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Visit the Centre for Alternative Technology

The Centre for Alternative Technology, Machynlleth, Powys.

At the Centre for Alternative Technology (CAT), you will see, among their many displays of energy saving devices and environmentally friendly technologies, a large wind turbine blade. It stands as an emblem of CAT’s unequivocal support for large-scale wind farms. In their information leaflet, Electricity from Renewable Sources, you are encouraged to invest in large turbines ‘… with a view to selling electricity to the grid and getting a good return from your money.’

But, according to CAT, there are many other benefits, besides financial, of wind farms. Let’s examine some of the statements that appear on the CAT website:

·    CO2 saved [by wind turbines] 750g/kWh’

    This claim is highly exaggerated. The official government figures, used by the Carbon Trust and the DTI, for calculating CO2 emissions savings is 0.43 tonnes per MWh, or 430g per kWh – just over half the CO2 savings claimed on the CAT website. The CAT website does not, of course, mention the fact that wind farms require spinning reserve backup, which produces CO2 even when not producing electricity.

·         ‘There is a small impact on wildlife while the machines are being put up, but after that there is no significant impact.

Wind farm construction involves extensive quarrying, building access roads, concrete foundations and crane pads, substations and grid connections; it often means clear felling and peat bog destruction. To say this has a ‘small impact’ is underestimating the devastating, and often permanent, impact these industrial works have on wildlife and their habitats.

Wind farm construction can disrupt the hydrology of the area and contaminate water supplies. If a wind farm is built on peat lands, and they often are, the disturbed peat will no longer act as a carbon store but will instead release CO2 and methane, an even more dangerous green-house gas. 

The negative impact of operational wind farms on wildlife, especially birds and bats, is well documented. (See this website’s page on bird watching.)

·         ‘… the wind is often louder than the turbines. The maximum sound from a large wind turbine at 350 m is 45 decibels, which is less than the noise at a normal meal table.’

Many people living near a wind farm would not agree with that statement. There is well-documented evidence that for some people the low-frequency vibrations, which are not measured by wind farm developers, are very disturbing and cause a recognised health problem known as "wind turbine syndrome" or vibro-acoustic disease (VAD). See our page on noise.

Mr and Mrs Davis live in the noisy shadow of a wind farm in Lincolnshire. Click here to download a national newspaper article (MS Word file) that describes their experiences of wind turbine noise.

  Yes, you see them. And visual intrusion is the reason most often cited for refusal to grant planning permission for a wind farm. The modern wind turbine is a gigantic, moving structure, often more than 400 feet high, built on high-altitude, prominent sites to catch the wind, marring some of the most scenic mountainous regions of Wales. These magnificent landscapes are further degraded by the miles of pylons and transmission lines needed to transport the electricity to the grid system.

The rotating blades of a wind turbine can create a disturbing flicker effect, depending on the position of the sun. In some cases turbines may require flashing red lights as warning for aircraft.

·         ‘Wind farms are now generating energy less than 3 p per unit, which is fairly cheap.’

The Royal Academy of Engineering, in their 2004 report ‘The Cost of Generating Electricity’, calculated the cost of onshore wind power with standby generating capacity at 5.4 pence per kWh and off-shore wind power with standby generating capacity at 7.2 pence per kWh. According to these figures, wind-generated electricity, far from being ‘fairly cheap’, is more expensive per unit than almost any other form of electricity generation.

·         ‘Wind farms create jobs in rural areas.’

The average wind farm employs one maintenance person.

The Centre for Alternative Technology’s community wind turbine at .Cilgwyn, Pantperthog, in the Dyfi Valley, mid Wales.

The CAT information sheet, ‘Community Wind Turbine’, claims a capacity factor of 30% for its turbine, explaining that ‘the average output is 30% of the maximum capacity’. The information sheet also says that the ‘projected annual output is 163 megawatt hours’ and that ‘this amount of electricity would release 70 tonnes of climate-changing carbon dioxide into the atmosphere if generated from fossil fuels.’

Sounds impressive, but let’s look more closely at these claims.

Recent research by the Renewable Energy Foundation (REF), based on Ofgem figures, paints quite a different picture. According to REF’s calculations the annual capacity factor the CAT turbine was 11.0% for 2004, 10.6% for 2005 and 6.5% for 2006.

  REF’s analysis also showed that the Renewable Obligation Certificates (ROCs) that were issued to CAT for 2004, 2005, and 2006 were based on the turbine’s actual output of 85, 82, and 50 megawatt hours respectively, which is far lower than the projected annual output of 163 megawatt hours.

So the replacement of ‘70 tonnes of climate-changing carbon dioxide’ is an unrealistic claim given the actual output of the CAT turbine. Furthermore, it appears from their website that CAT does not use the official government figure when calculating carbon saving, but a much higher figure.

The CAT wind turbine is located on Forestry Commission land, who charge a non-commercial rent. To find out more about the development of the CAT community wind turbine and the funding it received, see

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