Concentrating solar plants (CSP) generate solar thermal electricity (STE) while producing no greenhouse gas emissions, so it could be a key technology for mitigating climate change. In addition, the flexibility of CSP plants enhances energy security. Unlike solar photovoltaic (PV) technologies, CSP plants use steam turbines, and thus can provide most needed ancillary services. Moreover, they can store thermal energy for later conversion to electricity. CSP plants can also be equipped with backup from fossil fuels delivering additional heat to the system. When combined with thermal storage capacity of several hours of full-capacity generation, CSP plants can continue to produce electricity even when clouds block the sun, or after sundown or in early morning when power demand steps up.