The two bottlenecks inhibiting further use of renewable energy systems are cost and the fact that the sun doesn’t always shine or the wind blow-in one word, storage. While mass production of components such as solar photovoltaic cells means that their price has been dropping, the issue of storing and releasing electricity generated by renewable sources during their down times has led engineers worldwide to tackle the problem.

Large-scale, low-cost energy storage is needed to improve the reliability, resiliency, and efficiency of next-generation power grids. Energy storage can reduce power fluctuations, enhance system flexibility, and enable the storage and dispatch of electricity generated by variable renewable energy sources such as wind, solar, and water power.

Now one technology seems sufficiently promising that it is receiving funding from the U.S. Department of Energy’s Office of Electricity Delivery and Energy Reliability Energy Storage Program.

What is this promising new technology?

Isothermal compressed air energy storage (ICAES) refers to storage of compressed air at a constant temperature, which is a key element in the improved energy efficiency of the system.

SustainX has completed construction of its first utility scale ICAES system. It was hooked up to the grid earlier this month and it’s now in the process of revving up to speed. The DOE’s Office of Electricity Delivery and Energy Reliability’s Energy Storage Program underwrote $5,396,023 of the system’s cost.

SustainX is a relatively young company, founded in 2007 out of Dartmouth College’s Thayer School of Engineering. Despite its youth, SustainX has received funding not only from the U.S. Department of Energy’s Office of Electricity Delivery and Energy Reliability Energy Storage Program but the National Science Foundation Small Business Innovation Research Program as well as equity investments from Polaris Venture Partners, RockPort Capital Partners, Cadent Energy Partners, General Catalyst Partners, and GE Energy Financial Services.

In 2009 SustainX began working towards the goal of storing four megawatt-hours worth of energy in transportable 40-foot long containers, while achieving a 70 percent reduction in the amount of energy needed for conventional compressed air energy storage (CAES) systems. By 2012 the research was sufficiently promising that SustainX signed a technology licensing agreement with the University of Minnesota.

The new SustainX ICAES system is located in Seabrook, New Hampshire at the SustainX headquarters. The company describes the new system as a next-generation improvement over earlier CAES dating back to the 1970s, which were usually located underground and ran on fossil fuel. The SustainX prototype ICAES system generates 1.65 megawatts of power, enough to power roughly 1,600 homes. SustainX will use the system to gather performance data and to display the technology to potential investors and customers.

The DOE is certainly impressed, noting on its “Isothermal Compressed Air Energy Storage” webpage; “SustainX’s ICAES technology offers several advantages: it can be sited anywhere, and it is not dependent on advantageous geological formations. It allows power and energy to scale independently. It consumes no fuel and produces no emissions. It utilizes proven mechanical systems and is composed almost entirely of steel, water, and air. It offers 20 years of performance at full power and capacity and 100% depth of discharge.” Governmental endorsements don’t come much stronger than that.

And how big is the compressed air energy storage industry going to become? According to Navigant Research director Kerry-Ann Adamson, the market will grow dramatically over the next decade. Adamson remarked, “Rapidly changing energy mixes and increasing renewable energy penetration will continue to introduce instability onto electricity grids worldwide in the coming years, while the volatility of load profiles will challenge grid operators to deliver reliable and secure electricity. These macro conditions will drive demand for CAES, helping to rejuvenate a sector that has been largely dormant for the last two decades.”

By. John C.K. Daley of Oilprice.com