Wind turbines use kinetic energy from the wind to generate electricity. This involves interrupting the flow of the wind as it passes over the turbine blades.
This article will explain the impact that this can have on the wind patterns surrounding wind farms and the potential implications that it may have for the environment.
Before we begin, it may be helpful to establish a basic understanding of how wind turbines work in order to explain how they can affect wind patterns:
- On a windy day, air flows over the propellers, or blades, of a wind turbine.
- This creates lift, similar to what happens on an airplane’s wings, causing the turbine blades to spin.
- The blades are attached to a rotor which causes a generator to turn.
- The movement of the generator is what generates the electricity.
How do wind turbines affect wind patterns?
We know that wind turbines capture kinetic energy by harnessing the power of the wind.
We also understand that this energy gets converted into electricity by means of a generator.
This implies that there is less energy in the air exiting the blades of a wind turbine than in the air going in.
Essentially, this means that wind speeds are often much slower in the area behind a wind farm. This is because the turbines create a type of vacuum, or what is referred to as a “momentum deficit.”
While this wake effect is not necessarily detrimental to the environment (more about this in the section below), it can influence the amount of energy that wind farms can produce, especially when there are multiple wind farms in a given vicinity.
In fact, a study of several offshore wind farms in Germany found that the energy production of the wind farms was significantly reduced due to their relative proximity to one another.
In other words, the wind farms were close enough to be affected by each other’s wakes.
Thus, the turbines that were positioned higher up weakened the wind before it could reach the ones that were lower down.
Another way in which wind turbines can alter the wind patterns of an area is by mixing the air from above with the air at ground level.
In combination with the momentum deficit caused by the wake of the wind turbines, this redistribution of air can lead to an increase in turbulence.
It can also lead to small changes in the temperature of the region surrounding the wind farm.
What do the changes in wind patterns caused by wind turbines mean for the environment?
If the construction of wind farms were to take place on a much larger scale, it is possible that their cumulative momentum deficit could alter the wind speeds of the entire earth.
However, because wind power is unlikely to become the only form of renewable energy in the foreseeable future, the likelihood of this happening is relatively small.
In addition, changes in wind patterns would come about as a result of the wind turbines and depend on many other factors.
Another way in which the changes in wind patterns caused by wind turbines can affect the environment is by altering the local climate.
A US study found that wind farms can cause subtle rises in temperature around them, especially at night. However, this is due to the turbines mixing the warmer air from higher altitudes with cooler air near the earth’s surface. It is not, therefore, as a result of the type of climate change caused by carbon emissions.
Thus, wind turbines do not contribute to climate change in the same way as fossil fuels. Instead, they simply redistribute the heat that already exists in the atmosphere, causing a temperature change in the immediate area.
According to Scientific American, this warming effect also has some positive implications for agriculture.
Since the space underneath wind turbines is often used for crops, the warmer nighttime temperatures can help to protect the plants from frost.
Conclusion
So, although wind turbines can alter wind speeds and cause the nighttime temperatures near wind farms to rise, these changes are a relatively small price to pay for globally reduced carbon emissions.
In addition, unlike the effects of fossil fuels, which will take centuries – if not millennia – to undo, wind turbines’ impact on the environment can be immediately reversed simply by shutting them down.
