david_h wrote:
It seems to be a big increase in efficiency.
But - and sorry for the negative tone - is it enough move solar stills from 'survival aids' to being a practical, cost-effective source of clean water for people in the developing world? In round numbers we are talking about 3 litres/person/day just to sustain life. Minimum targets for clean water, for basic hygiene as well as drinking, start at about 15 litres/person/day. It has to cost less than a walk to a clean source. In many places people's own labour is cheap, what they don't have is money.
It is good to be critical, but. . .
Several points:
The test apparatus closely tracks the efficiency of a a theoretically perfect system. The test apparatus produced 5-7 ml purified water over a 7 hour period using a surface 20mm square. Scaling this up does not introduce loss of efficiency (one of the remarkable things about this setup).
This infrastructure has very little maintenance cost. After initial cost, you have a source of clean water, free of biological and chemical contaminants. You can recycle both black and grey water.
In many parts of the Sub-Sahara it takes between 2 to 4 man hours per day to procure potable water for a family of 4. This is a tremendous drain on productivity. Maintenance of a system scaled to provide the same amount of water would take between 15 minutes to one half hour per day. Rinsing away accumulated salts in the wicking capillaries.
The test apparatus demonstrates efficiency well beyond that of solar electric systems. Granted electricity is not water, but this speaks well for its place in a third world economy. Further, this technology doesn´t appear to have degradation over time that solar cells have, making the ROI very favorable.
Just as a side note, not only is the manpower saved to procure water,
but the purity and healthy nature of the water from this source is assured.I´m looking forward to the development of this novel technology.
Bob