U.S. company converts onion juice to electricity

Reuters: Laura Isensee - July 17, 2009

LOS ANGELES (Reuters Life!) - Onions make you cry, add flavor to food and are touted for their medicinal benefits. Now the vegetable has another use -- powering up green energy.

A new system debuts on Friday that converts onion juice into electricity at Gills Onions, the largest fresh onion processor in the United States.

The Oxnard, California-based company expects its new onion-fueled power to reduce its electric bill by $700,000 a year and cut its annual greenhouse gas emissions by up to 30,000 tons.

The happy ending to this green energy tale, however, started with another question: how to get rid of onion waste.

"When we peel an onion, 35 to 40 percent of the onion comes off before we have a usable onion. That's the top, tail and skin around the onion before you get to the meat," said Steven Gill, co-owner of the 25-year-old company.

They used to haul the waste to the fields for composting, but that became a problem. Ten years ago, Gill started looking at technology for a solution, including microturbines.

"We ended up shredding the skins as they come out of the plant and extracting all the juice, which is very high in sugars, and bacteria love that stuff," Gill said.

In the new system, bacteria produce methane gas from the juice. The gas then goes to two 300 kilowatt fuel cells, creating enough power for 460 homes. The company expects to get 35 to 40 percent of its electricity from the on-site generator.

The company invested $9.5 million in the project and will receive $2.7 million from Southern California Gas Co., a regulated subsidiary of Sempra Energy, as part of a state program to encourage self-contained generation by businesses. In addition to cutting its electric bill, the company will save $400,000 in hauling costs and expects pay-back in six years.

The onion grower now has new goal: to be a zero-waste facility by 2011.

"We wanted to follow it all the way through and make the full circle," Gill said.