Woodstove Efficiency: Costs and Concepts

To the Editors:

Implicit in the letter from L. A. Parks Daloz in the Spring ‘07 issue is the assumption that newer, more technologically advanced tools and appliances, in this case woodstoves that use less fuel and produce fewer emissions, are better for the planet than older products performing the same task less efficiently. While that assumption may sometimes be true, rarely is the environmental balance sheet so easily reconciled.

The manufacture and transport of any new product, even a woodstove with a large proportion of recycled iron in its plates, has an environmental price tag generally hidden from the ultimate retail purchaser. For example, what fuel fires the foundry? Where does that fuel come from? How does the finished stove get to its final destination? If you have no woodstove, and desire one, by all means get the most efficient, cleanest-burning one you can afford. But if you already have a stove, does it make environmental sense to scrap it and buy a new one? Perhaps, but not necessarily.

Part of my living I earn growing, harvesting, processing, and delivering firewood. My 1975 Ford truck carries 2.5 cords, loose-thrown, gets 6.5 miles per gallon of premium gas, and travels about 2,000 miles each year. Since I bought it in 1985, I’ve delivered thousands of cords with this truck, mostly within a 10-mile radius of my home. I maintain it well; it is as reliable as any machine can be. Certainly a late-model diesel could do the job for me using less fuel and releasing fewer emissions. . .but at what environmental cost? Given my relatively light use of the good old truck, our environment is better served if I run it until I retire than if I scrap it now. Think of the resources that go into the manufacture of a new seven-ton truck, and the environmental damage that accompanies their extraction and refining. And, of course, there is the question of how much more wood I need to harvest (with petroleum-fueled equipment) to pay for that fine new truck?

For a person striving to be environmentally responsible, few of life’s choices are as simple as Daloz suggests. Your writer who uses his old woodstove until it dies may indeed leave a lighter footprint than a consumer who must have the latest, most-advanced model.

Craig Troeger, Van Buren, Maine

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Woodstove Efficiency

To the Editors:

I enjoyed Craig Idlebrook’s article (Winter ‘06) on woodstoves and followed his thinking until the physics section. My initial confusion began with the statement: “The crux of the problem is that woodstoves need a certain amount of waste heat to push any unburned gases up the chimney.”

Heat is essential to the process, so it’s hardly wasted. And the burned gases need to exit the chimney, too. A more accurate statement would be that the chimney draws gases out of the stove (at a rate proportional to both the height of the chimney and to the difference in temperature between the ambient air at the top of the chimney and the gases at the thimble.) If stoves pushed, stovepipes and stoves would have to be completely sealed to avoid pushing gases into the room through draft controls and stovepipe joints. The term “airtight stove” would take on a new, unintended meaning. When properly functioning, gases flow steadily from the draft controls to the top of the chimney, the result being a negative pressure within the gas flow path. Stoves don’t push, chimneys suck.

The paragraph continues, “If woodstove fires became much more efficient…gases would cool to the point of condensation in the chimney.” Here, combustion efficiency is confused with heat extraction efficiency. Both are important, but they’re different. Combustion efficiency is the percentage of how much of the potential heat in the wood is converted to actual heat, while heat extraction efficiency is a measure of how much of that heat reaches the room. Higher combustion temperatures go hand in hand with higher combustion efficiencies, resulting in cleaner burns and less creosote. More efficient combustion results in gases with less potential for creosote formation, not more. Hotter fires, less creosote. Creosote results from a fire burning at low efficiency whose gases and smoke have been cooled. More cooling, more creosote. And herein lies the main problem with woodstove efficiency.

The ideal wood combustion device has a combustion chamber shaped and insulated to achieve high temperatures and near complete combustion, and a heat exchanger engineered to extract almost all of the heat in the combusted gases. These are two separate devices with opposing thermal characteristics – the combustion chamber is thermally insulated and relatively nonconductive while the heat exchanger is relatively
uninsulated and thermally conductive. Woodstoves combine the two devices with the predictable result of compromised performance, about 70 percent maximum efficiency. Combustion temperatures stay low because the fire is cooled by the iron walls. Masonry heaters, on the other hand, have separate combustion chambers and heat exchangers and achieve average efficiencies of over 90 percent. Another example is a wood boiler designed by Professor Hill (who Idlebrook wrote about it the article) a few years back that reached high efficiencies with a firebrick lined combustion chamber, forced draft, and a separate heat exchanger. All this sophistication comes with a price tag, though, which is why woodstoves are more popular. They’re inefficient, but they’re cheap.

All in all, a commendable and informative article by Mr. Idlebrook.

Neil Hochstedler, Vershire, Vermont

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Woodstove Efficiency

To The Editor:

Now that we are seriously considering what to do about climate change and our energy future, I believe that we should look closely at the tremendous amount of energy that is consumed by transporting both food and heating fuels into Vermont and other northeastern states from distant locations. Not only does this add greatly to air pollution and fossil fuel depletion but also it transports dollars out of our states and country while undermining local farming and forestry economies.

If we are at all concerned about local and regional security given any number of disruptive scenarios from fossil fuel shortages, to climate change, to terrorist attack, to pandemic flu outbreak, then we should be building robust, locally based fuel and food supply chains. This will entail a shift of farms away from dairy toward more diversified, more sustainable agriculture. It will also require a shift of our forestry practices toward positive impact forestry that rehabilitates our abused and fragmented woodlands while carefully extracting overcrowded, diseased, and low-quality trees for space heating, electricity generation, and biofuels.

With the Use Value Appraisal (UVA) program in Vermont already in place, but beginning to be of concern because of the tax shifting it causes, now may be the time to encourage UVA participating landowners to make a shift to more diversified, sustainable agriculture and positive impact forestry. I believe that, while the UVA program has been very helpful in keeping land in agriculture and forestry out of development, the standards of land and forest management have been designed more to prevent abuse and neglect rather than to promote the best, restorative management practices that will provide the greatest short- and long-term benefits to the environment, the landowners, the local economies, and the general public.

Gerry Hawkes, Woodstock, Vermont

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In Defense of the Tree Farm System

To the Editors:

Mr. Frost’s rather pessimistic thoughts on the credibility of the Tree Farm program in the Spring 2007 issue center on the program’s recent moves towards third-party certification and the integrity of the foresters involved in the program.

A short review of the history of the program confirms some of Frost’s concerns. Yes, the program was created by the wood products industry at a time when that industry was under pressure from the federal government to correct its ways. And during the first few decades, there were a lot of industrial and public foresters available to assist landowners in the program, at no cost. Tree Farm (American Tree Farm System, or ATFS) was the only show in town, and everyone involved appeared to be a winner for their involvement.

The latest environmental movement, within the past 10 years, has again forced our community to re-evaluate our commitment to good forestry practices. Third-party certification, a staple of integrity in the business world, has become the gold standard of sustainability. The movement of ATFS towards certification was due to an educated public’s pressure on markets to demand better forestry practices, but the infrastructure that made the Tree Farm program successful in the beginning has changed dramatically and has aggravated administrative attempts towards true third-party certification. Industrial foresters in Vermont are largely gone; most foresters are now private or of the consultant-type. In Vermont, most county foresters are overwhelmed with the inspection of Current Use properties and have little time to assist the public, let alone inspect Tree Farms. Nationally, similar problems exist, and that forced ATFS to implement a statistical sampling of Tree Farms, a system that requires fewer foresters to complete fewer forest inspections to insure program credibility.

Vermont has resisted this as we believe that the contact, and hopefully relationship, between the forester and the landowner is more important than the inspection. A successful Tree Farmer is more likely to be an individual that has a “family forester” the same way he/she has a family doctor. And, yes, these foresters often are called on to inspect their own properties. The system relies heavily on the integrity of the forester.  Vermont’s prototype program allows foresters to charge for all their services, the same way your doctor charges you for his services. Private foresters have to earn a living; why wouldn’t we allow them to charge for their time?

Does ATFS offer true third-party certification now? Yes, through their “Group Certification” program; this is working well in Maine, Wisconsin, and a few other states. It’s available anywhere enough landowners, faced with market demands, must prove third-party certification.

Is ATFS a lackey for the forest industry complex? Hardly. ATFS is run by a National Operating Committee consisting of Tree Farmers, foresters, and other stakeholders, and the chairman is a Tree Farmer. With the recent acquisition of the Canadian Soft Lumber Agreement Grant ($150 million), the program is overwhelmingly funded by a neutral annuity, along with significant contributions from Tree Farmers.

So, we are left considering the integrity of the private forester in New England in providing guidance to the landowner, and adjudicating his progress.  In Vermont, we are relying on our foresters to demonstrate the same level of professionalism that we would expect from a doctor, lawyer, engineer, or accountant. That is hardly a conflict of interest. While third-party certification hasn’t been achieved, our wood is certified as coming from sustainably managed forests. Third-party certification could be achieved with little effort, albeit at more cost to the landowner, if the markets require it, which they presently don’t. (Additionally, ATFS expects to receive international recognition as a true, third-party certified supplier late this fall from the Programme for the Endorsement of Forest Certification schemes – PEFC – who will approve and verify the system of third-party inspections to be accomplished by the ATFS.)

Finally, the saddest part of Mr. Frost’s “view” is his resignation as a Tree Farm forester. These are challenging times for our working forests, and the loss of a good forester in the program is regrettable. Instead of taking the high road and helping make the system work, Mr. Frost elected to take the low road and quit.

Alan M. Robinson, Sheffield, Vermont

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In Defense of the Tree Farm System

To the Editors:

As chair of the Maine Tree Farm Committee, I was asked to respond to Ehrhard Frost’s article in the Spring ‘07 issue of Northern Woodlands. In that article, Mr. Frost expressed his dissatisfaction with the ATFS. I read through the article a number of times looking for a common theme that has turned Mr. Frost away from the ATFS. From what I could see, the common theme is change.

The Tree Farm System has changed dramatically over the last few years. Whether it is inspector training, the actual ATFS standard, or the realities of running a nonprofit volunteer organization, change can be distracting. However, that change and direction is developed at the national level and delivered at the state level through sponsoring organizations and countless volunteer efforts.

Some of the drivers of that change have been a reduction in industry involvement, both in time and money, and the overall certification effort. However, this has transformed the ATFS from its industry-sponsored roots, which date back to 1941, to a landowner/Tree Farmer-focused organization that is evolving today. In 2006, Tree Farmers themselves were the largest financial contributing group to the ATFS.

It is landowner satisfaction that we really need to answer to. When Tree Farmers see no value in the program, they will leave. Sure, people leave the program. Property changes hands or individual needs change, but I have never had any landowner drop from the program because they did not believe in the mission and overall goals of the ATFS. If I had Tree Farmers wanting to resign from the system as Mr. Frost has done, then I would be concerned.

In the meantime, I want to thank those who work through the changes and support the ATFS at all levels. Change will come. What we must do is get more good forestry on the ground and keep it there.

Dave Harvey, Dixfield, Maine

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Mistaken Maples

To the Editors:

Oh, how I enjoyed reading Chuck Wooster’s comparative description of sugar and red maple in the Spring ‘07 issue. I was reminded of a most embarrassing and, as such often are, indelible learning experience. Many years ago I began a master’s degree program in botany at the University of Vermont (UVM) under Dr. Jim Marvin. Jim is maybe best known for having established the Proctor Maple Research Farm in Underhill, Vermont, and a sugar maple research program at UVM. For those (of whom there are many, including his son Dave) whose seasonal “highs” peak in March, Jim was “Mr. Maple.” From his graduate students, a degree of adoration was not uncommon.

My thesis project was to determine the short-term effects of temperature changes on sugar and starch concentrations in terminal shoots of sugar maple – to be done under controlled conditions in the lab. I collected frozen dormant shoots in December and stored them in a freezer room at the lab. This study, in my mind, was going to solve a long-standing puzzle of the spring sap-flow mechanism in maple. Once, and for all! My early years garnering an awareness and some understanding of the trees of Vermont, be it from an apple grower father or from summer jobs wielding an axe on a timber stand improvement crew, had well incubated my ego. I was fantasizing glory here.

Some weeks later as I began the study, my initial foray into the world of experimental tree physiology, my mentor, in his brisk but cheery way, appeared at my office door, his eyes sparkling with warm humor. I had collected red maple terminals! That afternoon, I returned to the Proctor Farm –  still quite chagrined, nay, mortified, but soon secure in the knowledge that sugar maple had light chocolate brown shoots, red maple…well, red.

Many thanks for a publication which is read cover to cover, and thoroughly enjoyed.

Sanford Witherell, Jr., Shoreham, Vermont

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Temperature, Day Length, and Leaf Fall

To the Editors:

In a letter to the editors in the Spring 2007 issue of Northern Woodlands, Charles Fergus comments on killing frosts and early snows, and states, “frost causes an abscission layer to form in the stems of leaves, and the leaves then lose their grip on the twigs and naturally fall off when the wind blows and rain or snow falls.” He then cites the lack of frost and heavy snow for storm damage on October 26, 2005.

The fact is, the abscission layer of the leaf is related to the formation of a separation layer extending across the base of the petiole. Toward the end of the growing season, triggered by the shortening length of the day, the pectins of the walls of this layer dissolve through the action of enzymes. The leaf falls, hastened by environmental factors such as wind, rain, or snow. But frost doesn’t have anything directly to do with the formation of the layer.

Mr. Fergus then adds his leaf fall theory to the global warming discussion. Sure is a lot of that going around.

Mike Dannehy, Woodsville, New Hampshire

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Inspired by Homesteaders

To the Editors:

I enjoyed the article in the Spring ‘07 issue on David and CC White’s homestead in Sandwich, New Hampshire. Their care for the land is inspiring and very moving.

As a friend of the Whites, I know that CC is an artist and was sorry the writer didn’t mention this. I would have been interested to read about the connection between CC’s art and her daily life. It seems this could bring up some important questions. How, for instance, does a life spent out-of-doors, working on and for the land, inspire us creatively?

I hope Northern Woodlands will continue to print articles that explore the connection between a close personal contact with nature and our creative selves.

Laura Waterman, East Corinth, Vermont

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Inspired by Homesteaders

To the Editors:

Reading the article about homesteaders David and CC White, it occurred to me that David’s previous life provides him with a metaphor for what he is doing now. As a bush pilot in Alaska, he would have been ever aware of the potential for an unexpected landing far from immediate help. Noticing the disastrous course we are on in many ways, he and CC are on a glide path to land in the future we will all come to – dependent on ourselves and those close by to make a life. The stereotype of homesteaders as anti-social escapists who wish to embrace the primitive is mostly, I believe, a product of an economic system that is increasingly remote, abusive, and unpredictable, and our apprehension about finding an alternative. In truth, stepping away from mainstream culture and refocusing one’s attention eventually reveals a life full of aesthetic, spiritual, and practical potential that we typically discard in favor of convenience or a vague promise of security.

These points are emphasized by Rebecca Kneale Gould, an associate professor of religion at Middlebury College, who has written a fascinating book titled At Home in Nature: Modern Homesteading and Spiritual Practice in America. Despite the impression the title might give, she does not overplay the religious beliefs of her subjects but gives a history of various people, some well known, who have explored the natural connection between a simpler and more direct way of life and a deeper awareness of nature as an abiding presence. Perhaps one of her subjects, John Burroughs, said it best: “Amid the decay of creeds, love of nature has high religious value. This has saved many persons in this world – saved them from Mammon worship and from the frivolity and insincerity of the crowd…it has given them an inexhaustible field for inquiry, for enjoyment, and for the exercise of all their powers, and in the end has not left them soured and dissatisfied. It has made them contented and at home wherever they are in nature.” Most of us don’t have the personal freedom or skills to suddenly take up homesteading, but it is a choice that can strengthen local economies and communities by maintaining the kind of resource base that is vanishing quickly: locally sufficient.

Brian Carter, Bradford, New Hampshire

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Straightening Out the Salamanders

To the Editors:

The photoessay on salamanders was informative and nicely illustrated. However, I would like to clarify a few points. Not all salamanders in the family Plethodontidae (the lungless salamanders), which includes five species in five different genera in our region, undergo metamorphosis within the egg. Species in the genus Plethodon, including the red-backed salamander (Plethodon cinereus), do complete metamorphosis inside the egg, emerging as tiny replicas of their parents. However, the four other species in our area that belong to the Plethodontidae family all hatch into aquatic, gilled larvae that metamorphose into lungless, terrestrial adults later.

Also, in the discussion of Ambystomatid or mole salamanders, the author referred to two all-female hybrid species, the Tremblay’s and the silvery, that result from cross-breeding of Jefferson (Ambystoma jeffersonianum) and blue-spotted salamanders (Ambystoma laterale). While older literature does refer to these hybrid populations as distinct unisexual species, studies from the last 20 years or so have shown that the hybrid populations are more complex than previously thought, and recognizing them as species is not warranted. Instead, salamanders in this group are simply referred to as the “Jefferson/blue-spotted complex.”

Steve Faccio, Strafford, Vermont

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