Twenty things you always wanted to know about wind farms, but were afraid to ask

1. What are wind turbines made of?
Wind turbines usually consist of a tower; a unit called a ‘nacelle’ containing the gearbox, generator and control systems, which is mounted on top of the tower; and three blades which rotate around a horizontal hub protruding from the nacelle.
The towers are mostly tubular and made of steel. The three blades are made of glass-fibre reinforced polyester or wood-epoxy. They are usually painted light grey, because this is the colour which is most inconspicuous under most lighting conditions. The finish is matt, to reduce reflected light.

2. How do they work?
A wind turbine works in exactly the opposite way to a fan. Instead of using electricity to make wind, like a fan, turbines use the wind to make electricity.
Most wind turbines have three blades which face into the wind; the wind turns the blades round, this spins the shaft, which connects to a generator and this is where the electricity is made.

3. Why don’t wind turbines have more blades?
Turbines for generating electricity need to operate at high speeds, but do not need much torque or turning force. They therefore generally have three or two blades. Wind pumps, on the other hand, operate with plenty of torque, but not much speed and therefore have many blades.

4. How strong does the wind have to be for the turbines to work?
Wind turbines start operating at wind speeds of 4 to 5 metres per second (that’s around 10 miles an hour) and reach maximum power output at around 15 metres per second (around 33 miles an hour). At very high wind speeds, ie gale force (over 50 miles an hour), wind turbines shut down.

To be commercially viable wind farms need to operate at an annual average wind speed of over 6.5 metres per second. This speed is commonly achieved or exceeded in the South Pennines area.

5. So what happens when the wind isn’t blowing?
Turbines on average turn, and therefore produce electricity, for about 80 – 85% of the time, depending on location. For the remainder of the time, it is necessary to support electricity demand by other forms of generation.

6. How much does it cost to make electricity from the wind?
Wind energy is one of the cheapest of the renewable technologies. It is competitive with new clean coal fired power stations and cheaper than nuclear power. The cost of wind energy varies according to many factors. An average for a new wind farm in a good location is 2.88 pence per unit, which compares favourably with the current market price of 2.4 pence.

7. Where does the electricity from the wind farm go?
The electricity is fed into a sub-station and transformed for distribution into the National Grid or the local distribution network. Once in the system, the electricity will actually be used in the homes, factories and offices nearest to the wind farm, regardless of which electricity supply company a customer buys from.

8. Does this mean you’ll have to build new power lines?
Yes. Sometimes these are on overhead poles and sometimes they are underground, depending on local planning requirements. All new power lines at Scout Moor will be installed underground.

9. Why don’t people living near wind farms get cheaper electricity?
The electricity goes into the local distribution grid and is bought by the electricity supply companies in the same way as electricity generated by other sources. Currently electricity from wind farms costs slightly more to produce, but this is outweighed by the environmental benefits.

10. Why don’t turbines look like the old-fashioned wind mills?
Wind mills are picturesque, but not very efficient at generating electricity. Modern turbines could conceivably be designed to look like wind mills, but this would increase the cost of the electricity. Besides, a lot of people like the sleek, modern look.

11. Why can’t we put all turbines out at sea?
Work is under way around the UK coast on a number of offshore wind farms. These are more difficult and expensive to construct than wind farms on land. Nevertheless, further development of offshore wind energy is very likely. In the meantime however, if the Government is to meet its targets for renewable energy, a combination of off-shore and on-shore wind farms is the best route.

12. How noisy are wind turbines?
Virtually everything with moving parts will make some sound and wind turbines are no exception. Well designed wind turbines are generally quiet in operation and compared to every day noises, like traffic and aircraft, the noise from wind turbines is very low.
From half a mile away, the usual distance from houses, the sound of a wind turbine is likely to be about the same level as the noise of leaves rustling in a gentle breeze. This is similar to the sound level inside a typical living room with a gas fire switched on, or an unoccupied, quiet, air-conditioned office. Even when wind speed increases, it is difficult to detect any increase in turbine sound above the increase in normal background sound, such as the noise the wind itself makes.

You will find that it is perfectly possible to stand underneath a turbine and have a normal conversation, without raising your voice.

13. Are wind turbines safe?
Wind energy is one of the safest energy technologies. No member of the public has ever been injured by wind energy or wind turbines anywhere in the world, despite the fact that there are now more than 55,000 operational turbines world-wide.

14. Will the turbines be fenced off? Can you walk right up to them?
You can stand under a wind turbine as the blades turn – there is no restriction on public access.

15. Do they frighten animals?
Livestock including horses, graze quite happily around wind turbines. However, some horses may be startled by turbines the first time they see them. The British Horse Society provides guidelines to wind farm developers on the appropriate distances turbines should be sited from equestrian routes to minimise any possible risk.

16. Do birds fly into them?
Danger to birds is not generally considered to be a major issue by the RSPB, who generally support the production of wind energy as part of tackling climate change. Sadly, there may of course be isolated incidents, just as there are with birds flying into power lines.

17. Will I still be able to use the footpaths and bridleways in the area?
Yes. In fact access across the moor will be improved by the creation of new access routes for the development.

18. How long do wind turbines last?
A wind turbine typically lasts around 20-25 years. During this time some parts may need replacing.

19. Do they ever break down?
Yes, occasionally they do. A maintenance team will be available round the clock to respond to any mechanical failure.

20. What happens when a wind farm is decommissioned?
The way that a planning authority wishes to have a wind farm decommissioned should be covered by clauses in its planning permission. These clauses typically require all visible traces of the wind farm to be removed. The concrete bases could be removed, but it may be better to leave them under the ground, as this causes less disturbance. If so, they would be covered with peat, stone or other local material and the site returned as closely as practicable to its original state.