Wind industry and Decc urged to come clean on output of wind farms

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A lack of technical and economic data on wind farms is making it difficult to judge the claims of industry and government

With a new analysis showing UK wind farms operating at just 20 per cent of their capacity in 2010, the potential of wind power has been called into question. Eifion Rees examines the arguments from both sides

The efficacy of wind power has been called into question by a new report suggesting wind turbines are not living up to their billing by government and industry. Opponents are now urging both to make public data they hold on wind power.

Proponents of wind reacted angrily to the publication of analysis of UK wind power generation researched by Stuart Young Consulting, accusing the wilderness charity that supported the report, the John Muir Trust (JMT), of acting 'irresponsibly'.

Using data taken from the Balancing Mechanism Reporting Service (BMRS) website and originating from the National Grid, the report finds that between November 2008 and December 2010 turbines operated below 20 per cent of their capacity more than half the time, and below 10 per cent for more than a third of the time.

If true, the UK may fall well short of its state goal of generating 30 per cent of its electricity from renewable sources – primarily wind – by 2020.

There are currently 292 wind farms in operation in the UK (279 onshore, 13 offshore) producing 5.2GW of energy, according to RenewableUK (formerly the British Wind and Energy Association). Forty-three are under construction (3.8GW), a further 210 have been approved (5.5GW) and 270 are planned (8.7GW).

But contrary to the average annual ‘capacity output’ figure of 30 per cent used by the wind industry and government, the report indicates UK wind turbines were working at 27.18 per cent of their theoretical output in 2009, 21.14 per cent in 2010 and 24.08 per cent between November 2008 and December 2010.

For the years 2006-2009, the Department of Energy and Climate Change (Decc) puts the figure at 27.6 per cent for onshore wind and 31.1 for offshore. Final figures for 2010 are not yet available.

Wind power unreliable

The report also says ‘low wind events’ are more frequent than previously acknowledged, concluding: ‘Wind cannot be relied upon to provide any significant level of generation at any defined time in the future... [there is] urgent need to re-evaluate the implications of reliance on wind for any significant proportion of our energy requirement.’

But Robert Norris of RenewableUK says the report is based only on the 50 per cent of UK wind energy that passes through metered stations and so is ‘visible’ to the National Grid – most of it located in Scotland. Projects commissioned partway through the period covered by the report have not been taken into account, he says, and where data has not been collected ‘output is simply registered as zero without any attempt to provide replacement estimations’.

‘With greater geographical dispersion across the UK, the frequency of low-wind periods will be smoothed and reduced,’ he says, adding that findings extrapolated from Scottish data will not be representative of a larger fleet of wind farms spread over a large geographical area.

A Decc spokesperson concurred saying the JMT’s figures only covered half of the UK’s installed capacity, most of it installed in one geographical region, not inclusive of offshore wind and not accounting for the fact that some of the data was for wind farms installed for less than six months.

Wind industry should release more data

Helen McDade, head of policy for JMT, acknowledges that only half the UK’s wind power is accounted for, including over 80 per cent of Scottish onshore installations, but says this is the only hard data publicly available, updated to December 2010.

‘The website data used in the report includes all wind developments feeding directly into the transmission grid managed by National Grid. In Scotland, this system includes lower-voltage power lines. In practice this means none of the English and Welsh onshore wind developments feed directly into the transmission and so are not monitored on the publicly available website.’

She flatly refutes Decc’s statement on offshore wind, highlighting the inclusion in the report of four English facilities: Burbo Bank and Barrow, Robin Rig East and West, Part Thanet 1 and 2, and Balance of Thanet, all of which came online in the last six months of 2010, with no demonstrable change to wind averages and variability.

‘We don’t claim this to be a perfect analysis of UK wind generation, but it’s the best anyone can do with the publicly available data,’ she says. ‘Indeed, one of the concerns about the expansion of wind power is the lack of technical and economic data by which to judge whether what is claimed is actually being delivered. We’d be delighted to see the more complete data held by Decc, the National Grid and the wind industry in the public domain so we can update our report.’

Wind can provide third of our energy

Alex Randall of the Centre for Alternative Technology says the slight disparity in claimed wind energy output doesn’t alter the fact that the UK needs a low-carbon way to generate electricity.

‘Wind is our most developed form of renewable energy generation and the one that offers the biggest potential for the UK. To be part of the debate about where our energy comes from means engaging with the issue in a realistic way, one that accepts there will have to be compromises. JMT has not approached it from an energy strategy perspective, but because it doesn’t like the look of wind turbines in wild spaces.’

‘The key target in terms of global environmental concern is to reduce greenhouse gas emissions – renewable energy targets are not in themselves useful if your emissions are not going down,’ says McDade, adding that JMT has spent years calling for a national energy strategy to consider issues of consumption and generation. ‘We should be looking at reducing our energy consumption and what is the most cost-effective way to use any taxpayer subsidy to do that. Where is the audit so we can know if there are better alternatives?’

Professor Peter Tavner, chair of new and renewable energy at Durham University, agrees there will be ‘quite a degree of variability’ in terms of wind energy going into the National Grid but that ‘the average capacity factor of big wind turbines is approximately 27 per cent. Those who claim it is less are incorrect.’

He says wind can provide 30 per cent of the UK’s energy needs, especially as offshore wind farms come into their own. Marine facilities will be capable of generating 3.5GW of energy once those currently under construction are completed; a strategic environmental assessment in 2009 concluded UK waters could take a further 30GW on top of that.

A Durham University paper on four Round 1 offshore wind farms has revealed capacity outputs of 29 per cent, according to Tavner, rising to 33 per cent with the ironing-out of initial operational and maintenance issues. Danish and Dutch offshore farms showing 35 per cent have much further to go, he says, while during one month recently the 30-turbine North Hoyle wind farm [off North Wales] was operating at 65 per cent. Fossil-fired plants operate at roughly 25 per cent of their capacity, he adds.

Wind does need to be supported by other means of generation – Tavner speculates that growing offshore capacity will spark a hydro revolution – but he says the efficacy of the technology is beyond doubt.

‘It works, but it works differently to the energy we get from coal and gas, which comes at us in a smooth and regular way. Wind requires balancing, care and control. It needs a change in mindset and a more rational and organised approach to engineering and harvesting too.’

The point is underlined by the recent announcement that, during windy weather on 5 April this year, six Scottish wind farms were paid £900,000 to halt their turbines, having generated too much energy for the National Grid to absorb.

It has led to calls for a more efficient main grid, greater electrical storage facilities and greater interconnection with EU countries, allowing excess power to be bought and sold.


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