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How big can a battery get?

May 27, 2011

Dear Control Engineering: It seems that battery technology is being used in more transportation applications and all sorts of places. Are there practical limits on battery size?

First, you have to remember what battery means, and I don’t mean clobbering the guy next to you. In the pre-electrical world, it meant a group of artillery pieces working as a unit. More recently, it was applied to a collection of individual electrical cells that are interconnected. Your car battery has six individual cells combining to make 12 V.

Individual cells do have practical size limits, but the number of them that can be lashed together can be anything for all practical purposes.

There are very large batteries that are used for UPSs (uninterruptable power supplies) for critical installations such as data centers and hospitals. Usually they only have to supply power for a few minutes until something like a Diesel generator can be fired up. Other large batteries are used to smooth out power supply and demand spikes as are common with more erratic generating technologies such as wind turbines.

ABB has built some installations along those lines, including one under construction right now for use in Switzerland. EKZ, a Swiss utility, is testing a 1 MW lithium-ion battery that will be put on the grid as a test. It’s designed to provide 350 to 500 kWh to help satisfy demand spikes. When finished, it will be about the same size as a 40 foot shipping container. It could probably keep you lap top going for at least several hours. (Just kidding.) If this works, the utility expects to install more.

If that isn’t impressive enough, ABB also worked on an installation in Alaska in 2003, that was recognized as the world’s largest battery (see photo). The Golden Valley Electric Association, the utility that serves Fairbanks and surrounding areas, installed a truly massive battery using 13,760 cells. In an emergency, it can put out 40 MW for 6 to 7 minutes, or 27 MW for about 15 minutes. This is enough to cover a community of 80,000 for the time required to get Diesel generators going. The building it is installed in is larger than a football field. The cells are rated for a 20 year life span.