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. In the UK, the pros and cons of onshore wind energy, in comparison with other low-carbon and fossil fuel energy sources, have recently been the subject of debate in the press and among politicians.

Onshore wind already plays a leading role in the generation of renewable electricity in the UK. In 2010, it generated around 7TWh – more than a quarter of the electricity provided by British renewables at that time and enough to save six million tonnes of CO2, according to government estimates. By 2020, onshore wind is expected to generate up to 30TWh. Onshore wind can therefore play a key role in reducing greenhouse gas emissions created by the UK’s power sector – which will be crucial to meeting the UK’s legally binding carbon budgets.

Onshore wind has the advantage of being one of the most affordable renewable energy sources. Generating electricity from onshore wind turbines typically costs around 7–9p per kWh, which is around half the cost of offshore wind and a quarter of the costs of solar photovoltaic panels. It is also slightly cheaper, on average, than nuclear power. Onshore wind generation is still slightly more expensive than fossil fuels (generating electricity from gas power plants currently costs between 4.1 and 7.5 p/kWh), but its price is expected to fall in the coming years.

Some emissions are created by the manufacture, transportation and installation of wind turbines, but these are considered fairly low. Additional emissions are attributed to the fact that wind energy (like solar and wave power) is intermittent, generating electricity 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”. The current small proportion of renewable electricity in the UK market requires 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 has been criticised for its visual impact. Although other power infrastructure, like fossil fuel and nuclear power stations, can also modify landscapes and habitats, onshore wind 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 also be affected by wind turbines – though bird fatalities due to turbine collisions are relatively low compared to other fatality causes, such as traffic and domestic cats. Impacts on wildlife can be minimised by careful site selection and by avoiding areas of high conservation or habitat value. A third potential issue is that turbines can contribute to noise pollution, but government studies find noise levels are comparatively low and should not significantly impact on nearby residents. New guidance is being drafted to inform future planning policy on noise issues.

Environmental Impact Assessments review these kinds of potential impacts on a case-by-case basis and seek to protect unsuitable areas, such as those of high conservation or heritage value. In some cases, undesirable local impacts may make more expensive renewable technologies, such as offshore wind or solar, more attractive. The extra cost of offshore wind can be seen as the premium society is willing to pay in order to avoid the local environmental cost of onshore turbines.

The choice between more affordable electricity (which would favour onshore wind) and local environmental protection (which may favour other low-carbon technologies) is ultimately a societal and political one. Given the economic and environmental trade-offs, technological uncertainty and the absence of one clear winner when it comes to energy sources, many economists suggest (pdf) the best approach is a portfolio of different technologies to balance the cost to consumers and environmental concerns. Onshore wind has a role to play in this energy mix and in helping the UK achieve its emission reduction targets.

• This article was written by Samuela Bassi and Naomi Hicks of the Grantham Research Institute on Climate Change and the Environment at LSE in collaboration with the Guardian

The ultimate climate change FAQ

• This answer last updated: 10.07.12
• Read about the project and suggest a question
• Report an error in this answer

Related questions
• What is the economic cost of climate change?
• What is the Stern review?
• Which nations are most responsible for climate change?

This editorial is free to reproduce under Creative Commons

This post by The Guardian is licensed under a Creative Commons Attribution-No Derivative Works 2.0 UK: England & Wales License.
Based on a work at guardian.co.uk