Vermont Environmental Consortium

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BRATTLEBORO REFORMER

#45, February 17, 2008
Pellet Stoves Allow Easy Access to Biomass Energy
by
Daniel Hecht

The quest for renewable energy is sparked by the need to reduce our dependence on dwindling supplies of greenhouse gas-emitting fossil fuels and replace them with regenerating, carbon-neutral sources. Using biomass – plant stuff of any kind – cuts GHG emissions because the CO² released when it’s burned is absorbed by the next crop of energy feedstock plants, a closed carbon cycle.

Making biomass energy available for use can be complex – cellulosic ethanol production, for example, requires a series of high-tech microbacterial, chemical, and mechanical processes. And since processing any biomass requires energy -- all too often from coal or oil -- many experts argue that the simplest is best. Just burning the stuff for heat may be the most efficient way to deliver its energy value for our use.

Charlie Page certainly thinks so. He’s an outspoken fan of pellet fuels, and after three decades in the field he can justly claim some expertise.

His Randolph-based company, HomeWarmth Inc., works for Harman Stoves, the largest U.S. manufacturer of pellet-burning appliances, providing training and technical support to over 100 dealers in New England and New York.

Harman pioneered pellet-fuel appliance development by adapting elements of coal stoves’ technology to biomass fuels: the under-burner system, which improves air flow to the fuel and allows ash to fall away.

Ash issues are crucial to the viability biomass combustion.
Much effort has been devoted to ash volume and characteristics – lots, little, fine, coarse, floating, falling, clinker-forming – and to ways of getting it out of the way of combustion. Harman stoves are now designed to burn not only wood pellets but those made from biomass with higher ash-production levels, such as switchgrass.

At first glance, the room-heating stoves look like conventional woodstoves: iron cabinet, glass door, visible flame. On closer inspection, though, you notice the absence of wood chunks in the firebox; the flame tends to rise in a fierce rush instead of a lazy flicker.

One advantage of pellet burners is convenience, the ease of feeding them: load pellets into the hopper, and the stove automatically feeds itself. A thermostatically-controlled gate drops pellets into an auger that delivers them to the burn pot, where an electrical element ignites them. A fan blows out the exhaust and sucks air through strategically-placed holes that deliver oxygen to the fire.

This convenience is augmented by computer-controlled air flow and fuel feed, resulting in far better temperature management than typical woodstoves.

Another big advantage is efficiency. Those high-tech controls create optimum combustion conditions, getting more heat out of the fuel and reducing particulate emissions from the chimney. Charlie says his stoves release only one-tenth the particulates of traditional woodstoves.

Emissions are another crucial concern in biomass combustion. Early in his career, Charlie worked for Vermont Castings at what turned out to be a critical time for the wood stove industry. The EPA found that burning wood produces large quantities of cancer-causing particulate emissions and required manufacturers to produce cleaner stoves. The result was what Charlie calls “the rebirth of the wood stove.” He helped spearhead Vermont Castings’ effort to develop the rear-mounted afterburner, now the dominant clean-burning technology, which adds a second-stage, hotter combustion chamber that re-burns exhaust from the main chamber, reducing particles to, mostly, gases.

The health of the wood-burning appliance industry is largely governed by the price of oil. When oil prices go up, so do stove sales -- and vice-versa. Suppressed oil prices in 2006 really hurt the industry, Charlie says. People stopped buying stoves; retailers started going out of business; manufacturers cut back production. And while oil prices can fluctuate rapidly, the stove manufacturing, distribution, and retailing infrastructure can’t rebound as fast. It was a shaky period for the industry.

Now, higher oil prices have rekindled demand; Charlie expects that his dealers will sell between 30,000 and 40,000 pellet-burning stoves and furnaces this year.

Another factor is the availability of pellets. Wood pellets are made from sawdust and scraps from mills and furniture makers. As with other manufacturing by-products, we’ve discovered the value of this resource, so there’s increasing competition for it, mostly for use as livestock bedding and in composite building materials.

Charlie isn’t too concerned. Pellets are readily, abundantly available now. Also, all new mills coming on line are setting up to serve the pellet market by processing dead trees and other low-quality, previously unused wood sources. And then there’s grass and other biomass crops on the horizon.

HomeWarmth doesn’t sell stoves at its Randolph HQ, but to get a feel for this new technology Vermonters can warm their hands on Charlie’s stoves at two I-89 rest areas, on the southbound side at Randolph and Sharon.

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Daniel Hecht is a novelist and executive director of Vermont Environmental Consortium. For more information on any Green Grapevine topic, contact vec@norwich.edu.

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