Sea breezes could turn deserts green
Date: 24-Jan-03
Country: UK
A research team led by Stephen Salter of the University of Edinburgh is developing mobile wind-driven turbines, 40 metres (131 ft) in diameter, that spray vaporised sea water into the air, increasing humidity and, in turn, the likelihood of rain.
"If it works the pay-off could be enormous, right from putting out bush fires to pushing back the desert," Salter said this week.
The turbines, which would be mounted on hundreds of catamaran-like barges, could be used to boost rainfall in some of the world's driest areas.
The engineering professor said he had found no major flaws in the idea.
"I'm putting a big part of my research into this and so far I haven't come across any impossible show-stoppers."
In theory water vapour sprayed from slits in the turbine rotors will partially evaporate in the air from the turbine wake. Residual salt will fall back into the sea and humidified air be blown inland to produce rain as it hits high ground.
But that theory is dependent on a number of factors. The wind must blow onshore, the air must be warm enough to get latent heat for evaporation and to produce rain the air must rise over high ground.
Salter said a meteorological computer model was being used to test the idea.
"One problem is that we can't be sure where (the vaporised air) will go. This is a very difficult meteorological question... we need a computer model," he said.
If the model is successful Salter hopes to set up a trial run.
"We would have to find somewhere with a narrow valley and high mountains." He said he had found possible locations in the Mediterranean island of Crete and on the Red Sea.
But not everyone is convinced by the project.
Philip Eden, meteorologist and weather correspondant for The Telegraph newspaper, said: "Deserts are deserts because the air in those regions is descending, and descending air does not create rain clouds however much moisture you pump into it."
Salter said the possible upsides to the project, which will run for 15 months, outweighed the sceptics' views.
"There are people who are willing to risk years of their active career on this. It's worth taking a very heavy odds against bet on it."