An NETL-supported project, which could offer a path to lower-cost power generation, has successfully demonstrated a supercritical turbine technology in a pilot plant that can produce enough power to supply electricity to approximately 4,000 homes — the largest scale demonstration of the technology ever accomplished.

The breakthrough was achieved at the Supercritical Transformational Electric Power (STEP) Demo test facility in San Antonio, Texas. The project demonstrated operation of the supercritical carbon dioxide (sCO₂) pilot plant at “simple cycle max” conditions, producing approximately 4 megawatts electric (MWe) of grid synchronized power.

The pilot plant was designed, constructed, and operated at the Southwest Research Institute (SwRI) site as part of the Supercritical Carbon Dioxide Pilot Plant Test Facility project.

Led by GTI Energy in collaboration with SwRI, GE Vernova, NETL and multiple industry partners, the project was designed to demonstrate and validate the sCO₂ Brayton power cycle. The plant is the world’s largest indirect-fired sCO₂ power cycle test facility.

The project received $116 million of federal funding and project management support from NETL.

Turbines need a working fluid to transfer energy to their blades so they can spin and produce electricity. Traditional power plants have used steam as the working fluid, but under specific conditions, carbon dioxide (CO₂) can also be used. When CO₂ is held above a critical temperature and pressure, it attains a supercritical state. The sCO₂ then acts like a gas while having the density of a liquid.

NETL Federal Project Manager Matthew Adams said there are multiple reasons for the interest in sCO₂ power cycle technology.

“sCO2 power cycles offer the potential for more compact, higher efficiency power cycles compared to state-of-the-art steam power cycles, resulting in lower cost of electricity, reduced fuel and water usage and lower emissions.” he said. “Additionally, sCO₂ power cycles are flexible in terms of the heat source, making it well-suited for integration with low-carbon and renewable energy sources.”

Adams explained that the STEP pilot plant achieved stable operation at max design conditions for the simple cycle configuration. This entails a turbine speed of 27,000 RPM and a turbine inlet temperature of 500°C, producing an output of approximately 4 MWe of grid synchronized power.

NETL Advanced Turbines Technology Manager John Crane said “Achieving the simple cycle max milestone is encouraging both for the project and commercialization of sCO₂ power cycle technology. This is the largest scale demonstration of the technology to date and, because the plant uses turbomachinery and process equipment that are representative of commercial implementation, it also demonstrates a scalable technology pathway to larger applications in the 10’s-100’s MW range.”

The next step for the project team is to begin reconfiguring the plant to accommodate Recompression Closed Brayton Cycle (RCBC) operation, which will enhance the efficiency and increase the energy output of the power cycle. During RCBC operation, the plant is expected to operate at a turbine inlet temperature of 715°C and generate 10 MW of electric power, enough to power approximately 10,000 homes.

This project is funded by the U.S. Department of Energy (DOE) Office of Fossil Energy and Carbon Management’s (FECM) Advanced Turbines Program. Along with FECM, the sCO₂ initiative is sponsored by the DOE Offices of Energy Efficiency and Renewable Energy, and Nuclear Energy. It is a collaborative program with the specific mission of reducing the technical barriers and risks to commercialization of the sCO₂ power cycle.

NETL is a U.S. Department of Energy national laboratory that drives innovation and delivers solutions for a clean and secure energy future. By leveraging its highly skilled innovators and state-of-the-art research facilities, NETL is advancing carbon management and resource sustainability technologies to enable environmental sustainability for all Americans.

GTI Energy is a leading technology development organization that works to scale solutions that shape energy transitions by leveraging gases, liquids, infrastructure, and efficiency. GTI Energy leads the STEP Demo project as the prime contractor with NETL.

SwRI is an independent, nonprofit research and development organization that uses multidisciplinary services to provide solutions to the world’s most challenging scientific and engineering problems. SwRI occupies more than 1,500 acres in San Antonio, Texas, providing 2.3 million square feet of laboratories, test facilities, workshops, and offices for approximately 3,000 employees who perform contract work for government and industry clients. SwRI is the host and operator of the STEP Demo plant.

GE Vernova is a purpose-built global energy company that includes power, wind, and electrification segments. GE Vernova is headquartered in Cambridge, Massachusetts, with more than 80,000 employees across 100 countries.