We all know about energy storage as we routinely charge our cell phones and hand held devices every evening. That same battery technology we employ in electric/hybrid vehicles. Thomas Edison charged his electric vehicles in his garage every evening-all the way back in 1908. In a world where we integrate intermittent solar and wind energy systems into our electric utility grids, developing robust, large-scale, energy storage systems makes sense. In fact, energy storage on a utility scale has been around for many years. Hydroelectric dams are the prime example, but the best hydro sites already have been used. Here are some ways we may be storing utility grade electricity in the years to come.

Inventions Thomas Edison Would Love: Energy Storage Advanced megawatt size battery storage, perhaps in the range of 5-20 MW blocks, may use unique combinations of chemical substances like sodium-sulfur, zinc-bromide/zinc-chlorine, and vanadium are now being tested and deployed. These systems are capable of being deeply discharged and recharged quickly for they must be capable of smoothing out surges on the national grid caused as solar electric and wind energy systems come off-line as solar or wind conditions wane. Designed to be highly modular for ease of construction and expansion, such systems might be located along existing utility system transmission line rights-of-way or near wind machine farms.

Inventions Thomas Edison Would Love: Energy Storage A much larger energy storage system might involve compressed air energy storage (CAES), where large amounts of compressed air are pumped into an underground cavern (natural or man-made). These cavern-filling periods would occur during off-peak grid periods or evening hours when load is low and excess generation capacity is available. Later, this valuable reservoir of stored energy can be taped, with the air released through turbo-generators to produce large amounts of utility-grade electricity. Of course the location of such a large storage system is dependent upon finding a suitable area for hosting the underground cavern. Since 1991, a 110 MW CAES plant has been in operation in McIntosh, Alabama. Another such plant, 290 MW, has been in operation in Huntorf, Germany since 1978.

Inventions Thomas Edison Would Love: Energy Storage A different approach to energy storage at the local level – i.e. home, commercial application – is the flywheel. A flywheel is a high speed rotating mechanical device that is used to store energy and can be discharged as needed to return that stored energy in the form of electricity. Flywheels can store kilowatts worth of power; and can be banked together to deliver larger megawatt size blocks of power. These systems are likely to be used for everything from commercial to utility applications-and may someday also find application in residential settings. Key concerns here are the materials considerations of the flywheels themselves-delicately balanced to spin at more than 10,000 RPM. Tremendous forces are evident in flywheel applications, with safety being of paramount concern. Nanotechnology is making inroads here, resulting in light-weight, very strong materials for the spinning components of the system.

In the 1880s, Thomas Edison knew the value of energy storage on his then developing electric utility system, and with solar and wind technologies being used ever more often, today, so will today’s utility system operators.

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