(240c) Leveraging Storage and Hybridization to Maximize Renewable Utilization

In the pursuit for renewable power generation, a sentiment of competition between renewables and fossil fuels has emerged among much of the population. Renewables are carbon free and sustainable, but lack the reliability of fossil fuels, which can be dispatched on demand. Hybridization is often overlooked as at least an interim solution. By hybridizing a system, the benefits of each type of technology is realized, with the emissions benefits of renewable generation and the reliability of a fossil fuel system. In this work, a hybrid solar thermal and natural gas concept is explored. A central receiver solar concentrating system is used to pre-heat compressed air before it enters a conventional natural gas combined cycle power generation system. High temperature packed-bed thermal energy storage (pre-gas combustion) is used to increase the solar share of the plant. With the plant operating in hybrid mode, the flexibility of the storage and the supplemental natural gas are used in an optimization-based control scheme to maximize the amount of solar energy collected. This configuration demonstrates that by using a fossil fuel with a variable source of renewable energy, a certain synergy is achieved, with the system flexibility being leveraged to maximize the amount of solar energy harvested. The study presented is based on experimental and simulation results and highlights many of the feasibility challenges associated with achieving such a concept at grid scale.