WIND PROJECTS AFFECT LOCAL WEATHER

Can Wind Farms Change the Weather?
Steve Tracton, July 15, 2009 (Washington Post)

"Large-scale wind farms…are likely to play an increasingly important role in providing a climate-friendly source of [emissions-free and pollution-free] energy…The efficiency, effectiveness and economic value of wind power clearly depends critically on the weather, along with factors such as terrain, vegetation and building structures, which affect the speed, direction and variability of the wind striking the blades of wind turbines. But can wind farms, in turn, affect the weather? …

"The question might seem far-fetched at first. But…Researchers are investigating the potential for large wind farms in one region to alter weather patterns in another region downwind. Specifically, the turning of the wind mill propellers creates considerable turbulence, which mixes air up and down. The resulting bumpiness of the air could significantly influence winds at low levels of the atmosphere…"

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"…[Researchers] used a global general circulation model of the atmosphere (similar to the models used to predict climate change) to calculate the effects of blanketing the Midwest with a grid of interconnected wind farms with thousands of wind turbines. On average, the study found that wind speeds were lowered by 5.5-6.7 miles per hour immediately downwind. More significantly, the wind turbines caused large-scale disruptions of air currents, which rippled out like waves that appeared to trigger substantial changes in the development and track of storms over the North Atlantic.

"The areal coverage and density of wind turbines in the study are admittedly unrealistic. Currently, the largest wind farm in the nation -- and world -- is the Horse Hollow Wind Energy Center in Taylor County, Texas, with 421 wind turbines in operation. However, ultra-large wind farms with thousands of turbines in especially wind-prone parts of Texas and the Midwest are considered within the realm of possibility…The magnitude and degree of the impact of such wind farms would presumably be less than in the model simulation. But still the consequences, while unintended, could be significant…"

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"What remains unclear is how the impact of wind farms might compare to, for example, the effects of high-rise complexes or, for that matter, the influence of building a whole new city dominated by skyscrapers, such as that occurring at several locations across China…Wind farms may also result in important changes in local climatology, potentially impacting, for example, agricultural interests…The turbulence induced by the propellers of wind turbines… can spread for miles around. This is especially true at night…

"Based on computer modeling…wind mill-generated turbulence raised pre-dawn surface temperatures by about four degrees and resulted in drier soil conditions…This is not dissimilar to the more familiar experience of a windy night keeping temperatures from falling as low as might otherwise be expected and also drying out pavement made wet by an evening shower."