Scaling Considerations for a Multi-Megawatt Class Supercritical CO2 Brayton Cycle and Path Forward for Commercialization

Abstract

Small-scale supercritical CO2 demonstration loops are successful at identifying the important technical issues that one must face in order to scale up to larger power levels. The Sandia National Laboratories (Sandia) Supercritical CO2 Brayton cycle test loops are identifying technical needs to scale the technology to commercial power levels such as 10 MWe. The small demonstration loops provide a scalable approach to identify cost, technical hurdles, and future commercialization plans of commercial applications. The small size of the Sandia 1 MWth loop has demonstration of the split flow loop efficiency and effectiveness of the Printed Circuit Heat Exchangers (PCHEs) leading to the design of a fully recuperated, split flow, supercritical CO2 Brayton cycle demonstration system. However there were many problems that were encountered such as; the high rotational speeds in these units identified the need to address bearing, seals, thermal boundaries, and motor controller problems to prove a reliable power source in the 300 kWe range. Although these issues were anticipated in smaller demonstration units, we also understood that commercially scaled hardware would eliminate these problems caused by high rotational speeds at small scale. The economic viability and development of the future scalable 10 MWe solely depends on the interest of DOE and private industry. The Intellectual Property collected by Sandia proves that the ∼10 MWe Supercritical CO2 power conversion loop to be very beneficial when coupled to a 20 MWth heat source (either solar, geothermal, fossil, or nuclear). This paper will identify a commercialization plan, as well as, a roadmap from the simple 1 MWth supercritical CO2 development loop to a power producing 10 MWe supercritical CO2 Brayton loop.