Biochar Stoves

The effort go provide clean-burning stoves to the world's poor continues. If you read environmental news magazines or web sites, you have probably gotten jaded about claims for the latest wonder stove. For at least the past 20 years, western engineers and do-gooders have been touting new designs that were supposed to reduce the health risk from smoke -- the WHO has raised its estimate of the number of premature deaths caused by inhaling smoke to 3.5 million a year, more than malaria and AIDS combined -- and consume less of the world's precious trees. In practice, though, they never seem to work as well  as promised. Either they break, or the people who are supposed to use them find them too cumbersome and they are discarded.

Now there is a new group of designs being pushed around the world,  so-called biochar stoves. These have two important characteristics.They are micro-gasifier stoves, designed to separate the combustible gas from the solid fuel that produces it; it is mostly this gas that actually burns, not the solid wood itself, and stoves can be designed to increase production of combustible gasses. When the gas is separated from the solid fuel, it burns more cleanly, producing as much as 90 percent less soot. These stoves are also designed to turn the un-burned wood into "biochar," a sort of charcoal very useful as compost. By burning wood more efficiently and turning the waste into valuable fertilizer that poor people will almost certainly dig into the soil or sell, they are said to reduce greenhouse emissions.

You can read about these stoves at National Geographic or at the web site of Sea Char, one of the charities promoting these new stoves;  those are Sea Char stoves in the pictures. It all sounds great, but then lots of other stove projects have sounded great but not really worked out in practice.