More Than Just a Power Source

Hydrogen is the most abundant chemical element in the universe, but producing it in pure form for a range of industrial processes is energy intensive, with a significant carbon footprint.

“Almost 95% of current hydrogen demand is met by utilizing carbon-intensive production processes such as steam methane reforming. This is unsustainable in light of the global clean energy transition, particularly considering that demand is already quite high and continues to grow,” said Ibrahim Khamis, a senior nuclear engineer at the IAEA. Hydrogen demand has more than tripled since 1975, according to the International Energy Agency.

Hydrogen is used in industrial processes ranging from producing synthetic fuels and petrochemicals to manufacturing semiconductors and powering fuel cell electric vehicles. In order to decrease the environmental impact of the annual production of over 70 million tonnes of hydrogen, some countries are looking to nuclear power.

“If, for example, just 4% of current hydrogen production were to be shifted to nuclear-generated electricity, this would result in as much as 60 million tonnes of carbon dioxide emissions being abated each year,” Khamis said. “And if all hydrogen were to be produced using nuclear energy, then we are talking about eliminating over 500 million tonnes of carbon dioxide emissions annually.”

Nuclear power reactors can be coupled with a hydrogen production plant to efficiently produce both energy and hydrogen as a cogeneration system. For hydrogen production, the cogeneration system is fitted with components for either electrolysis or thermochemical processes. Electrolysis is the process of inducing water molecules to split using a direct electric current, producing both hydrogen and oxygen. Water electrolysis operates at relatively low temperatures of around 80°C to 120°C, while steam electrolysis operates at much higher temperatures and is therefore more efficient. Steam electrolysis could be ideal for integration with advanced high temperature nuclear power plants, as the process requires heat input at around 700°C to 950°C.

Thermochemical processes can produce hydrogen by inducing chemical reactions with specific compounds at high temperatures to split water molecules. Advanced nuclear reactors capable of operating at very high temperatures can also be used to produce heat for these processes.

“Hydrogen production using the sulphur–iodine cycle in particular has great potential to be scaled up for sustainable, long term operation,” said Khamis. “The development of this method using Japan’s HTTR reactor design and China’s HTR–PM 600 and HTR-10 designs is very promising, and other research initiatives continue to make excellent progress.”

Several countries are now implementing or exploring hydrogen production using nuclear power plants to help decarbonize their energy, industrial and transportation sectors. It is also a way to get more out of a nuclear power plant, which can help to increase its profitability.

The IAEA provides support to countries interested in hydrogen production through initiatives including coordinated research projects and technical meetings. It has also developed the Hydrogen Economic Evaluation Programme (HEEP), a tool for assessing the economics of large-scale hydrogen production via nuclear energy. The IAEA also released an e-learning course on hydrogen production through nuclear cogeneration in early 2020.

“Hydrogen production using nuclear power plants has great potential to contribute to decarbonization efforts, but there are a number of challenges that must first be addressed, such as determining the economic viability of incorporating hydrogen production into a broader energy strategy,” said Khamis. “Hydrogen production through thermochemical water splitting processes requires innovative reactors operating at very high temperatures, and these reactors remain some years away from deployment. Similarly, the sulphur–iodine process still requires more years of research and development to reach maturity and achieve commercial scale-up status.” The licensing of nuclear energy systems incorporating non-electric applications can also be a challenge, he added.

Studying and testing feasibility

The H2-@-Scale initiative, launched in early 2020 by the United States Department of Energy (DOE), is examining the feasibility of developing nuclear energy systems that produce hydrogen in tandem with low carbon electricity. Among the dozens of projects funded through this initiative, one will be implemented by three US commercial electric utility companies in cooperation with the DOE’s Idaho National Laboratory. The project will include technical and economic assessments, as well as pilot demonstrations of hydrogen production at several nuclear power plants around the US.

One of the utility companies involved in the project, Exelon, the largest producer of low carbon power in the US, is now taking steps to install a one-megawatt polymer electrolyte membrane electrolyzer and associated infrastructure at one of its nuclear power plants. The system, which could be in service by 2023, will be used to demonstrate the economic viability of electrolytically-produced hydrogen to supply onsite needs of electric generation-related systems as well as future scalability opportunities.

“This project will be instrumental in helping us determine the prospects for nuclear-driven hydrogen production, including how financial considerations may affect any long term, large-scale production of hydrogen,” said Scot Greenlee, Senior Vice President
of Engineering and Technical Services at Exelon Generation. “The introduction of hydrogen production with nuclear power can go a long way towards enhancing the sustainability of nuclear power as we plan for a low carbon future.”

Assessments are also under way in the United Kingdom. The Energy Systems Catapult, a non-profit initiative in the UK, is modelling the whole energy system and now includes the option for advanced nuclear technologies for hydrogen production. This provides a look at the potentially lowest-cost energy mix that could deliver net zero greenhouse gas emissions by 2050, and the output indicates that advanced nuclear could play a role in hydrogen production alongside other technologies.

“While the exact role of hydrogen in the United Kingdom is still to be determined, analysis done by the Committee on Climate Change and the Department for Business, Energy and Industrial Strategy suggests that we may need to deploy around 270 terawatt-hours of low carbon hydrogen by 2050, although this could increase considerably depending on which applications across the heat, power and transport sectors hydrogen is ultimately used for,” said Philip Rogers, Senior Strategic and Economic Advisor at the United Kingdom’s Nuclear Innovation and Research Advisory Board.

New programmes

In 2019, Russia launched its first nuclear-driven hydrogen production initiative. The programme, run by the country’s State Atomic Energy Corporation “Rosatom”, will use nuclear-driven electrolysis as well as thermochemical generation using high temperature gas cooled reactors. The aim is to produce large quantities of hydrogen each year and shift production away from carbon-intensive production methods such as steam methane reforming.

The hydrogen it produces will be for domestic use and exports. A feasibility assessment is under way on exporting some of the hydrogen to Japan.

“As hydrogen demand continues to grow, driven in part by the expansion of industries such as metalworking, hydrogen production through nuclear energy offers an opportunity to drastically cut carbon emissions while also boosting the profitability of the nuclear power industry,” said Anton Moskvin, Vice President for Marketing and Business Development at Rusatom Overseas.