Power produced by wind farms slumped by a fifth in the second quarter of this year, despite hundreds of new turbines being built – because it wasn’t very windy.
Official Government statistics published on Thursday show that in the three months to the end of June, the amount of electricity produced by offshore wind farms fell by 22 per cent, to 2 terawatt-hours (TWh), compared with the same period the year before.
Yet the number of offshore wind turbines operating grew significantly – with 4.1 gigawatts (GW) of capacity installed in the seas around the UK by June this year, up from 3.5GW by June 2013.
Power output from onshore wind farms also fell, by 17 per cent to 3.22 TWh. The fall came despite dozens of new wind farms being built, increasing onshore wind capacity by 14 per cent over the same period.
There was 8GW of onshore capacity at the end of June, 1GW more than a year before.
The Department of Energy and Climate Change (DECC) said that the impact of increased capacity was “out-weighed by that of very low wind speeds”.
“Average wind speeds were 1.6 knots lower than a year earlier, and the lowest for quarter two for four years. Average wind speeds in June were the lowest for any month in the last 14 years,” it said.
About 900 turbines were constructed on and offshore over the course of 2013, according to Renewable UK.
Dr John Constable, director of the Renewable Energy Foundation, which publishes data on the sector and is critical of subsidy costs, said: “The latest DECC data is further confirmation that wind power output is highly variable over all timescales, minutes, hours, months, and even from year to year.
“These variabilities are physically manageable but they have highly significant negative economic impacts on the rest of the power generation fleet, whose market is made very uncertain, and these uncertainties ultimately mean much higher costs for consumers.”
While wind power output fell, the amount of electricity generated from solar farms soared by 67 per cent, to 1.2TWh.
The rise was in line with a near-identical increase in the amount of solar capacity installed.
Ministers have admitted that solar farms have been installed far more rapidly than they had expected, thanks to costs falling and developers taking advantage of generous subsidies.
In May they announced they were closing a subsidy scheme two years earlier than planned to stop the spread of the farms, which critics say are blighting the countryside.
Ministers originally anticipated between 2.4-4GW of large-scale solar being installed by 2020. Yet the latest DECC statistics show that the upper end of that range has now been exceeded, with 4.1GW installed by the end of June.
A spokesman for the wind industry trade association RenewableUK said: “Although it’s no secret that there are some periods that are even windier than others, the wider statistics show that wind energy is generating increasing amounts of clean electricity for British homes and businesses year on year.
“When you look at the last twelve months as a whole, generation from renewable sources in the UK went up to just over 17 per cent – up from 13 per cent in the previous 12 months. The lion’s share of that came from onshore and offshore wind – just over 50 per cent of it.
“In August, wind energy outstripped coal and nuclear for several days, and hit at all time 24-hour record high of 22 per cent of the UK’s electricity needs.
“National Grid has no problem taking clean power generated by wind whenever it’s available as often as it can, and it can predict exactly where the power will come from in advance with pinpoint accuracy. Every unit of electricity we generate from wind offsets a unit from polluting fossil fuels, so anyone who cares about climate change knows that we need to make the most of it whenever we can.”
One green power company, Infinis Energy, reported last month that its onshore wind farms had exported a third less power in the three months to June, compared to the same period the year before, blaming “low wind speeds experienced across the UK throughout the period”.
However, it said it would be “well placed to benefit from recovering wind speeds when they occur”.
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