Weighing the options of coal vs. wood

When Ron and Judy Wearing decided to take the pressure off their basement oil furnace (and its attendant bills) by installing a stove in their living room, they opted for a coal burner.

The couple thought briefly about woodburning stoves but, says Ron, an engineer by profession, wood stoves "were never really in contention at all." His choice, a heavy, barrel-shaped model that readily warms his lakeside home."

Why coal and not wood?

Here are two reasons: (1) storage and (2) availability.

I can store two to three months' heat [1 1/4 tons of anthracite] in a bin that takes up no more room than a standard [250-gallon] oil tank."

Roughly speaking, coal and wood (all types) provide the same amount of heat per pound. But hard coal (anthracite) is at least twice as heavy as wood. So, to get the equivalent amount of heat, even in good hard oak, would require the storage space for almost 1 1/2 cords.

To get the same heat from some of the less- dense types of wood would require up to two cords of wood.

Of course, there are advantages and disadvantages to burning coal and, in making their decision, the Wearings were aware of them all:

* Coal is the country's most abundant fossil fuel, and for the forseeable future it should be readily available and moderately priced.

* Unlike wood, coal does not need to be seasoned and, if left in the rain, will not absorb moisture the way wood will.

* Moreover, coal does not have to be cut to size and requires no splitting. When brought into the home, no unwanted insects ride in with it.

* Because of its density and the fact that it burns steadily, a 12-hour fire from a single loading is commonplace.Put another way, a coal-burning fire is less time consuming (once it has caught and is drawing well) than a wood-burning one.

While creosote is a common problem with wood burning, coal deposits very little creosote in the flue.

But there are some negative factors as well:

* Coal, for example, is a dirty fuel. It may not bring in the insects, but it does bring in coal dust if you are not careful.

* A whiff of smoke from a wood fire can be moderately pleasant, yet the smell of coal smoke definitely is not.

* Also, dry wood lights easily, but a coal fire requires much more kindling to get it going. Further, wood burns cleanly, while coal smoke is considered dirty.

If you do use coal, anthracite is a relarively clean-burning fuel with a low sulfur content. Because it is the hardest of coals, anthracite is also less prone to crumbling and consequently is less dusty.

Gardeners might find it worth noting that while wood ash is a good fertilizer (rich in potash), coal ash is definitely notm recommended for the garden.

Many coal stoves will burn a variety of coals; however, some manufacturers recommend specific types of coal and sizes of coal. So before investing in a stove be sure that the coal specified by the stovemaker is available in your location.

From time to time, the Wearings say they will burn wood in their stove. That's one advantage of coal stoves.

In contrast, most wood stoves are not equipped to handle coal or to take the considerably higher temperatures given off by burning coal. At least one stove company, Vermont Castings, which manufactures both wood and coal stoves, offers conversion kits for turning its wood burners into coal burners as well.

The same company has developed a fuel- comparison chart for anthracite coal burned in a good-quality stove with a 74 percent efficiency. The comparisons assume similarly high efficiencies in the units burning oil, gas, and wood.

By the time it reaches the home, electricity is used at 100 percent efficiency. According to this chart, if anthracite is delivered for $125 a ton (it currently sells at a little less than that in the Boston area), fuel oil would have sell at 68 cents a gallon to be competitive; hardwood at $84 a cord; electricity at 2 cents a kilowatt, and natural gas at 50 cents a therm.

The Wearings maintain that if they lived in the country or owned a woodlot, they would not have bought anything but a wood-burning stove.

But, they chime, "living in a metropolitan area as we do, coal seems to be the most sure way to go." COMPETING WITH COAL Anthracite at $125 a ton is the equivalent of: FUEL OIL 68 a gal HARDWOOD $84 a cord ELECTRICITY 2 a kilowatt NATURAL GAS 50 a therm