Officials show locals Burlington biomass site
BURLINGTON - While 25 people from Pownal signed up to take a bus trip to the McNeil Station, a 55-megawatt biomass power plant located at the north end of Burlington, only about a dozen attended.
The trip was organized by Beaver Wood Energy, LLC, a Maine developer that wishes to construct two 29.5-megawatt biomass and integrated wood pellet manufacturing facilities in Pownal and Fair Haven. The trip was intended to give residents an idea of what a biomass plant looks like and how one functions.
Throughout the tour, Thomas Emero, one of Beaver Wood’s owners, along with Bill Bousquet, its designer, pointed out where their plant will differ from the Burlington facility.
The most visible part of the station from the surrounding area is the 257-foot emissions stack, which produces largely water vapor that is only visible when the air is cold, and even then its hard to see against a cloudy sky. The tower was built by stacking concrete rings atop one another, like a pile of tires, and are held together by rivets.
Pollution controls within the process filter out 99.8 percent of particulate matter created by the burning of wood chips, said John Irving, manager of power supply for the Burlington Electric Department, which owns half of the plant (Central Vermont Public Service owns 20 percent of the plant, Green Mountain Power 11, and the Vermont Power Supply Authority, 19). Irving said the boiler and stack have never had
to be cleaned, unlike a residential wood stove and chimney, which wouldn’t burn as clean.
Bousquet said the Pownal and Fair Haven plants will be cleaner, as they will use the latest in pollution control technology. Like the McNeil Station, the Beaver Wood plants will make use of a device called an electrostatic precipitator, which uses electrically charged plates to charge particulate matter and dust, causing a static cling effect to filter it out of the air.
Once inside the plant proper, the most obvious feature to an observer is the cooling tower, a large building that produces a large cloud of steam from its top and sheets of water around the base. Irving explained that heated steam from the boiler is sent to the tower to be cooled. The plant’s water comes from underground wells, which recharge from Lake Champlain.
In Pownal, the plant would draw 80 percent of its cooling water from the Hoosic River. When the river is too low, the rest will come from an existing underground well. Developers have said the minimum the plant will draw is about 130 gallons per minute, while the maximum will be 500 gallons. Most of the time it will draw 330 gallons per minute.
Emero said the river water was recently tested after a heavy rainfall for PCBs. He said none were found. Pownal Select Board Chairman Nelson Brownell told the group that the federal Environmental Protection Agency has detected PCBs, an industrial pollutant, in the sediments and banks along the river, but not the water itself.
Residents had raised concerns about the PCBs being in the water after a hard rain.
The boiler, a 10-story piece of equipment that weighs more than 72 tons, resides in the main building. Fires that burn beneath it are fed by a conveyer belt that takes wood chips from an outdoor wood-yard. Most of the wood, 75 percent, comes in via train, he said, at the rate of about four trains per week. The rest is delivered by truck. Irving said trains are not an ideal way of shipping wood to a biomass plant, but because the McNeil Station is near a residential area, it was required by the state.
Shut down nightly
Irving said the plant monitors itself and sends the results to the state. The stack, he said, doesn’t emit enough to be monitored constantly, so once a year it gets checked for a seven day period. Ash from the plant is collected and sold to farmers as a lye substitute, he said, while dirt and other matter that comes in from the wood is gathered and used as road construction material.
The Pownal plant would also be monitored by the developer and the state, but it would operate around the clock except for 10 days out the year for scheduled maintenance. The Burlington facility was built in 1984, shuts down for two weeks every year and four weeks every seven years, and doesn’t operate at night.
He said plant hasn’t had any complaints in recent years, but about a year into its operation it had a problem with its fuel source. In 1985, forecasters predicted a hot summer and advised the station to stockpile a lot of fuel. The pile, he said, was allowed to get 100 feet high and cover six acres. Unfortunately, the weather predictions turned out inaccurate and the summer was wetter than expected.
To compound the problem, the demand for power wasn’t as high, and the station did not have an agreement in place with the owners to let it burn off excess fuel inventory.
Irving said the pile got moist and began to ferment. The amount of heat being generated inside it was also enough to cause it to smolder, so the pile was separated into two piles. That proved to be a mistake, he said, as it exposed the fermenting fuel to the air causing an odor which annoyed nearby residents. For some, it also caused respiratory problems. "It was a public relations nightmare," he said.
These days the piles don’t get higher than 35 feet, and are arranged in rows to dissipate heat. The station is also permitted to burn extra if it gets too much fuel, plus wood is burned on a first in, first out system so it’s never on site long enough to ferment. To smell the fuel yard, one had to be standing near it. Trucks come in, are weighed, and back up a ramp where a machine dips the trailers backwards at an angle, like a pitcher of water being poured. Front end loaders move the chips from place to place.
Bousquet said the Beaver Wood plants will store their fuel in silos. During seasons where it’s difficult to get equipment into the woods, it may pile some fuel on site but it won’t be there for longer than a few weeks. The fuel moving process at the Beaver Wood sites will be completely automated, he said, as the way the McNeil Station works is labor intensive.
Around 2000, the McNeil Station began to get complaints from a nearby subsidized housing development about dust, Irving said. Nothing had changed at the plant, but it was found that a nearby project had removed a stand of trees, which created a wind tunnel effect that went though the station’s loading yard. He said the trains are now covered and dust screens were erected and there have since been no complaints.
The plant managers are required to investigate all complaints, Irving said, and over the years the kinks have been ironed out. He said dust controls have been installed and machines use strobe lights instead of beeping sounds when they back up. The station used to be lit up at night, but now only turns lights on when equipment needs to be checked.
Brownell said the plants appear to be a number of components, and it’s important for people to understand the function of each. He said he’s suggested to Beaver Wood that they take into account deigns that are aesthetically pleasing.
Irving said most people in Burlington support the plant, and showed it by voting in 2008 to approve paying for a $10 million nitrous oxide reduction system to be installed at the plant. Irving said over 90 percent of voters agreed, and it halved the plant’s nitrous oxide emissions.
The loudest part of the plant is the generator room. It’s difficult to hear others speak next to the generator, which weighs 183 tons and rests on a section of floor suspended from the rest to reduce vibration. Outside the generator room, the machine’s sound isn’t noticeable.
Brownell said there are legitimate environmental concerns about the project and they should be addressed with sound scientific studies and not what he called "sound-bites" or claims that the hills will be clear-cut. They won’t, he added, because forestry in Vermont is highly regulated.
For the Pownal or Fair Haven projects to be approved, they must receive a certificate of public good by the Vermont Public Service Board. Beaver Wood expects to make an initial filing for the Pownal facility on Oct. 25. A copy will be available at the Town Office once filed.
Contact Keith Whitcomb at firstname.lastname@example.org.