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In order to convert the rated capacity of a turbine (given in MW) into power, as in usable kWh/year the following calculation needs to be made:
Rating of turbine (eg 2MW) x 24 (hrs in the day) x 365 (days in year) x 0.35 (the capacity factor*) x 1000 (to get into kWh, rather than MWh). This gives the kW/h produced per year per turbine. To find out how many households each turbine can service, divide this total by 4400 (the average kWh used per household per year).
(* 0.35, or 35 per cent is the average capacity of the turbine, as it does not produce at 100 per cent capacity all the time due to weather conditions etc.).
The theoretical maximum at which a wind turbine can extract energy from the wind is around 60 per cent.
People often confuse intermittency with efficiency. Wind farms are highly efficient at turning a free fuel source into electricity. However, the wind does not blow all the time, and that is why the average capacity is around 30-40 per cent.
Can wind farms produce significant amounts of electricity?
Collectively wind farms can make a huge difference. The DTI calculates that onshore wind could potentially make up 100 per cent of our current electricity demand, and that offshore supplies could generate 10 times this amount. More conservative estimates, taking land availability etc. into account, suggest a figure of 40 per cent of current electricity generation from on- and offshore wind sources.
How strong does the wind have to blow for the turbines to work?
Wind turbines start operating at wind speeds of four to five metres per second (around 10 miles an hour) and reach maximum power output at around 15 meters/second (around 33 miles per hour). At very high wind speeds, i.e. gale force winds, (25 metres/second, 50+ miles/hour) power controls kick-in to prevent damage to the turbine.
The UK's electricity system is mostly made up of large power stations, and the system has to be able to cope if one of these large plants goes out of action for any reason. It is therefore possible to have up to 10 per cent of the country's needs met by intermittent energy sources such as wind energy, without having to make any significant changes to the way the system operates.
No. Thanks to advances in wind turbine technology, well designed, and well sited turbines can be quiet enough to cause no disturbance to people living just a few hundred metres away. At these distances, any noise they do make is usually drowned out by the natural noise of the wind itself in the trees and vegetation. It is perfectly possible to stand beside a wind turbine and a have a conversation without raising your voice. To protect nearby residents from any undue disturbance, proposals to install wind turbines are required to meet strict noise standards.
People visiting wind farms are often surprised at how quiet they actually are. The Scottish Executive public opinion survey is one of several demonstrating that concerns about noise are often unfounded. A survey conducted before the construction of Scottish wind farms started found that 12 per cent of people living near the potential sites thought that the turbines would cause a noise nuisance. However, when people had experience of the wind farm operating, only one per cent stated this to be the case.
The main sound that can be heard if you are close to the turbines is the swishing of the blades through the air. By way of comparison, a wind farm 350 metres away produces 35-45 decibels. A car travelling at 40mph 100 metres away generates 55 decibels. Background noise in a rural setting at night time is 20-40 decibels.
A typical farm of 20 turbines extends over an area of one or two square kilometres, however only one to two percent of this land is actually occupied by the turbines and therefore can still be used for agriculture and animal grazing etc.
Wind farming is popular with farmers, because their land can continue to be used for growing crops or grazing livestock. Sheep, cows and horses are not disturbed by wind turbines.
The first wind farm built in the UK, Delabole in Cornwall, is home to a stud farm and riding school, and the farmer, Peter Edwards, often rides around the wind farm on his horse.
There is no evidence to suggest that wind farms deter tourists, indeed many wind farms are themselves tourist attractions.
For example, the UK's first commercial wind farm in Delabole, Cornwall received 350,000 visitors in its first eight years of operation. The Gaia energy centre was opened at the site in 2001 and received 50,000 visitors in its first year. In Swaffham, Norfolk, tourists queue to climb the wind turbine tower to the viewing platform at the top.
In Scotland, a Mori poll was undertaken in 2002 regarding wind farms in the Argyll area. Eighty per cent of tourists said they would be interested in visiting a wind farm if it were open to the public with a visitor centre.
Many opinion polls show that the majority of people are in favour of wind power. A 'before and after' study in Delabole, Cornwall showed that 80 per cent of people felt that it made no difference to their everyday life. Six months after construction, 84 per cent of people living nearby were found to either approve or strongly approve of wind power. A recent survey for Countryside Council for Wales showed that 74 to 83 per cent of people living near three Welsh wind farms found them to be acceptable developments.
The Scottish Executive public opinion survey is one of several demonstrating that concerns about noise are often unfounded. A survey conducted before the construction of Scottish wind farms started found that 12 per cent of people living near the potential sites thought that the turbines would cause a noise nuisance. However, when people had experience of the wind farm operating, only one per cent stated this to be the case.
Irrespective of how much we improve the way we use energy, it is always going to have to be generated and it is vital that we make more use of energy sources that are safe, clean, secure and renewable.
Both energy efficiency and wind power have important roles to play in a sustainable energy policy of the future and have massive potential to help solve serious local, national and international environmental problems.
They can occasionally affect TV and radio signals, however any problems identified during the planning process can easily be solved with suitable repeater equipment or TV aerial modifications.
Could wind turbines get damaged in a strong storm?
Wind turbines start operating at wind speeds of four to five metres per second (around 10 miles an hour) and reach maximum power output at around 15 meters/second (around 33 miles per hour). At very high wind speeds, i.e. gale force winds, (25 metres/second, 50+ miles/hour) power controls kick-in to prevent damage to the turbine.
Can I ask my electricity company to provide me with green electricity?
Since 1998 - when the energy market was opened up to competition - it's
been possible to switch your supplier to one supplying green energy. Now there's a new law that says all suppliers have to buy some green energy (currently three per cent).
There are two main types of green electricity tariffs:
Energy schemes which promise to buy renewable energy to match some of your electricity usage. Some of these schemes ensure that suppliers exceed their legally obliged levels of green supply
Fund schemes which put money aside to fund environmental projects.
I am a keen surfer, will offshore wind farms affect the wave quality on surfing beaches?
The structures that are built to support wind turbines are designed to encourage swell to roll over them avoiding waves crashing as this risks damaging the turbines. According to 'Surfers Against Sewage', the farms may actually benefit surfers by removing a fragment of onshore winds, reducing their potential to disturb the surf closer to the shore.
Information supplied by the DTI 'It's only natural' campaign
Notes to editors:
About 'It's only natural'
The UK Government has committed to renewable energy by signing up to international agreements such as the Kyoto Protocol, which means we are now legally bound to reduce greenhouse gas emissions to 12.5 per cent below 1990 levels by 2012. In addition, it has also set targets that by 2010, 10 per cent of the UK's electricity will come from renewable energy and that the percentage will increase to 20 per cent by 2020.
Currently just 3.86 per cent of the UK's electricity comes from renewables, so there is a lot of work to be done. This document is part of our campaign to provide you with more information about renewable energy sources such as wind, solar, biomass, wave and tidal power and why they are so important to the UK, to help us meet our international commitments and enable us to become a more sustainable nation.
For more information contact:
Aby Billi or Victoria Stainton, Porter Novelli
Tel: 01295 224533 or 01295 224397
Email: Firstname.lastname@cpn.co.uk
