US clean-tech start-up LightSail Energy raises US$37.3m from investors, including Bill Gates

6 Nov 2012

LightSail's industrial scale prototype machine. Image via

Microsoft chairman Bill Gates and PayPal co-founder Peter Thiel are two of the investors who have contributed to a US$37.3m funding injection into LightSail Energy, a US start-up that is pioneering a unique energy storage technology using compressed air

As reported in The Wall Street Journal yesterday, the three-year old start-up, based in Berkeley, California, has raised US$37.3m in a Series D funding round that included one of the company’s first investors Khosla Ventures, as well as PayPal co-founder Peter Thiel, who led the investment, and Microsoft founder Bill Gates.

LightSail was co-founded in 2008 by Danielle Fong after she dropped out of a PhD at the Plasma Physics lab at Princeton University. The start-up now employs around 30 engineers and scientists who are working on its energy storage technology.

To date, LightSail has raised US$52.3m in funding. Other backers in LightSail include Triple Point Capital and Silicon Valley Bank.

The start-up is on a mission to come up with the cleaner and more economical energy storage systems.

LightSail’s method is based on a new approach to capturing heat energy and regenerating energy from it. The idea behind the technology is to inject a mist of water spray, which absorbs the heat energy of compression and provides it during expansion.

To store energy, the company said an electric motor will drive an air compressor. Then, the process is reversed to deliver energy – the air compressor becomes an expander, while the electric motor becomes a generator.

LightSail anticipates that its first product will be ready in late 2013.

Carmel Doyle was a long-time reporter with Silicon Republic