Curtailment of Renewable Energy in California and Beyond

California is blazing a path to a low-carbon future through greater use of renewable electricity. But as wind and solar rapidly grow, grid operators are raising concerns about periods of over-generation and the specter of large amounts of curtailment. Curtailment is an easy response, but it is wasteful and undermines the investor confidence needed to transition the California power system. A host of supply-side and demand-side measures can keep curtailment to minimal levels, but policy reforms also are needed to make curtailment a viable tool.