Bob Downing

One home’s waste is about to be another’s source of energy.

By next month, officials say 100 percent of the sewage sludge from the city of Akron’s waste treatment plant will be converted into renewable, clean electricity.

This gee-whiz innovation will take place at the former Akron Composting Plant off Riverview Road.

The ultra-green complex has been given a new name — the Akron Renewable Energy Facility.

City officials along with partner KB BioEnergy Inc. held a ribbon-cutting ceremony on Wednesday to mark the $32 million transformation of the plant where bacteria will be used to convert solids from the sewage plant into a biogas to power generators to produce electricity for city operations.

“We’re proud of this project and we have a bright future,” said Tom Kurtz, president of KB BioEnergy.

A new plant was built and is owned by Akron-based KB BioEnergy — previously known as KB Compost Services Inc.

The effort was funded in part with a federal renewable energy tax credit that kicked in $9.6 million.

Akron provides the sludge and gets the electricity produced, said Akron spokesman Brian Gresser.

The plant’s complicated process is not easy to understand.

Akron Mayor Don Plusquellic said half-seriously that he doesn’t “know how, but it works.”

Sludge tanks

At the center of the expanded plant are two huge tanks — each measuring 68 feet in diameter and 26 feet high — each capable of holding 704,000 gallons of sludge pumped in from the sewage plant on the east side of the Cuyahoga River.

The sludge is heated to 95 degrees and remains in the plant for 28 to 29 days inside of the domed tanks that have a double membrane layer.

The system relies on bacteria that do not need oxygen, a process known as anaerobic digestion. The bacteria cause the sewage sludge to ferment. As the bacteria multiply they consume part of the sludge and produce a methane-rich, burnable gas.

The so-called biogas is 60 percent methane, 35 percent carbon dioxide and 5 percent other gases. In comparison, natural gas is 99 percent methane.

The technology, developed by a German company, Schmack Biogas AG, is widely used in Europe, where farm crops are used — not sludge.

Heat, electricity

The biogas in Akron will power three 600-kilowatt combined heat-power units.

About 45 percent of the energy produced will be heat and 41 percent will be electricity.

The plant can generate 10,000 megawatt hours annually, enough to power 1,400 homes for one year. An estimated 20 percent of the electricity will be used to power the plant.

The remaining electricity will power the city’s sewage plant, one of the biggest electric users in the region. The new plant will provide nearly all of its electricity.

The addition can handle all of the city’s sludge or about 15,000 tons a year.

Previously, the plant’s smaller system installed in 2007 could handle about 30 percent of the sludge or about 5,000 tons a year. That system cost about $7 million and was designed as a pilot project that was considered very successful. The original plant was hailed as the first facility of its kind in the country.

The plant’s two older tanks will soon be retrofitted and put back in service, said KB spokeswoman Annette Berger.

The new plant is three times larger than the pilot effort.

With the enlarged facility coming online, Akron no longer needs its composting plant.

It has not been used in 2013. Officials instead began using a small dryer that processes 15,000 cubic yards of pelletized fertilizer annually from the leftover biosolids, Berger said.

The old compost plant was known for its odors that drew complaints from neighbors.

It once handled 1.2 million gallons of sludge per week and cost Akron $6.2 million a year to operate.

The spark for the Akron biogas facility came during a trade trip that Plusquellic made to Germany in 2003. He inspected a similar facility near Zurich, Switzerland, and brought the idea back to Akron.

Akron is now a part-owner in the biogas technology and could generate royalty income as other cities invest in the process, Plusquellic said.

Another unit might be added to the Akron plant to process food wastes, oils and greases, Berger said.

Bob Downing can be reached at 330-996-3745 or bdowning@thebeaconjournal.com.