Making biomass work

Posted

Lauren Stevens

I burn biomass. I have a wood stove on which I depend for more than half of my home heat. Once the temperature inside the stove reaches about 500 degrees, I flip a handle to send the smoke through the catalytic combuster to burn the smoke and most of the noxious stuff, according to the manufacturer ( and the EPA). Almost no visible smoke exits the chimney.

So I followed with particular interest the Stop Spewing Carbon campaign in Massachusetts and intend to stay tuned to Beaver Wood Energy, LLC’s efforts to develop a biomass cogeneration plant at the old race track in Pownal, Vt., a mile north of the Massachusetts’ line.

As you might guess from my devotion to a wood stove, I am interested in clean forms of energy that aren’t fueled by coal or oil, for all the good reasons I needn’t go into right now. Stop Spewing Carbon said that wood-fired biomass puts 50 percent more carbon in the air than burning coal, then lists the pollution from wood incineration: particulates, carbon monoxide, formaldehyde, nitrogen and oxides. These lead to asthma, heart disease and cancer in humans.

Furthermore SSC shows graphic photos on its Website of felled trees, noting that if the five proposed biomass plants in Massachusetts went online, they would use 50 football fields worth of wood daily. So how is it, then, that the city of Burlington, Vt., a progressive and healthy place in general, has been generating electricity at its 50-megawatt McNeil wood chip plant for many years? Apparently it takes certain precautions. A year ago, for example, it received an award for cutting its nitrogen oxide emissions by over half, through catalytic reduction (just like my wood stove or your car).

All right, then, how is it Middlebury College, about three quarters of the way to Burlington from Pownal on the same Route 7, cut its consumption of fuel oil in half (by a million gallons) through biomass gasification? Is Middlebury, a school that has branded itself as the greenest of the green, endangering its students, faculty and staff? Is it sending more carbon upstairs? Middlebury takes so much pride in its innovation that it built its new heating plant with glass walls so that students and visitors alike can watch the process. And the college is depending on it and other steps (e.g., the Nordic ski team’s truck burns waste vegetable oil) to reach its goal of carbon neutrality by 2016.

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Carbon neutrality? I thought SSC said burning wood contributed 50 percent more than coal. No, wood burning is carbon neutral because it gives off only as much CO2 as the trees had absorbed, rather than introducing sequestered carbon, say from coal or oil, into the cycle.

And, as Middlebury burns wood chips to make steam, the exhaust is filtered, removing 99.7 percent of the particulates. It is safe and it has reduced Middlebury’s total carbon footprint by 40 percent. How about all those trees?

Middlebury is concerned that if many others went the route it has, tree harvesting might not be sustainable, even in well-forested Vermont, so it has planted fast-growing willows on old farm fields. The plan is to rotate cutting through three years, at 400 acres each year, to provide the plant’s annual appetite for 20,000 tons of chips.

Burning wood is carbon neutral and can be safe. Like so many things, it all depends on how it’s done. Last summer SSC successfully promoted tighter Massachusetts standards for biomass incineration, which is good, but in the process may have unfairly tarred wood burning. At least, that’s how it looks from the White Oaks.

Burning wood is carbon neutral and can be safe. Like so many things, it all depends on how it’s done.

Lauren R. Stevens is a writer and environmentalist. This column first appeared in the Berkshire Eagle.


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