Yang Miyake Economic Feasibility Hybrid Solar Biogas Food Dryer 1984 SolarBiomassWorkshop
...electrical heat. This is because: (1) digesters are a major part of the fixed cost in a solar-
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biogas system; (2) it requires more land to accommodate 710 digesters. Another assumption not mentioned is that the additional papaya wastes are obtained free beside those from making the dried slices. Subject to further refinement of these estimates and calculations, the solar-biogas dryer appears economically feasible especially if built for a cottage industry.
SUMMARY
Experimental results have demonstrated the feasibility of producing adequate quantity of biogas (50-62% methane) from processed papaya wastes in multiple anaerobic digesters. A pilot biogas collection, storage and combustion system augmented solar energy and allowed continuous drying of papaya slices to 5% final moisture in a total of 11-16 hrs. Assuming an annual throughput of 250,000 kg of dried papaya, a comparison of fixed and variable costs showed that a solar dryer is the least expensive at $3.08/kg dried fruit; a solar-biogas dryer is second at $3.41/kg in an urbanized setting (with automatic control of biogas collection, storage, ignition and drying tem erature), or at $3.20/kg in a cottage industry setting (manual control , and an...