The California Legislature has passed the nation’s first energy storage bill, which could result in the state’s utilities being required to bank a portion of the electricity they generate.

Assembly Bill 2514 (AB 2514) now heads to the desk of Gov. Arnold Schwarzenegger (R), who has made climate change and green technology his political legacy as his final term winds down.

Energy storage is considered crucial for the mass deployment of wind farms, solar power plants, and other sources of intermittent renewable energy, as well to build out the smart grid.

On the West Coast, for instance, the wind tends to blow hardest at night when demand for electricity is low. If utilities can store that wind-generated power — and energy from solar farms — in batteries, flywheels, and other devices, they can avoid building and firing up those billion-dollar, greenhouse gas-emitting, fossil-fuel power plants that are only used when demand spikes.

AB 2514 won the support of Jerry Brown, the California attorney general who is the Democratic candidate for governor. The Sierra Club and union groups also support the measure. Various business organizations, including the California Chamber of Commerce, opposed the bill.

Sponsored by Assembly member Nancy Skinner, a Berkeley Democrat, the bill was stripped of its more stringent provisions by the time it emerged from the legislative sausage-making process on Friday.

Originally, AB 2514 required California’s three big investor-owned utilities — PG&E, Southern California, and San Diego Gas & Electric — to have energy storage systems capable of providing at least 2.25 percent of average peak electrical demand by 2015. By 2020 the target would rise to at least 5 percent of average peak demand.

The bill now only requires that the California Public Utilities Commission determine the appropriate targets — if any — for energy storage systems, and then require the Big Three utilities to meet those mandates by 2015 and 2020. Publicly-owned utilities must set energy storage system targets to be met by 2016 and 2021.

Still, AB 2514 is a significant step and could ultimately help jump-start the market for energy storage, which remains in its infancy.

PG&E, for instance, plans to build an experimental facility that would tap electricity generated during peak wind farm production to pump compressed air into an underground reservoir. When demand jumps, the reservoir would release the air to run electricity-generating turbines which are capable of producing 300 megawatts of power.

And last week, PG&E proposed building a “pumped hydro” storage system. As its name implies, the system would pump water from one reservoir to another reservoir at a higher elevation during times of peak renewable energy production. Water in the upper reservoir would then be sent back downhill to power a turbine when electricity demand begins to spike.