U.S. Department of Energy: Energy Efficiency and Renewable Energy

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Water Electrolysis Working Group

The Water Electrolysis Working Group, inaugurated in May 2007, brings industry, academia, and national laboratories together to overcome the technical barriers to commercializing electrolysis technology for the production of hydrogen for transportation and industrial use.

Description

Water electrolysis is the conversion of electrical energy into chemical energy in the form of hydrogen with oxygen as a useful byproduct. The electrical energy is later recovered by reacting hydrogen with oxygen in a fuel cell or combustion engine. The conversion of electrical energy to chemical energy is done in an electrolyzer via:

Formula showing how H2O reacts in the presence of electricity to form H2 and one half O2.

Ideally, the electrical power needed to drive the reaction is provided by a renewable resource such as wind, solar, geothermal, or low-emission generators such as hydro or nuclear generators. The hydrogen produced can be used for fuel cell vehicles, electricity generation, or industrial applications. In addition, during periods of low electrical demand, many renewable power generators, such as wind turbines, produce excess electricity, which is lost. Electrolysis enables the storage of this excess energy as hydrogen that can be later converted to electrical energy on demand.

Diagram showing the flow of energy from wind, other renewables such as solar, geothermal, hydro, and biomass to an electrolyzer or short term energy storage to hydrogen storage or fuel cells and engines. From the hydrogen storage symbol, the energy flow leads either to fuel cells and engines or to fueling and hydrogen-fueled vehicles. from the fuel cells and engines graphic the energy flows to the electric grid. A line goes from the electric grid to the fueling station electrolyzer and to hydrogen fueling.

Renewable energy to electricity/hydrogen. See NREL's Wind to Hydrogen Project for videos and simulations on how the wind-to-hydrogen system operates.

According to the Fuel Cell and Hydrogen Energy Association, electrolysis systems supply 4%–5% of the world's hydrogen. It is ideal for sites where low-cost electricity is available or where smaller amounts of very high-purity hydrogen are required. Two basic types of electrolyzers are commercially available: alkaline and proton exchange membrane (PEM). Alkaline technology is the most mature and has been used in commercial systems for nearly a century; most of the larger commercial units are alkaline-based. PEM systems for smaller production capacities are also growing in market share. Solid-oxide-based high-temperature electrolyzers are in development but are not yet available for commercial markets.

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Technical Targets

The Department of Energy (DOE) has developed a set of technical and cost targets for water electrolysis. These targets are contained in the Multi-Year RD&D Plan Hydrogen Production section.

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Progress and Financial Opportunities

The DOE and others are funding research and development in all three electrolysis technologies: alkaline, PEM, and solid oxide. Progress has been made in lowering the cost of electrolyzer units while increasing their efficiency, durability, and safety. Information related to the DOE Hydrogen and Fuel Cells Program activities such as project descriptions and progress reports, technology workshops, and funding opportunities can be found in the Hydrogen Production R&D Activities Web site.

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Contacts

Jamie Holladay
Senior Research Engineer
Pacific Northwest National Laboratory
U.S. Department of Energy, EE-2H
1000 Independence Avenue, SW
Washington, D.C. 20585-0121
Phone: 202-586-8804

Cecelia Cropley
Director, Systems Engineering
Giner Electrochemical Systems, LLC
89 Rumford Avenue
Newton MA 02466-1311
Phone: 781-529-0500

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Content Last Updated: 10/05/2011