Assessing the UK's 'wind rush' 

Wind power is the fastest growing renewable energy sector in Britain.

The government is investing massive amounts of money in its future; but experts interviewed on BBC Radio 4’s Costing the Earth programme claim the power of the wind to deliver electricity is being overestimated by companies keen to cash in on big subsidies.

In order to fight climate change, the UK has to meet targets set by the EU which wants 20% of our energy to come from renewable sources, such as the wind, by 2020.

The government has admitted it’s struggling, but is determined to meet its obligations.

Companies that hit green energy targets are rewarded under the government’s Renewable Obligation Certificate Scheme, or ROCS, receiving payments for each unit of renewable energy generated.

Variable nature

On paper, wind power is a great proposition. Britain is the windiest nation in Europe. But despite the government having subsidised the wind industry by half-a-billion pounds so far, as yet it has failed to deliver a half of one per cent of our electricity needs; yet it is costing £90 a year per household.

Engineering consultant Jim Oswald has analysed the figures on renewable energy submitted to the electricity watchdog, Ofgem.

He says that wind farms are not performing as well as expected. This is because wind speeds across the country are too variable and unreliable.

In Central England, average wind speeds are fairly low. Sometimes we have high winds and often no wind at all, and there is no way of storing wind energy.

“The volatility thing is a bit like driving your car and I say to you, ‘OK, here’s a green car, it uses absolutely no fossil fuel but you can only use it when it’s windy’, he says.

“‘And if it’s medium wind, you can drive it at a sensible speed, but if it’s very windy you’re going to be driving at 90mph through the town centre; or some days you’ll have no wind at all and no car’.”

Assessing loads

Michael Jefferson, chairman of the Policies Committee of the World Renewable Energy Network and former chief economist with Shell, believes the industry often exaggerates the amount of wind energy a development will supply and the carbon emissions it will avoid.

He worries there are many badly sited, poorly performing wind farms in England.

Sites should be assessed for suitability on the basis of wind speeds and load factor.

The load factor is the average amount of wind in a particular spot measured throughout the year.

The wind industry recommends an average wind load factor of 30% for a turbine to operate efficiently.

In windier parts of the UK, such as Scotland and Wales, that load factor can be as high as 45%; but as the number of available sites for potential wind farms in those areas decreases, he says there are more developments being built in areas where there is simply not enough wind to make them viable.

Many developments achieve under 20%; the lowest recorded by Ofgem in 2006 were 3.3% and 7.6%.

Grid connection

“If you take an area from Lincolnshire down through East Anglia into Essex, across to Hertfordshire and up the central spine of England, there are only five schemes achieving load factors of 30% or more,” says Mr Jefferson.

“That’s just five out of 25. We should be putting our money where the wind is and that is quite often not where the development pressure is.

“Even in a high average-wind-speed area, you really have to be absolutely precise as to where you site them. In Cumbria, for instance, you’ve got two – one which achieves a load factor of about 36%; the other a mere 2.3km away which achieves just 20-21%. You’ve got to have them properly sited.”

And wind speeds are not the only factor in deciding where to build turbines.

In some more remote parts of Britain, access to the National Grid is extremely limited. In the North of Scotland, there is a backlog of wind farms awaiting connection that will not be cleared for several years.

Dennis Gowland, of the Fairwind company in Orkney, says it is a bit like “investing and paying to run a shop only to be told you can only open at certain times”.

Power swings

The National Grid is being upgraded but not quickly enough to cope with large inputs of renewable energy. Jim Oswald worries that too much reliance on wind energy over the next decade could lead to major power failures in future if the system is not redesigned.

“It’s the power swings that worry us,” he says.

“Over a 20-hour period you can go from almost 100% wind output to 20%. When you have a very large number of wind farms on the grid and that happens, you are talking about massive power swings on the system.

“To cope with those power swings all the other generators have to either turn off or be turned on; and they’re not designed for that, they’re not capable of that.”

He worries that the government is not doing proper engineering analysis or planning for a reliable energy system beyond the next decade.

But Energy Minister Malcolm Wicks says that wind is an important part of the mix of Britain’s renewable energy going into the future. The government wants to encourage more offshore development of wind farms in combination with tidal and marine power.

Mr Wicks says planned changes to the Renewable Obligations scheme will make it more efficient.

Different picture

The British Wind Energy Association (BWEA) has challenged the claims made in the programme.

It says subsidies are not paid for the building of plants, only per unit of electricity to the National Grid.

Maria McCaffery, the chief executive of the BWEA, said: “Nobody in their right mind, not a developer and not the government, would support the building of a wind farm where the wind speeds are not high enough to generate a viable amount of electricity.

“It’s absolute nonsense.”

Ms McCaffery added that most farms would be generating some electricity for 85% of the time.

She conceded that not every wind farm could be located in areas of highest wind speed, but instead the industry had to identify areas where wind speeds were “good enough” to be economically viable.

The BWEA chief executive stated that the connection backlog to the National Grid was being tackled and in the meantime these plants were not receiving subsidy.

By Maggie Ayre
Costing the Earth, BBC Radio 4

BBC News

30 August 2007