One of the most-discussed drawbacks to solar and wind as sources of electricity is that they don't always produce power when we need it. The sun goes down and the wind stops blowing, and suddenly the grid doesn't have those electrons to run our air conditioners and computers.
That's because electrical power on the grid is instantaneous. The grid doesn't store electrical power: it's either being generated when you use it, or it's not there for you to use.
But the agency responsible for regulating California power companies is working on changing that. The California Public Utilities Commission (CPUC) has released a draft of a policy that would require the state's three largest utilities to start acquiring power storage capacity, with a target of more than 1,300 megawatts of storage capacity by 2020.
As currently written, the rule would require Southern California Edison (SCE) and Pacific Gas & Electric (PG&E) to obtain 580 megawatts of electrical power storage capacity by 2020, while the smaller utility San Diego Gas & Electric (SDG&E) would have a target of 165 megawatts of storage. SCE's and PG&E's targets would be roughly equivalent to adding a mid-sized coal plant to the grid
The rule would also require Community Choice Aggregators (cities or counties that buy renewable energy in bulk for their residents) to buy or build enough power storage capacity to cover 1 percent of their peak demand by 2020, with other smaller utilities required to meet that standard by 2016.
Electrical power storage is relatively straightforward: the power can be stored as potential energy by pumping water uphill to run back down through turbines when power is needed, or in the form of mechanical energy as in a flywheel, or, as in the case of most batteries, as chemical energy. Tech breakthroughs in areas such as supercapacitance offer the possibility of storing the electrical power as electrical power, though practical applications are unlikely in the next year or two.
The problem with more established power storage technologies is how much they cost when scaled up to serve the needs of the grid. It's one thing to pay ten bucks for a backup battery to recharge your phone: it's another thing entirely to try to store enough power to charge all the state's phones. And laptops. And refrigerators.
The CPUC expects to begin discussing the proposed rule in October. Among the details to be worked out are whether pumped storage projects, like that proposed for Eagle Mountain, should be counted toward utilities' storage goals. Some parties to the discussion point out that pumped storage is a mature technology that needs state incentives less than other more experimental techs do. If there's one thing we already now how to do in California, it's pumping water uphill.
Utilities and trade groups will also likely quibble over some of the interim benchmarks in the proposed policy.
The proposed CPUC decision is part of the agency's attempt to comply with AB 2514, the state's energy storage mandate law signed in 2010 by former Governor Arnold Schwarzenegger.