US (CA): Giant flow battery from onion juice

For companies that process fruit and vegetables, there’s always some waste involved — from blemished produce to food scraps that can’t be used. Gills Onions, a processor in California, slices, dices and peels a million pounds of onions every day. At the end of the day, 300,000 pounds of skins and unusable parts end up as waste.

Now, instead of carting that waste away to a landfill, Gills uses an anaerobic digester to generate renewable electricity. The onion waste is squeezed into juice, and bacteria inside the digester produces methane gas. Fuel cells convert the gas into electricity, and a day’s worth of waste become 600 kilowatts of electricity.

The world's largest vanadium flow battery, made by Prudent Energy.

That’s a lot of power! An average household uses around 30 kilowatt-hours a day, by comparison. But a big industrial plant like Gills often needs even more power, and that can come at a large cost. Their utility charges more for electricity used at peak hours during weekdays, and also bills for the highest capacity that the company needs during a month. The solution? A giant battery.

Gills now uses a battery the size of a tennis court to store an extra 600 kW of power and release it as needed. Now, the company can purchase power at night, when rates are lowest, and use it the next day. The battery also protects against unexpected demand from the grid if one of the onion-powered fuel cells happens to shut down. Made by Prudent Energy, the battery is the largest of its kind in the world.

Source: revmodo.com