‘Biomass” is a term that floats through newspaper stories and earnest cocktail party conversations and indignant online debates. But how many of us have had the chance to see what it actually is and how it works? When I noticed the words “Biomass Maintenance Building” on the campus map of Bennington College, where I was teaching this month, I couldn’t resist checking it out.
It was January, it was Vermont, it was cold. I walked, shivering, down the hill to a modest-looking wood-and-metal building. The first thing I saw was a big pile of wood chips in the driveway. The first thing I heard from operations manager Todd Siclari was that those wood chips — the biomass — provide 85 percent of the heat for Bennington’s campus.
He took me on a tour of the building, literally walking me through the process. The wood chips would otherwise be waste — treetops left over from trees harvested for building and furniture, and from the thinning of forests according to sustainable forestry practices. Bennington buys what are known as “whole-tree chips” — a larger, cheaper grade — which are then screened and ground into little chunks within the biomass plant. These small chips are stored in a big concrete bunker and shaken onto a conveyor belt that feeds them into the furnace.
The furnace looks like a gigantic version of what you have in your basement — a big metal box with pipes coming out of the top. Inside it, the wood chips fuel a fire, which heats water and produces steam, which travels through Bennington’s old steam heating pipes into all of the large central buildings on campus.
Standing there looking at the furnace, I realized that the term “biomass,” which sounds so abstract and intimidating, simply refers to a way to boil water.
The grinding room was loud; the furnace room was pleasantly warm; and the third and last room, on the day of this tour, was cool and quiet. This third room contains a series of enormous oil tanks, which heated Bennington’s campus until 2008, when the shift to biomass occurred. These days the oil tanks represent the school’s backup heating system, connected to a generator and used occasionally in the event of an ice storm, power outage, or prolonged spell of exceptionally cold (20 below) weather. According to Siclari, the biomass plant has reduced Bennington’s heating oil consumption from 350,000 gallons a year to 10,000.
If the mechanics of biomass are fairly simple (you grind up waste wood and boil water), what about the various financial and environmental considerations? According to David Rees, Bennington’s senior vice president for administration and planning, the decision to switch to biomass was “one of those rare ‘aha’ moments.” Heating oil had been the college’s single largest budget item. The biomass plant was expensive up front, but as Rees points out, “institutions can afford to think long-term.” Government bond programs helped to finance the cost of construction. The overall expense to heat the campus with biomass is roughly one-quarter of what it was with oil; the college expects the plant to pay for itself within 10 years.
All over the world, biomass has generated fierce debates between those who stress its renewable aspect and those who deplore its reliance on burning. The environmental impact of using biomass varies depending on factors such as what kind of wood is being used (waste products or irresponsibly harvested timber?) and how far the wood has to travel. Bennington’s supplier uses only waste wood sustainably harvested in New England. The product is local, as are the people who grow it, cut it, and deliver it, which helps the region’s economy. And while burning anything creates greenhouse gases (unlike, say, solar or wind power), the forests that produced the biomass material can continue absorbing much of the resultant carbon.
The point of this column is not that biomass is good; the point is that biomass done thoughtfully and in the right place is good. This is a piece about biomass at Bennington, but it’s also a reminder of the need for nuance in public discourse. We need to look beyond broad-brush definitions and irascible opinions — to consider not just what the principle or law or technology is, but how it is being applied. As with so many social and political issues, it all boils down to context.
Joan Wickersham’s column appears regularly in the Globe. Her latest book is “The News From Spain: Seven Variations on a Love Story.’’