Akron's green-energy system might be getting an additional fuel: food waste.
The Ohio Environmental Protection Agency has approved a permit for the city to add organic wastes to the sewage sludge that generates an environmentally friendly biogas.
That gas powers turbines to produce electricity at the city-owned composting plant off Riverview Road.
In January, Akron filed the paperwork for a pilot project involving its ''anaerobic digester,'' the key equipment associated with the green system.
The 54-page state permit allows cola syrup, spent salad dressings, spent soda and beer, meat wastes from dog-food processing, corn chip mash, bakery wastes and pasta noodle wastes to be added to the sludge.
The city and its partner, KB Compost Services, expect to begin testing in the next few months, said Brian Gresser, Akron's water pollution control administrator.
The city's storm-water management plan for the plant must be modified before the testing can begin. That will take up to three months, he said.
The experiment will enable the city and KB Compost to determine how food waste would mix with the sludge, what wastes work best and perhaps which ones should be avoided, Gresser said.
The testing probably will take at least several months, he said.
KB Compost has contacted a few local food producers about getting loads of waste when the
testing begins, he said.
Akron and the company also would need to determine the market for the soil additives created in the process, he said.
Akron would like to see how the food wastes work out before deciding whether to expand the biogas system to handle all of the city's sewage sludge, Gresser said.
The current system handles about one-third of the city's sludge. Expanding the system to handle the remaining two-thirds would cost about $25 million, he said.
Akron is seeking federal stimulus funds and other grants to fund the expansion, he said.
If the tests on food waste are successful, Akron could enlarge the system slightly and charge food processors for taking their wastes — and perhaps sludge from other communities, he said. That would enable Akron to reduce costs to its sewer customers, he said.
Enlarging the system would also permit Akron to shut down the aging composting facility, which generates odor complaints.
Akron's $7 million biogas system has been operating since late 2007 and has been working well, officials said.
The new facility is owned by the city and operated by KB Compost, the company that also manages the composting plant.
KB Compost Services joined with German-based Schmack Biogas AG to form a new company, Schmack BioEnergy LLC in Independence, to promote the German technology in the United States. It is a process that is being pursued by other cities, including Canton and Columbus.
The system relies on decomposition by bacteria that do not need oxygen, a process known as anaerobic digestion. The bacteria make the high-solids sludge ferment. The bacteria multiply, consume part of the sludge and produce a burnable gas. The biogas is 60 percent methane, 35 percent carbon dioxide and 5 percent other gases. In comparison, natural gas is 99 percent methane.
The system includes two tanks: one capable of processing 160,000 gallons of sludge and a second that can hold 450,000 gallons. The sludge will be processed for 25 to 30 days at temperatures of 90 to 100 degrees.
The plant now handles up to 5,000 tons of sludge a year from the city's sewage treatment plant across the Cuyahoga River off Akron-Peninsula Road.
The current system produces 335 kilowatts, or enough electricity to power 325 homes.
About 9 percent of the electricity produced is used to operate the biogas facility, with the rest being used to power the composting plant. That produces a monthly savings of $14,000 over what Akron had been paying.
The savings represent about 10 percent of the total electric bill for the composting plant and sewage plant, he said. That bill in 2008 was more than $1.5 million.
Bob Downing can be reached at 330-996-3745 or bdowning@thebeaconjournal.com.
