What’s so funny about generating power from onion juice?

Michael Giberson

In the news, many stories about the debut of a power system at Gills Onion that will produce electricity from onion-based biogas. The topic seems to have spurred extra effort to insert jokes into headlines (Don’t cry for me, California; Energy, layer by layer; From The Onion … No, Not That One), but the technology is pretty cool.

At the food processing plant about 35 to 40 percent of the onion – tops, skins, edges – were leftover by-products, mostly used for composting the onsite vegetable fields. In the new power system, the leftover onions are pressed to separate the juice, the juice processed into biogas and the biogas fed into fuel cells to generate power on-site. An article in Distributed Generation describes some of the details of the processes. Video story here via the Boston Globe.

The company spent about $10 million to build a 600 kw power plant. Some of the money they’ll get back through incentives from the local electric utility supporting self-generation, so I suspect there is a California state subsidy behind it somewhere.  The plant is expected to reduce the company’s electric bill by $700,000 annually and save $400,000 in waste disposal costs.  The company expects a six-year payback period on their investment.