Conservation Currents
Heating With Wood
June 2008
by Jim Henderson
Firewood
Skyrocketing costs of fossil fuels have led to a renewed interest in alternate energy sources. At our house, we focus on wood - for heat (a very comfortable heat) and to cook our famous "Hendersap" (our sons' name for our homemade maple syrup.)
Wood, grown through good woodland management, has advantages over other fuels as a heat source:
- It is a renewable resource and supplies that are now available can be increased;
- In preparation or use, wood contributes little to air and water pollution, and,
- Wood can be burned independent of other energy sources.
- It is heavy, bulky, messy and requires a lot of storage space;
- Burning wood requires careful attention to refueling and controlling the burning rate, and,
- Poor burning practices, resulting in creosote buildup, can create a dangerous fire hazard.
The fuel value of wood depends on the wood species, its density, and its moisture content. The denser hardwoods such as ash, maple, oak and beech make the best fuel because they burn slower and contain more BTU's per volume than lighter woods such as aspen and basswood. Conifers, such as spruce and pine, have high resin content that increases the likelihood of creosote problems.
Too much moisture in wood greatly reduces its fuel value because so much heat goes into evaporating the moisture before the wood can actually burn. High moisture and smoldering fires will also allow creosote buildup in stovepipes and chimneys leading to inefficient stove operation, smoky homes, and a good chance of a dangerous chimney fire. Most hardwood that is properly split, stacked and protected from the weather will air-dry in 9 to 12 months resulting in moisture content of about 20%. Given the economics of further drying, 20% is quite acceptable.
Wood is sold by the cord, the truckload or by weight. A standard cord of wood is a stack 4 feet high, 4 feet wide and 8 feet long. Occasionally wood dealers may sell face cords, sometimes called false cords, which are stacks 4 feet high and 8 feet long, but of whatever width the pieces of wood are cut in. Other dealers may offer truckloads of saw log length wood. This is perhaps the most economical way of buying fuel wood but it requires a chainsaw and a strong back for bucking into fire wood logs. The splitting too is labor-intensive and time-consuming, even if - as my wife and I do - you have three sons. (If you have sons, you know they have their own agendas and they might not include splitting firewood.) Avoid buying wood by weight since species of wood vary so much in density and moisture content. You can't afford to pay for water when buying fuel wood.
Firewood is most often purchased split, cut to an agreed upon length and seasoned for at least one year. It is advisable to be present upon your wood delivery so you can verify the amount, mix of species, moisture content and size. Avoid coming home to a large pile of green wood sitting in your driveway that is too big to fit in your stove.
Is it worth all this extra work, storage space and messiness to heat with wood? Well consider this. According to a study by the University of Wisconsin-Extension Service one cord of equal potions of seasoned ash, beech, hard maple and red oak has the BTU equivalent of 125.5 gallons of heating oil. I'm afraid to think how much that amount of heating oil will cost this February.
Heating with wood can certainly save on heating bills, conserve other forms of energy, and be an enjoyable experience. Do it safely.
Jim Henderson is the GIS-Senior Planner for the Bennington County Regional Commision, and the vice-chair of the Bennington County Conservation District. The district's mission is promoting rural livelihoods and protecting natural resources in southwestern Vermont.
This column appeared in the Bennington Banner in June 2008, as one of the BCCD's Conservation Currents pieces, a bi-weekly feature written by BCCD board and staff members since August 2006.