Former Darrieus test facility of Dornier Photo: University of Stuttgart
Read The British engineer Stephen Salter wants to solve the water problems of the world with "rainmakers": Thousands of wind turbines should be built off the coasts of dry countries, he says. However, they do not serve to generate energy, but pump seawater upwards and blow it through fine nozzles into the air. This humidifies the air, which should lead to more rainfall on the mainland. On the bizarre idea of ​​the British, who had made in the seventies already with plans for wave power plants of themselves, reports the New Scientist in its issue of 25 May. The engineer from the University of Edinburgh wants to use turbines according to the so-called Darrieus principle: The huge "beater" consist of two or more curved rotors, which converge at the top and bottom, and rotate about its vertical axis. In power generation, they have proven to be less effective than the classic wind turbines. However, they would be well suited as a "rainmaker, " Salter believes. For this purpose, water pipes would have to be placed in the rotors and their edges would be provided with small nozzles.

At wind speeds of eight meters per second, such a turbine would carry 500 liters of water per second in ten meters, the Briton has calculated. Hundreds or perhaps thousands of these turbines, built in hot climates, could prevent drought and solve the water problems of billions of people, Salter speculates.

To reverse a sea level rise of one meter due to global warming, 100, 000 such turbines would have to run for a hundred years, Salter has calculated. It makes use of the fact that some of the rainwater is stored in areas with low water tables, for example, under the Sahara.

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