Turning food scraps into energy source

The idea of using food or municipal and farm waste to generate energy is not new. Europe is far ahead in harnessing biogas, said Mackinnon Lawrence, who leads the Energy Technologies and Utility Transformations programs at Navigant Research. In the United States, with plenty of land left to fill, he said, there had not been much incentive to change the practice of dumping organics, so it has remained “a niche opportunity,” but one that is expected to expand.

A recent Navigant report for the Advanced Energy Economy, a business-backed policy and advocacy group, estimated that the waste-to-energy market could generate $40 billion in revenue over the next decade. Already, energy-recovery projects contribute nearly $500 million in annual revenue in the United States.

Wastewater and manure treatment plants have been using anaerobic digesters to capture methane for decades. Some companies like Waste Management convert landfill gas to vehicle fuel for use in their trucks, but much of it is still collected and burned off.

As government policies shift to encourage extracting the energy from organic trash, the United States is beginning to catch up. The East Bay Municipal Utility District in California, for example, has been funneling food waste from restaurants and other large producers to a digester for years as part of a federal pilot program, and some cities have experimented with similar diversion efforts. Harvest Power, a start-up backed by Waste Management and Kleiner Perkins and based in Waltham, Mass., has been operating a facility in Orlando, Fla., since 2013 that turns waste from Disney World into fuel and fertilizer.

In theory, adding food to digesters processing manure or sewage has advantages, said Chad Kruger, director of the Washington State University Center for Sustaining Agriculture and Natural Resources, chief among them that it increases methane production. But without an infrastructure in place to handle, transport and process the material, building that kind of energy system has been too difficult and expensive to spread widely.

“We’ve kind of stalled out on some of these issues,” he said. “That said, the industry, the composters, in particular the bigger ones, are really set on this — they think it’s the right thing to do.”

The partnership between Quasar and InSinkErator follows years of research and development at both companies. Managers at InSinkErator had been looking into the potential of anaerobic digestion and energy production at wastewater treatment plants. They came upon Quasar, a fast-growing company that was incubating its business at Ohio State University’s agricultural research campus in Wooster and was aiming to build a digester network nationwide.

“One of the things that they basically were looking for was a clean feedstock of organic material that was consistent and low in contamination but had high energy content in terms of methane potential,” said Matt Whitener, general manager of the Grind2Energy business at Emerson, the parent company of InSinkErator. “On-site, point-of-generation grinding technology was kind of the missing piece to make an efficient model where the food waste generator has a mechanism to convert their food scraps into a slurry.”

At Progressive Field, Mr. Gholston and the other dishwashers feed loads of food waste into the grinder, which is about 13 to 20 times as powerful as home models. The milkshake-consistency slurry that results from the discarded fruit and vegetable peelings, uneaten pasta, used cooking grease or leftover hot dogs that cannot go to a food bank is then pumped into a 3,000-gallon tank.

Once the tank signals to Grind2Energy that it is full, Quasar is alerted to send a truck to take the mass to its plant, where it is put into giant anaerobic digesters full of bacteria that break down the slurry. The system captures the released gas, which is then converted into electricity for the grid or transportation fuel. The leftover solids become fertilizer.

Peg Kalberer, assistant manager of concessions at Delaware North Sportservice, which runs the stadium’s food operation, said she was happier with the system than one that funneled the waste to a composting company, in part because it helps document their sustainability efforts.

“Over all it worked, but this is better,” she said. “I don’t know what happened to the product when it left. Here I know exactly what’s happening: 90 days from tank to energy.”

For now, workers are feeding only preconsumer waste to the machine, except for food from the Terrace Club, where workers scrape plates and can keep contaminants like paper napkins or plastic wrappers out of the mix. Indians fans dining there were largely unaware of the fate of their leftover fried pickles and uneaten cheeseburgers, but expressed support for the program.

“That’s better than going to the landfill — reuse, energy, that’s all cool,” said Jim Vanco, 57, a commercial real estate broker who was eating wings, calamari and crab dip with his son John, 27, and their friend Roger Riachi, 49. “Wind, solar — any independence you can get from the Middle East is best.”

At a table just below them, Barb Saiter, 60, and her brother Bob, 63, also welcomed the approach.

“Using it as an energy source — that works,” she said. He agreed: “Too many people waste — it’s a throwaway society.”

And Mr. Gholston, who makes about eight trips to the energy machine during games and took roughly six minutes to process about 20 pounds of food scraps, said it had changed his habits.

“It made me think about being green at home,” he said, as hundreds of Progressive Insurance employees wearing aprons like their pitchwoman, Flo, prepared nearby for pregame festivities. He and his wife recycle more now, but he is also simply fond of the contraption.

“I enjoy big machines,” he said, pointing out how the slurry moves from the grinding apparatus up through tubes into the tank. “I’m just a guy that likes any machine.”