Pellet Stoves vs. Wood Stoves: Which is Greener?
Pellet stoves have become darlings of the green home heating world, in some ways; they’re more efficient and have fewer particle emissions than their wood-burning stove brethren, but they aren’t a perfect solution. Many pellet stoves require electricity, taking them out of service when the power goes out, and pellets and other fuel can be hard to find in all areas.
Wood stoves, on the other hand, burn fuel that is plentiful, and can create heat without electricity. Newer stoves, too, have devices that cut way back on polluting emissions, making them much more efficient than stoves once were. So, which stove is the greener way to go?
Pellet stoves: Pros
Pellet stoves are very efficient — 75 percent to 90 percent overall efficiency — and have a BTU output
content four to five times higher than cord wood or wood chips. Pellet stoves also have very low particulate emissions; 50 times less than older, non-EPA certified wood stoves, and two to five times lower than more efficient, EPA-certified woodstoves. If you’re looking for a new stove, pellet stoves can be a good option for those without a fireplace or chimney, because they can often be vented through a small hole in the wall, rather than a whole chimney. Pellets themselves are also often made from sawdust and other small wood particles which are byproducts of wood milling, and might otherwise be headed for the landfill.
Pellet stoves: Cons
Most pellet stoves require electricity — about 100 kilowatt-hours per month — which adds about 171 pounds of carbon dioxide to the atmosphere, on average (it depends on your source of electricity, of course). That also means that if the power goes out, your pellet stove does, too, though some have battery backup to help keep them going.
Pellet stoves also require pellets — homeowners who use a pellet appliance as a main source of heat use two to three tons of pellet fuel per year, on average — and, though they’re becoming more available, having a reliable source of pellets is essential (and trucking them in from across the country isn’t a green way to get them). And though the pellets don’t require any adhesive to keep them in pellet form, very high, energy-intensive pressure is used to squish them into pellet form during production.
Wood burning stoves: Pros
Newer EPA-certified wood stoves burn much more cleanly than open fireplaces and non EPA-certified stoves — look for a hang tag like the one pictured above to see how much smoke a stove produces. When harvested and managed responsibly (from a sustainably-harvested source, or when trees are blown over in the wind, killed by beetles, etc.), using wood for heat can be an entirely renewable resource.
Plus, if you can use wood that would have decomposed otherwise, you’ll get the added benefit of heat while the wood releases the carbon dioxide it has sequestered during growth — if left to rot in the woods, all the carbon dioxide gets released (albeit much more slowly) and you’re left in the cold. Cord wood tends to be easier to come by than pellets, and wood stoves don’t require electricity, so wood stoves can provide heat when the power goes out.
Wood burning stoves: Cons
Wood stoves aren’t as efficient as pellet stoves — the most efficient wood stoves top out at about the low end for pellet stove efficiency — and well-seasoned (or dried) cord wood has about two or three times more moisture than pellets. Wood stoves also provide 75 to 80 percent fewer BTUs per cubic foot of fuel. It also takes a lot of wood — a cord is about 15 trees that have a 10-inch diameter at breast height (or DBH — a common method for measuring tree size) — and those who use wood stoves consistently throughout the chilly months can use three cords of wood per year.
Pellet stoves vs. wood stoves: Which is greener?
So, given all this information, which fuel source is greener: Pellets or wood? Let’s assume you don’t have to buy a new stove for either scenario; we’ll just consider the fuel sources. Pellets are more efficient, but you can’t get them from your backyard; wood is generally easier to come by, but you need more of it to generate the same amount of heat.
Because they’re both carbon-neutral fuels (that’s up for some debate, depending on whom you ask, but that’s another post. According to the U.K.’s Biomass Energy Centre, they’re pretty darn close; all the details are on the next page), how far each fuel goes to get to you can make a difference. According to the Pellet Fuel Institute, there are pellet fuel manufacturers in 33 U.S. states and 6 Canadian provinces, so if you can get pellets that are both manufactured and sold nearby, that’s probably the greener route (so long as you’re okay with the pluses and minuses of operating the stove, including the electricity you need).
But, if you don’t have a reliable source of two or three tons of pellets per year, what do you do? Consider that shipping one ton of your pellets emits between 16 and 18 pounds of CO2 per 100 miles (160 to 180 pounds per 1,000 miles, and so forth), and their efficiency begins to diminish. To wit: Shipping one ton of pellets about 600 miles uses as much energy as the pellets themselves contain; go much further than that, and you’re using more energy to ship than you’ll get from burning them. So, if you can’t get pellets that are manufactured and sold within about 600 miles, you’re better off going with wood.