Testing of the STEP 10 MWe sCO2 Power Plant in Simple Recuperated Cycle Configuration and Model Comparisons

The 10 MWe Supercritical Transformational Electric Power (STEP) Demo pilot plant has completed its first phase of testing and has achieved full operational speed of 27,000 rpm at a target turbine inlet temperature of 500°C in the Simple recuperated Cycle (SC) configuration. This milestone was achieved while synchronized with the electrical grid generating a gross turbine aerodynamic power of 8.3 MW (11,500 hp) and approximately 4 MWe of net power to the grid. This is the highest capacity to date in the world for indirect-fired sCO2 power technology. This $170 million project is a partnership between GTI Energy, SwRI, GE Vernova, and the US DOE. Mechanical completion was achieved in October 2023. In May 2024, the plant ran and generated electricity for the first time. Subsequent testing continued leading to the maximum power in the SC configuration achieved in September 2024. The results of testing of the plant’s major systems including the compressor and turbine machinery trains, the cooling tower system, the heater, inventory management system, and heat exchangers generally show performance in line with expectations and simulation modelling. The next phase of the project will transform the pilot from Simple Cycle to a Recompression Brayton Cycle (RCBC) configuration and operate up to 715°C. The modifications include adding a second compressor, a second recuperator, and a higher temperature turbine stop valve, which will improve thermal efficiency, increase mass flows and more than double the power output. This project is on-going and is making a significant contribution to the advancement of this promising power generation technology offering efficiency, cost, and emissions improvements over existing approaches.