Manufacture and installation account for about 98% of emissions during a wind turbine’s 20 to 25-year working lifetime. Routine maintenance accounts for the other 2%.
The carbon footprint of a large wind turbine – how much greenhouse gas it emits during its working lifetime – is about 10 grams of carbon dioxide-equivalent for each kilowatt-hour of electricity it generates (gCO2e/kWh), according to government statistics.
Normal operation of a wind turbine while generating electricity does not produce greenhouse gases. But their manufacture involves processes that do, and installing wind turbines requires machinery that typically runs on fossil fuels that produce greenhouse gases when burned. Routine maintenance requires transport that again typically runs on fossil fuels.
Offshore wind turbines have a higher carbon footprint than those onshore because they are harder to reach, and so give rise to higher emissions from transport.
The carbon footprint of a large wind turbine is among the smallest of all energy sources used in the UK. The Government is committed to increasing the proportion of our energy generated from renewable sources to 15% by 2020. Most of this new renewable energy is expected to come from wind farms.
While wind farms are generating electricity, how much electricity other power stations need to generate to meet demand is reduced, and fossil fuel power stations will usually reduce their output.
While fossil fuels maintain a significant presence in the UK energy mix, each kWh of electricity produced by a wind farm will effectively displace a kWh of electricity that would otherwise have been produced by burning fossil fuels.
As of June 2015, the Renewable UK shows that wind capacity in the UK is over 13GW. Installed onshore wind in the UK is greater than 5,000 wind turbines with a combined capacity of 8,2 million kilowatts (kW).
With offshore wind, the UK has more than 1,400 wind turbines with a combined capacity of 5 million kilowatts (kW).
This wind capacity is enough to supply more than 7.7 million homes and it is estimated to reduce UK carbon dioxide emissions by over 13.9 million tonnes each year by displacing electricity from fossil fuel power stations.