Wood stove: new device cleans up its act
Cheap heat has always been the main selling point of the wood stove, yet with the low fuel bills have come problems. Wood stoves typically give off uneven heat and are not very efficient. Too, there is the risk of chimney fires. And with millions of stoves being sold every year, wood smoke is becoming a major contributor to atmospheric pollution.
In Vail, Colo., for instance, with its concentration of wood-burning units, a blue haze hangs between the mountains on still days. In Oregon, a study last year by the state Department of Environmental Quality points out that local wood stoves now put more polluting material into the atmosphere than industry.
The study concludes that without some form of strategy of controlling wood-burning appliances in the future, ''it will be impossible to attain and maintain compliance with national ambient air-quality standards.''
These wood-stove problems may look like permanent drawbacks. However, according to Dr. Stockton Barnett of the Condar Company here, when technical problems crop up in a field such as this, someone is working on the solution - ''often in a garage laboratory.''
Dr. Barnett adds, ''It is just a matter of time, but the solutions are on the way.''
An earth scientist on leave from New York State University, Dr. Barnett is director of research and development at Condar, a company that develops and supplies equipment related to alternative energy sources.
What brought him to Condar was his ingenious invention (developed in his garage laboratory) of a thermostatic control that can be easily installed in most conventional wood stoves. Its function is to track the stove's temperature and control the airflow into the unit, thus improving efficiency.
Once the invention went into production, Dr. Barnett's interest turned to the application of catalytic technology to the efficiency and pollution problems of the wood-stove industry.
''Catalytic combustor'' became a household term in the 1970s, when Congress passed tough emissions standards for automobiles. In response, the automobile industry turned to the catalytic converter.
About five years ago Corning Glass Works began working on an adaptation of the idea to wood stoves. What came out of its search is a honeycomb unit made of ceramic material and coated with a special catalyst made of palladium and platinum.
As smoke from the wood fire passes through the honeycomb, the catalyst initiates a chemical process that causes the smoke to burn at a much lower temperature than normal - 500 degrees F. instead of 1,200.
The result is a ''cool burn,'' thus releasing steam and carbon dioxide up the chimney instead of the black soot that condenses in creosote deposits on the inside of the stovepipe or flushes into the atmosphere, causing a pollution problem.
While Corning solved the chemistry problems of burning smoke, Dr. Barnett found that the engineering hadn't yet been developed to make sure the catalyst would work at top efficiency.
A catalyst can't just be welded into a stove to do the job properly. The amount of air introduced into the stove is important as well as the flow of smoke through the combustor.
Dr. Barnett spent many months at Condar building a baffle plate which would be secured under the catalyst to produce enough turbulence to ensure that a maximum amount of smoke touches the catalyst's surfaces.
When the baffle plate and catalytic unit were placed in a properly proportioned firebox with the thermostatic control attached, researchers found that this high-tech wood stove achieved 80 percent efficiency, burned evenly with less wood, and reduced pollutants by 90 percent.
Admittedly, the addition of a catalytic unit to a wood stove does add to its cost, now about $250. But the manufacturers claim that this extra amount can be recouped within a few years in savings on wood and chimney cleaning.
A certain amount of care is involved, too, since the stove must be started properly in order to ignite the catalyst. Also, care must be taken that the unit isn't damaged or clogged with ash or ''poisoned'' by burning materials such as plastics, painted wood, or paper logs.
Corning is now working on ways to lengthen the average life expectancy of the catalyst, which is now 2.5 years, as well as reduce the cost to between $50 and
Heating with an advanced catalytic stove can whittle the average household fuel bill down to $350, according to a study of households in the Northeastern United States.
Because wood is the nation's primary renewable fuel, some experts believe US forests hold a vast untapped source of fuel just in the form of trees that are unsuitable for commercial purposes. Culling forests for firewood can actually make more wood available in the future. So, if the technical problems of wood stoves can be solved, there is little which would seem to hinder their potential usefulness.
The wood-burning-appliance industry has had its ups - mainly in the mid-1970s , when the Arab oil embargo was on everyone's mind - and downs - as in 1980 when sales collapsed and about half of the 700 stove manufacturers in the US went out of business.
Sales rebounded in 1981, however, with the Wood Heating Alliance, the industry's Chicago-based trade association, estimating residential installations for the year at 2.1 million units, about double the level of the year before.
The catalytic technology is so new that the biggest problem right now is making potential stove buyers aware of its existence.
Still, Corning is encouraged by the level of response it is receiving to promotional campaigns and officials are convinced this is the ''new wave'' that will keep future American home fires burning - safely, efficiently, and within the ambient air-quality standards of the Environmental Protection Agency.