SustainX Delivers Compressed Air Energy Storage System

July 1. 2014. 3 mins read
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In a previous article, we highlighted LightSail Energy, an interesting company which aims to produce the world’s cleanest and most economical energy storage systems using compressed air. Compressed air energy storage has been regarded as possibly the lowest-cost technology available for large-scale energy storage, however, it has never been commercially viable due to the thermodynamic inefficiency of conventional air compressors and motors. Too much energy is lost while compressing and then decompressing the air to make the process commercially viable. Lightsail Energy claims to have solved this problem with a fine water mist, but they aren’t the only ones with a solution. A company called SustainX has developed their own “isothermal compressed air energy storage (ICAES™)” technology which claims to have a thermal efficiency of 95%, just beating LightSail Energy’s claimed thermal efficiency of 90%.

About SustainX

Founded in 2007, Seaview Newhampshire based SustainX was spun out of the Thayer School of Engineering at Dartmouth and has taken in$30 million in funding so far from the US Department of Energy and the National Science Foundation as well as top-tier investors. Firms such as Polaris Venture Partners, General Catalyst Partners, RockPort Capital Partners, Cadent Energy Partners, and GE Energy Financial Services have made investments in SustainX so far. The Company has a strong IP position which is comprised of over 100 filings for ICAES™ innovations and at least 32 issued patents which they have listed on their website.


Although compressed air energy storage systems have been around since the 1970s, they need to be placed in caverns in order to achieve sufficient thermal efficiency and require substantial amounts of time and money to develop. Given these limitations, SustainX claims there are only two such installations worldwide. However, in September of 2013, SustainX delivered the world’s first megawatt-scale compressed air energy storage system built anywhere since 1991.

SustainX’s First Installation (Source: IEEE Spectrum)

Located at their company headquarters, this 1.5-megawatt ICAES™ system uses foam-based heat exchange to cool the compressed air so that it achieves stated thermal efficiencies of >95% according to this white paper by SustainX that describes the method in detail. Because the system is based on proven mechanical principles and mature industrial components, it has a 20-year operating life with a very low cost of energy. According to an article by IEEE Spectrum, the project cost at least $10.8 million to fund with half of that amount coming from the U.S. Department of Energy. SustainX will use the machine to gather data on performance and to show off the technology to potential investors and customers.


Both SustainX and Lightsail Energy have focused on developing formidable intellectual property portfolios, attracted around the same amount of equity investments so far from some of the most notable venture capital companies in the world, and have reached an efficiency that makes compressed air energy storage commercially viable at a grid scale. With the two companies being so alike, competition will be intense and this will likely continue to spur further efficiencies and cost reductions. While SustainX appears to be first to market with their compressed air energy storage solution, neither company is providing enough information to see who will be the most capable when it comes to selling and delivering upon commercial implementations of their respective technologies. Regardless of which company comes out ahead in the end, the resulting technology may just make this a likely solution for solving our grid-scale energy storage needs.


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