A Thermally-Driven Transcritical CO2 Heat Pump for Upgrading LWR-Grade Heat to High Temperatures

The relatively low temperature of light water nuclear reactors significantly limits the ability to store and utilize heat to provide the flexible dispatch of electricity that will be needed to compensate for the intermittency of a rapidly-growing renewable energy generation fleet. While heat pumps have been used in small-scale, lower-temperature applications for many years, industrial-scale heat pumps capable of the scales and temperatures needed for the target application do not exist today. Objective and Approach The goal of this program is to develop a superior thermally-driven transcritical carbon dioxide heat pump that provides an efficient means of upgrading heat from nuclear steam generators. Phase I of this program will use numerical modeling to complete the conceptual design of a turbine-driven heat pump capable of increasing 250°C steam from a light water reactor heat source to 500°C or greater (750°C and 1000°C). Scope Phase I of the program will include the customization of advanced steady-state technoeconomic thermodynamic models to optimize the conceptual design of a system and components. Optimization parameters will include the fraction of the source steam that is superheated to the final temperature, the source of the steam, and the transcritical carbon dioxide heat pump configuration and operating conditions, as well as overall nuclear plant metrics. Commercial Applications and Other Benefits A system which efficiently upgrades heat from nuclear plants will enable these plants to continue baseload operation while supplying high-temperature heat that can be stored for dispatchable deployment. A thermally-driven transcritical carbon dioxide heat pump is promising as an efficient method of upgrading light water reactor-grade heat.