Energy-storage startup SustainX receives $5.4mn from DOE

WEST LEBANON, USA: SustainX, Inc., a startup developing a new technology for utility-scale energy storage, has received a $5.39 million award from the US Department of Energy (DOE).

The award will enable SustainX to develop its technology and eventually deploy a full-scale demonstration of its method for storing large amounts of energy using compressed air.

The DOE considers energy storage a crucial technology for the Smart Grid, the modernized version of the electrical grid that will be built over the next decade or two. The goals of the Smart Grid are higher efficiency, lower pollution, and lower cost.

The traditional grid stores almost no energy: electric supply from power plants must track user demand within seconds or minutes. When demand rises suddenly, so-called "peaking" turbines, fired by natural gas, must rapidly come on-line.

Since such plants are idle most of the time, they are an expensive source of power. With storage units scattered at strategic points throughout a Smart Grid, however, shifts in demand could be met more flexibly, lowering transmission and generation costs. For example, fewer peaking turbines would be needed.

Energy storage will also enable the grid to support greater integration of renewable energy sources. For example, wind turbines generate electricity only when the wind is blowing and solar panels only generate electricity when the sun is shining.

At present, the grid is able to accommodate only a certain amount of power from such sources, but with affordable storage, the grid will become more flexible and renewable generators will able to produce energy more steadily. However, no low-cost technology for utility-scale energy storage is yet on the market.

The SustainX energy storage system addresses this need by storing energy in the form of compressed air. Electrically-driven hydraulic pumps are used to compress air to high pressure (up to 3,000 psi) for storage above-ground in standard industrial pressure vessels.

This air is later expanded, powering a hydraulic motor that drives an electric generator. The technology uses isothermal cycling -- that is, the air is kept at a constant temperature -- coupled with staged hydraulic compression and expansion to deliver efficient, cost-effective energy storage.

SustainX's technology relies on off-the-shelf mechanical components, contains no toxic materials other than ordinary hydraulic fluid, and emits no air pollution or effluents. The company anticipates that its units will have extremely long cycle lifetime -- that is, will be able to charge and discharge thousands of times before needing replacement -- and will achieve high round-trip efficiency, allowing recovery of 70-80 percent of the energy required to charge them.

Using simple materials, reliable off-the-shelf components, and efficient air-handling techniques based on basic thermodynamic principles will result in breakthrough cost savings.

Each SustainX energy-storage unit acts, in effect, like a large storage battery. No fuel is needed to run the unit. A cluster of such units will produce megawatts of electricity for hours on end. (A megawatt is enough power for about 1000 typical New England homes.)

The DOE award is funded under the American Recovery and Reinvestment Act of 2009. Previously, SustainX has received a Small Business Innovation Research grant from the National Science Foundation and venture-capital funding from Polaris Venture Partners and Rockport Capital Partners.

The company was spun out of Dartmouth College last year and now employs 10 people at its site in West Lebanon, New Hampshire. It is contracting with several companies to handle different aspects of technology development and testing, including Creare, Parker Hannifin, The Hope Group, MTechnology, and KEMA. The DOE- and SustainX-funded demonstration will culminate in the deployment of a 1 megawatt, 4 megawatt-hour system hosted at an AES Energy Storage LLC-affiliated site.