Renewable Electrolysis

NREL's renewable electrolysis research focuses on designing, developing, and testing advanced experimental and analytical methods to improve electrolyzer stack and system efficiency.

Related activities include:

  • Characterizing electrolyzer performance under variable-input power conditions
  • Designing and developing shared power-electronics packages and controllers to reduce system cost and optimize performance
  • Identifying opportunities for cost reductions through component integration breakthroughs
  • Testing, evaluating, and optimizing renewable electrolysis system performance for hydrogen production and electricity/hydrogen cogeneration.

Learn about the wind-to-hydrogen project, which uses electricity from wind turbines and solar panels to produce hydrogen.

Systems Engineering, Modeling, and Analysis

NREL develops and validates component and system models to assess and optimize a variety of system scenarios and control strategies for renewable hydrogen production and electricity/hydrogen cogeneration.

Graphic displaying various system configurations for using renewable energy to supply hydrogen and electricity for end-use applications. In the first configuration, a corn stalk/biomass pyrolysis graphic is connected via hydrogen piping to a hydrogen storage tank; the tank is connected via hydrogen piping to a hydrogen dispenser at a local fueling station; and the dispenser is connected via hydrogen piping to a hydrogen-fueled vehicle. In the second configuration, a wind turbine is connected via an electric line to an electrolyzer; the electrolyzer is connected via hydrogen piping to a hydrogen storage tank; the tank is connected via hydrogen piping to a hydrogen dispenser at a local fueling station; and the dispenser is connected via hydrogen piping to a hydrogen-fueled vehicle. In this scenario, the hydrogen storage tank is also connected via hydrogen piping to a fuel cells/engines graphic, which is connected via an electric line to the electric grid. In the third scenario, other renewables (solar, geothermal, and hydro) are connected via an electric line to short-term energy storage tanks or to the electric grid. In addition, the electric grid is connected via an electric line to the fueling station electrolyzer, which is connected via hydrogen piping to the fueling dispenser at the local fueling station. Additionally, carbon dioxide storage tanks are connected via carbon dioxide piping to a bioreactor; the bioreactor is connected via natural gas piping to a natural gas storage tank; the natural gas storage tank is connected via natural gas piping to 1) compressed natural gas fueling station for fueling natural gas vehicles and 2) to a home for heating and hot water and 3) to a natural gas turbine, which is connected via an electric line to the electric grid.

This diagram depicts various scenarios for producing renewable hydrogen and electricity.

Systems Integration and Component Development

NREL develops power electronics interfaces for renewable electrolysis systems to characterize and test the performance of electrochemical devices. Testing also examines how the fluctuating power output of a wind turbine impacts electrolyzer operation. Systems performance is quantified based on the efficiency of stack and electrolyzer systems as well as their ability to accommodate renewable electricity sources.

The renewable-electrolysis systems that NREL studies incorporate a common direct current (DC) bus (electrical conductor) fixed with a battery bank connected to a wind turbine, photovoltaic array, and an electrolyzer. Typically, small wind turbines are set up to charge batteries and require connection to a constant voltage DC bus and power electronics to regulate power output and to convert wild alternating current (AC) to DC.

In commercially available electrolyzer systems, the electrolyzer stack accepts DC power input from its onboard power converter. The electrolyzer regulates power to the stack and operates at a fixed stack current. Characterization testing addresses the operation of hydrogen-producing stacks at variable current, without a fixed power supply.

Characterization and Testing

NREL works with national and international industry leaders to develop consensus-based characterization and testing protocols for renewable-based electrolyzers and to compare the performance of electrolyzers from various manufacturers.

Based on actual operational data from wind farms, photovoltaic cells, and projected load-shifting, these test protocols apply to electrolyzer operation under varying-input power conditions.

NREL uses the protocols to test on-site electrolyzers. Specific performance measures include the purity of hydrogen at low power and the long-term effects of variable power operation on electrolyzer system and stack efficiency.

Facilities

NREL's renewable electrolysis research is conducted at the Energy Systems Integration Laboratory at the Energy Systems Integration Facility.

Contact

Kevin Harrison

Senior Engineer

Email
303-630-2439

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