Peter Thiel, Bill Gates, Khosla Get Behind Energy Storage Start-Up LightSail in $37M Deal

A clean-tech start-up that thinks it has solved a problem that has vexed engineers for decades–how to effectively store energy generated by wind and sunshine–has gained some heavyweight financial backers.

An investment group that includes Bill Gates and Peter Thiel, the co-founder of PayPal and the first outside investor in Facebook Inc. FB +2.49%, has poured $37.3 million into LightSail Energy, a three-year-old start-up dreamed up by a Princeton graduate school dropout. Thiel led the investment.

Danielle Fong, now 25, said it took LightSail about a year to raise the Series D funding because investors are more wary of clean technology since solar power company Solyndra spectacularly failed in 2011. Solyndra burned through nearly $1 billion from private investors and more than $500 million in Department of Energy loans before declaring bankruptcy.

LightSail has found investors “who can truly think for themselves,” she said.

While wind produces energy when it’s blowing and the sun when it’s shining, storing renewable energy in large quantities, for ongoing use, is tricky. Common approaches have included electrochemical batteries, mechanical devices such as flywheels, and liquefied air.

“The overall problem of how to store large amounts of energy is one we’ve been working on for a century without a lot of success,” said co-founder and Chief Executive Steve Crane. “We’re good at cell phone and laptop batteries and maybe scaling to run cars, but that’s as far as we’ve gone successfully up to now.”

Fong, who at the time she co-founded the company had dropped out of a Ph.D. program at Princeton University that she began when she was 17, began thinking that water and compressed air could be combined to solve the energy storage problem. Water spray, because of its high surface area and heat capacity, would work extremely well as a heat exchanger, she reasoned.

By spraying water droplets into the air as it compresses in a technique called isothermal compression, the droplets absorb most of the heat, so that the air’s temperature doesn’t change much and most of the energy is still available. The water is then separated from the air and recycled.

The founding team ripped up an old firehouse in Oakland, Calif., so they could install pipes and build a prototype of a reversible system that stores and releases energy by compressing and expanding air.

There are hurdles to LightSail’s approach–water droplets, for instance, need to be the right size and volume, and they need to be pumped in without using too much energy.

Another risk of isothermal compression is that water can get trapped inside a cylinder, in a condition called hydrolock, and cause the cylinder to explode, Crane said. But these problems haven’t occurred with LightSail’s technology, he said.

The technology intrigued Gates, the Microsoft co-founder who is a limited partner in Khosla Ventures, a LightSail backer since 2009. Thiel, who created controversy last year when he declared at a TechCrunch conference in San Francisco that clean-tech was a “disaster,” was also convinced.

In a statement, Thiel said that “it’s time to find honest companies that can develop technologies that stand on real innovation instead of the backs of taxpayers.”

Two competitors, General Compression and SustainX, are also working on technology that uses compressed air to store energy. Both companies have received funding from the U.S. Department of Energy. Crane said LightSail was rejected in its bid for Department of Energy funding, though he wouldn’t rule out pursuing government funding in the future.

LightSail is now in talks with potential customers, which include solar and wind developers and large industrial companies that want more control over their power supplies, Crane said. Over time, he said, the technology should cease to be exotic and will become “mainstream, grid-scale energy technology.”

First, though, the company has to ship products. LightSail’s website depicts them as air storage tanks with power units that can fit inside shipping containers. They are now likely due in 2014.

LightSail has raised a total of $52.3 million. Other financial backers include Innovacorp and individual investors. Valuation is not disclosed.

 

WSJ