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FAQ

Wind energy and environmental impact

Doesn’t the dirty back up power required when the wind stops blowing mean that the CO2 saving is wiped out?

This rather bizarre claim is increasingly common among anti-wind campaigners. Their argument runs like this:

Because wind power is intermittent (it varies with the weather) it needs dedicated back-up for when the wind doesn’t blow. This back up will be coal powered stations that have to be kept ‘spinning’ (ie burning) at low level so they are ready to go immediately that the wind drops. Burning like this is inefficient so the emissions they make are roughly the same as if they were actually generating electricity. Therefore wind power saves no carbon because the back-up emits the same as if there were no wind turbines in the first place.

This argument is quite simply wrong. The national grid has back-up on it regardless of wind power. Back-up is needed for all forms of energy generation because of unexpected increases in demand (a cold snap for example, or when England play soccer on television). In fact one of the biggest back-up requirements on the system today is due to Sizewell B nuclear power station - because when it fails (as it does - and has done recently for safety concerns) it knocks out a huge amount of capacity in an instant - unlike wind where any variation is both gentle and very predictable. Only when there is a very large capacity of wind on the system (above 10%) does the variation of the wind even become noticeable over the ‘normal’ variation on the system. Only then is any of the back-up specifically due to wind power. And only at this point could any carbon emissions from back-up plant be counted against wind power.

It is widely accepted that only very minor levels of back-up are needed for wind up to about 20% wind on the system (much higher levels of wind power are possible, but require a little more back-up). Under current government policies this level of wind power is not likely until after 2020. In terms of emissions - even if the back-up was the dirtiest option - coal power - at 10% wind power on the system only 1% of the CO2 saved by the wind would be emitted from the back-up - and 99% is saved. Coal is not the only option for back-up. Gas is about half as dirty and both hydro power and biomass are renewable forms of energy that can play the same role. In the future a wide range of renewable energy technologies would compliment one another and offer the chance for completely secure and completely clean energy system - including both primary generation and back-up.

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