STEP Demo pilot plant hits full speed in initial testing phase

STEP Demo pilot plant hits full speed in initial testing phase
by Clarence Oxford
Los Angeles CA (SPX) Oct 17, 2024

The Supercritical Transformational Electric Power (STEP) Demo pilot plant, a $169 million, 10-megawatt supercritical carbon dioxide (sCO2) testing facility at Southwest Research Institute (SwRI) in San Antonio, has completed the first phase of testing. The plant successfully reached its full operational speed of 27,000 rpm while maintaining a target turbine inlet temperature of 500 degrees Celsius. At this stage, the plant synchronized with the electrical grid, generating around four megawatts of net power.

"Achieving full operating conditions while connected to the grid is a major advancement of the commercial maturity of these transformative power systems," stated Dr. Tim Allison, director of SwRI's Machinery Department. "This accomplishment represents many technical 'firsts' due to the combination of power and operating temperatures and showcases the tenacity and perseverance of STEP's engineering and project teams."

The STEP Demo pilot plant, one of the world's largest facilities for sCO2 technology demonstration, reached mechanical completion in October 2023, when its major subsystems were installed, and commissioning began. In May 2024, the facility generated electricity for the first time.

The successful completion of Phase 1 testing has demonstrated the commercial potential of sCO2 technology, confirming its ability to meet initial performance targets. In 2025, plans include reconfiguring the pilot plant into a recompression Brayton cycle, a variation that will enhance power output and efficiency. The next phase of testing will aim to achieve the full 10-megawatt net power capacity, sufficient to supply power to approximately 10,000 homes.

"I could not be prouder of the STEP team achieving this major milestone, including reaching the greatest amount of power ever generated using sCO2 as the working fluid," said SwRI Project Manager Dr. Jeff Moore.

The pilot plant stands out from conventional power plants by using high-temperature sCO2 rather than water as a thermal medium in its power cycles. This approach boosts efficiency by up to 10% due to sCO2's advantageous thermodynamic properties. Additionally, carbon dioxide is nontoxic and nonflammable, and the use of sCO2 enables the STEP turbomachinery to be roughly one-tenth the size of traditional power plant components. This size reduction could lower the environmental footprint and construction costs of new facilities. The technology is also adaptable to various heat sources, including concentrated solar power, advanced nuclear reactors, industrial waste heat, thermal energy storage, and geothermal heat.

The STEP Demo project is spearheaded by GTI Energy, in partnership with SwRI, GE Vernova Advanced Research, the U.S. Department of Energy/National Energy Technology Laboratory (U.S. DOE/NETL), and other industry collaborators. New partners are encouraged to join the project for in-depth technical insights and access to operational data.