Engineer feeds a thirsty desert on ice
An Indian engineer has invented a way of creating ice pyramids that slowly release water to irrigate the desert of the Himalayas.
The lack of water imperils the livelihood of about 300,000 farmers in the region, which is at an altitude of 3500m.
It was while walking near a bridge that Sonam Wangchuk, 50, came up with his novel concept.
"I saw that there was ice under the bridge which, at 3000m, was the warmest and lowest altitude in the whole area.
"And this was in May. So, I thought that we could keep ice right here if we protect it from the sun.
"But where do you get shade? I began to think about reflective materials and about reducing the surface area [of the stored] ice exposed to the sun."
Wangchuk realised that if the ice were stored as a cone it would have minimal surface area and melt much more slowly than a flat field of ice .
His innovation recently earned him a Rolex Award for Enterprise, making him one of five scientists this year to be so honoured.
Wangchuk now plans to build up to 20 ice "stupas" (a stupa is a Buddhist monument), each 30m high and capable of supplying millions of litres of water.
"Glacial water is carried down from higher ground through buried pipes and the final section of pipes is vertical."
The water fountains out of the pipes into the subzero air, freezes, and accumulates as a stupa.
In late spring the ice melts and is collected in large tanks, then fed onto planted land through drip-irrigation pipes.