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Turning Onion Juice Into Electricity

A California company wins awards, saves money and cuts greenhouse gas emissions by turning agricultural waste into energy.

Think about innovative California companies and what probably comes to mind are Google in search engines, Oracle in business software, Intel in silicon chips, and Hewlett-Packard in printers and computers. Certainly not Gills Onions.

Think again. This family-owned processor of onions in the coastal town of Oxnard, about 95 kilometers north of Los Angeles, is making electricity from onion juice—and saving itself more than $1 million a year in the process. By installing what the lead engineer on the ground-breaking project calls “a big stomach” at its plant, Gills is turning agricultural waste into energy and winning praise from engineers and environmentalists alike.

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.

“I had to solve the problem of our onion waste,” Steve Gill says in a SPAN interview. “It was very expensive to haul away and we were spreading so much of it on the fields that it was beginning to affect the crops we were growing. I had to find another way.”

The solution didn’t happen overnight, but the 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.

“It took me 12 years to figure it out,” Gill says. “The technology wasn’t available to handle waste like this when I started looking into it, and I had to do all the research and development myself. But I was persistent. Then the permitting process took quite a while, and financing was difficult, too. The technology is ahead of what everybody is used to, so that slows everything down a lot.”

What became the company’s Advanced Energy Recovery System ultimately cost $10.8 million, with 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 per cent 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.

To put the innovative project together, Gills brought in Bill Deaton of Utah-based Deaton & Associates. An independent consultant with a background in chemical engineering and 25 years of food industry experience, Deaton took Gills into the finer points of waste-to-energy conversion and assembled a team to turn concept into reality.

“It was a great project to manage because we had a lot of sharp people who were all eager to do things, and that was critical because we had to create our own resources as we went along,” Deaton says. “Nobody had really done a project like this before, and nobody was working with onions.”

Deaton’s team included engineers from HDR, Inc., an Omaha, Nebraska-based architecture, engineering and consulting firm that has done projects in all 50 American states and 60 countries. Among HDR’s many unique projects are a solar power system for Alcatraz Island, the infamous former prison in the middle of San Francisco Bay that is now a U.S. national park; and design and construction support on the Hoover Dam Bypass, which took car traffic off the mammoth dam and onto what is now one of the longest concrete arch bridges in North America.

The HDR contingent was led by Juan Josse, who is now vice president of engineering at UTS BioEnergy in Irvine, California.

“We had to develop the technology to extract the onion juice and we had to develop a way to digest the onion juice, which no one had done before,” Josse tells SPAN. “Then one of the biggest challenges was how to put together all the different technologies involved. We couldn’t get anyone to commit to do the whole thing and give us a package, so we decided to put together the best equipment we could find and we did that successfully.”

The energy recovery system essentially involves piping the 113,500 liters of onion juice Gills winds up with each day into what’s known as a high-rate upflow anaerobic sludge blanket reactor or, as Deaton puts it, “a big stomach.” Spurred by bacteria purchased from a beer brewery, the onion juice ferments inside the 548,800-liter digester and produces meth-ane gas, which is treated and compressed, then used to power two fuel cells Gills purchased and had installed at the company’s 5.6-hectare plant. The fuel cells produce enough electricity to power about 450 homes—or most of the company’s energy needs. Onion waste that can’t be converted into juice is sliced into fine pieces that are compressed into onion “cake” used for animal feed.

While the fuel cell technology was relatively straightforward, getting the digester to consume high-sulfur onion juice was somewhat trickier.
“The digester seems like it has a mind of its own and we had to deal with that,” Gill says. “But once we let it do what it wanted to do, it started producing a high-quality gas.”

The showcase project won a number of awards, including the Grand Conceptor Award of the American Council of Engineering Companies, the governor’s Environmental and Economic Leadership Award (California’s highest environmental honor), the Cool Planets Projects Award and McDonald’s 2010 Best of Sustain-ability Supply Chain. In winning the engineering companies award, the innovations at Gills came in ahead of much larger projects that included the $1.3 billion Dallas Cowboys Stadium in Arlington, Texas and the Sea-to-Sky Highway project in British Columbia, Canada.

“They’re setting the standard,” California Environmental Protection Agency Sec-retary Linda Adams said at an event Gills hosted in July to mark the first year of successful operations of the recovery system. “It’s really a tremendous thing to see private industry taking this kind of leadership.”

Deaton and Josse believe more companies will follow the example that Gills set.

“These projects are getting to be very popular and there are going to be a whole lot more of them,” Deaton says. “You go to countries like Sweden and Germany and you’ll find that they have converted lots of things into compressed biogas. The important thing is that it’s renewable. You’re taking something that was grown above the ground, converting most of it into energy and putting the rest back into the ground and renewing the cycle.”

“What we did can be applied widely in any food processing industry, not just in the plant but out in the fields,” Josse says. “A lot of the waste from harvesting that’s now plowed into the ground could become energy, electricity. It could be done anywhere. It’s just a matter of using the right engineering and the right technology.”

Renewability and sustainability are now standard operating procedure at Gills, with the company looking at turning the plant into a zero-waste facility by, among other things, recycling employees’ lunch leftovers.

“Our goal is to recycle as much of our waste as we can,” Gill says. “It’s a dollars and cents thing, but it’s also accountability to the environment.”


Steve Fox is a freelance writer, former newspaper publisher and reporter based in Ventura, California.