Thermal Efficiency of Natural Gas-Fired Generation in California: 2017 Update

Senate Bill 1389 (Bowen and Sher, Chapter 568, Statutes of 2002) directed the California Energy Commission to adopt an Integrated Energy Policy Report (IEPR) every two years. This staff paper supports the IEPR technical analyses by describing general trends in the average thermal efficiency of natural gas-fired generation in California from 2001 through 2016. Over this 16-year period, California’s systemwide thermal efficiency improved by 23 percent due to the successful development of new combined-cycle power plants. A leveling off of gains in thermal efficiency in recent years is due to the impact from the large growth in wind and solar generation combined with the return of significant hydroelectric generation after a four-year drought displaced total output from gas-fired generation. In 2016, California’s non-GHG emitting electric generation accounted for 50 percent of total in-state generation, compared to 40 percent in 2015.