Onions make you cry, add flavor to food and are touted for their medicinal benefits. Now the vegetable has another use. It can also be used for electricity.
Gills Onions, a California wholesale producer of sliced, diced, slivered and pureed onions, introduced a system to turn its 300,000 pounds of daily agricultural waste into valuable energy.
The Advanced Energy Recovery System (AERS) is an anaerobic digester that turns shredded and pressed onion waste (aka onion juice) into biogas, which is then conditioned and turned into methane–the main component of natural gas. The gas goes into Fuel Cell Energy’s 600-kilowatt fuel cell to be turned into power. Leftover onion waste–mostly pulp–is used as cattle feed.
As one of the largest processors of raw onions in the United States, Gills slices up some 362,800 kilograms of the pungent vegetable every day for a wide variety of customers, including supermarket chains, restaurants and fast-food companies such as McDonald’s. About 40 percent of the onion is lost in the process, leaving Steve and David Gill, the brothers who own the company, with a challenge that might bring some to tears.
Gills, who started their company in 1983 with 16 people and now employ 400, learned patience on a family farm in California’s fertile Central Valley where they grew tomatoes and peppers. Gills Onions receiving assistance in the form of $1.8 million in investment tax credits from the federal government and $2.7 million from Sempra Energy as part of the utility’s renewable energy Self Generation Incentive Program.
Gills now gets about 80 percent of its power from onion juice and expects to recover its investment in six years while removing more than 90,700 kilograms of onion peelings from the plant’s waste stream every day. The company also eliminated a significant amount of greenhouse gas emissions associated with the thousands of truck trips formerly needed to haul the waste away.
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