Christopher LaMarca

Lee Richards lives with his wife

in a 1957 brick rancher in a neighborhood of cookie-cutter homes in Charlottesville, Va., where he works as the city's commissioner of revenue. In the past decade, he decided to become a more self-sufficient consumer of energy. He commutes to work on foot and by bus. He powers his home with 18 solar panels bolted to his roof and sells the excess electricity back to the grid. He heats his water with a solar-thermal system. And he heats his home in winter with biomass—in this case, firewood—using three small but highly efficient Jøtul wood stoves in the living room, sunroom and basement. He spends $1200 a year on wood—five truckloads, split and delivered—and gets up at four o'clock each winter morning to stoke dying embers so his wife will be warm when she wakes. When he returns from work, he throws on a few more logs, and the stoves whoosh to life. His gas-fired central heating system remains installed as backup. Yet he saves over $1000 per year on fuel costs, and his utility bills rarely total more than $100 a month.

A century ago, and for about 400,000 years before that, most people burned wood to stay warm. Then the arrival of oil- and gas-fired central boilers and furnaces liberated them from the toil, mess and smoke. Today, fluctuating prices, a desire for independence and a new generation of clean, efficient stoves have attracted homeowners like Richards to a flourishing back-to-basics home-heating movement. Annual shipments of pellet stoves, which burn biomass in the form of compressed sawdust from lumber mills or managed forests, jumped from 18,360 to 141,211 units between 1999 and 2008, a 650 percent increase. Large-scale installations include Vermont's Bennington College, which uses a wood-chip-fueled biomass boiler to heat 85 percent of its campus.

Consumer incentives are also helping drive the shift to biomass heat. A $1500 federal tax credit for high-efficiency wood and pellet stoves—part of the American Recovery and Reinvestment Act of 2009—expires at the end of 2010. But at least two pending bills propose to expand and increase the credit up to $6000 to subsidize the purchase of stoves, biomass boilers and furnaces. Congress is pushing the passage of its Homestar legislation, a $6 billion incentive program to encourage residential energy efficiency, which could spur adoption of wood stoves and other biomass heat sources.

The impact of a widespread switch to biomass would be huge. Heating accounts for about half of U.S. residential energy consumption. The most popular fuel, natural gas, heats 50 percent of U.S. homes. About a third of the country heats homes with electricity. John ­Ackerly, president of the Maryland-based Alliance for Green Heat, says, "Electricity is too inefficient and too expensive to make and waste on heat." The same goes for the 5 billion gallons of oil and 15 billion gallons of propane that are used annually to heat 20 percent of American homes. If all oil customers switched to biomass, the savings could amount to 120 million­ barrels—1.68 percent of the 7.14 billion total barrels of oil consumed per year. Pellet stove inventor Jerry ­Whitfield's objective is clear: "We're trying to displace oil as a home heating source," he says.

Improved technology is also helping drive the biomass revival. New stoves designed to handle clean-­burning wood-waste pellets mean greater efficiency and lower emissions. In the past 25 years, the North American wood-pellet industry has grown from a few small outfits to well over 100 companies that produce more than 1.8 million tons of pellets per year. New systems to efficiently transport and store pellets make the fuel economically viable in more locations than cordwood. New England Wood Pellet pioneered a bulk delivery system modeled on agriculture and the heating-oil industry. "Pellet fuel flows like grain, so you can use conventional storage technology and a flexible auger tube to move the fuel around," Charles Niebling, general manager of New England Wood Pellet, says. "It lends itself to automation." Companies like WoodPellets.com, started in 2005 by two engineers with graduate degrees from MIT's Sloan School of Management, are hoping to increase fuel distribution efficiencies by creating a system modeled on European infrastructure, complete with pneumatic pressurized-air trucks and satellite storage depots.

These advances will reduce the price. "Virtually everyone who owns solar panels has either green motivation or a fascination with new technology,"­ says Dan Freihofer, vice president of operations at WoodPellets.com. "But the average pellet-stove owner buys one of these things because he's sick of writing $600 checks to the oil man. He puts one in to save money—tomorrow." Central heating powered by electricity or fossil fuels has relegated biomass-burning stoves to a supporting role in the U.S. As in Richards's case, they are often retrofitted supplements to existing systems. In some European countries, ­biomass is the primary heat source, fueling central boilers for residences, apartment buildings and even whole towns.

In the U.S., the biggest hurdle that New England Wood Pellet CEO Steve Walker sees is the high cost of the equipment, particularly central boilers that could bring biomass into the mainstream. "It's the classic Catch-22 of any new technology," he says. "You need to scale up manufacturing in order to produce something for a reasonable cost, but you need a market before you can do that." Still, Walker says biomass has great potential. "People want to be independent. They want a choice. Now more than ever they want to know where their money is going." But, while large-scale adoption of biomass energy might require new technology and infrastructure, consumers have a number of options today.

How to Heat a House

The average 2400-square-foot house burns around 100 million Btu of fuel per year. The prices below for natural gas, fuel oil and propane are based on 100,000-Btu furnaces and boilers with installation costs of $1000 to $2000. Note that electricity seems cheap only on a kwh basis, not in total.





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Melissa Golden

CORRECTION: "In the "How to Heat a House" chart, "Electric Heat Pump" should read "Electric Heat."

Melissa Golden

Cordwood Stoves

Wood stoves balance performance and cost. The best stoves are 60 to 70 percent efficient at converting well-seasoned wood into heat. At an average price of $200 per cord, firewood is one of the cheapest fuels per unit of heat. Prices tend to rise and fall along with fossil-fuel heat sources, but because wood is sourced locally, the shifts in cost are less dramatic.

Wood is cheaper if you harvest your own. Jerry Marquez, a homebuilder in Libby, Mont., heats his two-bedroom house for about $200 per year, but he spends a couple of grueling weeks each spring harvesting and splitting standing deadwood in Kootenai National Forest. Like Richards, he shovels ash from his stove weekly. It's hard work, but the price is right, and Marquez says he loves the way the flames crackle in his Enviro Kodiak 1700 stove, warming his living room and kitchen on subzero Montana mornings.

Marquez's house is small enough to get by on what is essentially a 74,000-Btu room heater. Lee Richards heats his larger Virginia ranch home by strategically installing multiple wood stoves to blanket the house in heat. But the stoves cost $3000 to $4200 each (including flue installation). So pushing a single stove to its limit can make more economic sense. "You have a nice toasty living room and kitchen and maybe the edges of your home are a little chilly at five o'clock in the morning," says Charles Niebling, a forester in New Hampshire.

Wood stoves have become much cleaner since the EPA began regulating their maximum particulate emission levels. Stove manufacturers first added catalytic combustors—tubes with honeycomb chambers coated in a corrosion-free noble metal, usually palladium. Similar to catalytic converters on cars, these turn exhaust gases into heat. Catalytic-combustion stoves have been improved by a new process called secondary burn, which converts wood smoke to heat, drawing extra fuel from logs and boosting stove efficiency.

Another option is a masonry stove, sometimes known as a Russian stove. These built-in units resemble free-standing fireplaces made of dense stone or brick, with snaking channels leading from the firebox to the chimney. The channels maximize the transfer of heat from the gases to the surrounding masonry, allowing the stoves to store and radiate warmth from very hot fires for long periods. They are efficient and clean-burning and require less stoking, though they are expensive because they are almost always custom-built. Installed prices range from $13,000 to well above $20,000.

Pellet Stoves

Owners of these stoves can't harvest their own fuel, but what they give up in price and freedom they gain in ease of use. A $250 ton of pellets yields three-quarters of the heat generated by a cord of wood, yet pellet stoves operate at higher efficiency rates—usually around 80 percent. Thermostats allow some pellet stoves to automatically control temperature and heat output.

Pellet fuel offers many advantages over cordwood: It has a moisture content of less than 8 percent, compared to 20 percent or more for seasoned wood and 50 to 60 percent for unseasoned wood. (Btus are wasted in vaporizing moisture.) Dry pellet fuel is inert and nontoxic. It has an infinite shelf life, and it doesn't harbor bacteria, fungus, bugs or mice. Its energy density rivals that of coal, but it doesn't produce as much ash as either coal or wood. A high surface-to-volume ratio makes pellets combust more like kindling than logs. The pellets' standard size means they can be fed automatically by the turn of an auger. Once pellets enter the stove's fire pot, airflow is metered to maintain a steady burn. The hopper usually must be refilled daily. Efficient combustion produces particulate emissions levels of around 1 to 3 grams per hour—comparable to oil or gas.

Pellets are cheaper than oil, propane or electricity, and they don't cost much more than natural gas. But because of the recent collapse in the housing market, the number of lumber and furniture mills producing high-grade sawdust has decreased, driving the price of a ton of pellets from less than $200 to $250.

Jerry Whitfield, a former Boeing engineer in northern Washington, is tackling the price problem by improving stove technology. Whitfield is researching a next-generation stove that burns a variety of pellet types and grades, including pelletized grasses, straws, hay, rice husks, sugarcane bagasse, corn stover, even poultry manure.

"I can envision a future," Freihofer says, "where there would be the equivalent of a local community pellet mill. It would recycle everything from newspapers to yard trimmings to waste wood, the way a grist mill might have operated 150 years ago."

Pellet Boilers

With the firepower to provide whole-house heat, these machines circulate hot water through radiators or force hot air through ducts. The results are comparable, in performance and efficiency, to oil and gas heat.

Like pellet stoves, these are not as hands-off as fossil-fuel or electric appliances. Owners typically refill the hopper of a pellet boiler or furnace daily, although some models draw fuel automatically from large storage containers, much like an oil furnace draws from a tank. And they require ash dumping and an annual cleaning.

American companies, including Harman Home Heating, make pellet boilers and forced-air furnaces for around $6000, roughly double the cost of a comparable oil or gas appliance. The most advanced European central heating units must be custom-­retrofitted to meet American Society for Testing and Materials (ASTM International) standards for use in this country, so prices crest at $20,000.

But if a shift toward biomass persists, boiler prices may begin to rival those of oil and gas appliances, according to New England Wood Pellet CEO Steve Walker. In restricting foreign boilers, he says, "we're keeping out the super-clean models that can build an industry here." With fuel distributed in bulk and fed into a boiler automatically from a basement tank, Walker's vision sounds as convenient as the heating-oil industry today. "It isn't entirely plug-and-play, but it's coming," he says.

How Pellet Stoves Work

A typical free-standing 400-pound pellet stove produces just over 45,000 Btu per hour, enough to heat about 2250 square feet of living space. The average home burns 3 to 6 tons of pellets in a season.

Step 1

Pellets loaded into a hopper are fed by a motor-driven auger into a fire pot. Stoves require pellets made from clean sawdust—dirt turns into a stove-clogging clot called a clinker. The auger and a pair of fans consume electricity, at a cost of about $65 a year. Exhaust gases require a vent, either into a chimney flue or via a direct conduit bored through an exterior wall.

Step 2

A combustion fan draws the room's ambient air over a hot electrical coil and into the fire pot, igniting the pellets in about 10 minutes. After 15 to 20 minutes, the igniter shuts off as the auger continues to drop pellets into the burning fire pot. This same fan channels combustion exhaust gases into a vent to the home's exterior. Only clean, smoke-free air enters the room.

Step 3

A convection fan pulls ambient air from the room across a heat ­exchanger, circulating hot air into the room. A computer-controlled thermostat adjusts the auger speed and convection-fan rate to maintain even indoor temperatures. Pellet stoves shut down automatically if the stove leaks, the door is left open, or the hopper runs out of fuel.

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