EDINBURGH, June 3: Tribal rainmakers may soon be out of a job if an invention by a Scottish-based scientist proves economically viable.

The device uses wind turbines to suck water out of the oceans and could end droughts around the world and compensate for a predicted rise in sea level caused by ocean warming, it is claimed.

The idea is the brainchild of British engineer Stephen Salter, who wants to turn the machines into water-borne rain-makers.

Salter, from Edinburgh University, became well known in the 1970s for pioneering wave-power technology. His latest concept is a floating wind turbine that sprays water vapour high into the air, increasing evaporation from the sea and rain over the land.

The proposal is to convert an existing design called a Darrieus turbine that resembles a 130ft high food mixer with slender blades at the top and bottom that spin about a vertical axis.

Salter plans to suck water from the ocean into the blades, which would shoot a fine spray from their trailing edges up to 65 feet above the sea surface. He argues that the turbine would overcome one of the main brakes on evaporation from the ocean - a wafer-thin layer of stagnant, humid air that forms a barrier at sea-level.

With a wind speed of eight metres per second, each spray turbine could lift more than half a cubic metre of water a second to a height of 10 metres.

Salter has calculated that hundreds or even thousands of the machines in hot areas of the world could make enough rain to prevent droughts.

“The successful large-scale deployment of spray turbines could reduce the number of people who are short of water by several billion,” Salter told New Scientist magazine. About 100,000 turbines operating for 100 years would theoretically be enough to reverse the one-metre rise in sea level expected to result from global warming, he says.—dpa