Hydropower generation in California dropped to 10.5% of total electricity generation during the four-year period from October 2011 through September 2015, according to a new report, Impacts of California’s Ongoing Drought: Hydroelectricity Generation 2015 Update.
The report was authored by Peter H. Gleick with the Pacific Institute, which “creates and advances solutions to the world’s most pressing water challenges.”
The past four years were the driest and hottest in the instrumental record and one of the worst droughts in memory, the report says.
Reductions in supply as a result of lower hydroelectric generation were made up primarily by burning more natural gas, increasing purchases from out-of-state sources, and expanding wind and solar generation.
During the 2007-2009 drought, hydroelectric production accounted for about 13% of the state’s overall electricity generation. Hydropower averaged a contribution of 18% from 1983 to 2013. Total installed hydroelectric capacity in the state is about 14,000 MW.
Because hydropower is “considerably less expensive than other forms of electricity” the drought increased electricity costs to California ratepayers. The report indicates the drought increased statewide electricity costs by about $2 billion.
The drought has an environmental cost as well. “The additional combustion of fossil fuels for electric generation also led to a 10% increase in the release of carbon dioxide from California power plants.”
The Pacific Institute has analyzed the consequences of several California droughts, including the 1987-1992 drought.