STEP Demo Supercritical CO2 Pilot Plant Produces Electricity

STEP Demo Supercritical CO2 Pilot Plant Produces Electricity
by Clarence Oxford
Los Angeles CA (SPX) May 31, 2024

The Supercritical Transformational Electric Power (STEP) Demo pilot plant has successfully generated electricity using supercritical carbon dioxide (sCO2) power cycles. The $169 million, 10-megawatt facility at Southwest Research Institute (SwRI) in San Antonio is showcasing next-generation power production technology in a project led by GTI Energy, along with SwRI, GE Vernova, the U.S. Department of Energy/National Energy Technology Laboratory (U.S. DOE/NETL), and several industry participants.

"The impact of demonstrating that the sCO2 technology works cannot be overstated," said SwRI Project Manager Dr. Jeff Moore. "I truly believe this project will change how we approach power generation in the near future."

For the first time, the pilot plant's turbine reached its full speed of 27,000 RPM at an operating temperature of 260C, generating a small amount of power. Over the next few weeks, the STEP team will gradually increase the operating temperature to 500C, producing 5 megawatts (MWe) of power, enough to supply 5,000 homes.

Following this initial test configuration, the STEP Demo project will enter its final phase. The pilot plant will be reconfigured to enhance efficiency and energy output, necessitating the installation of new equipment and a subsequent commission and test phase extending into 2025. By the end of this phase, the pilot plant will produce 10 MWe hourly, sufficient to power 10,000 homes.

The STEP Demo pilot plant is among the largest demonstration facilities globally for sCO2 technology. Unlike traditional steam power plants that use water as the thermal medium, STEP employs high-temperature sCO2 to increase efficiency by up to 10% due to its favorable thermodynamic properties. Carbon dioxide is nontoxic and nonflammable, and when held above a critical temperature and pressure, it behaves like a gas while having a density near that of a liquid.

The sCO2 turbomachinery at the pilot plant is approximately one-tenth the size of conventional power plant components, reducing the physical footprint and construction costs of new facilities. Additionally, sCO2 power cycles are compatible with various heat sources, including concentrated solar power, industrial waste heat, geothermal power, and advanced nuclear power plants.

SwRI, GTI Energy, and GE began construction on the STEP Demo site in 2018. The facility reached mechanical completion in October 2023, initiating the commissioning of major subsystems.