What are Power Cycles?

Power cycles are used in all thermal energy plants—including coal, natural gas, and nuclear energy plants—to convert heat into electricity. Concentrating solar-thermal power (CSP) plants are no different, but use sunlight to generate the heat to power a turbine. Conventional power cycles primarily use steam as the working fluid to drive turbines, but advanced power cycles under consideration for CSP use supercritical carbon dioxide, which can reach higher efficiencies at lower cost than steam-based cycles. Learn more about how CSP works.

Why are Power Cycles Important?

Simply put, higher temperature input to the power cycle leads to a higher efficiency to convert thermal energy to electricity. Existing CSP systems are only able to deliver steam at approximately 550 °C. With next generation CSP plants that will be able to collect and store heat above 700 °C, the development of supercritical carbon dioxide-based cycles have the potential to achieve low capital costs of less than $900 per kilowatt for cycles that have thermal-to-electric efficiency of greater than 50%. This will significantly lower the cost of the electricity generated by CSP plants. The Department of Energy Solar Energy Technologies Office (SETO) set a cost goal of $0.05 per kilowatt-hour for baseload CSP plants with at least 12 hours of thermal energy storage. Learn more about SETO’s CSP goals.

SETO Research on Power Cycles

SETO funds power cycle research and development projects that are focused on advanced, high-efficiency power cycles that explore components of supercritical carbon dioxide turbomachinery, thermal energy storage and supercritical carbon dioxide cycle interactions, and primary heat exchanger designs. Several of SETO’s funding programs have projects that focus on power cycles:

  • Solar Energy Technologies Office Fiscal Year 2019 funding program – developing thermal storage technologies to make solar energy available on demand, as well as technologies that reduce the cost and improve performance of CSP plants.
  • Solar Energy Technologies Office Fiscal Year 2018 funding program – advancing components found in CSP sub-systems, including collectors, power cycles, and thermal transport systems, while pursuing new methods for introducing innovation to CSP research.

To view specific CSP power cycle projects, search the Solar Energy Research Database.

Additional Resources

Learn more about CSP research, other solar energy research in SETO, and current and former SETO funding programs.