Decarbonizing the electric sector: Combining renewable and nuclear energy using thermal storage

Both renewable and nuclear energy can provide significant contributions to decarbonizing the electric sector. However, a grid employing large amounts of wind and solar energy requires the balance of the system to be highly flexible to respond to the increased variability of the net load. This makes deployment of conventional nuclear power challenging both due to the technical challenges of plant cycling and economic limits of reduced capacity factor. In the United States nuclear power plants generally provide constant, base load power and are most economic when operated at constant power levels. Operating nuclear power plants in load-following modes decreases the plants' annual energy output and increases the levelized cost of energy, decreasing economic competitiveness.One possible solution is to couple thermal energy storage to nuclear power plants. This would enable the reactor to remain at nearly constant output, while cycling the electrical generator in response to the variability of the net load. This paper conceptually explores combinations of wind, solar, and nuclear that can provide a large fraction of a system's electricity, assuming the use of thermal energy storage that would allow nuclear power to provide load following and cycling duty while operating at a constant reactor power output.

► Both renewable and nuclear energy have been proposed to decarbonize the electric sector.
► Deploying large amounts of wind and solar energy requires the balance of the grid to be highly flexible.
► Current reactor designs have technical and economic challenges in providing load-following power.
► Coupling thermal energy storage to nuclear power plants could improve their flexibility.
► Renewables and flexible nuclear power could together significantly decarbonize the electric sector.