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Posts Tagged: waste-to-energy

Biodigester turns campus waste into campus energy

Campus and community food and yard waste will be put inside large, white, oxygen-deprived tanks. Bacterial microbes in the tanks feast on the waste, converting it into clean energy that feeds the campus electrical grid. (graphic: Russ Thebaud/UC Davis)
More than a decade ago, Ruihong Zhang, a professor of biological and agricultural engineering at the University of California, Davis, started working on a problem: How to turn as much organic waste as possible into as much renewable energy as possible.

Last week, on Earth Day, the university and Sacramento-based technology partner CleanWorld unveiled the UC Davis Renewable Energy Anaerobic Digester (READ) at the campus' former landfill. Here, the anaerobic digestion technology Zhang invented is being used inside large, white, oxygen-deprived tanks. Bacterial microbes in the tanks feast on campus and community food and yard waste, converting it into clean energy that feeds the campus electrical grid.

“This technology can change the way we manage our solid waste,” Zhang said. “It will allow us to be more economically and environmentally sustainable."

It is the third commercial biodigester CleanWorld has opened using Zhang's technology within the past two years and is the nation's largest anaerobic biodigester on a college campus.

The system is designed to convert 50 tons of organic waste to 12,000 kWh of renewable electricity each day using state-of-the-art generators, diverting 20,000 tons of waste from local landfills each year. It is expected to reduce greenhouse gas emissions by 13,500 tons per year.

The READ BioDigester encompasses several of the university's goals: reducing campus waste in a way that makes both economic and environmental sense, generating renewable energy, and transferring technology developed at UC Davis to the commercial marketplace.

The biodigester will enable the more than 100 million tons of organic waste each year that is currently being landfilled in the U.S. to be converted to clean energy and soil products. The READ BioDigester is a closed loop system, moving from farm to fork to fuel and back to farm. Whatever is not turned into biogas to generate renewable electricity can be used as fertilizer and soil amendments — 4 million gallons of it per year, which could provide natural fertilizers for an estimated 145 acres of farmlands each day.

Nearly half of the organic waste, or feedstock, needed to operate the biodigester to full benefit will come from UC Davis dining halls, animal facilities and grounds. CleanWorld is working with area food processing and distribution centers to supply the remaining amount. Meanwhile, UC Davis will earn 100 percent of the project's green energy and carbon credits and receive all of the electricity generated.

Anaerobic digestion is an age-old process. However, Zhang's patented technology made it more efficient — capable of eating a broader variety and bigger quantity of waste, turning it into clean energy faster and more consistently than other commercial anaerobic biodigesters.

View a video about the UC David biodigester here:

(This blog post is condensed from a UC Davis news release about the biodigester.)

Additional information:

Posted on Wednesday, April 30, 2014 at 6:34 AM

How UC helped turn onion waste into clean energy

Ten years ago, a California family's food-processing business was booming -- so much so that it was in danger of drowning in its own success. A new idea out of UC Davis helped them stay on top.

In 1983, Gills Onions had been asked by La Victoria Salsa to provide large quantities of high-quality, fresh-cut onions when no automated equipment and processes existed. With typical farmers’ "can do" attitude, brothers Steve and David Gill and their 16 employees developed a system to peel, slice, dice and deliver the first fresh-cut onions in the food processing industry.

By 2000, the Gills and their 400 employees were processing millions of pounds of sliced and diced onions weekly for restaurants, salsa makers and grocery stores. They had become the largest fresh-cut onion processor in the nation.

But they were being buried in onion waste -- the unused tops, tails and skins, which account for about 40 percent of the original onion mass.

Previously, their solution had been to truck these onion leftovers from their Oxnard processing plant to surrounding farm fields and plow them into the soil as compost. But now they had so much waste – up to 1.5 million pounds every week - that this solution had become too costly and environmentally unsustainable.

So they went looking for new ideas. They found them in the bright minds and laboratories of UC Davis research scientists and students.

UC Davis engineering professor Ruihong Zhang, a leading innovator with a passion and genius for turning food waste into energy, determined that onion juice was very good food for methane-producing microbes. With her research data, Gills’ engineers and contractors developed an anaerobic digester system that turns their leftover onions into electricity.

They squeeze the onions, feed the juice to the microbes, and use the methane that the microbes excrete to run a fuel cell that makes electricity.

Today that electricity powers the Oxnard processing plant. This year, they expect to save $700,000 on power bills and $400,000 on trucking costs. (They even sell the squeezed-out onion pulp, as a high-quality cattle food.)

Thanks to Professor Zhang and the University of California, Gills’ waste problem is now an energy source and new product line. The firm expects to make back its $9.5 million capital investment in six years.

And they are famous in the produce and energy industries. People come from all over the world to learn from their experience. They are winning engineering and environmental awards. (They are especially proud of beating the Dallas Cowboys' new $3 billion super-high-tech football stadium in a competition by the American Council of Engineering Companies.)

The help Gills Onions needed with their business problem was available to them, and the rest of the world, in part because California's public research universities get financial support from the private sector. In Ruihong Zhang's UC Davis lab alone, in the seven years she has been perfecting waste-to-energy technology, six donors (including Gills Onions) have given $221,000 to pay graduate student researchers' stipends, tuitions and fees; pay postdoctoral scholars; and purchase bioreactors and laboratory supplies. They also have donated $305,000 worth of equipment.

In fact, California's public colleges and universities have done more to make this state an international agricultural powerhouse than most of us realize. Yet state funding for public universities is unpredictable, and when universities seek philanthropic support, they risk criticism that they are privatizing or selling out – even though private support remains a small percentage of public university budgets (at UC Davis, it’s less than 7 percent).

The University of California needs California businesspeople to support its programs -- with their influence and their wallets. What sector of the state has more to lose if the new ideas dry up?

(Photo: Karin Higgins, UC Davis)
(Photo: Karin Higgins, UC Davis)

UC Davis professor Ruihong Zhang turns waste into energy.

Posted on Wednesday, January 5, 2011 at 8:08 AM
  • Author: Sylvia Wright
 
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