This week in the magazine, I write about engineers who have set their sights on the low end: a ten-dollar stove that even the world’s poorest people can afford. In the past few years, though, industrial giants like Bosch-Siemens, British Petroleum, and Philips Electronics have all tried their hand at building more expensive and sophisticated devices—stoves that cost between twenty and a hundred dollars retail, and are clean enough to run indoors. The results have been mixed.

The Germans, at Bosch-Siemens, developed an elegant oil-burning unit called the Protos, but it never really took off. (It’s as noisy as a blast torch, I was told). The British, at BP, spent millions designing a stove that runs on pellets, then promptly abandoned the project and sold the design to an Indian company. The Dutch, at Philips, have just finished field tests of a stainless-steel fan stove, a prototype of which I tried out this fall. The Philips stove has a rechargeable fan in its base that works as a kind of bellows: it helps the fire light quickly and keeps it burning hot and clean. The stove that I used boiled a pot of water faster than my GE gas range, produced almost no smoke, and left only a thin residue of ash behind.

Even more promising is a stove designed by an Italian-American engineer named Nathaniel Mulcahy. The LuciaStove, as he calls it, is a gasifier made of beautifully injection-molded aluminum. It’s modular in design, so its most intricate parts can be packed flat and shipped inexpensively, while the rest can be manufactured locally. (In the Congo, the combustion chambers have been made of spent munitions shells.) Mulcahy, who is a former research director at Emerson appliances, claims that his stoves can cut fuel use nearly in half and burn fuel with ninety-three per cent efficiency. Whether they can also overcome the tetchiness inherent to gasifiers remains to be seen, in ongoing programs in Africa, Mongolia and Afghanistan.

Finally, Dean Still and the engineers at Aprovecho have joined with a start-up firm called Biolite to create a new generation of low-emissions stoves. Their design incorporates a thermoelectric fan designed by Jonathan Cedar and Alec Drummond, co-founders of BioLite. The fan runs without batteries or external electricity. Instead, it uses the heat from the fire to generate its own power. Cedar and the Aprovecho staff built the prototype in October and presented it for the first time at an international stove meeting in Bangkok, in November. The new stove reduces emissions by more than ninety per cent, compared to an open fire, and should cost about twenty dollars a unit to build. Best of all, it’s user-friendly: unlike other fan stoves, it has a side-feeding combustion chamber that’s easy to refuel. Aprovecho and BioLite hope to make it commercially available by 2011.