Compressed Air Energy Storage from LightSail Energy

In past articles, we discussed the rapidly growing grid storage market, and looked at one of the 5-largest recipients of VC funding in history, Bloom Energy, which is addressing this market with solid oxide fuel cells. However, fuel cells and flow batteries are not the only viable methods of storing grid energy. For many years now, compressed air energy storage has been regarded as the possibly lowest-cost technology available for large-scale energy storage. However, this potential has also been somewhat shelved due to the thermodynamic inefficiency of conventional air compressors and motors. For the first time in the history of energy storage technology, a group of experts claims to have designed a technology that enables large-scale storage systems with high round-trip thermal efficiency and high power density for a low cost. LightSail Energy aims to produce the world’s cleanest and most economical energy storage systems using compressed air.

About LightSail Energy

In 2009, a group of expert scientists united with business-minded people to found Berkeley, California-based LightSail Energy. The company’s co-founder and Chief Scientist, Danielle Fong, was featured as one of Forbes Magazine’s 30 Under 30 energy Innovators for three consecutive years and was hailed as the youngest name of last year’s MIT Technology Review 35.  Several months ago, former senior GE executive Volker Schulte was named COO, while Quantum Technologies’ former CTO Neel Sirosh also moved to LightSail Energy as its VP and General Manager of Gas Storage. In 2012 Lightsail raised $37.3 million in a series “D” investment round led by PayPal co-founder Peter Thiel and included Khosla Ventures, Total, as well as Microsoft founder Bill Gates.

The Process

LightSail’s process is simple. To store energy, an electric motor drives an air compressor. To deliver energy, they reverse the process and the air compressor becomes an expander, and the electric motor becomes a generator. The key to their system is an innovation which involves “an elegant method of capturing heat energy and regenerating useful energy from it.” The company’s new technology allows the injection of a fine, dense mist of water spray during air compression which in turn absorbs the heat energy of compression in a notably quick span of time. Once heat is captured by the water spray, the compressed air is now stored securely in a tank for a later use. When the energy is needed, the expansion process allows the previously stored heat to be sprayed into the air which is then converted back to be used as a cheap and environmental-friendly source of mechanical energy. LightSail Energy’s unique energy storage design makes it possible to supply power even when the conventional grid is undependable or absent for any reason and can do so at a round trip thermal efficiency of 90 percent.

LightSail Energy is confident that its “first-generation product” will help renewable energy resources to come up with cheaper electricity “than that produced by diesel generators, the fossil fuel-based competitor to beat on islands and isolated grids.” The company adds that its “second generation product will be the first energy storage system to outcompete gas peaker plants and will drive massive adoption of green energy worldwide.” The below cost comparison chart shows just how efficient LightSail expects their system to be:

Source: Lightsail Energy

If the process of compressing air sounds simple, LightSail has gone to great lengths to protect their proprietary process having 30 patents under the title “Compressed air energy storage system utilizing two-phase flow to facilitate heat exchange“. Additionally, the company is filing patent applications consistently over time to further improve upon their technology:

Source: Patentdocs

With strong financial backing from notable investors, and with air being the cheapest thing there is, LightSail looks to be a formidable competitor in the race to capture market share in the rapidly growing grid storage market.

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