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Increasing wind power in America would also increase the country's temperatures, according to a new study at Harvard.
Although wind energy is widely recognized as environmentally friendly, the researchers concluded that a dramatic expansion in the number of wind turbines could warm the country even more than climate change due to burning coal and other fossil fuels, because of the way the blades turn. disrupt the layers of hot and cold air in the atmosphere.
Some parts of the central United States are already seeing warmer nights because of the nearby wind farms, according to the study's lead author, Lee Miller, an environmental scientist at Harvard.
"Any big energy system has an environmental impact," said David Keith, professor of engineering and physics at Harvard, co-author of the study. "There is no free meal, you have a pretty strong wind … it's going to change things."
Researchers and other scientists have pointed out that turbine-induced wind-up, which is temporary and stops when the blades are not rotating, is clearly more threatening in the long term globally and in the long run by greenhouse gas.
Despite potential drawbacks, wind energy still makes more sense for the environment than fossil fuels, Keith said.
It's just that proponents of wind energy have ignored growing evidence of a drawback, he said.
Overall, the Harvard study, published Thursday in the Joule newspaper, revealed that, in the unlikely event that the United States would rock massively toward the wind to provide almost all of its electricity, there would be so many wind turbines that the national temperature would rise 0.4 degrees (0.2 Celsius). Some central areas will experience localized warming of about 2.5 degrees (1.4 degrees Celsius), although there is also some cooling in places such as the east coast.
At present, wind power supplies 6.3% of the country's electricity, according to the American Wind Energy Association.
The study, which only looked at the United States, revealed that turbines would cause more warming in the short term in this century than would the carbon dioxide that America released into the atmosphere.
The reason for this effect: normally, the air is quieter at night, the cold air stays close to the surface and the warmer air rests a little higher. But the turbines reduce hot air and cold air, making the soil a bit harder. The effect is seen less during the day but is still there.
Nevertheless, the effect of turbines is different from the climate change caused by humans. It's mainly about warming, it's local and temporary. When the turbines are stationary because the air is calm, there is no warming.
Climate change, on the other hand, is a global effect that involves many more elements than temperature, such as sea level rise, extreme weather conditions, melting glaciers, and shifts in temperature. jet stream. Even if a country ceases to emit greenhouse gases, it would suffer climate change if the rest of the world continues to pollute.
Previous studies have observed a temporary nighttime warming of up to 2 degrees (1.1 Celsius) in locations with many wind turbines, such as North Texas. The Harvard study took observations and used a computer simulation to project what a dramatic increase in the number of wind turbines would look like.
Other technologies considered environmentally friendly also have their drawbacks. Nuclear energy does not emit carbon dioxide, but waste, safety and costs are of concern. The ethanol boom has wiped out habitats, pushed farmers to weed in the Prairies, polluted water and pushed up food prices.
Wind's advocates pointed out that the Harvard study did not show that turbines were causing global warming, but only local heating.
"If the document looked more closely at long-term and sustainable deadlines that matter, renewable resources would have hundreds of times, if not infinite, better performance than fossil resources," said Michael Goggin, vice president of Grid Strategies and former researcher. of a wind energy group, said in a statement.
Ken Caldeira, a climatologist from the Carnegie Institution for Science who was not part of the research, said the study was valid.
"The impact of burning fossil fuels on the climate is cumulative," Caldeira said in an email. "The more you operate a coal-fired power plant, the more climate change gets worse. On the other hand, the climatic effect of wind turbines is what it is. You build the wind turbine. The climate is affected. But as long as you use the wind turbine, climate change does not get worse. So, in the long run, when it comes to the climate, wind turbines are obviously better than fossil fuels. "
SETH BORENSTEIN
AP Scientific Writer
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