California this week moved a step closer to mandating the rollout of energy storage systems capable of supporting new renewable energy projects, passing a critical bill in the state senate.

Bill AB2514 would require the Public Utilities Commission to set targets for systems that store energy. Both public and private utilities in the state would then be required to help meet the targets, the legislation said.

"This bill requires load-serving entities to meet any targets adopted by the commission by 2015 and 2020," it stated. "This bill requires publicly owned utilities to set their own targets for the procurement of energy storage and then meet those targets by 2016 and 2021."

Energy storage systems are widely regarded as crucial for the efficient operation of power grids that are reliant on a high proportion of renewable energy sources such as wind and solar power. Experts claim that large-scale energy storage systems would allow grid operators to cope with fluctuations in renewable energy output, ensuring they can always meet base load requirements.

Energy storage also enables utilities to sell stored renewable energy during peak times when energy prices are higher, helping to make renewable projects more economically viable.

The bill was voted through the California senate this week, but it is still not law. It now returns to the state assembly for concurrence in senate amendments, which will assess amendments made to the legislation during its senate hearing. If it succeeds there, it will go before governor Schwarzenegger. The deadline for the governor to sign the bill into law is September 30.

The passage of the bill would provide a major boost to emerging energy storage firms working on various grid-scale energy storage systems.

Most notably, battery specialist A123Systems recently launched a new spin off firm, named 24M, that is working on the development of large-scale flow batteries, while Beacon Power is currently working on the first large-scale flywheel energy storage facility in Stephentown, New York.

In related news, California's plans to increase it solar capacity have also moved forward after the state energy commission's siting committee last week recommended approval for a proposed 250MW solar thermal power plant.

The project, which is being developed by NextEra Energy at a site in the county of Riverside, is the latest in a series of large-scale solar plants backed by the committee.

In total, the committee has recommended approval for over 2,100MW of solar capacity in the past month, including the 250MW Abengoa Mojave facility, 250MW Beacon site, 1,000MW Blythe project and 370MW Ivanpah development.

As with the other projects the committee's recommendation does not represent a final decision on the planning application as the ruling will now be subject to consultation. However, if the recommendation is upheld NextEra could begin work at the site before the end of the year.