Winning Wood Stove Designs Announced: FPL'er one of the judges in worldwide competition

Last week in Washington, D.C., the National Mall was lit up by contestants in the Wood Stove Decathlon, sponsored by the Alliance for Green Heat.

wood_stoveTwelve teams from around the world brought their best designs, aimed at finding the cleanest, cheapest, most renewable ways to heat with wood. After five days of testing and judging, the New Hampshire company Woodstock Soapstone claimed the $25,000 first prize with a hybrid design.

A great article and video from National Geographic provides more detailed information on the various stoves, their designers, and the testing process.

Mark Knaebe, a Natural Resources Specialist at the Forest Products Laboratory, was one of the contest judges. In a previous Lab Notes post on the decathalon, Knaebe explained that many wood stoves and boilers are not very efficient, and the competition provides a way to both educate and encourage the development of “pollution-free burning devices.”

Wood for Warmth: Choosing the Right Firewood


Different species of wood make for different fires.

For all of FPL’s technological advances in wood science over the past century, the simple act of wood providing warmth and ambiance in fireplaces and wood stoves is still important.

The chart below outlines characteristics of several species and may help you decide which wood to use the next time you’re looking to keep warm by the fire.

Click image to enlarge.

Click image to enlarge.

According to the USDA publication “Firewood for Your Fireplace,” choosing the best wood for your fire depends on several factors. Consider what species are readily available, any personal preference regarding aroma, and what type of fire you want to build.

Softwood species are easy to ignite and burn with a hot flame. However, they also burn rapidly and require frequent replenishing to stay lit. Softwood species are recommended if you’re looking to warm up with a short fire that will burn out quickly.

For a longer lasting fire, hardwood species are a good choice. These woods burn less vigorously with a shorter flame and produce long-lasting, steady glowing coals.

The ideal fire, then, would use a mix of softwood logs for easy ignition and hardwood logs for longevity. By adding wood from fruit trees (such as apple and cherry) or nut trees (such as hickory, beech, or pecan), your fire will also emit a pleasant aroma.

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Wood Stove Design Contest Heats Up

Wood stove

Warm your home and dry your shoes. Photo credit: Dan Phiffer.

It’s time to give your fiery passions a voice. No, not those fiery passions, we’re talking wood stoves here!

You can help shape the future of wood stove design by voting for your favorite high-efficiency, next-generation wood stove in a contest sponsored by the Alliance for Green Heat and Popular Mechanics magazine.

Mark Knaebe, a natural resources and bioenergy expert with FPL, is one of the judges for this unique competition. Many wood stoves and boilers are not very efficient, says Knaebe. Some may burn well but then push much of the heat up the chimney. Others may include precipitators to capture fine particulate matter but still emit carbon monoxide, a poisonous gas. “And those are the good ones,” says Knaebe.

“We can do far better,” Knaebe says of classic wood stove design and performance. “This competition is both a way to educate as well as encourage the brightest and best to develop pollution free burning devices.”

The final phase of the contest will be a Wood Stove Decathalon on the National Mall in Washington, D.C. held this November.


A Hot Debate: Stacking Firewood Bark Up or Bark Down?

“You can tell a lot about a person from his firewood stack.”

So declared Lars Mytting in a New York Times piece about the debate among firewood-splitters in Norway. The central question remains: bark up or down?


Mytting has ignited a national passion for Norwegian wood in books and on television. Given that the audience in Norway seems split 50/50 on proper firewood stacking technique, we put the question to a couple of our Forest Service experts.

“It would be humorous if it was all semantics.” says Mark Knaebe, natural resources specialist with the FPL Forest Products Marketing Unit. But it does make a difference, he says. If split wood is stored outdoors, stacking it with the bark side down can allow water to collect in the u-shaped trough. This moisture retention can prolong drying and accelerate decay, says Knaebe. Stacking it outdoors with the bark-side-up, on the other hand, can help protect the pile of wood below from rain and other weather.

Many people store wood in a shed or some other type of shelter. In climates with even moderate precipitation, having a roof over your wood is advantageous. In this case, the bark up-or-down debate becomes fairly inconsequential, says Knaebe. With even a slight breeze moving through the shelter, he says, drying occurs considerably faster than in a dead-air space.

Whether stacking it inside or out, many people lay a few small logs or lumber on the ground perpendicular to the first row of stacked wood. This allows for better air-flow and reduces the potential for bacterial or fungal infestation due to close proximity to the ground, says Jan Wiedenbeck, Research Forest Products Technologist with the U.S. Forest Service Northern Research Station.

“I also wonder if the bark, when on top, might protect unsheltered wood from long-term photo-degradation?”  says Wiedenbeck. “Sunlight can certainly affect checking and splitting in wood, but does it affect Btu’s?”

Knaebe, a wood energy expert, responds that while ultra-violet light can indeed destroy lignin, which has a higher Btu than the rest of wood’s constitutive parts, it wouldn’t be enough to significantly affect actual thermal output.

In the end, an answer to the “bark up or bark down” question seems to be: it depends. When storing split wood under shelter, where air-flow becomes more important, bark up or bark down seems to be a matter of personal preference. There is also the question of ease of handling, says Wiedenbeck. Bark down, she says, means wedge-side-up makes it easier to pick off the pile.

To see how firewood compares to other sources of energy, take a look at FPL’s ever-popular Fuel Value Calculator.