Madsen Pirie

I was intrigued by the BBC story that a billboard outside Lima in Peru is making drinking water available to anyone who needs it.  It uses condensers and filters to take water out of the humid air and pipe it down to a tap accessible to everybody.  Dreamed up by a partnership between Lima’s University of Engineering and Technology and advertising agency Mayo Peru DraftFCB, it cost $1,200 to set up, and has so far produced over 9,000 litres of drinking water – about 96 litres a day.

I am not impressed by  scare stories about a future world water shortage or even of “water wars” between nations desperately short of usable water.  Since four-fifths of the planet is covered in water, the problem comes down to developing the right technology that can treat water and convey it to where it is needed.  Cost is a factor here, and the race is on to develop cheaper ways of purifying water.  There are some very innovative small-scale ways of doing this, including one that re-uses plastic drinks bottles on the roofs of houses.  For large scale treatment the future probably lies with osmosis, the use of membranes that will let water molecules through but not the larger molecules of salt or contaminants.  It is energy-intensive to drive the water through, and the membranes do become clogged and have to be cleaned.  A recent breakthrough by NanoH2O is to embed nano-particles into the membrane to let water pass through more easily with 20% less energy needed to drive it, but still blocking the contaminants.  As the costs come down, the prospect becomes nearer of automatic purification plants, each with its own dedicated power station, turning vast quantities of sea-water into water suitable for drinking and irrigation.  Three cheers again for human ingenuity.

Filed under: Updates |