Washington Electric Co-op General Manager Avram Patt surveys the methane collection tank in the gas scrubbing room of the co-op’s Coventry methane plant. Photo by Joseph Gresser
COVENTRY — When life hands you lemons, make lemonade. When the dump passes methane gas, make electricity.
The latter piece of advice seems to have been a guiding principle for the Washington Electric Cooperative, which recently started generating electricity at a plant built in New England Waste Services’ Coventry landfill.
Avram Patt, the co-op’s general manager, gave a tour of the $8-million plant. It is housed in a cinder block building that sits in a small hollow just inside the landfill. A low, steady hum comes from the building.
At one end of the building a chain link fence plastered with graphic warning signs surrounds an electric transformer. Wires run from the transformer to the road. They look no different than normal electric lines, other than rising from the cross bars of the utility poles atop foot-high insulators.
The lines presently carry about three megawatts of electricity, says Mr. Patt. The plant will gradually increase its production to 3.7 or so megawatts over the next two months, he says.
“They’re tuning the landfill to produce more methane,” says Mr. Patt. “They used to focus on keeping the odor down. They still try to do that, but they have to consider methane production too.”
At the moment the plant, which went on line July 7, produces almost a third of the power the co-op uses, which averages ten to 11 megawatts. The co-op’s peak load, which occurs in the winter, is about 15 megawatts.
As the landfill is tuned and the operators get to know the plant, it may meet about half the co-op’s needs, Mr. Patt says.
“It’s base load,” he says, “like nuclear power it’s very reliable. It will be available about 95 percent of the time.”
A vertical pipe looking like the unlit tip of a giant’s propane torch stands nearby.
Mr. Patt points to the pipe and explains that the landfill used it to burn off excess methane. A four-foot high pillar of blue flame used to burn at its top, he says. The pipe remains in place as a safety measure in case the plant stops running.
Decomposing material within the landfill produces methane, and NEWS-VT’s ACT 250 permits required them to gather and flare off the gas.
Inside the plant’s control room the noise rises to a dull roar. A placard next to the generator room door forbids entry to anyone without ear protection. The warning is convincing.
The room is sparely furnished. It holds little more than a couple of rows of gray metal cabinets with gauges and lights, a few chairs, a desk and a table bearing a computer.
The co-op, says Mr. Patt, hired an experienced company to operate the plant. Innovative Energy Systems owns several similar plants in New York State. Mr. Patt says the co-op thought it cheaper to hire expertise rather than attempt to gain it themselves.
Plant Operator Scott Wilson enters from the generator room. The roar is deafening while the door remains open. Mr. Wilson smiles and nods, wearing the kind of ear protectors that airport workers use when they wave their paddles at the jets.
Mr. Wilson points to a box of foam earplugs and Mr. Patt fishes out a couple of pairs. Once all ears are plugged the tour moves into the generator room.
With earplugs the noise is quite bearable, but conversation, of course, is impossible.
Within are three long, yellow Caterpillar engines. Each is connected to a yellow pipe marked “gas.” Mr. Patt points to a large hole in the concrete floor surrounded by a pipe railing. That, he mouths, is where a fourth generator will be placed.
The engines make a lot of noise for machines that are apparently at rest. Mr. Patt leads the way through a door at the far side of the generator room.
There the noise abates to a tolerable level and the earplugs are no longer necessary.
Mr. Patt gestures at a maze of pipes that lead to a cylindrical black tank.
This is the gas scrubbing room. Gas from the landfill is not a pure substance. Right now, says Mr. Wilson, it is 47 percent methane, 2 percent oxygen and the rest undesirable impurities. According to Mr. Wilson the ideal value of the gas would be around 54 percent methane.
At that level the gas would produce about half as many BTUs per cubic foot as natural gas.
“It’s still a valuable fuel to utilize,” says Mr. Wilson.
In the scrubbing room impurities and methane are separated. The latter goes to the generator room to run the engines.
The former are collected to be disposed of. Some of the impurities are taken to a hazardous waste treatment facility. The remainder, leachate, otherwise known as garbage juice, is trucked to Montpelier’s sewage treatment plant.
“The plant does not create any more waste that would be otherwise created,” says Mr. Patt, who notes that he sees tanker trucks full of leachate drive past the window of his East Montpelier office on the way to the Montpelier plant.
The Coventry generators came out of a “full-blown strategic planning process” the co-op carried out five years ago. The problem was the impending loss of base power from the Vermont Yankee nuclear plant as well as the foreseeable loss of other power sources.
The co-op worked with a power planning consultant to find ways to replace fading sources of power with renewable sources while remaining sensitive about cost. They contacted everyone in New England says Mr. Patt.
The co-op considered buying into a Rhode Island plant before finding a New Milford, Connecticut, methane plant running in a closed landfill.
“We knocked on their door the right day,” says Mr. Patt.
Operators of the plant thought they might have three years of methane left, and the co-op contracted to buy the power. It turned out that the landfill was able to produce enough methane for yet another year, he says.
If they have a fifth year left, and if the co-op can reach acceptable terms with plant operators, Mr. Patt says, they will continue to buy Connecticut methane power.
In any event the experience taught the co-op about methane power.
When the co-op heard that Casella Waste Services, Inc., the owners of the NEWS-VT landfill, very much wanted to use the methane produced by the landfill and was looking for a partner, they opened negotiations.
The result was the agreement allowing the co-op to build the present plant. They also have rights to the methane produced by newer areas of the growing landfill.
Building the plant was complicated, the requirements of ACT 250 were extremely rigorous, said Mr. Patt. In addition the landfill itself was going through the ACT 250 process.
“We couldn’t stick a shovel in the ground until we knew Casella would be permitted,” he said.
Five divisions of the Agency of Natural Resources were involved in setting conditions. When a new transformer had to be installed at the VELCO sub-station in Irasburg and the perimeter fence had to be extended 15 feet to accommodate the new equipment, an endangered plant was discovered which forced a delay for study.
“As a citizen I wouldn’t want it any other way,” says Mr. Patt. “As a developer it’s ‘What’s next?’”
The various delays pushed construction into the winter, the most expensive time to build.
Even the delivery of the engines was complicated, Mr. Patt says. Caterpillar was supposed to deliver them on a day specified by the contractor.
The time came for shipment, but three engines did not arrive on the same day. One of the trucks scheduled for the job was commandeered by the U.S. government to move armored Humvees toward Iraq. The other two trucks set out, but both were stopped by New York police who discovered that one of the drivers had been working too long without rest.
Generator delivery took a week to complete.
The co-op will continue to seek more power from renewable sources, says Mr. Patt. “We’re looking not to build,” says Mr. Patt, “we’re looking for developers we can work with.”
In addition to the windmill project on Hardscrabble Mountain in Sheffield, the co-op is looking into projects all over the state.
The cost of power is something the co-op thinks it can control, Mr. Patt says. For a utility that serves an average of less than eight residential customers per mile, more than half of the co-op member’s bill is spent for system overhead.
“Vermont no longer has the highest rates in the Northeast,” says Mr. Patt. But Vermont will never be a low-cost energy state, he added.
“We’re at the end of the pipeline. Whatever pipe you’re talking about, we’re at the end of it.”
