Wood Chips Keep School Warm

Principal Ted Ridden shows off his school’s wood-chip boiler. Photo by John Douglas/Flying Squirrel.

Well before first light on an icy winter morning, a tractor-trailer unit wheels out of the yard at the Claire Lathrop sawmill in Bristol, Vermont, and heads for Barre Town Elementary and Middle School atop Quarry Hill. Dawn is just breaking as the rig pulls into the still-empty school parking lot and backs up to one of the twin bays in a small building adjacent to the school itself. When the bay door opens, the driver activates the moveable floor of the truck, and 30 tons of wood chips cascade into the storage bin.

Throughout the week, the chips will move in a herky-jerky fashion out of the bin onto a conveyer system, across the floor of the building, up above head height to a hopper, and then into a huge boiler, where they are burned to heat water in a heat exchanger. The hot water is then pumped through the school to heat the main building.

This system, which cost about half a million dollars, was installed in 1996 to replace electrical heat that had been installed in the 1970s, when electricity was so cheap that people said it wasn’t worth metering. By the mid 1990s, however, electricity was ferociously expensive, so as soon as the wood chip system went online, the school’s fuel costs dropped by 90 percent. They saved $100,000 the first year; the system paid for itself in five years.

Ted Riggen, the principal at Barre Elementary, loves everything about the system. He likes the reduced heating bill, of course, but he is also a former forester, and the idea of a sustainable fuel source has tremendous appeal to him. Administrators considering wood heat in their schools often visit, and Riggen likes giving them the tour himself.He especially likes taking them out to the storage bin and smelling the raw chips.

“Sometimes I think I could pour milk over a bowl of these chips and eat them like cereal,” he says.

The most powerful appeal, of course, is the relatively low cost of the chips. Twenty-five Vermont elementary and high schools, serving roughly 10 percent of the state’s students, use wood heat. In the last several years, they have saved 35 to 40 percent over oil heat, the most common alternative fuel. And that margin has been rising with the run-up in oil prices over the last year or two. According to the Vermont Superintendents Association, Vermont schools using wood in the last full school year saved a total of more than $600,000, a figure that gets a lot of attention in a financially strapped system.

According to Cathy Hilgendorf, the school construction coordinator for the Vermont Department of Education, several more communities have approved or are actively considering installing wood chip systems in their schools. “It’s such a slam dunk, especially for larger schools,” she says. “These systems pay for themselves in a few years. They’re an easy sell, particularly since the state will reimburse the community for 90 percent of a renewable energy system.” In contrast, the state pays just 30 percent of other elements of construction projects, including conventional heating systems.

While Vermont is poised to take even greater advantage of the abundant fuel its extensive forests provide, other states across the Northeast have thus far mostly ignored wood heat’s potential for their schools. New York has no wood-heated schools; Maine, the most heavily forested state in the country, has just one, in Turner, in the middle of the state; New Hampshire has two, one of which is in a twin-state district with Norwich,Vermont.

Massachusetts has just one high school with wood chip heat, in Athol, in the northern part of the state. Cooley Dickenson Hospital in Northampton uses wood heat, as does the Mt. Wachusett Community College in Gardner. Joe Smith, who heads the Forest and Wood Products Institute at the college, says that wood-heat advocates in his region had to overcome considerable original resistance to heating with wood. There was the simple fact that they had to cut trees, which some people thought was bad, he says. Moreover, the shift to wood heat entailed significant changes in infrastructure, especially retrofitting an electricheat campus. Just the planning and implementation of the conversion required the addition of full-time staff. Yet the conversion has paid off handsomely. The project cost was about two million dollars, but according to Rob Rizzo, the facilities chief at Mt. Wachusett, the $35-per-ton cost of wood chips is just one-tenth the cost of electricity and a fifth the cost of oil. This performance, according to Smith, has inspired Massachusetts state education officials to launch a major study of the advantages of converting elementary and secondary schools to wood heat.

It was 20 years ago that wood chip heat first came to schools in Vermont. It started in the little town of Calais, in the north central part of the state. In the mid 1980s, Calais was paying a fortune for electric heat for its elementary school, so the town set up an ad hoc committee of volunteers to look for a solution. After considering a range of alternatives, the committee settled on wood heat; it estimated the town could save 80 percent of its fuel costs by switching from electric heat to chips and convinced the town to go ahead and install a system.

One of the local volunteers was Tim Maker, who had worked in the residential energy audit program run by the University of Vermont Extension Service and then, when that program lost its funding, established his own energy consulting company. Now 59, Maker grew up in Springfield, Vermont, and earned a degree in engineering physics at Cornell University.After working on the Calais project,Maker went on to serve as project manager for wood installations in 10 Vermont schools.

And in 2000, he set up the Biomass Energy Research Center (BERC), with offices in Montpelier,Vermont. BERC is a nonprofit corporation that carries out a wide range of studies and projects on wood energy. One of the most important of these efforts has been to serve as midwife to the installation of wood systems in schools.

In addition to the Vermont projects, Maker has served as a consultant to school districts in Idaho, Montana, and New Mexico. The Center is now functioning as a partner with the Massachusetts education officials to consider extending wood heat in their schools. Maker is an unabashed advocate for wood chips; he also believes that the best way to advance this interest is by the most rigorous technical analysis of all of the issues involved – technical, scientific, environmental, political, economic. At the root of this analysis is Maker’s conviction that the use of wood chips for heat is good for everybody in the Northern Forest.

It is good for rural communities because it turns a byproduct into public use and produces both revenues and jobs; it saves school systems large amounts of money; it improves the forest by encouraging the weeding out of low-quality trees; and it slows global warming because it backs out the use of fossil fuels, whose consumption only adds carbon to the atmosphere. The only ambiguous area is air quality. Wood chip heat in small institutions produces lower sulfate emissions than oil heat and about the same level of nitrate emissions. But its particulate emissions are higher. These tiny particles are a problem because they can get into people’s lungs. The school projects deal with this by building tall enough smoke stacks to get the particulates away from the school site; and in any event, the school system boilers are far less of a problem than woodstoves in homes, Maker argues.

The use of wood chip heat in schools has been pretty much an unalloyed success, but now the system is coming under some pressure, with chip prices drifting up after remaining low for more than a decade, and with some of the advocates beginning to worry about the stability of the chip supply. No shortages have appeared yet, but technical issues and the health of the forest products industry itself have become a concern to people like Maker.

The key to the whole system is the wood chip itself. The chips come from two sources: sawmills like Lathrop’s and mobile chippers used on log landings. By far the highest-quality chips come from sawmills. The mills acquire logs, mostly hardwood, remove the bark, and saw the clean logs into lumber. Turning an imperfect round log into sound, square-edged lumber produces some waste wood – slabs and edgings – which is then passed through a chipper and then run through a screen to ensure uniform size. The result is a pale, tan piece of hardwood about two-thirds the size of a paper book of matches. Paper mills buy these chips to augment the chips they produce themselves from debarked logs. And they are coveted by the schools. As Steve Murray, the operations chief at Barre Town Elementary, says, “These are the Cadillac of chips.”

At the other end of the spectrum are chips that are not even of Kia quality: whole-tree chips that come from logging jobs and land-clearing operations. In these circumstances, whole trees are fed into a chipper, and the resulting biomass is shipped off to wood-fired power plants. The chips include bark, twigs, and leaves, and they are not screened, so that there are lots of odd sizes, including long, skinny stringers that often result when small branches are chipped. These are called “dirty chips,” as opposed to papermaking-grade “clean chips.”

In between is a third category, called “bole chips,” which are similar to whole-tree chips except that they come from the tree’s bole – there are no small branches, only trunks and large limbs. The chips aren’t screened, but since there are no small branches, there are few if any stringers.

It is ironic that schools, the smallest systems and by far the smallest consumer of chips, have to use the highest-quality chips. The reason is that the delivery systems in the schools, which move the chips from the storage conveyer systems and from the hoppers into the boilers themselves, have relatively small augers. These augers are easily jammed by stringers, so schools will have nothing to do with whole-tree chips, though they are the most readily available kind.

Despite these stringent requirements, nobody has worried about the supply of these chips to schools – until now. In the last year, the price of chips to schools has begun to rise, and there is considerable concern about the supply. One of the problems is that the schools use such a small piece of the chip stream, just 16,000 to 18,000 tons of the million or so tons that are harvested in Vermont each year, so they have little pricing power with the chip suppliers. In fact, Bob DeGeus of Vermont Department of Forests, Parks and Recreation, says that the mills essentially supply the schools as a community service. “They have a good-neighbor policy,” he says.

Moreover, the special equipment needed to supply the schools is expensive. The big users, such as electric power plants and pulp and paper companies, have massive infrastructure to process wood, but most schools have only simple, below-ground storage bins. Jim Lathrop says the walking-bottom trailers needed to get chips to schools cost $45,000 apiece; he has two. Also, the tractors that pull the trailers have to have special hydraulics to operate the walking bottoms; he has five of those. Then there is the screening and the extra work to guarantee the highest-quality chips. “You’ve got a million-dollar deal to stay in this business,” he says.

Finally, wood-heat advocates worry about gathering stresses and crosscurrents within the forest products industry itself. From the perspective of the schools, the biggest threat is erosion in the financial outlook for loggers and mills. One problem is the struggle going on in the pulp and paper industry, one of the biggest purchasers of wood. The Northeast segment of that industry is being pressured by competitors in other parts of the U.S., South America, Europe, and now Asia.

The sawmills are also in a financial squeeze. Their costs are going up steadily, and the price of lumber is not keeping pace. And the loggers who supply them have their own set of challenges, including high workers’ comp rates and high fuel costs that erode profitability. According to Tim Maker, this dynamic can eat away at the infrastructure needed to keep the wood chip stream flowing.

“If the paper mills go out and the number of sawmills declines, the infrastructure that supports the industry likewise begins to contract – the chipping machines and the log trucks, and the special equipment gets scarcer,” he says. The chip supply for schools is critically at risk from this perspective.

BERC now has a $50,000 grant from the federal and state governments, along with some contributions from private industry, to seek a solution to this gathering problem. Maker says they are looking for ways to tweak the business model for chip producers in a way that would bolster the chip supply. “We now see an advantage to higher chip prices,” he says. “Schools would still save a lot of money over oil, and it might be possible for someone to make a living in this business.”

However that works out, there appears to be one step that the schools can make themselves: they could persuade the manufacturers of the wood boilers to beef up the augers and other elements of the delivery system so that the schools could routinely use bole chips. Jim Lathrop strongly supports that. “They would be a bit more expensive,” he says, “but they would be much more flexible.”

Though most schools prefer sawmill chips, some are making the gradual shift to bole chips. This year, about half of the supply at Barre Town is bole chips, supplied by Limlaw Chipping, one of the largest chip suppliers. Adam Sherman, who works with Maker at BERC, says, “I think the future for the schools is bole chips.”

Despite these caveats, Vermont school officials at all levels continue to be upbeat about wood chip heat. Cathy Hilgendorf at the state education department is pushing it as hard as she can. And principals like Ted Riggen do likewise. Riggen, in fact, is talking about how to use the 88 acres of woods surrounding his school as a source of sustainable fuel. He thinks that the local vocational high school should consider adding a forest products course to its academic offerings.

“You manage the forest well,” he says, “and you can sustain this flow forever.”


No discussion as of yet.

Join the discussion

To ensure a respectful dialogue, please refrain from posting content that is unlawful, harassing, discriminatory, libelous, obscene, or inflammatory. Northern Woodlands assumes no responsibility or liability arising from forum postings and reserves the right to edit all postings. Thanks for joining the discussion.

Please help us reduce spam by spelling out the answer to this math question
three plus three adds up to (3 characters required)