California is exploring a unique type of battery to help power the clean energy revolution: compressed air batteries. This underground $1 billion battery is a giant, clean energy generator that could change the game for sustainable renewables. Why a new type of battery? Compressed air batteries can help store more solar power at night, making this sun-powered energy source more viable as a 24/7 source of clean power for homes and businesses.

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Why do we need another new form of battery?

Here’s why compressed air batteries are a hot new area of interest. They don’t require lithium, which is expensive and hard to procure and potentially polluting. Also, they store energy like solar and wind when the sun isn’t shining and the wind isn’t blowing. In short, this expensive new technology could make renewable energy cheaper, more reliable at all hours of the day as an energy source and could power entire communities.

Related: What you need to know about batteries to store solar power

A group of local municipalities in California just signed a 25-year $775 million contract to buy power from what will be the world’s largest compressed air storage project. This could help California transition off fossil fuels without causing blackouts.

“We need a diverse fleet of resources. This new technology is a critical component of that,” said Robert Shaw, chief operating officer at Central Coast Community Energy, who signed the contract. “That’s how we get to 100% renewables.”

Phasing out coal and natural gas is important to curbing climate change. It’s also important to build energy infrastructure that can cope with the increasingly extreme weather that plagues places like California and soon will affect the whole world. California’s recent experience of generational floods replenishing reservoirs can’t make up for the thousand-year drought the state has struggled with in recent years, though it does buy some time. The state is a case study in how communities affected by climate change can build energy infrastructure that is designed for ups and down of weather extremes.

What about lithium ion batteries?

Solar and wind are great low-cost renewable energy solutions, but transitioning over to clean energy requires battery technology to store and distribute that power at times when sourcing it is not reliable. Lithium ion batteries help, but lithium prices rose sharply in 2022 after the demand for electric cars rose.

And mining lithium can be fraught with problems from harm to local wildlife to exploitation of the environment in Indigenous communities and around sacred sites. Besides, the world knows that precious metals currently powering our battery technologies are in short supply, so a new solution is needed. Lithium ion batteries also only offer a few hours’ worth of electricity storage.

How compressed air batteries are superior to lithium ion batteries

Hydrostor, the developer of the California compressed air battery project, will drill three shafts several thousand feet below ground. They will then send down miners to dig out a set of rows and columns amounting to the volume of two football fields 300 feet high.

The company will use cheap electricity on sunny afternoons when California has more solar power than it needs to push air down into the caverns. When Hydrostor’s client Central Coast Community Energy needs to draw on that power on a cloudy day, they will open a valve and funnel high-pressure air through a turbine, generating electricity. Think of it like a hydroelectric dam using air.

The technology has already been used in places with natural underground salt domes, where companies pump water down to dissolve salt and hollow out large caves. There have been salt dome compressed air storage projects in Alabama and Germany. Traditionally, these projects depend partly on natural gas to heat compressed air as it leaves caverns to make it more efficient.

Hydrostor is fixing these deficiencies in the technology. They have figured out a way to capture and reuse heat generated when the air is compressed, which means no gas needs to be burned. The company also found a way to dig caverns out of rock rather than salt, opening up the possibility of compressed air battery storage all over the world.

Does compressed air battery storage really work?

Is this yet another greenwashing project to make a startup some money while the world frets over climate change? Time will tell, but Hydrostor has built a small commercial project in Canada already. The new facility in California will be one of its first two large-scale developments of this technology.

Goldman Sachs backed Hydrostor with $250 million last year. The Canadian Pension Plan offered $25 million. Analysts say any new technology will need to work out the kinks, but they have some degree of confidence that Hydrostor can pull this off, making California even more energy independent and sustainable. Hydrostor projects that it can produce 60% to 65% of the electricity it consumes, which is a larger loss of energy than with lithium ion batteries or similar types of storage. This makes it a pricey inefficient alternative to today’s batteries. There are also questions about the environmental impact on local wildlife of the project still being worked out by local officials.

Why go with a battery technology that is pricier and less efficient? Because it lasts. A long time. Lithium ion batteries degrade and must be replaced every few years, while compressed air caverns can store energy for decades without any loss of efficiency. They can supply the grid energy for longer than a four-hour battery: the 200 megawatts under contract to Central Coast that is part of Hydrostor’s 500-megawatt project will provide eight hours of backup power.

California is going ahead with this project despite its drawbacks to make the initial investment in what it sees as a long-term solution to the volatility in the lithium market and the long-term costs and challenges of energy storage.

Via L.A. Times

Lead image via Hydrostor