Hello, Members of the List, Back in September, there was some discussion of the Watercone solar water distiller, now available in the US. Its price of about $125 seemed too high. But on second thought, maybe not. The watercone produces 1.0 to 1.4 liters per day, and has a life-expectancy of about 5 years (1825 days.) Its life expectancy is based on its eventual deterioration of its polycarbonate material under UV exposure.
This works out to between 125/(1825 x 1.0) = $0.07 to 125/(1825 x 1.4) = $0.05 per liter. This can be compared to retail DW that can cost around $1.00 per liter, and home-made table-top distiller energy costs of around $0.25 per liter (assuming the feedwater is not pre-heated.) In the long run, the chief expense of EIS is in the DW, not the .9999 silver. And in the long run, the chief expense of the DW is in the energy consumed, not in the initial investment in a distiller. Unless feedwater is preheated by free heat, the energy cost overtakes the cost of the still after about 400 or 500 gallons or so. So, in a Third World or long-term usage situation, it might be cheaper to use a solar still like the Watercone. A surface treatment that would extend the life of the polycarbonate might improve the economics even more. Can anybody suggest what to use to protect it from UV? Best regards, Matthew
