This paper from 1991, funded by the Indian Department of Non-Conventional Energy Sources of the Ministry of Energy in New Delhi, reports the successful use of solar energy for the distillation of alcohol.
A flat plate solar collector system with a collector area of 38 m2 was coupled to a pilot-scale distillation plant with a capacity of 1.8 l/h of 95% v/v ethanol. The data collected on this system over 4000 hours of operation shows that the average daily insolation was 1.68 kWh/m2.day and the collection efficiency was 28%. The average specific ethanol production rate was 0.63 l/ m2.day and the yearly solar load was 65%.
The paper gives details on the pilot plants used in this project. The tests made are evaluated and allow determining that solar distillation of ethanol using flat plate collectors is not an economically viable proposition. However, conclusions also pointed out that the low temperature solar collector systems, like solar ponds, constitute a viable alternative.
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