Hold That Wind: Wind Storage Technology Hits the Market

Wind variability along with the lack of storage capacity have commonly been cited as the principle drawbacks of the burgeoning wind power industry.

Wind farmers often discover that at any given time, the wind fails to cooperate with consumer energy needs. Optimal wind conditions can occur at night when consumers are sleeping and in need of little electricity. Poor wind conditions can occur during the day when consumers are ready to cook their dinners, wash their clothes and play with their electronic gadgets.

Improvements in energy storage technologies have now reached a point where wind farmers can take a serious look at deploying them at their facilities.

Duke Energy decided to choose a storage technology, Dynamic Power Resource, developed by an Austin, TX company called Xtreme Power.

In brief, Xtreme's storage strategy builds on integrating specialty 12V dry cell batteries with software (and the like) to manage the battery storage and battery use process. Its modular design allows for scale, and Duke Energy chose a 36 MW-capacity storage system.

For contextual purposes, while the companies did not provide statistics on the topic, a quick search around the internet suggests that 36 MW of electricity could power anywhere from 10,000 to 14,000 homes per year. In more down to earth terms, the 36 MW storage facility accounts for a bit less than 25% of the Notrees wind farm's 153 MW capacity.

Xtreme claims their battery technology to be nonhazardous and 98% recyclable. Sometime in the near future, real world work applications will determine its reliability.

According to a recent report by the National Renewable Energy Laboratory (NREL), storage reliability remains the big industry uncertainty.

"When considering the technical performance or costs of energy storage, there are a number of caveats to consider. The first is the technical and commercial maturity of the storage technology. As of 2009, only four energy storage technologies (sodium-sulfur batteries, pumped hydro, CAES, and thermal storage) have a total worldwide installed capacity that exceeds 100 MW. This doesn't mean that there isn't market potential for any individual technology or storage, in general; but it makes it difficult to assess the state of any individual technology given its limited deployment to date."

The concept of pumped hydro as an energy storage system, for example, is relatively straight forward.

It starts by building two reservoirs (one uphill and one downhill) adjacent to a renewable energy facility (wind or solar). During non-peak electricity producing times, the renewable energy facility pumps the water to the up hill reservoir. When energy demand increases above the capacity of the renewable energy facility, as might be the case when insufficient winds lower wind farm generating capacities, the water from the uphill reservoir can be released down the hill to move electricity generating turbines.

To date, pumped hydro represents the most cost effective storage technology. However, given the need for both water and suitable terrain, its suitability is limited to certain geographic locations.

If Xtreme's storage technology, along with the other types of storage technologies mentioned, are deemed reliable, the wind energy industry could be looking at their next big deployment increase.

© 2011. Patricia A. Michaels