What is wind energy?
Wind energy is a form of renewable energy. It provided 29.5% of Ireland’s total electricity in 2021. It is by far Ireland’s largest contributor to renewable energy. For context, in 2021, the other renewable energy sources produced a 5.6% share of Ireland’s electricity.
So how does it work?
A wind turbine is a device that takes in kinetic energy from the wind and converts it into electricity. Kinetic energy is the energy that particles have due to their motion. A group of wind turbines together are called a wind farm. There most common type of wind turbine is called a “Horizontal- Axis Turbine”, named so because the blades spin around a horizontal axis. The main factors that influence how much electricity a wind turbine can produce are wind speed, blade radius, and air density. The stronger the wind, the more energy that is produced. The larger the “swept area” of the blades, the more energy that can be produced- doubling the radius can result in 4 times more power. The denser, or “heavier” the air, the more lift that is exerted on a rotor and hence the more energy that is produced- this is why farms at sea level are favoured over farms at altitude; the air is denser at sea level. Other factors that can influence wind farm production are the layout of the turbines and the grid connection of the farm. The turbines cannot be too close to one another as the turbulence caused by one turbine will affect the others around it- wind turbines are generally more effective when hit with laminar flow as opposed to turbulent flow, i.e., a smooth and orderly flow is generally better than chaotic motion of fluid particles when it comes to wind energy production.
The drawbacks to wind energy
The main drawback is the obvious one- when there is no wind, there is no wind energy. Although we live on a windy island, we do (occasionally) get periods of high-pressure weather systems when the weather is calm. Wind turbines have a range of wind speeds for which they are safe and efficient to operate in. If the weather is such that the wind speed is outside this range, the wind turbines must be switched off. This also means that when we get stormy weather with lots of gusts, a time when there is lots of wind energy to be harvested, we actually get none.
Other challenges to wind energy include the installation challenges associated with building wind farms in remote areas, sometimes even at sea. Upgrading national grid networks to reliably connect these isolate wind farms to urban areas is an ongoing project in many countries, something which could significantly reduce the cost of expanding wind energy capabilities. Turbine noise, and interference with wildlife are also drawbacks to wind energy, although it is worth noting that noise and interference with wildlife are not unique problems to wind energy production and wind energy does have a relatively low impact on wildlife. Public perception and the fear of the impact that wind turbines will have on the landscape are also challenges which wind energy faces.
Another (more physics- related) point to note is Betz’s Law which states that theoretically no turbine can extract more than of the kinetic energy of the wind, irrespective of turbine design. This limit puts a bound on the amount of energy which can be extracted from a site.
The way forward
Is there a way around the drawbacks to wind energy or is it doomed to be an intermittent power supply, ultimately incapable of meeting a nation’s energy needs?
The answer is that wind energy is part of the solution. The other part is energy storage. Within the last decade, novel ideas have sprung regarding the storage of excess wind power. The main idea is that the wind will generate electricity when it is windy, and then use a battery to discharge power when the wind stops blowing. The wind will charge the battery when the power grid does not need the electricity that it is generating. One such solution was built in Tullahennel, Co. Kerry, where each of the turbines was fitted with a lithium- ion battery roughly the size of a car.
Another, more daring, solution was designed in Germany. This solution involved the integration of wind and hydro- power. The design involved placing wind turbines, fitted with large water reservoirs around their bases, on a hill above a hydro-power plant. The water reservoirs were the “batteries”, analogous to the lithium batteries in Kerry. Water would be pumped uphill to the reservoirs when the energy demand was low and released back downhill to power to the hydro-plant when needed.
These collaborative ideas might be the future of renewable energy. Such ideas allow for renewable energy to overtake and eliminate fossil fuel power, hopefully leading to a less volatile energy market and a greener future.
Here are the sources I used for this blog:
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