The power of small-scale gasifiers

In the highland areas of Vietnam where a lot of coffee is grown, gasifier heat can be used to dry coffee cherries and parchment beans. In the lowland areas where rice is grown, it can be used to dry paddy rice. Many Vietnamese exporters of rice use coal at a cost of $200 US per ton to dry paddy rice. They buy coal and dump or burn rice hulls. It’s hard to imagine a more senseless use of fossil fuels.

Gasifier heat can even be used in the complex and precise process of roasting coffee. I designed a roaster drum of a diameter of 20 cm. It can roast up to 1.85 kg of green beans per batch.

Michael Wood and Cana Little of the non-profit, filanthrope, brought this first gasifier roaster to Laos and presented it to a coffee co-operative there of 58 minority villages. It is hard to overstate the positive financial impact that this device has had on these minority people. Instead of selling green beans (Typica and Cantimor) for $3.00 US per kg, they now sell brewed coffee for $40 US per kg. This gasifier roaster can roast as much as 8 kg of coffee beans per hour. It costs about $250 US, in sharp contrast to one-kg roasters that typically sell for over $6,000 US. This gasifier roaster in Laos paid for itself in the first few hours of operation.

In this video Michael Wood is teaching a young minority man in Laos how to roast coffee with the gasifier roaster. The gasifier puts out just the right amount of heat for the roaster, and it is fueled entirely by waste biomass. The total electrical power consumption per kg of coffee beans is less than one watt-hour.
Small-scale gasification has great potential. This technology should be continually engineered and re- engineered for widespread use even in the developed world. To view this technology as primarily for poor people in developing countries is dreadfully short-sighted. Many households, small farms and coffee shops throughout the world could tap into the power of fire that is free.

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