02/06/12    EXPLORADIO-From the Belly of the Beast web       JSC/MM

Waste? Not.

A truck idles while its load of rancid cooking oil is pumped into an underground pit in Wooster. For plant manager Georg Marien, the pungent effluent has the sweet smell of green energy. Food waste is converted in a long, long process to electricity and later natural gas.

Yesterday, it was a semi truck full of spoiled noodles.  Marien says his digester isn’t picky. “It could be fruits and vegetables, food waste from food- producing companies, could be hot dogs, it could be bread or whatever, and also from grease traps, fat, oil and grease.”

Marien joined Cleveland-based Quasar Energy in 2010, about the time this biodigester at Ohio State University’s Agricultural Research and Development Center campus came on line. He helps run Quasar’s five other digesters in Ohio. Still, it’s minor compared to his native Germany, which Marien says has more than 6,800 biodigesters.

“So we have a little more experience there,” says Marien. “We’ve been building digesters for the last 20 years.”

From the belly of the beast

Marien says the technology behind the digester has a simple, natural counterpart. It’s much like the stomach of a cow. And like coww, they produce methane, which is then used to run a generator.

The belly of the digester is a massive 500,000-gallon steel cylinder capped by a black rubber dome.  Two adjacent towers provide a continual flow of spoiled food. Marien says the anaerobic, or oxygen-hating, bacteria working inside the digester are identical to those inside a cow’s belly.  Cow manure gets the process started.  

When most efficient, the digester’s gas output is around 60 to 65 percent methane, the energy equivalent of 1,500 gallons of gasoline per day. But Marien says, like any digestion system, there can be hiccups.

“We see there might be a problem with the biology, so we may have to reduce the feeding if it looks like we overfed the digester. It’s like a human being:  if you eat too much you feel sick. … And if we see a serious problem, we take a sample and send it to our lab.”

Testing a dry run

Lo Niee Liew runs the Quasar lab down the street from the digester. She says too much nitrogen in the feed stock can convert into ammonia and inhibit the digester’s process.

Lo Niee and her colleagues in the lab test other digester feed stocks like grass clippings, corn stalks, and waste from hog farms. With monitoring, digesters can run 24 hours a day on just about any natural waste product.

Quasar founder and president Melvin Kurtz is taking advantage of the biogas his company produces to save money on fuel. Quasar has converted about 17 vehicles to run on natural gas, from its own fleets to customer’s fleets. His vehicle is among the converts.

Ohio’s energy independence

Kurtz envisions biogas as a road to Ohio’s energy independence.

“If all of the biomass in Ohio, the crop residuals, manure, sewage sludge, all of the organic waste in Ohio were processed via anaerobic digestion—we produce natural gas and converted to fuel in the form of compressed natural gas—20 percent of the total motor vehicle fuel consumed in Ohio could be produced in Ohio.”

While biogas produced in other states mainly fuels generators for electricity, Kurtz says vehicle fuel is the more profitable commodity in Ohio. The only obstacle is an insufficient volume of vehicles to run on biogas.

Kurtz says with loans from the U.S. Department of Agriculture and state help, Quasar will have a dozen biodigesters online here by this summer. In his world nothing is wasted. Kurtz even sells spent digester sludge as topsoil.
-- Web story by Matt Meduri