Company Converts Onion Waste into Energy, Gills Onions

Gills Onions in Oxnard California generates 1.5 million pounds of onion waste a week, and converts 100% of it into ultra-clean, renewable energy and cattle feed. 

The company’s system converts methane from fermented onion juice into energy burned in two fuel cells.  The energy operates the company’s refrigerators and lighting, saving $700,000 annually off the electric bill and $400,000 a year on waste disposal costs. The government and power companies have given the company an additional $3 million in incentives. Steven Gill, owner of the company, expects the $9.5-million system to pay for itself in less than six years.

Gills Onions operates the largest fresh onion processing plant in the world and manages over 15,000 acres of farmland and over 300,000 square feet of processing and warehousing facilities.  The factory’s machines slice off about 40% of each onion, leaving 150 tons of waste a day. The company had used this waste as fertilizer over their fields or sold them as cattle feed.  But the detritus was expensive to handle, and could become a groundwater contaminant.

"It's a great sustainability story, but it was first a business decision to solve a waste problem," said Gill. "But in doing so, we solved a lot of environmental problems too.  I didn't want to depend on anyone taking my waste for me. It was my problem, and I had to solve it. It's a relief to find a solution.”

In order to convert the waste to energy, machines extract about 30,000 gallons of onion juice that is then sent to a 145,000-gallon holding tank where bacteria produce methane gas while eating the carbohydrates in the fermenting juice.  The gas is compressed and then burned in the fuel cells, producing enough electricity to power 460 homes annually. The company would like to install a battery that could store excess electricity to be used during peak hours.

Gills Onions is wary of their eco-footprint in other ways. The company also cleans its wastewater and funnels it into a cooling tower. By using drip irrigation in most of its fields, Gills Onions saves enough water to meet the annual needs of 2,900 homes.  The processing facility uses an Advanced Energy Recovery System (AERS) that reduces up to 30,000 tons/year CO2 equivalent emissions - roughly the annual emissions from 5,000 cars.

U.S. companies are increasingly interested in generating their own electricity on site with waste from their production processes.  Some companies are daunted by the upfront costs of these closed-loop systems. But volatile energy prices and the rising cost of waste disposal are leading more firms to take a look. 

In February, Gills Onions was presented the Energy Solutions Center’s tri-annual Partnership Award for its energy saving projects at the Oxnard facility. This award is presented to customers and energy utilities that work together to deploy new energy-efficient gas solutions that increase comfort and reliability.

It was an honor to be … recognized at this conference,” Steven Gill said of the award. “The attendees are major players in the energy industry, and it is very gratifying for Gills Onions to be acknowledged as a leader in energy conservation after our years of research, and finally, success.”