Gas from Iron Gut Powers Homes, Farms
May 2, 2012
John Noble’s family has farmed the quilt of green fields and rolling hills around Covington in western New York for five generations. Every day, Noble’s herd of 2,000 dairy cows produce 20,000 gallons of milk, which he sells to local yogurt and cheese factories. But starting this year, he’s tapped another bovine asset, liquid cow manure.
Noble’s farm, Synergy Dairy, teamed up with the renewable energy company CH4 Biogas, which built on his property the largest on-farm biogas power plant in New York. That’s a big deal when you consider that the state is the country’s third largest milk producer. The plant’s innovative “digestion” technology blends cow manure with cheese whey, school lunch leftovers and other food waste to make methane, and turns it into electricity in GE’s clean-burning Jenbacher engine. “It’s a commercial grade stomach,” says Lauren Toretta, vice president of CH4 Biogas.
trucks collect liquid food waste like whey from nearby dairy plants, and oils and fats from bakeries and food manufacturers as far as Rochester, some 60 miles away, while workers at the farm pump manure from Noble’s cow barns. They transfer the slush into a large receiving tank, macerate it to gain even consistency, and pasteurize it. “The pasteurization step is unique,” Toretta says, speaking like the Harvard MBA and former McKinsey & Co management consultant that she is. “It kills the pathogens that come in through the waste. We then put in the right bacteria to do its job and maximize gas output.”
Pumps push the mix into a looming 120,000-gallon digester, where it sits for three weeks as Toretta’s “good” microbes do their work and break grease, fats, and proteins into bubbles of methane in a process called “anaerobic digestion.” The gas then flows through a scrubber, which removes hydrogen and other impurities, warms up in a heater, and pools inside a compressor. “You want the gas to come out evenly,” Toretta explains the steps. “ You want an even output of electricity and temperature and pressure affect the gas throughput.”
Turning the pressurized methane into a steady flow of electric power is where GE’secomagination-qualified Jenbacher engine comes in. It is designed to run around the clock with as much as 95 percent uptime. Unlike wind or solar plants, the electricity generated by the methane-fired Jenbacher is so stable and reliable that it can be fed directly to the grid. “We run all the time, which is one of the reasons why other farms like us and the utilities like us,” Toretta says. “They rely on us.”
The biogas plant started generating electricity in December. It produces some 10,000 megawatt-hours of renewable electricity annually, enough to power almost 1,000 homes. The project received $1 million in funding from the New York State Research and Development Authority (NYSERDA) and another $750,000 in a grant from the National Grid utility company.
For farmer Noble, his partners, and the community the benefits are manifold. Noble gets rid of smelly manure and cuts annual greenhouse gas emissions from his farm equivalent to emissions from 1,700 cars. He also saves many thousands of dollars by using the plant’s dried up residue as bedding for his cows. CH4 Biogas sells electricity to the grid for revenue and Covington gets a lift, too. In addition to the 30 workers em