How Wind Farms Affect the Global Climate
Wind energy has been a fast growing sector of the overall energy market. It is renewable energy that can be produced on an industrial scale that can rival the older established energy sources of coal, gas, oil, hydro, and nuclear. Now, it accounts for only two percent of the whole energy market, but government officials expect wind to produce one fifth of the total electricity supply in the United States by 2030. Proponents claim wind power can reduce the threat of global warming. However, a recent study from the Massachusetts Institute of Technology (MIT) has found that the opposite is true. Mass produced wind farms can actually affect climate in a negative way.
The analysis was conducted by Ron Prinn, TEPCO Professor of Atmosphere, and Chien Wang, principal research scientist at the Department of Earth, Atmospheric, and Planetary Sciences. Using a climate model, they analyzed the effects of the massive deployment of wind turbines needed to meet the ambitious national goals. The millions of turbines over large areas of land and sea would in themselves affect the climate.
Over land, the temperatures around wind farms would rise by one degree Celsius due their associated friction it produces with the air, similar to trees and hills. The wind farms reduce wind speed on the downwind side of the turbines. This in turn reduces the strength of the vertical turbulent motion, which is heat being transferred from the land surface into the lower atmosphere. It also decreases the flow of air from high pressure areas to low pressure areas, affecting places far from the wind turbines themselves. It is similar to temperatures at a windy beach; when the wind dies, the beach gets much warmer.
On the other hand, over water, wind turbines can lower the temperature by more than one degree Celsius. However, according to Prinn and Wang, these results were unreliable because they used artificial waves to produce surface friction in their models. They admit that better ways of simulating marine-based wind farms must be developed to produce more reliable conclusions.
The new wind patterns from massive scale wind farms might also affect precipitation, especially in the mid-latitudes of the northern hemisphere. The study found that changes could exceed ten percent in certain areas, but total changes would not be very large.
Ron Prinn, one of the authors of this study, published on February 22, 2010 in the online journal, Atmospheric Chemistry and Physics, also stated that the paper should not be regarded as an argument against the development of wind energy. He urged that it served as a guide for researching the downsides of large scale wind development, which is important before serious investments are made. Prinn states, "we haven't absolutely proven this effect, and we'd rather see that people do further research."
Link to published study: http://www.atmos-chem-phys.net/10/2053/2010/acp-10-2053-2010.html