It’s no news to most people that renewable energy sources like wind and solar power have their off-moments, or off-days. A potential remedy was just signed into law by California Gov. Arnold Schwarzenegger, whose governorship has long had a greenish tinge. The state will now require utilities (first, investor-owned utilities, and later, publicly owned ones) to have storage capacity on hand that can quickly be put into use when the wind dies down.
As a technological and engineering concept, energy storage is as old as the concept of having two reservoirs at different altitudes (more about this in a minute) and as new as the lithium-ion battery. Like California’s renewable energy mandates, the requirement is meant to jump-start new battery and storage technologies by guaranteeing them a broader market.
Of course, it’s hard to imagine that battery designers need any more incentives, given the hunger of car manufacturers for a light, cheap, powerful battery that could take a car 300 miles on a single charge. But storage on the scale of power plants does present a different set of challenges.
The law will also serve another purpose, said Cliff Rechtschaffen, a special assistant to Jerry Brown, California’s attorney general and the Democratic candidate for governor, who was the originator of the bill: determining how energy storage should be defined for regulatory purposes.
The storage technology “shares aspects of both transmission, distribution, generation — at least in the way those things are defined technically,” he said. As a result of the law and the definitions to be developed by regulators, “there will be more market certainty about what storage is and what you use it for.”
The most common form of large-scale energy storage nationwide is hydro-storage, which involves pumping water from a lower-altitude reservoir into a higher-altitude one at times of low energy demand, when it is cost-effective to do so. When energy demands peak — or when the sun stops shining or the wind stops blowing — the water is released through narrow tunnels that house turbines that generate electricity. The turbines can be activated quickly and generate as much power as 300 megawatts or more.
The Sacramento Metropolitan Utility District has announced plans to build a new hydro storage facility near Placerville, not far from California’s Sierra Mountains.
But lawmakers backed away from the idea of setting timetables for the new program or determining how much storage the utilities must have on hand. So it will be up to the California Public Utilities Commission and the board of publicly owned utilities to work out those details over the next two years.