A Connoisseur's Guide to Wood Fuel

Whether you want a quick, hot burn or a slow, warm one, here's how to find the right fuel wood.


| October/November 1994



146 wood fuel - cutting wood

The best way to make sure you get a good variety of wood fuel is to cut it yourself.


PHOTO: H. ABERNATHY/H. ARMSTRONG ROBERTS

For those of us who appreciate a fine fire, selecting fuelwood is as much an art as selecting wine or cheese. Just as you can achieve distinctive effects by combining certain cheeses with just the right wines, so too can you achieve desired effects by judiciously selecting and mixing different species of firewood.

One time you may want to get the chill out with a fire that burns hot and fast, then spends itself quickly so you can go about your business. Another time you may prefer a steady flame that produces glowing coals and long-lasting warmth. For special effects, a log that pops and crackles lends an air of excitement, while one that emits aromatic smoke offers a touch of romance. Here, then, is a connoisseur's guide to fine wood fuel.

Heat Value  

Pound for pound, every species of wood produces the same amount of heat and each consists of woody fiber, water, resin, and ash. But the proportions of these four elements vary from one species to another. As a result, some woods weigh more per unit volume — in other words, they're denser — than others. The denser the wood, the more concentrated its fuel value.

Hickory, for example, has an average density of 0.72 grams per cubic centimeter, while pine has half the density at 0.36. Hickory therefore yields twice as much heat as pine. Since density changes as wood dries and shrinks, density measurements are taken after the wood has dried to a specific water content, usually ranging from 12% to 20%.

In forestry, all deciduous trees are classified as hardwoods and all conifers are classified as softwoods. Hardwoods are usually denser. Exceptions include aspen, basswood, cottonwood, and poplar — all hardwoods that are less dense than some of the softwoods. In our part of the country, they're called "soft hardwoods." Since they have less heat content than denser hardwoods, they're not particularly popular as fuel wood. On the other hand, some softwoods (including Douglas fir, loblolly pine, and red cedar) are denser than the lower-end hardwoods, so their heat-producing potential is greater.

The most common way to measure the heating potential of wood is not by density but by the number of units of heat (called British thermal units, or BTUs) emitted. One BTU is the amount of heat needed to raise the temperature of 1 lb of water 1°F. Dense hardwoods (beech, hickory, oak, and some maples) produce in the neighborhood of 21 to 25 million BTUs per cord. Soft hardwoods and the harder softwoods yield some 30% less heat. The remainder of the softwoods give off about half as much heat.

thefeckerwest
12/5/2015 2:38:51 PM

Dry bark burns very easily and is great for starting a fire, at least in my part of the World.






mother earth news fair

MOTHER EARTH NEWS FAIR

Oct. 21-22, 2017
Topeka, KS.

More than 150 workshops, great deals from more than 200 exhibitors, off-stage demos, inspirational keynotes, and great food!

LEARN MORE