STEP Pilot Plant Achieves sCO2 Milestone

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The STEP pilot project, located at the Southwest Research Institute, achieved successful operation in its compressor section.

The Supercritical Transformational Electric Power (STEP) Demo pilot plant, a $155 million, 10 MW supercritical carbon dioxide (sCO2) test facility located at Southwest Research Institute (SwRI) in San Antonio, has successfully achieved its first operation with CO2 at supercritical fluid conditions in its compressor section. The project was developed in partnership with GTI Energy and GE Research and is sponsored by the U.S. Department of Energy (DOE).

"This exciting milestone represents a significant advancement for a truly transformational project,” Dr. Tim Allison, Director of SwRI’s Department of Machinery, said. “STEP Demo is laying the groundwork for power generation that is more efficient, with a smaller footprint."

Unlike conventional power plants that use water as the thermal medium in power cycles, STEP is designed to use high temperature sCO2, which can increase efficiency by as much as 10% due to its favorable thermodynamic properties. CO2 is nontoxic and nonflammable, and when held above a critical temperature and pressure, it can act like a gas while having the density near that of a liquid.

The efficiency of sCO2 as a working fluid allows STEP turbomachinery to be approximately one-tenth the size of conventional power plant components, providing the opportunity to reduce the environmental footprint and construction cost of new facilities. For instance, a desk-sized sCO2 turbine can power up to 10,000 homes. The technology is also compatible with concentrated solar power and industrial waste heat.


Bhima Sastri, Director of Energy Asset Transformation at the DOE Office of Fossil Energy and Carbon Management, commented: "The sCO2 power cycle is a breakthrough clean, compact, and high-efficiency power generation technology that can deliver significant environmental performance. We look forward to continued operation of the current test to demonstrate control and operability of this power cycle while validating system performance over long periods of time."

The STEP Demo pilot plant turbine is currently being installed and will be tested later this year.