CleanWorld News

Sacramento Bee: New CWP ‘digesters’ will turn Sacramento food waste into energy and natural gas

Posted at June 26, 2012

Two new projects in Sacramento are proving that one person’s trash is another’s big business.

With the nation’s largest commercial solid waste digester about to be built in Sacramento, the area could soon be a leader in creating value out of garbage.

Clean World Partners and Atlas Disposal Industries, both of Sacramento, recently broke ground on a $13 million anaerobic digester and renewable natural gas fueling station in south Sacramento.

The Organic Waste Recycling Center at the South Area Transfer Station on Fruitridge Road will process 25 tons of food waste a day – 9,100 tons annually – collected by Atlas Disposal from local food-processing companies, restaurants and supermarkets and convert it into natural gas, electricity and heat, as well as fertilizer and soil amendments for agriculture. The project’s first phase is expected to be completed this summer.

In 2013, CWP plans to expand the plant to process 100 tons of waste per day – 36,500 tons annually – making it the largest commercial-scale, high-solids anaerobic system in the United States, according to company officials.

It will be CWP’s second commercial digester, joining one launched at American River Packaging in North Natomas in March.

Warren Smith, senior vice president for CWP, said the plants are a “triple benefit,” as they divert landfill waste, create renewable energy and eliminate greenhouse gases. And, he said, they are an example of how “green” business can make money and create jobs for the Sacramento region.

“The world is changing, and technology can be implemented to satisfy new regulations,” said Smith, a former Sacramento River Cats executive and a co-founder of CWP. “There’s worldwide promise in this market. Hopefully, we can create some new business opportunities out of it, and some jobs in the Sacramento area.”

The two plants are expected to create 16 long-term jobs and generate more than $1.1 million in annual combined tax revenue for the city of Sacramento, Sacramento County and the state.

The basic technology of anaerobic digesters is safe, reliable and being used in thousands of locations through the world, but commercial adoption hasn’t been widespread in the United States, CWP officials said.

In the conversion process, natural microorganisms break down biodegradable waste material to produce gas, including methane, carbon dioxide and small amounts of hydrogen and hydrogen sulfide. The gas can be used to generate electricity or as fuel for vehicles.

CWP was formed in January 2009 to commercialize a new anaerobic digester technology developed by Ruihong Zhang of UC Davis.

In January 2011, the company was acquired by Synergex Ventures, a subsidiary of Synergex International Corp., a software and professional services company based in Gold River. Synergex president and CEO Michele Wong also serves as CEO of Clean World Partners.

Zhang’s research focused on reducing the amount of time required to convert waste material into usable gaseous products. Zhang still serves as the company’s technology adviser.

“We founded the company around the technology, but it was struggling to find a market,” Smith said. “Since I have a commercialization background, I came on board, and I fell in love with the idea. I feel we can be better stewards of the earth, and it’s a great way for our community to play a significant role in this industry.”

CWP’s organic waste recycling plant at American River Packaging’s headquarters was the first commercial high-solid anaerobic digestion system in the United States. It was the product of a public-private partnership including the packaging company, Campbell Soup Co., Atlas Disposal, Otto Construction, UC Davis and Sacramento Municipal Utility District. CWP is sole owner of the plant, which it paid for with private financing and a federal grant. A $1.31 million grant from the California Energy Commission helped with pre-development work.

The $2.9 million plant co-digests 7.5 tons of food scraps – collected and delivered daily by Atlas – and unrecyclable corrugated material from the packaging plant, diverting 2,900 tons of waste annually from area landfills.

It generates 1,300 kilowatt-hours of green energy each day – about 37 percent of American River Packaging’s needs – and produces an estimated 1,000 tons a year of compost and soil amendments for regional farming and gardening operations.

The new digester in south Sacramento will produce natural gas to fuel part of Atlas Disposal’s truck fleet, said Dave Sikich, president and chief executive officer of Atlas.

Sikich said the company, which manages waste for the greater Sacramento area, already has 14 trucks, about 25 percent of its fleet, running on cleaner-burning compressed natural gas.

At first, the renewable natural gas will power Atlas Disposal trucks, but eventually, the fuel could be used by local school districts, transit and distribution companies. Sikich envisions the center in five years fueling 100 to 150 trucks and up to 80 school buses.

“I’ve been talking to school districts, such as Elk Grove, and Sacramento City,” Sikich said. “We’re looking at city, county and state vehicles, and privately owned fleets, such as distribution trucks. If we educate our customers about this, and it catches on, it could blow our initial numbers out of the park, which would be great.”

Sikich said diesel prices are at $3.80 a gallon, while an equivalent amount of CNG costs around $2.25.

And natural-gas-powered heavy-duty vehicles reduce smog-causing emissions by more than 80 percent and reduce greenhouse gas emission by 10 to 15 percent over a comparable diesel vehicle, Sikich said.

They are also as much as 90 percent quieter.

When complete, the new center will replace 1 million gallons of diesel per year with renewable natural gas, produce 2 million kilowatt-hours of electricity per year and divert 37,000 tons of waste annually from landfills, CWP officials say.

Roughly 90 percent of the electricity produced will be used to power the digester and refueling station, and the balance will be sold to SMUD though a net metering agreement, Smith said.

The state energy commission gave CWP a $6 million grant, and Atlas a $300,000 grant, to build and run the the new site. The rest of the cost was covered by Synergex Ventures, through cash and securities.

Smith said CWP hopes to start making money from the plants by early next year. The local plants are just the beginning of CWP’s foray into building anaerobic digesters, he said. The company plans to make and package the technology behind the digesters, along with designing and building plants for customers.

There’s plenty of opportunity – the U.S. Environmental Protection Agency said the country produced more than 34 million tons of food waste in 2010.

“We’re trying to privatize the system, develop standards and replicate those standards,” Smith said. “There’s unbelievable market potential, once we learn how to do it. I’m getting calls from Boston, L.A., Chicago, and there’s just as much international interest.”


• Americans dump nearly 225 million tons of municipal solid waste in landfills every year.

• Between 25 and 40 percent of this waste stream is made up of food and agricultural waste, which if left untreated is a major source of harmful greenhouse gas emissions.

• In California, about 16 million tons of organic waste is dumped every year, at an average cost of $40 per ton, or roughly $640 million annually.

– U.S. Environmental Protection Agency