California faces grid challenge to implement 33% aim

US: Accommodating California governor Arnold Schwarzenegger's goal of 33% renewables by 2020 will require the state's grid operator to make "major changes" to its operations, a report has concluded.

California governor Arnold Schwarzenegger aims to derive 33% of energy from renewable sources by 2020

The report by energy consultancy KEMA for the California Independent System Operator (CAISO) said reaching the goal, set by Schwarzenegger in November 2008, will require major changes to CAISO’s electricity scheduling practices.

The study examined the benefits of using electricity storage to balance the state’s electric load and reduce reliance on conventional generation. The report concluded that a 30MW to 50MW storage device can be as effective as a 100MW combustion turbine.

This would allow CAISO to respond to minute-by-minute changes in renewable energy production, KEMA said.

Without the recommended changes in operation or sufficient storage, meeting the 33% goal would require between 3GW and 5GW or more of fossil fuel-powered or hydroelectric generation to balance the system, the report concluded.

It did not compare the relative costs of storage and conventional generation.

The report is available at