Wind turbines are not inherently noisy. The evolution of wind farm technology over the past decade has rendered mechanical noise from the turbine motors almost undetectable. Some noise is produced by the blades sweeping through the air, but there are strict guidelines to ensure that noise emissions do not affect residential amenity in the vicinity of a wind farm. It is possible to stand underneath a turbine and hold a conversation without having to raise your voice. As wind speed rises, the noise of the wind itself usually masks the noise made by wind turbines. Measurements of wind turbine noise undertaken in the UK, Denmark, Germany and the USA show that the levels noise produced by modern, upwind configuration wind turbines are generally so low that they lie below the threshold of perception.
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, has a stud farm and riding school on site and the farmer, Peter Edwards, often rides around the wind farm on his horse.
There is no evidence to suggest this. The UK’s first commercial wind farm at Delabole received 350,000 visitors in its first ten years of operation. A MORI poll in Scotland showed that 80 per cent of tourists would be interested in visiting a wind farm. Furthermore, wind farm developers are often asked to provide a visitor centre, viewing platforms and rights of way to their sites. But, these tend to be at much larger sites than Wandylaw.
Wind turbines start operating at wind speeds of 4 to 5 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) wind turbines shut down automatically to protect their structural integrity.
When the wind stops blowing, there will be a commensurate increase in electricity injected into the National Grid from conventional sources of generation: coal, gas and nuclear. It will be possible for up to 10 per cent of the country's needs to be met by intermittent energy sources such as wind energy, without having to make any significant changes to the way the system operates. More can be accommodated, but extra storage capacity or spinning reserve would be necessary, which would have a cost implication.
The theoretical maximum energy which a wind turbine can extract from the wind impinging upon it is around 60 per cent. However the meaning of efficiency is different with wind energy, where the fuel is free. The primary concern is not the efficiency for its own sake, but to improve productivity in order to bring the price of wind energy down.
The comparison of energy used in manufacture with the energy produced by a power station is known as the 'energy balance'. It can be expressed in terms of energy 'pay back' time, i.e. as the time needed to generate the equivalent amount of energy used in manufacturing the wind turbine or power station. According to the British Wind Energy Association, the average wind farm in the UK will pay back the energy used in its manufacture within three to five months, this compares favourably with coal or nuclear power stations, which take about six months.
It is usually cheaper to save electricity than to generate it, by whatever method. The latest information on how much it costs to save electricity is available from the Energy Savings Trust. However, to combat climate change, the UK will need a mix of both renewable energy technologies and energy efficiency measures. You can help by turning off electrical appliances once they have finished their cycle – and the standby button on your television.
One 2.0 MW wind turbine at a reasonable site would produce over 6 million kWh of electricity each year, enough to meet the annual needs of over 1,100 households. |
