Sodium-sulfur Batteries Store the Extra Juice

In North America, the hazy days of summer are back. That means it's time to conserve energy during peak hours. The U.S. Southwest is currently sweltering under daytime temperatures of over 100 degrees (Fahrenheit), but that doesn't mean businesses and individuals shouldn't be trying their level best to avoid excess power consumption while the sun is scorching. The risk of electricity outages is just too great under such circumstances. It's better to wait until the sun goes down to do things like running the washing machine. If we could find a way to store the extra juice power plants produce during off-peak hours and keep it on-hand during particularly stressful periods, we'd all be better off.

But wait a minute -- we already can. At least, we have a device, just finding emerging use, that's capable of doing just that. It's the sodium-sulfur (NaS) battery, and it's in the news today. USA Today carries an article, "New battery packs powerful punch", that touts the merits of NaS technology as a means of storing that extra juice for emergency situations.

NaS batteries are industrial-size units that could fill a garage. They offer the promise of enabling utilities to store energy in much the same way that reservoirs store water but in a much more efficient fashion than the typical vaults of lead-acid batteries now employed by some power companies. They could also make the electricity generated by wind farms more attractive as a commodity.

While they've been in development for decades, it's only now that NaS systems are beginning to see deployment in countries such as Japan and the United States. The city of Tsunashima, Japan, has installed a 6-megawatt unit attached to its local grid. And American Electric Power (AEP), one of the largest U.S. utilities, has been using a 1.2-MW unit in Charleston, W.Va., the past year and plans to install one twice that size elsewhere in the state next year, according to a spokesperson.

"Our vision is to have [batteries] throughout our system," Ali Nourai, AEP's manager of distributed energy, told USA Today.

Other utilities are planning or considering the technology, according to the national newspaper. On Long Island, N.Y., the New York Power Authority plans to install a NaS unit at a bus depot. They'll charge the battery at night, when power prices are low, and discharge it during the day to pump natural gas into the fuel tanks of the buses. That should lower costs for the transit company and ease stress on the local grid. And Pacific Gas and Electric has plans to install a 5-MW battery for backup purposes by 2009.

Look to see more NaS installations following suit. If there are more efficient and less expensive means of wringing every last watt of energy out of the electrical grid, look for power engineers to find them. The latest tool in their kit could be a technology that has been waiting for years to get its chance to keep the juice flowing.

Just don't start thinking, however, that this will give you an excuse to waste a precious commodity when you know you shouldn't. Remember to conserve.

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