The Value of CSP with Thermal Energy Storage in the Western United States

The value of electricity generation varies as a function of season, time of day, location, and the mix of conventional and renewable energy sources. The ability to control the output of a concentrating solar power (CSP) plant via the use of thermal energy storage (TES) creates the opportunity to maximize its value to the grid. This study performs a series of simulations of the grid in the western United States to determine how a CSP plant with TES might be dispatched to maximize its value when replacing conventional fossil fuel plants. The value of CSP with TES is compared to renewable generators without storage including PV. The study finds that TES adds value by timing CSP generation to periods when high marginal cost units would typically be generating. This includes periods of peak net demand in the summer, as well as periods where changes in demand require start-up and operation of high ramp-rate fossil generators. As a result, CSP with TES can avoid the least efficient generators, as well as avoid costly power plant starts. A significant source of value is the ability of CSP to provide operating reserves, requiring greater operation at part-load. This represents a potentially important opportunity for CSP plants, especially in high renewable scenarios where the requirements for reserves will increase. In addition to its operational value, the ability of CSP with TES to provide firm system capacity is also a quantifiable benefit and another important source of value.