Later On

A blog written for those whose interests more or less match mine.

A cleaner-burning wood stove

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My grandmother used a wood stove to heat her house, and as a boy I enjoyed making the fire, poking sticks into the flames, and so on. But woodstoves now are high-tech, as described in the NY Times by Matthew Wald:

Only blocks away, the Energy Department manages the search for quarks and NASA scours the heavens for Earth-like planets. But inside a big white tent on the National Mall, the focus is on something simpler: oak, ash and elm, and how to make them heat a house with as little pollution as possible.

It is not rocket science, but the 12 teams that are competing to solve the problem are finding ways to get twice as much heat out of a log of firewood. The effort preserves woodlands, reduces the labor and expense for the mostly low-income people who use wood, and cleans the air.

The stoves on display here, in a tent with a dozen chimneys incongruously poking through the roof, use combinations of computer controls, catalytic converters and sophisticated gas-flow modeling.

“It’s a combination of low tech and high tech,” said James B. Meigs, one of the judges. “It’s a humble area that doesn’t get enough attention.”

Late Tuesday, the judges announced a winner, based on efficiency, cleanliness, consumer appeal and price: an entry by Woodstock Soapstone, of Woodstock, Vt., which builds stoves that are not only clean and efficient, but are intended to be eye-catching, too. The company was awarded $25,000, but the bragging rights are probably worth more, said John Ackerly, president of the Alliance for Green Heat. His group ran the competition, which was sponsored by the New York State Energy Research and Development Authority, the federal departments of Energy and Agriculture, Popular Mechanics magazine and others.

Mr. Ackerly, citing census data, said wood was the primary source of heat for about 2.3 million American households, largely in rural areas.

Wood stoves typically deliver only 40 to 50 percent of the energy potential of the wood in the space they are supposed to heat. Some of the models in the competition deliver more than 90 percent and make the smoke cleaner. In wood stoves, cleanliness and efficiency turn out to be the same thing.

“If you can see it, if you can smell it, that’s energy that isn’t heating your house,” said another judge, Philip K. Hopke, a professor at Clarkson University and the director of the Institute for a Sustainable Environment there. Parts of the smoke that can be smelled or seen are particles and gases that failed to burn, Professor Hopke said.

The stoves are mostly cast iron or steel, and some are covered in enamel or soapstone. They look like low-tech devices, but in the tent they have been hooked up to digital meters that count their output of carbon monoxide and fine particles, which, like the particles from coal plants, cause respiratory problems. In places with many stove-equipped houses and unfavorable topography, the particles can build up to high concentrations.

A successful stove produces a white ash, made up of minerals like silica, calcium and magnesium, and not much else, because all the wood has been burned. Managing the combustion for efficiency and cleanliness — a problem recognized for hundreds of years — means providing just enough air for thorough burning, but not too much because the more air that enters, the more heat leaves the room as exhaust. Some stoves use oxygen sensors, like the ones in cars, to adjust a fan or valve to keep the balance right. . .

Continue reading.

Here’s a Popular Mechanics article about one of the entries, which sounds quite intriguing.

Written by LeisureGuy

21 November 2013 at 8:25 am

Posted in Technology

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