National Geographic News

Tanya Basu

National Geographic

Published November 20, 2013

For anyone seeking respite from the chilly fall air in Washington, D.C., this week, the National Mall was a hot place to be: Twelve wood stoves were burning away as part of a fiery competition for efficient heating.

The Wood Stove Decathlon concluded Tuesday after five days of testing and judging among teams that came from around the world. The goal? "Heat more cleanly, cheaply, and renewably," said John Ackerly, organizer and president of the Alliance for Green Heat. (See related story: "Wood Stove Contest Seeks to Fire High-Tech Solutions for Smoke.")

The New Hampshire company Woodstock Soapstone snared the $25,000 first prize with its hybrid stove, which regulates combustion and includes a regulator to ensure efficient heat. It also comes with unique plates that can be personalized to a homeowner's taste. (See related quiz: "What You Don't Know About Home Heating.")

Beyond the heating element, the decathlon had a warm air of collaboration and congeniality. Woodstock Soapstone shared its prize with the two teams that competed without financial sponsorship, Walker Stoves and IntensiFire. The $10,000 second prize was shared by Wittus-Fire by Design and Travis Industries, which donated its share of the prize back to the Alliance for Green Heat.

Winners for individual categories were HWAM for innovation; Travis Industries for lowest carbon monoxide emissions and also for market appeal; IntensiFire for affordability; the University of Maryland's Mulciber for lowest particulate emissions; and Woodstock Soapstone for efficiency.

Revival of Wood Stoves

The use of wood for residential heating in the United States has increased nearly 40 percent over the past decade, according to government figures. And Europe, where wood pellet stoves are widely used, has been at the forefront of developing wood stove technology, said Ackerly and others. (See related: "High Fuel Costs Spark Increased Use of Wood for Home Heating.") Given the robust demand, proponents of wood stoves want to ensure environmental sustainability, but future economic growth as well.

Wood stoves are diverse. Materials range from traditional steel-plated fireboxes to soapstone or other natural minerals that conduct heat naturally. Combustion chamber designs vary, and air flow can be regulated with fans or drafts. Tied to the wood stove that's been in your family for generations? No need to buy a fancy new-age machine-retrofit models are abundant.

So how does a person judge what makes a wood stove the best? The answer goes beyond how hot the room gets.

European Techniques

Testing of wood stoves is not as simple as tossing a few logs into a fire chamber.

Tom Butcher of the Energy Research Division at the U.S. Department of Energy's Brookhaven National Laboratory, one of the judges for the decathlon, explained the process.

"We're measuring primarily for two things: particulate emissions and carbon monoxide emissions," Butcher said.

There's a Goldilocks point of testing as well: Temperatures are generally the highest near the beginning of burning and the lowest at the end, so testing has to occur in the middle of the process, where it's just right.

"The sampling period is just 15 minutes," Butcher said. In other words, being precise, fast, and accurate is important.

To test the output of the wood stoves, judges climbed a ladder and measured emission levels with a suitcase-like device that held analyzers specifically developed and used for the first time in the decathlon, according to Butcher. In the U.S., testing usually occurs in a lab, but in Europe, where wood stoves are much more common, field testing is the norm.

But what about the wood? As experts have pointed out, different tree species, consistencies, and moisture content of wood can affect how efficiently and cleanly it burns.

That's where the "woodmeister" comes in.

The "Woodmeister"

Ben Myren is the guy in charge of making sure "the game is fair," at least as far as the wood is concerned.

His company, Myren Consulting in Colville, Washington, is an independent laboratory accredited by the Environmental Protection Agency to certify that wood stoves comply with EPA standards.

Using a meter to gauge the moisture levels of wood, Myren makes sure the wood is sufficiently dry before splitting it into pieces. Myren said the wood used for the competition was bought in May to ensure that it was dry.

"The key is to dry your own wood," Myren said. "There's less pollution and higher efficiency if you do. The wetter the wood, the more energy is wasted."

There are still obstacles to creating the perfect wood stove, but this decathlon was a start, said Ackerly.

"The goal is to get people to be aware that this technology is efficient," Ackerly said. "We need to get wood stoves a facelift by showing there really is a high-tech future."

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17 comments
Stu P.
Stu P.

I like wood heat because I don't have to rely on someone else to produce it.  As long as I have an axe and a stove I can keep my family warm and that's really all that matters.

Bill Lewin
Bill Lewin

(generating only 0.54 grams of particulate emissions ) Still a pretty darn high rate when even an oil furnace produces only 0.13 grams and gas 0.0083. And of course in the real world wood stoves are never operated as in a lab. Fail.

Jeremy D'Herville
Jeremy D'Herville

Of course the indoctrinated social marketers for energy/ fuel expansion, needing those phantom futures investments and continued public tax, fines, consents use the wood burner = smoke/ smoke is bad, story. The science and engineering against their naive 'expert' certified, pro psycho-shock marketing 'greenwash to hell natural gas expansionist policies' will win. Your mass marketing behavioural sciences are no match for physics and real science - bunch of cost benefit projectionist waste of timers. It's quite simple. Reduce emissions by engaging in atmospheric physics as well chemistry, measuring, statistics and hockey stick presentations. You are fake. Nothing wrong with wood burning, little wrong with woodsmoke. You are playing for market opportunity and offsetting the needed reduction on fossil fuel subsidies. Those cleaning up wood heating are actually engaging in something useful and practical. Go back to college and learn science. Get rid of the political spin doctoring.

Vic Steblin
Vic Steblin

Many wood burners claim that heating a home with wood is clean, green, safe and cheap. I disagree with all these claims.

First, the clean claim. Scientific studies show that wood smoke has thousands of dangerous types of particles. This should be as obvious as comparing smoke to natural gas exhaust. Even the best EPA approved system with all the modern technological advances cannot match the liquid or gas fuels. The best “clean” is to wear layers of clothes in a colder house.

Second, the green claim. Green usually means sustainable, which works if the resource does not get overwhelmed. Sustainable is fine for rural areas or where trees vastly outnumber people. With more than 7 billion people on Earth, burning trees is clearly not a sustainable practice. Recent studies also show that the black carbon particles from smoke substantially add to the warming effect when the polar ice absorbs more solar heat. True environmentalists should NOT be burning wood.

Third, the safe claim. Natural practices like forest fires are not always safe. The claim that wood smoke is safe is disproved by epidemiological studies and the simple observation that people avoid campfire smoke.

Finally, the cheap claim. A top quality, modern wood stove with all the latest pollution reduction equipment is not cheap. The supporting equipment like shed, truck, saw, splitter, moisture meter and safety barriers are not needed with clean systems. And when the health effects of lots of wood smoke in an area are included in taxpayer costs, wood burning is off the chart. Fire department callouts for creosote fires and insurance costs of wood caused house fires swamp cleaner systems. Burning wood just transfers true costs to taxpayers.

In summary, wood burning is NOT clean, green, safe or cheap. Considerate people butt with this outdated practice in crowded areas. Officials should ban this silly practice when natural gas is available.

Vic Steblin
Vic Steblin

Sorry, people, I just cannot buy this solid fuel burning in a modern age. Wood, be it logs or pellets is just too complex for ordinary humans to use consistently in crowded areas when cleaner liquid and gas fuels are available. Where are the wood fueled trucks, cars, locomotives, cruise ships and jets? The steam engine did not last into a modern age, and disappeared along with the outhouse, ice box and shooting in city limits. Where are the rocket boosters fueled by wood?  Wood is fine for the rural areas and when no one complains. In crowded places, 4 billion city dwellers should be using natural gas by law! And wear layers of clothes to heat the individual in a house that is at 60F, the world average, to care about the environment. Butt out already with the solid fuels for home heat in crowded areas. Spend your time and energy on geothermal.

joseph yechout
joseph yechout

This will have to be controlled by this socialist/fascist state. 

And  taxed out of existence. " necessarily."  As  fearless leader

warned us  on  energy costs. They  will, " necessarily skyrocket." 


victor Unkow
victor Unkow

Wood stoves in or near urban areas causes smoke and toxic air especially to neighbors. It's fine when you are in the home but your neighbor gets the bad smoke. I have neighbors with wood stoves that don't realize that wind changes and depressions caused by lower altitudes just cause the smoke to just sit. What is amusing is many of the people with wood stoves are ardent environmentalists. So complain about big oil and burn wood and cause global warming. Same thing especially in the NW Urban area.

Ryan Ferris
Ryan Ferris

The high tech future for heating is efficient housing design and low temperature heat pumps. Some locations will always need to heat by wood; but it should be banned in any urban setting. Come live in places like the Pacific Northwest where some neighborhoods have simply toxic air quality. Burning carbon for heat is a technology from the stone age. The effects on health of "ground level" smokestacks spread throughout residential neighborhoods are devastating to health. No matter how you clean up this technology; it will still be a point source emitter of pm 2.5 and any toxics associated with plant storage like Cs137.

Jeremy D'Herville
Jeremy D'Herville

Political and business lobbyists are trying to stop people burning in them! Neville D'Herville who has invented the FlueCube cowl in New Zealand, no matter how many positive customer testimonials are produced, no matter how noticeably effective it is to the naked eye on many models of enclosed burner manufactured from the late seventies, he has to end up in conflict over appliance specialists who seem to think the flue and atmosphere has nothing to do emissions and law makers who, though it’s a non-inclusion snub it at the expense of air quality inside and out of the home. This is the new laws and Clean Air Act Endangerment Finding lobbyists talking, it is not the expression of good science, that takes into account ‘variants’. I can empathise with the desire to have a fail-safe appliance, but adding electricity to a wood burner can never be a logical advance in the technology for me, nor should an electric fan ever be needed to get the leftover (cleaned?) smoke up the flue to disperse it. No smoke should leave the flue a few minutes after cold start. If the atmospheric conditions above the flue terminal and the effects were analysed as much as the appliances’ ones, I think we would have had a norm of low emission burners years ago. People are having to repaint living rooms here in New Zealand from new bureaucracy 'certified' appliances, so by theory while the air is cleaner outside...? By making appliances more complex and in calibrating them to atmospheric variant free, ventilation conditions free testing, is causing a growing problem of back draft/ smoke entering the living room and because they are not tested in the conditions the heater is most likely to be used in, we can only expect more ineffective policy loopholes and perpetuation of the anti-wood heater natural gas/ electric paid environmental lobbyist. There needs to be proper, relevant ventilation improvements to match anything that is being done to the firebox. Those who design retrofits to the flue system to reduce emissions are not nut jobs against the instituted appliance experts who believe you cannot leave a fire going overnight, reduce damper controls, who extend flues, chop down trees near the chimney, or generally blame everything on the installer or the operator.

Jeremy D'Herville
Jeremy D'Herville

It’s good to see positive work being done with heating methods consumers want without the manipulative anti-wood heating, economic healthscare endangerments from energy politics I’ve been reading over the past 15 years. In light of a recent retrofit innovation (2009) that specifically concentrates on the atmospheric effects on flue terminals, i.e. inversions/ continually cooling air, negative pressure, and how much a difference it makes on visible emissions, I am still quite anxious for engineers and policy lobbyists to stop focussing all the attention into one single area (the firebox/ certified appliance). I believe and I witness a great deal of good as far as low emission, complete combustion conditions had already been achieved prior to EPA/ OMNI/ UL business lobby certification, with air tight - double combustion, easy to operate heaters made from the mid 1970s. I observe that the appliance testing - separated from variants, is and has been for a long while, been flawed. Verticle flue draw is important and it is not a problem solved from the bottom of the solid fuel heating system, but rather one that is solved at the very top of it. NO FAN SHOULD BE NEEDED and with proper ventilation protection, emissions then maybe something better solved inside the appliance. It is only the convenience of certification at the appliance level that the flue and atmospheric variants are being ignored. I experience this, and it can repeatedly prove itself true to the naked eye. As soon as any new appliance built to the appliance standard, which needs these ideal burn times to monitor, is placed in an inversion/ cold morning/ cold evening, the conditions from the lab don't mean jot, as they are simply not there. It's in those atmospheric conditions that people are likely to be needing their heating most and it’s those conditions that really matter!

Swiftright Right
Swiftright Right

congrates. Im pretty impressed by the level of sportsmanship displayed. If I ever wa going to buy a wood buring stove that the kinda thing ill remember down the road.

Libby Z
Libby Z

What a great selection of entries! Congratulations to all the finalists. And what yeoman's work the test personnel did!  You did fail to mention anything about the masonry heaters, which you have pictured on your cover. They are state of the art in Europe right now, providing much lower emissions when output is compared over a full day instead of fifteen minutes. And the cost per BTU has a substantial difference if you factor in the life of the appliance and amount of fuel used. A masonry heater has just one or two very hot fires a day and stores the heat in its mass. Without need of another fire, it keeps your home warm and toasty with radiant heat. There is no need to get up in the night to put on another log to be warm. The chimney can be closed off either manually or with a computer control as soon as the wood combusts, so the heat stays in the house. And best of all, you can put your back against them to warm your bones.
Wood burning technology has been moving forward in Europe for 400 years. We can learn a lot from them.

Todd Warner
Todd Warner

@victor Unkow I don't think you watched the video or read about these modern super efficient wood stoves and what their capabilities are.

John Strohl
John Strohl

@Ryan Ferris - Sorry, my friend, I'll have to disagree. First, while it will never be a recommendable technology for an urban setting, particularly concentrated settings, it is by far the most efficient way, no matter how you measure the output for many rural and small town settings. It does not have to be a point source emitter at all. I know of technologies that were not entered in the contest that emit nothing but some warm water vapor and CO2. In our area of the country (s.e. Ohio), that is vastly preferable to the overall environmental footprint of fracking for natural gas, which include as yet inneffectively mapped (much less controlled) methane releases, extensive hydrocarbon emissions during well development, and poisoning of the groundwater for miles. THAT is a step up from the manifest ways that the previous coal economy (central to this area for half a century or more) laid waste to the land and the people who lived here and may take another half century to recover. While I agree with the notion that we must stop putting carbon into the atmosphere in any form, right now, until we can do better I'll opt for the lowest possible environmental footprint to stay warm in the winter, and that is wood heat using optimized burn technology. Completely renewable, integrated with the local environment, non-poisonous to the land and the ground water, some stone age technologies are still the best and most natural processes. Obsidian blades are still the sharpest physical blades known to man used in very high precision surgery. That's also stone age technology.

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