Wind holds enough energy to meet or exceed the world's total demand for power by 2030, according to new research from Stanford University and the University of Delaware.
Four million wind turbines, each 100 meters high, could supply well over half the world's power demand without significant negative effect on climate, said Mark Jacobson, professor of civil and environmental engineering at Stanford and Cristina Archer, associate professor of geography and physical ocean science and engineering at the University of Delaware.
Jacobson and Archer would place half of the 4 million turbines over water. The remaining 2 million would take up a little more than one-half of 1 percent of the earth's land surface -- about half the area of Alaska.
Rather than put all the turbines in a single location, Archer and Jacobson said it would be best and most efficient to spread out wind farms in high-wind sites across the globe -- the Gobi Desert, the American plains and the Sahara, for example.
"We're not saying 'put turbines everywhere,' but we have shown that there is no fundamental barrier to obtaining half or even several times the world's all-purpose power from wind by 2030," Jacobson said.
"The potential is there if we can build enough turbines.
"To get there, however, we have a long way to go. Today we have installed a little over 1 percent of the wind power needed," Jacobson said.
The professors' conclusions come from adaptations of three-dimensional, atmosphere-ocean-land computer modeling, which calculates the theoretical maximum wind power potential on the planet, accounting for wind reduction by turbines.
The model assumed wind turbines could be installed anywhere and everywhere, without regard to societal, environmental, climatic or economic considerations.
The new paper contradicts two earlier studies that said wind potential falls far short of the aggressive goal because each turbine steals too much wind energy from other turbines, and that turbines introduce harmful climate consequences that would negate some of the positive aspects of renewable wind energy.
The new computer model provides a more sophisticated look than previously possible by separating winds in the atmosphere into hypothetical boxes stacked atop and beside one another. Each box has its own wind speed and weather. In their model, Jacobson and Archer exposed individual turbines to winds from several boxes at once, a degree of resolution earlier global models did not match.
"Modeling the climate consequences of wind turbines is complex science," said Jacobson.
"This software allows that level of detail for the first time."
The researchers were able to calculate the exposure of each wind turbine in the model to winds that vary in space and time. Additionally, the model accounts for the wind that gets claimed by the turbines. It then calculates the effect of these wind speed changes on global temperatures, moisture, clouds and climate.
Among the most promising things the researchers learned is that there is a lot of potential in the wind -- hundreds of terawatts. At some point, however, the return on building new turbines would plateau, reaching a level in which no additional energy could be extracted even with the installation of more turbines.
"Each turbine reduces the amount of energy available for others," Archer said. The reduction, however, becomes significant only when large numbers of turbines are installed, many more than would ever be needed.
"And that's the point that was very important for us to find," Archer said.
The researchers have dubbed this point the saturation wind power potential. The saturation potential, they say, is more than 250 terawatts if an army of 100-meter-tall wind turbines were placed across the entire land and water of planet Earth. Alternatively, if they were placed only on land (minus Antarctica) and along the coastal ocean, there is still some 80 terawatts available -- about seven times the total power demand of all civilization. Hypothetical turbines operating in the jet streams 6 miles up in the atmosphere could extract as much as 380 terawatts.
Jacobson and Archer's findings were published in the Proceedings of the National Academy of Sciences.
Research funding sources included the National Science Foundation, the U.S. Environmental Protection Agency and the National Aeronautics and Space Administration High-End Computing Program.