Blowing hot

A new MIT analysis used a climate model to analyze the effects of millions of wind turbines that would need to be installed across vast stretches of land and ocean to generate wind power on a global scale. Such a massive deployment could cause temperature to rise by one degree Celsius on land (though offshore ones could cause a drop in ocean temperatures).

In a paper published online Feb. 22 in Atmospheric Chemistry and Physics, the scientists suggest that using wind turbines to meet 10 percent of global energy demand in 2100 could cause the temperatures to rise.

Previous studies have predicted that annual world energy demand will increase from 14terawatts (trillion watts) in 2002 to 44 terawatts by 2100. In the recent analysis, the focus was on the impact of using wind turbines to generate five terawatts of electric power.

For the land analysis, they simulated the effects of wind farms by using data about how objects similar to turbines, such as undulating hills and clumps of trees, affect surface “roughness,” or friction that can disturb wind flow. This temperature increase occurs because the wind turbines affect two crucial processes: vertical turbulent motion and horizontal heat transport. Turbulent motion refers to the process by which heat and moisture are transferred from the land or ocean surface to the lower atmosphere. Horizontal heat transport is the process by which steady large-scale winds transport excessive heat away from warm regions, generally in a horizontal direction, and redistribute it to cooler regions. This process is critical for large-scale heat redistribution, whereas the effects of turbulent motion are generally more localized.

The wind turbines on land reduced wind speed, particularly on the downwind side of the wind farms, which reduced the strength of the turbulent motion and horizontal heat transport processes that move heat away from the Earth’s surface. This resulted in less heat being transported to the upper parts of the atmosphere, as well as to other regions farther away from the wind farms.

Obviously the solution is not to overdo it! A bit of wind, a dash of biofuel and a generous sprinkle of solar might be the right recipe. What do you think?