A New California Law May Make Renewable Energy More Viable Than Ever

The bountiful potential of renewable energy can't fully be realized until we figure out how to effectively store power for when the sun goes down. In a bid to solve the storage problem, the California Public Utilities Commission has created the first mandate for utilities to create energy storage systems in United States.

Under the just-decided plan, the three investor-owned utilities in the states, PG&E, Southern California Edison, and San Diego Gas & Electric, will have to establish 1.3 gigawatts of energy storage by 2020. The exact technology used is not specified, but applications describing their initial efforts to supply 200 megawatts of this storage must be filed by March 1 of next year, with the full storage capacity being completed by the end of 2024.

The target capacity of 1.3 gigawatts is sufficient to supply roughly 1 million average California homes with electricity. At the state's current electrical generating capacity, this is about 1.8 percent of all the power generated in the state. It's a considerably smaller percentage factoring in that California imports a bit under half of all the electricity it uses.

The mandate also establishes a target for community choice aggregators and electric service providers to "procure energy storage equal to 1 percent of their annual 2020 peak load," again by a 2020 deadline, with installation completed by the end of 2024.

Energy storage is of utmost importance in creating an electricity supply coming from all renewable sources. Quoted in the San Jose Mercury News, Public Utilities Commissioner Mike Florio said, "Storage really is the game changer in the electric industry. While this new policy is not without risk, the potential rewards are enormous."

Energy storage is a crucial component in addressing the intermittency of renewable energy production. Unlike combustible fuels used to generate electricity (that is, pretty much all of what's now used, saving hydropower) which can be simply used as needed with the daily and seasonal rise and fall of power demand, you've got to make electricity from most renewables when the weather conditions are suitable. Solar panels don't work well in the rain; wind turbines only turn when the wind is blowing. This can mean there are times when more electricity is produced than is needed, and vice versa. Energy storage evens that out.

The new mandate doesn't specific which technologies utilities are required to be used, just as how they will generate one-third of their electricity from renewables is not specified.

The most common grid-scale energy storage used today is pumped-storage hydropower, but this backs a miniscule fraction of all the energy produced. Expansion of the tech is limited by geography—you need two bodies of water nearby one another with a suitable gradient in between—and there's little room for expansion because of this.

Compressed air energy storage, which essentially fills a large underground cavern with compressed air that can be released at will to turn a turbine, has potential and room for expansion. Molten salt storage is a compelling option for concentrating solar power plants. Grid-scale batteries and fuel cells are calling out for more R&D and deployment, keeping in mind the radically different amounts of embedded energy in them, depending on their construction. Flywheel energy storage is another option, though less widely known and touted than the previous methods.

Regardless of what ends up taking off—like renewable power generation itself, it's likely to be a mix—solving the storage problem is key to building a grid that can rely on renewable sources, rather than be augmented by them. With the new mandate, California may be the first to figure it out.