Intelligent Energy

How SustainX's latest patent will improve grid storage

How SustainX's latest patent will improve grid storage

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Compressed air energy storage company SustainX recently received a patent for technology that could help improve grid storage and make utility-scale renewable energy less reliant on 'peaker' plants.

Compressed air energy storage company SustainX recently received a patent -- its seventh -- for technology that will make it easier and more efficient to transfer large amounts of power, which will support the construction of the company's megawatt-scale storage systems. In other words, the patent could help improve grid storage and solve intermittency, a critical issue with utility-scale solar and wind power plants.

This latest patent piggybacks on SustainX's existing technology by adding a mechanical crankshaft or hydraulics to its isothermal (meaning constant-temperature) compressed-air energy storage system. The crankshaft design has low frictional losses, making it efficient, and can transfer large of amounts of power, according to SustainX. In short, the crankshaft will help SustainX design more powerful, compact and efficient energy storage systems.

Traditionally, compressed air energy storage uses excess energy captured from a power plant to run air compressors, which pump air into underground tanks where it's stored under pressure. Once the air is released, it drives a turbine to generate electricity. Compressed air technology has, in fact, been around for decades, but it's not widely used in the United States. SustainX hopes to change that.

SustainX has helped drive innovation in compressed air technology and has created a next-gen system that eliminates one of the big problems: heat. When air is compressed to store energy, it heats up. If the heat isn't recaptured that energy is wasted. Solve the heat problem, and you'll make the system more efficient and cost effective.

SustainX has designed an energy storage system that removes heat from air being compressed for storage and adds heat to air being expanded to generate electricity. The company also uses overground tanks that use pistons to increase storage capacity further. And it uses off-the-shelf parts to drive down the cost to "disruptively" low levels. Meaning the cost could be low enough to displace natural gas power plants, which often play a back-up role to renewable energy.

The company has yet to reach commercialization, although it's getting closer. The company built a 40 kW project at its old headquarters in Lebanon, N.H. (Headquarters are now in Seabrook, N.H.) The four-year old company says it's on track to demonstrate its first megawatt-scale, grid-connected system in collaboration with AES Energy Storage.

SustainX is working both ends of the emerging market for utility grid-scale energy storage: conventional and renewable energy power plants. It could be particularly useful on large-scale wind and solar farms, which don't generate power when the wind doesn't blow and the sun doesn't shine. It could eliminate the need for alternative energy power plants to use so-called peaker plants, which burn natural gas to generate electricity when the clean energy isn't available.

Photo: EWEA

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Kirsten Korosec

Contributing Editor

Kirsten Korosec has written for Technology Review, Marketing News, The Hill, BNET and Bloomberg News. She holds a degree from Northwestern University's Medill School of Journalism. She is based in Tucson, Arizona. Follow her on Twitter. Disclosure