Greentech Innovations: Storing Wind Power With Sodium Batteries

The wind blows. In more ways than one.

Timing has always been the bane of wind farms. Winds can be stronger at night in California and Texas than in the day. Unfortunately, most regional customers are asleep, so utilities and power providers often have to dump the power generated by windmills during the wee hours. When utilities dump power, not only do they lose a sale, they lose the attendant tax credits.

GeoBattery will try to solve this problem with sodium sulfur batteries, said CEO Dan Vogler. Sodium batteries are one of the best vehicles on the market for storing electrons. (Vogler will speak at the upcoming Greentech Innovations End to End Electricity conference on November 17.)

“They have the lowest cost and highest charge density of any battery,” he said.

Sodium batteries, however, are also extremely heavy. Worse, they only work at high temperatures of 285 Celsius and higher. Below that level, the batteries go into a dormant state. That makes them a tough choice for a notebook or an electric scooter.

But weight, temperature and extra real estate aren’t problems for wind farms. GeoBattery’s plan is to build datacenter-like rooms of these batteries next to renewable energy facilities. A single 6U-tall sodium battery can hold a kilowatt hour worth of power. (A U is 1.75 inches tall. It comes from the computer industry and is not some ancient Celtic term.). A 25,000 square foot facility could hold enough batteries to store 10 megawatt hours worth of power.

Once in place, these sodium storage facilities could be used in a variety of ways. They could capture and store energy generated at night. Some wind farms could also try to work the system to sell their power at peak times, thereby increasing profits or reducing the time to break-even. Conceivably, these systems could also be used to store waste heat in factories.

Power storage is often called the Google opportunity in greentech. The various ideas for storing power include large-format fuel cells, vanadium flow batteries, molten sodium, flywheels, compressed air and water columns. Most of these ideas are only moving out of the experimental stage now.

Like GeoBattery, Japan’s NGK is also working with sodium batteries.