What is onshore wind energy and what contribution does it make?

Wind turbines harness the energy of moving air to generate electricity. Onshore wind refers to turbines located on land, while offshore turbines are located out at sea or in freshwater. Onshore wind plays a leading role in the generation of renewable electricity in the UK. In the third quarter of 2017 it generated 5.6 terawatt-hours (TWh) of electricity, an increase of 20 per cent on the previous year. This accounted for a quarter of the electricity generated by renewable sources in in that period, and 7.5 per cent of all electricity generation. In comparison, offshore wind produced 4 TWh over the same period. Together, onshore and offshore wind contributed nearly 13 per cent of total global renewable energy generation.

What are the main advantages of onshore wind energy?

Wind energy has a relatively small carbon footprint. Some greenhouse gas emissions are created by the manufacture, transportation and installation of wind turbines, but these are considered fairly low, at around 9 gCO2/KWh. By comparison, the average footprint of gas power generators is around 450 gCO2/KWh and that of coal power generators around 1,050 gCO2/KWh. Researchers from the University of Edinburgh found that wind power in the UK prevented the creation of almost 36 million tonnes of emissions from sources such as coal and gas between 2008 and 2014, the equivalent of taking 2.3 million cars off the road.

New onshore wind was identified in 2015 by Bloomberg New Energy Finance as being fully cost-competitive with gas and coal in some parts of the world and the cheapest source of power generation in the UK for the first time. This competitiveness was ‘helped by cheaper technology but also by lower finance costs’, while coal and gas became more expensive.

What are the main disadvantages of onshore wind energy?

Onshore wind is an intermittent source of energy, as turbines cannot generate electricity on demand, but only when the wind is blowing, and at sufficient strength. When wind strength is insufficient for turbines to operate, fossil-fuel-based power supply is needed as backup, which can temporarily increase greenhouse gas emissions. The proportion of intermittent renewable electricity in the UK market is currently small enough to require very little backup, but as the share increases additional backup will be needed. However, other technologies, such as inter-linkages with other countries’ grids, energy storage and electricity demand management, are expected to help tackle intermittency in the future, so the overall future impact on emissions is considered relatively low.

Onshore wind turbines have been criticised for their visual impact. Turbines are typically more spread out than other large-scale energy infrastructure projects and so can affect a larger area.

Another criticism is that species such as birds and bats may be affected by turbines. However, bird fatalities due to turbine collisions are relatively low compared with those from traffic or domestic cats and the benefits for wildlife of mitigating climate change are considered by conservation charities such as the RSPB to outweigh the risks, provided that the right planning safeguards are put in place, including careful site selection.

Turbines can contribute to noise pollution, but UK government studies have found noise levels to be comparatively low and state they should not significantly impact on nearby residents.

In the UK Environmental Impact Assessments review these kinds of potential impacts on a case-by-case basis and seek to protect unsuitable areas. In some cases, the extra cost of offshore wind can be seen as a premium society is willing to pay in order to avoid the local environmental cost of onshore turbines.


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