million tonnes (Mt) of fertiliser or 5-6,00,000 tonnes of bunkering fuel.

Production of green hydrogen and ammonia will facilitate decarbonisation of shipping, agriculture, and industrial sectors.

Additionally, local green ammonia production will ensure steady supply in the Danish market and eliminate the need to import ammonia-based fertilizers.

Currently, Denmark imports ammonia-based fertilizers produced using natural gas.

According to HØST PtX Esbjerg developer, the project may also help Denmark to become a net exporter of green fertilizer.

Contracts and Agreements

International consulting group COWI was appointed as the owner’s engineer for the project. The company will deliver planning and permitting services.

In February 2023, HØST PtX Esbjerg signed a Commercial Collaboration Agreement (CCA) with Monjasa, which focuses on trading and supplying marine fuels.

As per the agreement, Monjasa will deliver logistical services to distribute green ammonia from the HØST PtX Esbjerg project to the market.

In January 2023, DNV was awarded a Framework Agreement (FA) contract by CIP to provide independent safety and environmental and sustainability technical assurance to the project.

CIP and Uniper signed a Memorandum of Understanding (MoU) in May 2024 to deliver green hydrogen to Germany.

The companies expect that the HØST PtX Esbjerg project will be connected to the German hydrogen network via a hydrogen pipeline developed by Energinet, a Danish transmission system operator, and Gasunie Deutschland Transport Services.

Up to 140,000 tonnes of green hydrogen would be delivered annually to Germany under the partnership.

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