Construction of huge chimneys in the Israeli desert for generating pollution free energy from powerful man-made downdrafts is to be the subject of feasibility study sponsored by Israel's ministry of energy and infrastructure. "If water is sprayed into the top of a hollow cylindrical structure it will tend to evaporate immediately, thus cooling the surrounding air and increasing its specific gravity. That will cause the air to fall in the chimney, setting up a considerable downdraft. If turbo-generators are placed at openings near the bottom of the structure, that downdraft will activate them to produce electricity," explains the Israel Export Institute in announcing the project. The study team is being led by Haifa Technion professor Dan Zaslavsky. He says that optimum performance will probably be achieved with very large "wind power chimneys" up to 1000 metres tall and 300 metres in diameter. "Whether such large structures are technically and economically feasible remains to be demonstrated," states the institute.