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Clean-Burning Cookstoves

Joshua McNichols

The Cancun Climate talks wind down this Friday. The talks may not have solved the world's climate problems. But that hasn't stopped activists from trying to stop global warming themselves. Many activists have been swept up in the movement to develop clean–burning cookstoves.

Donnelly: "When I first really got involved two years ago, you could not get the mainstream clean stove movement excited about this. Two years later, this is the buzz."

That's Seattle area artist Art Donnelly, founder of the nonprofit company called Seachar. He invented a clean–burning stove that some people describe as carbon negative. KUOW's Joshua McNichols dropped in on a recent stove–building workshop. He wanted to find out what's getting environmentalists so fired up.


About forty people gathered on a freezing Saturday outside a metal shop in Ballard. They're learning to build a stove that runs on garden waste. Art Donnelly shows them how to bend and rivet the metal pieces together to make their stoves.

He was inspired to build a better stove while travelling around South America. He saw women and children cooking food on dirty cook fires. And he knew it was killing them.

Donnelly: "Typically you'll see literally curtains of soot hanging off the rafters, and if you're there when they're actually cooking it's difficult usually to see across the room. My eyes will sting so badly, my headache will be so bad that I can't really be inside."

And what fuels those dirty cook fires? Trees.

Donnelly: "Fuel use for cooking and for processing or for commercial–scale cooking is deforesting the global south. That's because it relies on primary forestry resources."

To understand how these stoves work, you have to understand how a fire burns. When you burn a piece of wood in a campfire, it actually burns twice. At the beginning the fire is bright, with lots of flames. Later, after all the resins and things have burned off, the flame dies down a bit and you're left with glowing embers, charcoal. This is the stage of the campfire where you pull out the sticks and roast hot dogs. It's also when the wood releases most of its carbon to the atmosphere.

Donnelly's stove makes efficient use of the first stage of the fire. It's so efficient, even the smoke is consumed in the flames. So there's almost no emissions. Because it's so efficient you don't need to go to the second stage of the fire. Instead, you remove the burning embers from the stove with a pair of tongs and drop them in a bucket full of water.

Donnelly sticks his hand in a bucket and pulls out a piece of charcoal.

Donnelly: "Here's a corncob. A little worse for the wear, because it's been in the quench bucket for awhile. But that is still essentially a little bitty black corncob. That is the skeleton, the carbon skeleton of that corncob."

Donnelly's stove has made that corncob chemically inert. In this form, that corncob won't release its carbon into the atmosphere for a long time. Tens of thousands of years. It will hold on to that carbon, even if you bury it.

The gardeners at this workshop intend to use their stoves to create charcoal for their gardens. That's because there's something special about charcoal. Because it has a huge surface area it makes a great home for soil microbes. Because it has a slight negative charge it helps soil hold on to water and nutrients longer. This technology works so well some people want to scale it way up and bury lots and lots of carbon. They say this could help reduce global warming.

But critics worry that people will start burning trees. They say that would release too much carbon into the atmosphere. Trees do a fine job locking up carbon without any help. That's what makes Donnelly's stoves so special. They don't need to use wood for fuel. They can run on everything from corncobs to goat poop.

And that's why Donnelly has taken his stoves down to Costa Rica. He's brought stoves to the same women and children he saw cooking at smoky fires years ago. Over the next cacao harvest season, Donnelly will carefully track what they put into their stoves — and what they take out.

For KUOW News, I'm Josh McNichols.

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