The draft report by the Public Utility Commission nails down costs for the most ambitious clean energy plan in the nation at a time of economic turmoil and as Congress considers federal legislation.
California already requires 20 percent renewable energy by 2010, and the PUC report said that, if all that power was in place by 2020, new generation and transmission building costs would be $51.8 billion and electricity costs would rise to 15.
8 cents per kilowatt hour from 13.2 cents in 2008.
Aiming for 33 percent renewables by 2020, as Governor Arnold Schwarzenegger has advocated, would more than double capital costs to $114.5 billion and would increase state electricity costs to 16.9 cents per kilowatt hour, the report said.
It also said that hitting the 33 percent target was realistic only in 2021, which it called the "best case" scenario.