Falling costs and greater acceptance have made wind energy one of the fastest-growing renewable technologies in recent years. According to IRENA, wind energy accounted for 16% of all renewable energy generated in 2016 and this figure is likely to rise further in the future. The installed wind energy capacity has increased exponentially over the last 20 years and has grown about 75 times.
Just before the new millennium, the worldwide installed capacity was 9.94GW. Ten years later (2008) this figure rose to 115.36 GW and the most recent figures (2018) show an installed wind energy capacity of 564.35GW. This includes both on-shore and offshore wind. If the capacity is broken down to individual countries, China (187GW) and the USA (94GW) top the list. Germany (59GW) ranks first in Europe, with the UK showing the strongest growth with an increase of 2.39GW in 2019.
Advantages and disadvantages of wind energy
The advantages of wind energy are obvious: it is available in unlimited quantities, freely available and environmentally friendly. It can, therefore, make an important contribution to the fight against climate change if wind power replaces carbon-intensive energy sources. However, there are also critical voices, which are listed below and examined more closely.
Advantages of wind power
- The wind is at our disposal for an unlimited period of time.
- Wind power reduces the emission of carbon dioxide (CO2) caused by energy production.
- Thus, wind energy makes an important contribution to the fight against climate change.
- Wind energy has a key role to play in achieving UN climate protection goals.
- The use of wind energy does not pose any elementary dangers to humans or nature, such as nuclear energy or oil.
- Through wind energy, we can reconcile ecological and economic goals, because:
- Wind turbines have a positive energy balance: wind turbines generate considerably more energy than the production, logistics, construction and maintenance of wind turbines as a whole require.
- The wind energy sector is growing exponentially creating and securing thousands of jobs.
- Electricity from wind power is cheaper than electricity from conventional generation and the costs for dismantling and disposal are much lower than for conventional generation plants, such as nuclear power plants.
Disadvantages of wind energy
- Wind turbines only generate electricity if there is sufficient wind. If the isn’t enough wind speed, we have to switch to other energy sources at short notice.
- Keeping alternative sources ready to jump in when the wind is scarce, is costly, though.
- On warm and windy days, wind power production can lead to grid overloads due to overcapacities.
- Wind turbines impair the landscape.
- Wind turbines cast shadows, generate noise and even infrasonic waves. Some people, therefore, worry about their health.
- Wind turbines impact animals.
Considering those critical voices, let’s face some of the classic prejudices.
Do wind turbines affect human health?
To answer this question, we break it down into three parts: shadow casts, which are said to cause anxiety and even epileptic seizures, audible noise pollution, and finally infrasonic noise level, which is said to be harmful to health.
First of all, if the blades rotate in the sunshine, the wind turbines may cast flickering shadows. This means that shadow and light alternate due to the movement of the rotor. In order to keep the burden for the residents as low as possible, the authorities provide clear guidelines. In Germany, for example, a value of a maximum of 30 minutes per day and 30 hours per year is set by the approval authority. From a scientific point of view, however, these flickering shadows are not harmful to health, but merely a “nuisance”, as a study by the Epilepsy Society showed.
Secondly, wind turbines cause the propagation of sound which can be perceived as disturbing. In order for the plants to be approved, predefined sound immissions must therefore be observed. This means that the noises reaching residents must not exceed prescribed values. However, this can vary from country to country. Whether or not a wind turbine is audible to residents depends on much more than the wind turbine itself: Traffic noise, strong wind and normal ambient noise are usually dominant. However, this is a clear advantage of offshore wind turbines, where this question does not arise.
And finally, some critics claim that the inaudible sound waves are harmful to the human health. According to the current state of science, however, infrasound from wind turbines does not cause any harmful effects in humans and compared to means of transport such as cars or airplanes, the infrasound from wind turbines is low. If one considers the entire frequency range, the noise of a wind turbine at a distance of only a few hundred metres is usually hardly distinguishable from the natural noise of wind and vegetation.
Are wind turbines dangerous for wildlife?
A lot of concern is voiced about the potential threat to birds, bats and other animals. Objections to wind farms are therefore often raised by nature conservation organisations. The Scientific Service of the German Government has examined various studies and published a report on the ecological effects of wind turbines. The report comes to the conclusion that birds and bats can be affected depending on the location of a wind turbine. However, we must also put these findings in relations to other events. According to a cited American study, between 600,000 – 888,000 bats and 573,000 birds were killed by wind turbines in the USA in 2012. During the same period, however, 5.63 million birds were killed by electric shocks, 22.8 million birds by power line collisions, 199.6 million birds by car collisions, 599 million birds by collisions with buildings and 2.4 billion birds were eaten by cats.
There are similar allegations for offshore wind farms, namely a decline in seabirds as well as whales and fish species. But at least for birds, there are two sides to the coin. The same study that measured a decrease in gannets and guillemots, recorded a significant increase in herring gulls and silver gulls.
Whether and how dangerous wind farms are is therefore difficult to answer. It is clear that wind turbines do impact certain species. In the overall ratio, however, most studies conclude that the impact is relatively small. Nowadays, site analyses are part of the standard procedure before a wind turbine is granted permission. Among other things, it must be shown which species could be affected and what is being done to minimise the impact.