Wind Power: Reaching the Physical Limit?

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Wind turbine may be the cause of bird mortality. Photo by Southgeist on Flickr

Wind turbines may be the cause of bird mortality. Photo by Southgeist

Wind Slowing Effect Model

The study examined several turbine arrays of different sizes (between 2,700 and 2,700,000 km2), and considered different turbine densities (between 0.5 and 16 turbines per square kilometer). This model corresponds to power density values between 0.5 and 16 W/m2. Researchers evaluated maximum possible energy generated in each case and compared them to the values already available in the scientific literature, calculated using different models.

Reaching a Saturation Point

These calculations showed that the decrease in wind speed is more pronounced for arrays with higher turbine densities compared to those with lower densities. The researchers both predicted and expected this data, but the impact that this slowing effect can have on energy generation was unexpected. The simulations showed that, independent of the array size and turbine density, the maximum value of energy generated was about 1 W/m2.

Professor David Keith, leading researcher on the project, explained to Decoded Science:

“It seems that we reach a saturation value we cannot go beyond. Arrays with smaller turbine density have smaller effect on the wind but, having less turbines, generate relatively less energy. Arrays with higher density could, in theory, generate more energy. However, due to the enhanced slowing effect, the resulting energy is not higher.”

Wind Turbine: Unexpected Results

Previous modeling studies predicted that, over large areas, the energy generated is between 2 and 4 W/m2. However, these investigations did not properly take into account the slowing effect. “These data show that the problem is more complex than we thought,” said Professor Keith. “This does not mean we should abandon wind power, but we should definitively consider realistically how much energy we can get out of that.

Increasing Wind Power

A different approach in the planning and construction of turbine arrays can increase the wind power they generate. The development of new policies may also be needed to ensure this alternative energy source is worthwhile.

Sources

European Wind Energy Association. Wind in Power: 2012 European Statistics. (2013). Accessed February28, 2013.

Adams, A.S. and Keith, D.W. Are global wind power resource estimates overstated? (Text). Video Abstract(2013). Environmental Research Letters, doi:10.1088/1748-9326/8/1/015021. Accessed February 28, 2013.

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