New furnace replaces barrels of oil with bushels of corn

CORNCOBS in your furnace? Some Ohio scientists have designed an automated home furnace that burns corn cobs and other wastes. Not only does it appear to be an inexpensive and clean-burning method of heating, but it could also someday provide a little relief from the nation's overwhelming grain surplus.

Scientists at the Ohio Agricultural Research and Development Center, looking for ways to cut energy costs in the home and on the farm, have developed what is known as a ``fluidized-bed combuster,'' principally to burn corn cobs that would otherwise go to waste.

In this type of furnace, a bed of very hot sand is kept in a fluid state by blowing a stream of air through it. In such an oxygen-enriched state, any fuel poured onto the hot sand (900 degrees F.) burns so completely that there is virtually no pollution. Ash passes out of the burner with the combustion air and is collected - sometimes for use as a valued fertilizer, depending on the fuel used.

The burning fuel maintains, even increases, the sand temperature, and also produces enough excess heat to warm homes, buildings, domestic hot water, and, through the addition of a turbine, to generate electricity. The sand is initially brought up to temperature with an oil or gas flame.

The fluidized-bed furnace was developed in Britain some years ago to turn coal fines (particles so small as to be useless in conventional furnaces) into usable fuel. Large fluidized-bed furnaces have since been adopted by industry in many countries. Ohio State scientists took this concept, scaled it down to fit the home, and adapted it to accommodate corncobs as a fuel.

The prototype has proven very effective in producing ``clean hot air for heating,'' says Harold Keener, a scientist involved in the project. He says 11.8 pounds of the ground corn cobs has the heating capacity of one gallon of propane. That means the furnace could heat a contemporary three-bedroom home in an Ohio-type climate for a year on corn cobs from about 10 acres of corn.

More recently, shelled corn has tested out as an almost ideal fuel, says Mr. Keener. One bushel of corn has the same gross heat energy as 4.2 gallons of propane, he notes. ``With the average cost of propane at 85 cents per gallon, the heat value of a bushel of corn is $3.57,'' he points out. ``This makes it worth more as a fuel than a feed at current prices.''

He says corn grown expressly for fuel could become an attractive farm crop, ``particularly as yields approach 200 bushels an acre,'' he says.

Still ``more appealing'' to Keener is the fact that fluidized-bed combustion can burn even high-sulfur coal ``with little or no air pollution.'' The Ohio State furnace, he says, can be readily adapted to burn coal or wood pellets - which means it doesn't have to be confined merely to the corn belt.

The combuster has been patented, and a manufacturer is being sought to adapt the idea to commercial use.