[Stoves] Wood Stove Contest Seeks to Fire High-Tech Solutions for Smoke

[Crispin Pemberton-Pigott]

Dear Friends

Some list members may not be familiar with the 'rocket' stove mentioned
below. It is actually called a Rocket Mass Heater and is promoted by a few
guys who used to be associated with Aprovecho but works quite differently.
There is one, apparently, here in Ulaanbaatar. I understand from reading
that the technology is very ancient and well suited to being made from
stone. The rest of the discussion is about very modern approaches using
quite a range of fire layouts.

Regards

Crispin

Date: 11/15/2013 02:01 PM
Subject: Today's Top Energy News - November 15, 2013


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Wood Stove Contest Seeks to Fire High-Tech Solutions for Smoke 

In a chilly room at the <http://www.umd.edu/>  University of Maryland in
College Park, a small group of students is working to make wood stoves cool.


They gather around a black steel box, on top of which is a funnel,
shepherding smoke away. They tensely watch the thermometer. The room is
still cold, but it normally takes about 20 minutes for the stove to begin
warming up. 

Eventually someone sighs. Hunched shoulders relax. 

"It's working," says Taylor Myers, captain of Mulciber, one of 14 teams from
around the world that will be competing as finalists in the first-ever
<http://www.forgreenheat.org/stovedesign.html>  Wood Stove Decathlon, which
begins Thursday and continues through the weekend on the National Mall in
Washington, D.C. 

The competitors are applying new materials, configurations, and high-tech
control systems to an old problem: How do you burn wood with less smoke?
(See related, "Quiz:
<http://environment.nationalgeographic.com/environment/energy/great-energy-c
hallenge/wood-energy-quiz/>  What You Don't Know About Wood Energy.") 

It's an important question with implications for both health and energy
efficiency at a time when high heating costs have more homeowners in cold
climates turning to wood stoves in the winter. (See related, "
<http://news.nationalgeographic.com/news/energy/2012/10/121022-wood-for-heat
ing/> High Fuel Costs Spark Increased Use of Wood for Home Heating.") 

Decathlon sponsors, including the  <http://www.nyserda.ny.gov/> New York
State Energy Research and Development Authority (NYSERDA),
<http://www.nyserda.ny.gov/> the U.S. Forest Service, and a broad range of
wood stove industry groups, are seeking to spur innovative ideas for
remaking the wood stove for the modern age: high-efficiency, low emissions,
and affordable. 

Beyond the Franklin Stove 

Wood stoves have a small, devoted following today in the industrialized
world, but not long ago they were a staple in homes far beyond the cozy
mountain cabin. Wood was the dominant source of fuel from the founding of
the American colonies until 1885, when it was surpassed by coal. (See
related "
<http://environment.nationalgeographic.com/environment/energy/great-energy-c
hallenge/home-heating-quiz/> Quiz: What You Don't Know About Home Heating.")


Benjamin Franklin's stove, the mid-room cast iron furnace, was the
efficiency breakthrough of its day, generating heat in all directions and
providing warmth even after the fire was extinguished. But another
Philadelphia inventor, David Rittenhouse, is credited with making a crucial
safety improvement to the Franklin stove-a chimney to vent smoke. 

Some 240 years later, organizers of the Wood Stove Decathlon call the event
"the first high-profile technology competition for wood stoves since Ben
Franklin's time." 

Although the high-efficiency wood stoves on the market today, especially in
Europe, are a far cry from the Franklin and Rittenhouse stoves, many
consumers aren't aware of the options or are turned off by the cost of
high-end appliances. The U.S. Environmental Protection Agency has a
<http://www.epa.gov/burnwise/woodstoves.html> certification program to
encourage consumers to switch to modern stoves that reduce smoke and dust,
and cut heating expenses. But the Wood Stove Decathlon, modeled after the
U.S. Department of Energy's popular <http://www.solardecathlon.gov/>  Solar
Decathlon, seeks to take innovation a step further. 

The competition is seeking to spur ideas for a new generation of wood stoves
that are greener, more aesthetically pleasing, easier to use,  safer, and
more affordable. 

"A lot of what wood stoves deal with is a PR problem," said John Ackerley,
<http://www.forgreenheat.org/>  president for the Alliance for Green Heat,
the event organizer.  "People associate them with what they saw when they
were growing up." 

Where There's Smoke 

The biggest problem with wood stoves is the plume of smoke that rises from
burning wood. Smoke "always has been a problem and always will be a
problem," said <http://www.gulland.ca/>  John Gulland, a hearth products
consultant in Killaloe, Ontario. Smoke is a pollutant and irritant, and it
can be dangerous, particularly for children and older people. (Take the
quiz:
<http://environment.nationalgeographic.com/environment/energy/great-energy-c
hallenge/wood-energy-quiz/>  What You Don't Know About Wood Energy.) 

It's difficult to come up with one system that will reduce smoke by burning
wood consistently and efficiently because there are so many types of wood. 

"You've got wood stoves in Alaska that burn spruce, in Washington state they
burn Douglas fir, and in New England, they burn maple and oak," Gulland
said. "There's no way you can have a highly refined combustion system that
will burn all those things." 

Wood quality is a problem as well: depending on precipitation, wood from one
region may hold more moisture than the same type of wood from a different
location. 

"No microprocessor can control for [moisture]," Gulland said. "So the
problem is that we have a nonstandardized fuel that varies widely." 

Wood pellet stoves, widely used in Europe and gaining popularity in the
United States, have proven to be an efficient solution to the problem of
variability. 

Pellets are "just sawdust that's been compressed," said the Alliance for
Green Heat's Ackerley. "They're already very dry and very consistent. They
can automatically be loaded into a firebox. You can control combustion in a
firebox. It's more transportable." 

But some consumers shun pellet stoves because they're looking for the warm
look of logs burning. 

Gulland, who has been in the industry for about 35 years, says trade-offs
between form and function are common. 

"Every manufacturer of a wood stove has to compromise . . . design to
fueling practice," he said. "I've seen really great design come and leave
the market because [it] could not cope with" the limitations of working with
a variable fuel like wood. 

Not Dampers, But a Controller 

Students in the  <http://www.enfp.umd.edu/sitehome.php> Fire Protection
Engineering Department at the University of Maryland decided to take on the
challenge of creating a wood stove that doesn't sacrifice form for function.
Naming their team Mulciber, after the Roman god of fire, the students
focused on a key fire ingredient that is far less variable than the wood:
the air. The team's innovation is a piece of equipment--a controller that
continually adjusts the flow of air needed for combustion. 

"In the typical wood stove, air flow is driven by combustion," said team
captain Myers. "So as the fire heats up, it heats up the air inside the box
and it draws air in from the outside room into the fire. That means your air
flow is entirely dependent on how hot your fire is." Wood stoves typically
include dampers to close off the air flow slightly, but dampers are a
one-size-fits-all effort that is not always effective. 

Instead, the Maryland students designed a controller that will calibrate the
air flow based on temperature measurements it takes inside the fire box.
"Based on those measurements and [an] algorithm we program, [the controller]
will control the air-flow rate," team member Mark McKinnon said. 

Fans will adjust to control the air-flow rate-meaning the efficiency of
combustion process will be markedly improved. The fans will react to the
controller and vice versa, a "feedback loop," McKinnon said. 

The team also incorporated catalysts and particulate scrubbers into its
design to make the appliance burn cleaner. But the air-flow system is what
makes Mulciber's wood stove cutting edge and unique. 

"If you optimize the wood-burning process with sensors, you're doing so much
more than you ever could with just tending to your stove with whatever wood
you have lying around," said teammate Anita Alexander. "I think that's one
of the biggest problems with wood stove technology right now. [wood stove
owners] don't know the oxygen levels or what's going on with the
fire-burning process." 

Simplicity is key to the design of the stove. 

"There's not a whole lot of moving parts," Myers said. "It's basically a big
steel box that we blow air into. But even in that, we found the complexity
it takes to manufacture it is intimidating." 

Researching and building the stove proved to be pricey and time-consuming
for the only student team to reach the finals of the Wood Stove Decathlon.
Competing against professional engineers and commercial wood stove
companies, the Mulciber team had no corporate ties or sponsorship, but was
able to  secure some funding from the university. The students spent the
better part of a year producing a prototype  unlike most in the market. The
final product was produced on campus by the campus machine shop. "We started
our work from scratch," explained Alexander. "We don't have any other
influences but our own ideas." 

In the end, the students relished the challenges. 

"I think, just by being in the fire protection department, burning yourself
a little bit is part of the job," McKinnon said with a chuckle. 

Downdraft and Rocket Heaters 

The University of Maryland team's air-flow controller is just one of the
wood stove heating solutions that will be on display on what is expected to
be a fittingly cold weekend in the U.S. capital. Some teams have sought more
efficient burning by using turbulence or downdraft. There will be convection
heat exchangers and "rocket" heaters-insulated vertical chimneys. Don't
expect to see ugly, bulky boxes. The finalist stoves are sleek and chic,
using everything from recycled steel oil barrels to soapstone, a powdery
rock long praised for its heating capabilities. 

The competition has real-world relevance. So many American households are
returning to wood stoves that the U.S. Energy Information Administration
(EIA), the government's main energy forecasters, last year began including
an analysis of firewood and pellets in the
<http://www.eia.gov/forecasts/steo/report/winterfuels.cfm>  annual Winter
Fuels Outlook. EIA calculates that 2.5 million U.S. households used wood as
their primary heating source in 2012, forecasting the number would grow 3
percent within a year, faster growth than for any other heating fuel. (See
related, "
<http://news.nationalgeographic.com/news/energy/2013/10/131018-no-freeze-on-
winter-energy-prices/> No Freeze on Winter Energy Prices, Despite Natural
Gas Boom.") 

Still, wood stoves are not typically seen as a modern renewable energy
appliance, said Ackerley. 

"Only one in ten homes in America have wood stoves," Ackerley continued.
"Twenty-, thirty-, forty-year-olds don't associate the new [wood stoves]
with being far more efficient than the old ones." 

Typically, installation of a wood stove is treated as an energy efficiency
improvement, subject to far more modest tax breaks than those available for
solar energy, for example. 

Ackerley hopes that the Wood Stove Decathlon contest judges, many of whom
are state regulators engaged in energy and environmental issues, might be
inspired  to push for greater recognition of the positive role cleaner wood
stoves can play. 

"Maybe states can develop their own ... incentives for them, do something
stricter than Washington mandates," Ackerley said. "There's not an effective
lobby, no big multinationals involved." 

Ackerley and others said Europe, with higher energy costs and plenty of
dense forests, has been far ahead of the United States in developing
high-tech solutions for wood stoves. (Teams from Austria, Finland, and
Denmark are among the finalists in the Wood Stove Decathlon.) (See related "
<http://news.nationalgeographic.com/news/energy/2013/10/131018-no-freeze-on-
winter-energy-prices/> Pictures: Hungary Literally Burns Money For Fuel.") 

In the United States, the allure of wood stoves competes with what Gulland
refers to as "the cult of convenience." Unless a stove owner opts for a
pellet stove, burning wood will require plenty of collecting, drying, and
stacking. "Wood heating is the absolute opposite of convenient," Gulland
said. 

But members of Maryland's Mulciber team see a future for high-tech,
high-efficiency wood stoves. 

"I don't know why" wood stoves lost popularity in the United States, said
<http://fpe.umd.edu/faculty/stoliarov>  Stanislav Stoliarov, the assistant
professor mentoring the team. "Perhaps we thought we were going to walk away
from this technology at some point. But that's a mistake. We're not walking
away from it. This technology is going to stay with us." 

Stoliarov thinks of firewood as "the perfect renewable fuel." 

"You can 'regrow' it," he said. "We largely overlook the ideas that make it
more efficient and clean." 

At the Wood Stove Decathlon, the teams are hoping those ideas catch fire. 

Follow Tanya Basu on  <https://twitter.com/mstanyabasu> Twitter.

Source:
http://news.nationalgeographic.com/news/2013/11/131114-wood-stove-decathlon/

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