Page 20 RAIN May 1981 William R. Day Kurt A. Schloth Between 1925 and 1950 America'~ traditional reliance on woodburning domestic heating collapsed under the impact of amazing growth in fossil fuel production and'the consequent fall in price of both oil and gas-fired central-heating systems. Lacking oil and gas reserves of their own, Western European countries never made this conversion. England, Norway, Germany, and many other countries in that region continued to improve and refine their traditional woodand coal-burning domestic heating appliances. Their design successes,.and their resulting near-uni'versal use of biomass for domestic heating, led inevitably to both public and government corn;ern over increases in noxious emissions and increased air pollution over large areas. v\7oodburning technology was reborn in America less than a decade ago as a result of skyrock~ting fossil fuel prices, periodic shortages, and public concern occasionally bordering on panic. Woodstove sales in Am~rica have averaged about a million a year for the last two years, and currently we use more energy derived from the burning of wood than we do from nuclear power plants. Although the•process is far from complete, American energy consumers and· American manufacturers of woodburning stoves are rapidly becoming more sophisticated. The number of marginal manufacturers is dwindling rapidly, and stove buyers are learning about design features that can make one stove more efficient, more durable, or both, th~n another stove. Some loc~lities with high concentrations of woodstoves are experiencing air-quality problems, and local government agencies are expressing their concern through conferences, press releases, and calls for legislative action. Developments in Woodburning Technology The surviving American stove manufacturers are intensely competitive, jealously protecting their market share and seeking to expand it at the expense of other manufacturers. A number of the largest and most successful qf these manufacturers are now adver-' rising their own concerns with the public effects of their products. Adopting a tone similar to that of Exxon and Gulf Oil, these manufacturers express a lofty concern with the safety, efficiency, and non-polluting qualities of their products. . The drive towards product improvement is real, and it 1s motivated by the traditional stimuli of capitalism, greed and fear. New industry-wide goals are emerging to improve efficiency, reduce pollution, and increase safety and durability, and the largest manufacturers are spending money on research and development to achieve these goals. Although lip-service.still exists, the trend is toward bonafide improvements as manufacturers fear eventual intervention and possible regulati.on by government at on!;! or more levels. Old-line European manufacturers were aware of the awakening market ~n America. In the mid-1970s a cooperative research project began between the government of Norway and A/S Jotul, a stove manufacturer since 1844. After working for five years, they have recently and cautiously announced their development of a new, freestanding, woodburning heater (their Model 604) which boasts •extremely high efficiency and consequent low emissions. The technical details of how this stove works will be unveiled at the Interna:- tional Conference discussed later in this article. The worldwide reputation of the Jotul foundry for quality, durability, and ease of maintenance make this product .something to look forward to. It should be on the market next fall. In this country, the Corning Glass Works has developed a catalytic combustion device for use in wood stoves: The combustor is designed to burn volatile gases at temperatures between 500 and 850 degrees Fahrenheit, gases which might otherwise leave the stove unburned and mingle with the atmosphere. These gases represent potential heat energy contained in the wood; unburned, they constitute wood smoke, wasted energy, and air poUution that in sufficient concentrations may cause health problems for some people. The purpose of the combustor is to foster secondary.combustion, a feature wo_odstove designers have been striving to achieve in many \'Vays arid with varying degrees of success for hundreds of years. At the Wood Heating Alliance tradeshow held in New Orleans this February, several manufacturers' prototypes incorporating catalytic combustors were shown and enthusiastically received by the industry as a potential solution to the pollution problem. We ;mticipate a more limited usefulness for this 4evice for the following reasons: 1. Certain materials burned in a combustor-equipped stove will quickly ruin the combustor. Should the stove operator lapse from his operating instructions and burn paper printed with colored inks, or plastic or other types of household trash, the combustor will be rendered useless. 2. Replacement cost for the critical parts of the combustor are very high ($100), and though these costs are coming down with increased production, it does not appear likely they will ever be cheap owing to their use of precious metals as a vital ingredient. 3. Many new appliances featuring the combustor are designed and assembled in such a manner as to make future repairs difficult, if not impossible. This design philosophy unfortunately continues to prevail among many American stove manufacturers. A New Relati 4. The haste of one manufacturer to market his product has already led to the spread of inaccurate information about it to both the industry and the public. It is possible that the catalytic combustor may already be obsolete, when its performance is compared with other new technologies arriving in the marketplace. Another approach towards fostering safety, durability, efficien-, cy, and low levels of pollution has been the research originating at the University of Maine under the direction,of Richard Hill on woodburning cei;ttral-heating systems. Three highly efficient central heating systems have been developed by licensees using Dr. Hill's patents. Details ·of their general operating principles, and the names and addresses of their manufacturers are included in "Wood Furnace Tips" in Rainpaper No. 1, 1981 revision. The State of Oregon has provided further encouragement to domestic manufacturers to improve their products by providing a testing program. Sponsored by the Pacific Northwest Regional Commission of Oregon's D~partment of Energy, and by .the U.S. Environmental Protection Agency in cooperation with Oregon's Department of Environmental Quality, the program invited manufacturers to submit for testing the appliances they believed to be · highly efficient and low in emissions. Tests were conducted in and around the Portland area in December, 1980, and several general conclusions can be drawn as a result: 1. Central heating systems performed much better th;in did freestanding stoves. 2. Most emissions were produced at the very beginning of the burning cycle. • 3. The water-jacketed furnace had the lowest particulate emission rate of all units tested. This may be due in part to the unit's high
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