In yet another testament to the power of renewable energy and energy efficiency, they are responsible for a historic downturn in California's carbon emissions.
From 2010-2011, the state's emissions dropped an impressive 22%, and from where? From the very power plants that until then were the state's leading source of greenhouse gas emissions.
As of last August, the three biggest utilities all get 20% of their electricity from renewable sources.
And 2011 was the third consecutive year that California's carbon emissions came down. The state is solidly on track to meet its 2020 target, says the state's Air Resources Board (ARB).
The goal is to cut emissions 15% by 2020, from 1990 levels.
This is all because of California's strong Renewable Portfolio Standards, which require utilities to source 33% of electricity from renewable energy by 2020. Last February, the state hit an important milestone - wind now supplies 5% of its electricity.
And because the state officially prioritizes energy efficiency as the "first" power source, followed by renewables to meet energy demand.
Emissions from industrial sources, on the other hand, are still rising, from sources such as refineries (single biggest source), oil and gas production and cement plants. Those sources are the target of California's new cap-and-trade program.
The program requires the state's biggest polluters to disclose greenhouse gas emissions each year.
About 430 utilities, oil refineries and producers, and large manufacturers are subject to the program, which sets industry-wide limits on those emissions.
California's next carbon auction is scheduled for February. Many people aren't aware that it's open to individual investors as well as corporations.
Take a look at the status of renewable energy in every US state.