Technology modeled after a cow's digestion system could pave the way to Ohio's energy independence.
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.
“We receive food waste and convert it in a long-long process to electricity and later gas, natural gas.” Yesterday it was a semi 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 group in 2010, about the time this biodigester at Ohio State University’s Agricultural Research campus came on line. He helps run Quasar’s 5 other digesters in Ohio. Still, its small potatoes compared to his native Germany where Marien says there are more than 6800 biodigesters.
“So we have a little more experience there. 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 very simple, natural counterpart…“We can describe this as a big stomach of a cow. Cows also produce methane. What we produce is methane. And this methane has a high energy value which runs 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 is used to get the process started.
When happy, the digester’s gas output is around 60 to 65 percent methane, the energy equivalent of 15-hundred gallons of gasoline per day. But Marien says, like any digestion system, there can be hiccups, and…
“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 just down the street from the digester. She says too much nitrogen in the feed stock, for example, could upset the digester’s digestion –
“The Nitrogen could convert into ammonia which could inhibit the process.”
Lo Niee and her colleagues in the lab test other digester feed stocks like grass clippings, corn stalks…waste from hog farms… She says with monitoring , digesters can run 24/7 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 -
“We’ve converted about 17 vehicles from our fleets and customers fleets to run on natural gas already, including my own vehicle.”
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% 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 - with one catch -
“We just don’t have the vehicles in sufficient volume to run on them.”
Kurtz says with loans from the US Department of Agriculture and state help, quasar will have a dozen biodigesters online here by this summer.
In his world nothing’s wasted - Kurtz even sells spent digester sludge as topsoil.