UCD scientist helps farmers turn waste into electricity

Brothers Steve and David Gill, co-owners of Gill Onions in Oxnard, credit a UC Davis researcher for helping them turn a liability - millions of pounds of onion waste - into an asset.

The brothers wrote in an article published last week in The Business Journal that their fresh-cut onion processing firm used to truck onion leftovers to surrounding farm fields and plow them into the soil as compost. But as the company grew and produced up to 1.5 million pounds of onion waste each week, the solution became too costly and environmentally unsustainable.

UC Davis bioenvironmental engineering professor Ruihong Zhang determined that onion juice was very good food for methane-producing microbes. With her research data, the company's engineers and contractors developed an anaerobic digester system that turned leftover onions into electricity.

This year, the system will save the company $700,000 on power bills and $400,000 on trucking costs, the article said. The leftover onion pulp is a high-quality cattle food.

"Thanks to Professor Zhang, our waste problem is now an energy source and new product line. We expect to make back our $9.5 million capital investment in six years," the brothers wrote.

The Gill Brothers used their opinion piece to support UC Davis' $1 billion fundraising campaign, launched two weeks ago.

Onion waste can be turned into electricity.

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