A Resurgence We Can’t Afford

California is working toward supplying 33 percent of its electricity from renewables by 2020 and considering a 50 percent target by 2030. To maintain grid reliability without relying on carbon-emitting natural gas plants for ancillary services, the state must address 'overgeneration'—where renewable supply exceeds demand—which currently leads to the curtailment of clean energy. The document proposes several grid integration solutions: targeting energy efficiency during evening hours, diversifying the renewable fleet (wind, solar, bioenergy, and geothermal), increasing coordination between regional grid operators, deploying energy storage (pumped hydro, compressed air, and batteries), and using demand response technologies to shift electricity consumption to peak renewable output periods.

• California is progressing toward a target of 33 percent renewable electricity by 2020 and is evaluating a more ambitious goal of 50 percent by 2030.
• Grid reliability requires 'ancillary services' to balance supply and demand; these are currently largely provided by natural gas and hydropower, meaning natural gas plants often remain online and emitting pollution even when their energy is not needed.
• The California Independent System Operator (CAISO) currently manages 'overgeneration'—when renewable supply exceeds demand—by curtailing renewable energy, which wastes clean electricity while keeping natural gas plants active.
• To integrate more renewables and reduce natural gas reliance, California should implement strategies including energy efficiency for evening peaks, a diverse mix of renewables (wind, solar, bioenergy, geothermal), regional grid coordination, energy storage (batteries, pumped hydro, compressed air), and demand response technologies.

APA

Union of Concerned Scientists (2015). A Resurgence We Can’t Afford. https://www.ucs.org/sites/default/files/attach/2015/03/california-renewables-and-reliability.pdf

Chicago

Union of Concerned Scientists. A Resurgence We Can’t Afford. 2015. https://www.ucs.org/sites/default/files/attach/2015/03/california-renewables-and-reliability.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=A Resurgence We Can’t Afford |date=March 2015 |url=https://www.ucs.org/sites/default/files/attach/2015/03/california-renewables-and-reliability.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2015resurgence, author = {{Union of Concerned Scientists}}, title = {{A Resurgence We Can’t Afford}}, institution = {Union of Concerned Scientists}, year = {2015}, month = mar, url = {https://www.ucs.org/sites/default/files/attach/2015/03/california-renewables-and-reliability.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }