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

SunShot Initiative

Thermochemical Energy Storage for Stirling CSP Systems

Pacific Northwest National Laboratory logo Photo of large silver dish angled to the sky and anchored to the ground.

Pictured is a proof-of-concept demonstration of a high-efficiency, solar reformer using an Infinia parabolic dish solar concentrator in Kennewick, Washington. Solar-to-chemical energy conversion of approximately 63% was successfully demonstrated in 2011.

Pacific Northwest National Laboratory (PNNL), under an ARRA CSP Award, is working to develop and commercialize thermochemical energy storage technologies that enable CSP systems based on parabolic dish concentrators and Stirling Cycle heat engines to generate power when sunlight is unavailable.


PNNL's approach for thermochemical energy storage consists of operating a thermochemical energy cycle in conjunction with a Stirling Cycle heat engine. This strategy incorporates the following elements:

  • A parabolic dish reflector provides concentrated solar energy to a heat engine and to an endothermic chemical reactor when direct sunlight is available.
  • The heat engine produces electricity.
  • The thermochemical reactor produces a storable chemical product when the chemical energy content of a reacting fluid is increased.
  • The chemical product can be used to produce heat for the heat engine, enabling additional electricity production when direct sunlight is not available.

Benefits of this approach include an increase in the plant's capacity factor and reductions in the levelized cost of energy (LCOE).


The PNNL research team's technical objective is to perform preliminary development activities, including an on-sun, proof-of-concept demonstration of a high-efficiency, solar thermochemical energy storage system based on the integration of compact, process-intensive microchannel reactors and heat exchangers within a dish-Stirling solar power system.

Publications, Patents, and Awards

At this time, this project does not have published articles, patents, or awards.

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Quarterly Progress Reports

Learn about other DOE competitive awards for concentrating solar power research that are in progress.