Cafe Compadre

The Cafe Compadre allows coffee farmers to roast their own beans with solar energy, by concentrating the sun on a rotating drum containing the coffee beans. The sturdy device has been developed for use in rural areas and can be maintained locally. With the capacity to roast 1 kg of coffee beans in approximately 15–25 minutes, this roasting technology is comparable to the capacities of conventional roasting equipment of the same dimensions.
Based on a Scheffler-type parabolic solar concentrator, the technology concentrates the sun's rays onto a single focal point. This type of concentrator can be used with simple solar tracker systems.
At the concentrator's focal point is a drum with one side open, where the coffee beans are put in and sunlight enters. This open section allows the gases and moisture created during the roasting process to escape. Clad in black tiles, the drum's inner surface can absorb a large proportion of the sun's radiation. With an insulation system to boost its energy efficiency, the drum also has a small photovoltaic rotation system enabling even roasting. Finally, an air suction system cools the roasted beans on a stainless steel surface guaranteeing excellent quality in the roasted beans.