Power Storage, Missing Link in Path to Renewables, Gets a Mandate in California

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Electricity, despite having transformed nearly every aspect of life on Earth, remains a technology with some significant limitations. More than half of the energy that goes into producing electricity is lost, and even the energy that is successfully converted into electricity is a use-it-or-lose it proposition, so much of it ends up wasted as well.

The inability to store electrical power has become more important as the developed world has begun to try to adopt cleaner energy sources, such as solar and wind power. The sun isn’t always shining and the wind isn’t always blowing, but people and factories always need electricity.

But energy storage is getting its mainstream debut in California. The state has mandated that by 2024, its three major utilities provide 1,325 megawatts of storage, roughly equivalent to what one major power plant produces and about a fifth of a percent of what the state used on average per day, according to the most recent state statistics.

“Storage is a game-changer that can help people manage their energy use and expand the capacity of renewable resources to provide power to homes and businesses. This decision will spur investment and innovation in energy storage and help Californians unleash their creative and economic power,” Catherine Sandoval, a member of the California Public Utility Commission that issued the new requirement, said in a news release.

Castaic-pumped-storage-californiaStoring electrical power isn’t technically difficult; the challenge is doing it at a price that makes it worthwhile as a regular practice. California hopes to push the industry to get there faster, just as it did in 2002 with its early requirement that utilities use renewable sources for 20 percent of the power they sell.

Worldwide, there’s only enough storage on the grid to handle 1 or 2 percent of what’s generated, according to Gregg Maryniak, who leads Singularity University’s Energy and Environment instruction.

“It’s really important that there’s that mandate. It’s an important and progressive step to have for storage,” he said.

The most common method of storing electrical power involves pumping water uphill when power is abundant, and then using the water to generate power hydroelectrically when power is needed. The new rule limits how much of this type of storage utilities can count toward the mandate. Other methods in use also rely on particular types of geography to work, sidelining them from wider use.

The renewable energy industry has had stronger motivation than conventional utilities to make storage work.

solana-arizonaConcentrating solar power arrays, which tap the thermal energy of the sun, also sometimes use molten salt to store heat for later use. The salt is stored in tanks and used to drive a steam turbine when energy is needed and the sun isn’t shining.

There are new methods in the making as well. Halotechnics, based in Emeryville, Calif., has developed a glass with an even higher melting point than salt in order to increase storage efficiency. Berkeley-based Lightsail has pioneered more efficient methods to compress, and later decompress, air as a way to store electricity.

These companies and others will get a boost from California’s new requirement. And if storage works in the Golden State, similar requirements will likely march across the rest of the U.S. and Europe.

But only time will tell: The storage facilities aren’t required to be operational until 2024.

Parabolic trough concentrating solar array by Z22 via Wikimedia Commons
Castaic Power Plant, a pumped-storage plant near Los Angeles: State of California via Wikimedia Commons
Solana power plant, an Arizona plant that uses molten-salt storage, Concentrating Solar Power Alliance

Discussion — 15 Responses

  • Barnaby Dawson November 1, 2013 on 2:47 pm

    For an energy storage solution to make sense it needs to be efficient, high density and use materials that are abundant (so it can scale).

    Air storage (pressure potential energy) and hydro (gravitational potential energy) require special geology so they won’t scale. Battery power (chemical energy) doesn’t use abundant materials and is low density. Creating oil using electricity is possible but inefficient. Nuclear energy isn’t on the table. Kinetic energy is too low density. Thermal energy doesn’t require special geology and can be stored using abundant materials (salt).

    My money is on molten salt as the most promising technology.

  • Andrew Guenthner November 1, 2013 on 10:45 pm

    The author has confused units of energy (MW h — the total energy delivered by the grid over time) and power (MW — the instantaneous “load” on the grid). The mandate is for 1,325 MW of “storage”, but in this case the commission’s decision states that “MW represents the peak power capacity of the storage resource in terms of the maximum
    discharge rate”, not the actual amount of energy stored (which would be MW h). The CASIO grid typically serves 20,000 – 50,000 MW of load, so the mandate states that utilities must have the ability to supply roughly 2 – 5% of that by tapping sources of stored energy. The intent is not mainly to provide the power in a sustained fashion over long periods, except perhaps near the times of peak usage, but rather to smooth out the fluctuations in wind and solar power caused by things like clouds moving over a large photovoltaic array. For instance, when the sun is shining, the owner of the storage system will buy some electricity and charge the system, then when it’s cloudy, the owner will sell back the power (presumably at a premium because it is needed) and discharge the system. When the sun returns, the owner will draw some of the newly available power to recharge, and so on. This could happen many times in one day. The actual storage capacity will depend on things like how long the capacity has to be maintained in order for the system to be allowed to connect to the grid, the patterns of charging and discharging (at varied levels) needed, and the economics of selling electricity on the “spot” market, none of which I understand. The main point is: you can’t divide the instantaneous power (MW) by how much electricity is used in a day (MW h) and get a meaningful number.

  • billy the worm November 5, 2013 on 9:45 am

    From “Whispers in a silent universe” google it

    The Singularity arrives with much fanfare. Millions gladly volunteer their life’s savings to become pioneers in a world that holds the promises of heaven. The inaugural celebration is marred by the recent death of Ray Kurzweil, the visionary whose dream they had followed. They hail him in death a techno messiah, so tragically taken a mere month before by choking on a handful of vitamins he himself had invented. The people enter this new cyberverse with new bodies that never grew old, living in habitations that require no work, where every house is a mansion and all do as they please in opulent splendor. The people left behind, the religious, the frightened, the stubborn, are soon forgotten. Life is a dream for nearly three hundred years. Then cracks begin to form. People with similar interests–golf, climbing, card games, and the like–spontaneously begin adding page after page of new rules and regulations to their club charters, new dress codes, new clarified rules governing conduct and guests. People now able to think of any meal and have it appear in front of them are no longer happy with the dish. The citizens of the Singularity start making public displays of their dissatisfaction: “So help me, Janet, if I have to eat steak tartar again I am going to stick a fork in your eye,” and so forth. People become increasingly less tolerant of company and their surroundings. The powers that be think that there must be a glitch in the system, so they conduct rigorous troubleshooting efforts to find the problem. They find none. Everyone is getting exactly what they want, when they want it, but still they can’t shake the collective feeling that everything is “Going to Hell in a handbasket.” The feeling of discontent grows to a point that a vote is to be held, whose outcome will decide whether even to continue on at all. The ballots finally are cast, and the people overwhelmingly support soldiering on still. The powers that be, however, override the majority as a “Bunch of know-nothing assholes,” and pull the plug on the Singularity, killing themselves and five billion other perfect humans.

  • Quantium April 14, 2014 on 1:40 am