Jun 11, 2003
Tube wells in the sky
Water is a big issue today in India. Scarcity of it and the societal problems looming ahead have been well enough stated. But what of solutions? They range between touching local efforts, which are alas, not numerous and the grandiose ones like linking of rivers and big dams proposed by minds, which are alas too numerous.
Let me throw this idea in the ring. Why not, wind powered desalination? In this proposal windmills along the edge of the sea coast are used to power desalinators.
But these windmills don’t generate electricity. They generate friction and consequently heat. This heat will be used to power flash evaporators in which under a moderate vacuum, sea water is converted to potable water. This is a proven idea: almost every sea going vessel has a system for its water needs; they use the main diesel engine’s waste heat to obtain this by-product water for free.
Cost of production of water is likely to be far lower than the reverse osmosis [ro] systems. Power, maintenance and operator skills are are very low. Flash evaporators are almost zero-cost maintenance systems.
The windmill itself would come cheaper because the expensive generator, gear boxes and regulation systems would not be required. They need scarcely be reefed in. Their speed does not matter. The shaft would drive a ‘windage’ machine made of some sort of ceramic. An armature would rotate in a stator with engineered air gap between them offering friction. The generated heat would be carried away by a closed loop fluid system and circulated in coils placed in the flash evaporator. Or superheated air itself can be circulated.