Advanced science.  Applied technology.


Supercritical Transformational Electric Power Pilot Plant

Southwest Research Institute is home to the Supercritical Transformational Electric Power (STEP) Demo pilot plant to demonstrate supercritical carbon dioxide (sCO2) technology. The novel 15-acre facility, located on the grounds of SwRI in San Antonio, will house first-of-its-kind equipment to demonstrate and test sCO2 as the working fluid in power system components. The pilot plant achieved its first operation of its compressor with CO2 at supercritical fluid conditions in 2023. Commissioning of the facility will continue through early 2024.

The $169 million, 10-megawatt sCO2 facility at Southwest Research Institute in San Antonio is led by GTI Energy in collaboration with Southwest Research Institute (SwRI), GE Vernova, the U.S. Department of Energy/National Energy Technology Laboratory (U.S. DOE/NETL), and several industry partners, to demonstrate next-generation power production technology.  The system is part of an effort to advance a power generation technology with the potential to produce lower cost electricity with reduced emissions.

The 10-MWe STEP Demo power plant will use sCO2 as a power source.

Supercritical CO2 Brayton Cycle

About 60 percent of all power in North America comes from the burning of fossil fuel. Most power plants in the United States are close to 30 years old, with many operating at 35 percent efficiency or less while creating significant greenhouse gas emissions from burning large amount of hydrocarbon fuels.

The supercritical CO2 Brayton cycle differs from steam Rankine cycles used in traditional power generation. sCO2 is carbon dioxide held above a critical temperature and pressure, which causes it to act like a gas while having the density of a liquid. It’s also nontoxic and nonflammable, and its supercritical state makes sCO2 a highly efficient fluid to generate power because small changes in temperature or pressure cause significant shifts in its density. Current power plants use water as a thermal medium in power cycles. Replacing it with sCO2 increases efficiency by as much as 10 percent.

The STEP Demo facility is designed to address some specific technical challenges to commercialization of the promising sCO2 technology. The benefits of developing and deploying this are crucial to efficiently using conventional power supplies as we move forward implementing alternatives.

Because of the efficiency of sCO2 as a thermal medium, STEP turbomachinery can be one-tenth the size of conventional power plant components, providing the potential to shrink the environmental footprint as well as the construction cost of any new facilities. The new STEP Demo facility will be significantly smaller than today’s power plants. For example, a desk-sized sCO2 turbine could power 10,000 homes.

STEP Demo project objectives include refining the sCO2 power cycle, demonstrating component performance and scalability, and designing the facility to accommodate multiple new supporting technologies.

SwRI, sCO2, and San Antonio

When the STEP Demo facility is completed, SwRI researchers will strive to advance the technology for commercial adoption. They’ll also work to refine the sCO2 power cycle, demonstrate the machinery’s scalability and performance ability.

The plant can be configured to provide on-site user training as well as operations experience, which will contribute to the effort to commercialize this technology. It has also been designed to adapt to industry changes as well as to provide educational and research advantages.

SwRI researchers are striving to advance the technology for commercial adoption, refining the sCO2 power cycle while demonstrating the machinery’s scalability and performance ability.

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Or call Jonathan Wade at +1 210 522 2532.