SupCritical CO2 (sCO2) Brayton cycle generators emerging as alternative for data center power density.
Elemental Nuclear has announced a strategic partnership with the U.S. Department of Energy, administered through Sandia National Laboratories, to support development of supercritical carbon dioxide (sCO₂)–based Brayton Cycle Generator systems for data centers and other applications.
Sandia National Laboratories is a leading expert in closed-loop, recompression Brayton cycle systems and operates one of the world's foremost sCO₂ test facilities. Under the partnership, Sandia and Elemental Nuclear will design, build, and demonstrate advanced sCO₂ power generation technology across two system scales.
The first system is a 1 MWe natural-gas- and waste-heat-fired power and cooling system targeted for small modular data centers and remote military installations. Elemental plans to follow with a scaled-up 10 MWe unit designed to operate with multiple heat sources, including the Elemental ISTR nuclear reactor. This larger system will focus on behind-the-meter power applications for data centers, microgrids, and industrial customers.
Elemental Nuclear aims to become the first company to demonstrate the long-term viability of sCO₂ Brayton cycle power generation systems at this scale. The first system is expected to be operational in 2027, with commercial system deliveries beginning in 2028.
"Approval of this Strategic Partnership Project is a major validation of Elemental's vision and an important milestone for our company," said David Blythe, Chief Executive Officer of Elemental Nuclear. "Working alongside Sandia National Laboratories — the world's foremost authority on Brayton cycle systems — we intend to prove that sCO₂ power generation can be delivered reliably and at commercial scale, as a viable source of on-site power to data centers, industrial operators, and critical installations."
The Brayton Cycle uses heated supercritical carbon dioxide instead of steam to generate electricity. Named after 19th-century engineer George Brayton, the method harnesses hot, pressurized fluid to spin a turbine—much like a jet engine.
Supercritical carbon dioxide is a non-toxic, stable substance under such extreme pressure that it behaves as both a liquid and a gas. The CO₂ remains within the closed system and is not released as a greenhouse gas. It can reach temperatures up to 1,290 degrees Fahrenheit (700 Celsius), significantly hotter than steam.
Because of this heat capacity, researchers say the Brayton Cycle has the potential to convert waste heat into energy far more efficiently than the traditional steam-based Rankine cycle.
In a simple closed-loop Brayton cycle, supercritical CO₂ is heated through a heat exchanger, then energy is extracted in a turbine. After exiting the turbine, the CO₂ is cooled in a recuperator before entering a compressor. The compressor raises the supercritical CO₂ to the necessary pressure, where it meets waste heat in the recuperator and returns to the heater to continue the cycle. The recuperator significantly improves overall system efficiency.