USA - Utility stores wind power in huge batteries

One of the drawbacks of renewable energy is that it often isn’t available in the same timeframe that we use it – that is, around the clock. Solar is available when the sun shines, and wind is likewise usually available with a solar-related periodicity. But what’s an efficient way of storing the energy for use when it’s not being generated? One east coast utility, American Electric Power, has invested in movable banks of sodium sulphur batteries, each about the size of a double-decker bus, to store wind-generated energy.

The batteries can each deliver one megawatt of power, which AEP says is enough to run a medium-sized shopping center for a little more than seven hours. The batteries are only about 80% efficient. Ouch. (The article says the batteries can operate at temperatures exceeding 800[deg]F. No idea why a utility needs that kind of temp range.)

According to the NY Times article, the batteries “will be used to smooth the power delivery from wind turbines. They can charge at night, when the wind is strong but prices are low, and give the electricity back the next afternoon, when there is hardly any wind but power prices are many times higher, company officials said. That strategy would reduce the amount of power generated from inefficient peak-demand units.”

Now let’s talk cost: “…$27 million for six megawatts of capacity, or about $4,500 a kilowatt, including the price of substation improvements. Building a gas turbine of that size to meet peak needs would cost substantially less. But the battery system would be able to store power made from wind, a form of generation that does not produce any carbon dioxide.” Sounds like the company may be positioning itself to sell carbon offsets. But more on that later.