Concentrating solar power (CSP) with thermal energy storage (TES) is a dispatchable source of renewable electricity generation. However, the dispatchability of this resource is limited by the availability of solar energy. This makes it challenging to quantify the value of CSP and provide comparisons to alternative generation sources.
The California Independent System Operator (CAISO) has prepared a number of analyses of the grid operational challenges associated with the state’s 33% renewable portfolio standard (RPS). These analyses, which used a commercial production cost model, created a publically available database of the CAISO system. This database can be used as a basis for analyzing the potential value of CSP with TES in California.
This analysis used the “Environmentally Constrained” 33% RPS scenario database in the PLEXOS grid simulation tool to estimate the value of CSP in avoiding conventional fossil generation, and compared this value to other sources of generation. To perform this analysis, we created a baseline scenario and added four types of generators, each in a separate scenario. The four generator types were photovoltaic (PV), a baseload generator with constant output, a CSP plant providing dispatchable energy, and a CSP plant providing both energy and operating reserves. Each generator added the same amount of energy (about 1% of annual demand) for an equal comparison of their value. In each case, we calculated the difference in production costs between the base case and the case with the added generator. This difference in cost was attributed to the added generator as its operational value to the system.