By Mike Dunphy
Since high-grade Austrian wood pellet boilers first began arriving in Vermont about 10 years ago, they have grown significantly in popularity, providing ever increasing amounts of supposedly carbon-neutral heat to Vermont homes and buildings, with 85 systems installed statewide in 2017, the highest amount yet on record.
These are not the simple, compact pellet stoves that heat living rooms and bedrooms around the state, but state-of-the-art systems dubbed “advanced wood heat” (AWH) by proponents such as Ansley Bloomer, assistant director of Renewable Energy Vermont, and Emma Hanson, wood energy coordinator of the Vermont Department of Forests, Parks and Recreation.
“It’s literally just like any other fuel type,” says Bloomer, with a delivery truck that pulls up and delivers the fuel to either a storage bin or silo to be automatically fed into the boiler as needed and free of the heavy lifting, muscle straining, or constant cleaning associated with traditional wood stoves, fireplaces, or pellet stoves. Just turn the thermostat on the wall, as you would with oil, propane, or gas.
Technological improvements in advanced wood heating in the past decade have put its energy efficiency at 85 percent or more, on par with the most up-to-date gas and oil systems. One example is the inclusion of “turbulators,” which plunge up and down the heat exchanger cylinders to keep the point of contact between the hot flue gas and water free of particulate matter and ash, thereby maintaining the heat transfer rate. Systems now also come with thermostats that can read weather forecasts and adjust accordingly.
The economic benefits of AWH are also improving, according to supporters. They point to the wildly fluctuating cost of oil to start with. “Who knows how much a gallon of oil will cost next month,” Bloomer asks, “let alone next year. With advanced wood heating, you know that your fuel is going to stay the same and will help save more money over time.”
The data does seem to bear this out, with the price of heating oil per gallon in Vermont bouncing between $1.79 and $4.04 since 2012, according to the U.S. Energy Information Administration. Propane in the same time period ranged between $4.36 and $2.84 per gallon. Pellets on the other hand, show much less variation in price, with the current price of about $235–$290 a ton little different than the $247 average per ton in 2012 or $294 in 2015.
“We track fuel prices and the amount of oil and propane that is replaced with wood pellets for the 164 boilers we’ve helped install in the region,” points out Maura Adams of the Northern Forest Center, “and switching to pellets has generated $3.5 million in economic benefit for the region. Plus, the homeowners, businesses, schools, and municipalities that switched have saved more than $200,000 thanks to the stable cost of wood pellets.” It goes without saying that the economic benefit of advanced wood heat also extends to the many workers who keep the industry going, most of whom are local, from harvesters to millers to deliverers. With fossil fuels, 78 cents of every fuel dollar leaves the state.
But the greatest benefit of AWH to proponents is the “carbon-neutral” (or “low-carbon,” “carbon-beneficial,” or “carbon-better” in the literature) element of the energy. The basic argument is that whatever carbon is released by burning the wood will be reabsorbed by the trees growing back.
A case study can be found in a report, “A Summary of Carbon Emission Impact of Modern Wood Heating in Northeastern U.S.,” by the Biomass Energy Resource Center, a program of Vermont Energy Investment Corp. While a total short-term gross emissions of a biomass boiler plant and “upstream” supply chain activity (basically all the carbon released in the process of producing and transporting pellets) accounts for 214.8 pounds of carbon dioxide per one million British Thermal Units (MMBtu)—compared with 165.5 pounds per MMBtu from burning heating oil—forest regrowth sucks 90 percent of it back in over 20 to 100 years, making a sum total of 29.58 pounds—an 82 percent reduction in the long term.
A second important element to this formula is in the type of carbon produced, with fossil fuels considered “geologic” and wood “biogenic.” “The easier way to look at it,” explains Adam Sherman, a manager at Biomass Energy Resource Center, “is that oil is a really old biomass that took a hundred million years to convert from organic matter to dense carbon stored below the surface of the Earth over a geologic time period.” When released, they take a one-way route to the atmosphere.
“Forests, on the other hand, are constantly emitting and absorbing carbon,” Sherman adds. “There are times and stages in forest growth where they’re sequestering more carbon than they’re emitting. But that carbon then gets released when they grow older, or a pest comes in, or a windstorm or a wildfire. And then they’re releasing more than they’re absorbing. So while there’s more carbon emitted per unit of energy from the wood system than an oil system, you can’t really compare them as apples to apples.”
So why not just burn only fossil fuels, don’t chop any trees, and let the forest absorb that carbon? “The forest will eventually emit carbon, so you won’t achieve any offset. So then it’s hands down, wood heating, if it’s displacing a fossil fuel, is an incredibly effective long-term carbon emission mitigation strategy,” Sherman said.
Furthermore, the existence of a pellet industry, which draws on low-grade wood in Vermont, helps maintain the health and growth of the forests. Having healthy markets for both high- and low-grade wood is essential to forest health, Hanson emphasizes, noting the current low-grade-wood market crisis in Vermont after the collapse of the paper industry. “Without the pair it is impossible to carry out a sustainable forest management plan. The majority of forest land in Vermont is privately owned, and when landowners can’t make a small income off of their forest land that’s when we start to see forest fragmentation and development. Wood heat represents one solution to this low-grade-wood market crisis.”
Harvesting wood responsibly also helps Vermont’s forests, particularly when low-quality, damaged, diseased, dying, or other trees are removed. “You’re stimulating more growth and vigor of the remaining trees by opening up the canopy and allowing more sunlight and nutrients and water to the remaining trees,” explains Sherman. Healthier forests sequester more carbon and add value to future timber value so that 20 years from now they’ll be worth more as timber products than they would otherwise.
Vermont certainly has plenty of forest to keep healthy, too, and is nowhere near its allowable harvest. “Vermont is 76 percent forested, and we are currently harvesting less than half the net growth in the forest,” explains Hanson. In other words, the forest grows each year twice as much as is being harvested, be it high-grade wood for carpentry, or low-grade wood for wood chips, pellets, and the like.
The key, however, to achieving this carbon-neutral effect is that forests indeed be managed ecologically and sustainably—and therein lies the rub. If they are not, then the end result can be greater environmental devastation than fossil fuels. This has been borne out in the mega pellet plants in the South, where producers such as Enviva—the United States’ largest exporter of wood pellets—for example, have been charged with clear-cutting ecologically sensitive bottomlands. They are not alone.
Andy Boutin, general manager and founder of Pellergy (an advertiser in The Bridge) stresses the sustainability of the industry in Vermont. “We have to separate that style of pellet manufacture with what happens in the Northeast,” he explains. “I would even broaden that to include all of New England and even Quebec. Every pellet that comes out of Quebec now is sawmill residue. So they are actually using waste product that would otherwise be left to rot or decompose.”
Vermont’s lone pellet producer, Vermont Wood Pellet Co., also claims sustainable practices, focusing on “local softwoods from Vermont woodlands that have a Forest Stewardship Plan administered by Vermont County Foresters and overseen by the Vermont Agency of Natural Resources,” according to the website.
While softwoods do grow back faster, and thereby re-absorb carbon faster, it’s somewhat too simplistic for Sherman, in part because the Intergovernmental Panel on Climate Change, the foremost entity looking at climate change and policy, looks at everything on a 100-year life cycle—plenty of time for hardwood trees to grow back. Other important reasons for a preference for softwood are that it’s easier to debark and there is a lack of a good market for softwoods in the area, making the price cheaper. “Does it make a good pellet? Yes,” says Sherman confidently, “but is it the only type of feedstock that is sustainable? Absolutely not.”
Thanks to the success of AWH, Vermont Wood Pellet Co. can’t come anywhere near to meeting local demand, with more than 90 percent of pellets used in the state coming regionally from Quebec, New York, New Hampshire, and Maine, but also from as far away as British Columbia. That’s led some AWH advocates such as Sherman to push for a “Heat Local” slogan, and possibly even a label on locally produced pellets—just as they appear on food products. “We want people to be mindful of where their BTUs come from in the same way that people are mindful where their food comes from,” he says.
Just asking that question is step forward to achieving carbon-neutral energy, Sheman believes. “What’s interesting about wood heating is that it actually creates an opportunity for people to ask that question,” he explains. “Nobody calls their oil dealer and says, ‘You know that 500 gallons you delivered to my house yesterday, was that Venezuelan or Saudi oil, or Alberta tar sands? Where did that come from and who made it?’ But when we buy pellets, we do ask that question. It gets people thinking about their energy consumption and where it comes from and how it was produced.”