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Wind farm research triggers CO2 row

Energy experts this week challenged claims that an over-reliance on wind power would undermine Britain’s efforts to cut carbon emissions.

Last month Parsons Brinckerhoff warned that plans to install up to 30GW of wind energy around the UK would not necessarily deliver the carbon reductions expected.

Its report Powering the Future says that extra back-up power generation capacity will be needed to pick up shortfalls in wind generated electricity during calm weather.It argues that this capacity would have to come from high emission gas fired plants (NCE 26 November).

This week it has emerged that two key pieces of research used by the consultant were published by an anti-wind lobby group the Renewable Energy Foundation (REF).

Both studies find major flaws with wind energy. One says that electricity prices were adversely affected by the intermittency of wind. The other challenges the ability of wind energy to cope with fluctuating demand.

Energy experts claimed that relying on REF’s research to assess wind power’s capabilities to supply reliable power was questionable.

“We followed its [the REF report’s] data but did not follow its logic.”

Paul Willson, Parsons Brinckerhoff

Pro-renewables groups British Wind Energy Association (BWEA) and Greenpeace have said REF lacks credibility. Parsons Brinckerhoff said it had not known that REF was anti-wind power and that it had only used its data as so little was actually known about wind intermittency.

It added that it conducted further research to draw its own conclusions. “We followed its [the REF report’s] data but did not follow its logic,” said report author Paul Willson. “Our research addressed feasibility,” he said. “Our objective was to understand how effective wind power would be to reduce carbon emissions.”

“There was no objective to prove or disprove [the viability of ] wind, which is a carbonneutral technology,” he said. Wind Power and Spot Prices: German & Danish Experience 2006-2008 was written by Paul-Frederik Bach and published by REF in May this year.

Adverse effect

The study concluded that electricity prices are adversely affected by the intermittency of wind, and that: “Wind power may, together with other factors, create significant price volatility on such a scale that it undermines confidence in the electricity market, and thus acts as a disincentive to investment in urgently needed new, reliable low-carbon conventional plant.”

The study also suggests that the intermittency of the wind means that considerable back-up capacity is needed for those days when the wind is not blowing. This would most likely be created by “fast-start” gas plants, which are high emitters of CO2, the study claimed.

However, the report’s relevance to the UK energy market is disputed as weather and sea conditions are different to those of Denmark and Germany.

“Great care must be taken when claims are made that variability in Denmark can tell us much about putative variability of a large wind fleet in Britain.”

Andrew Smith, London Analytics

“The wider the geographic area the smoother the wind output. Britain and its seas are a huge area compared to Western Denmark, so great care must be taken when claims are made that variability in Denmark can tell us much about putative variability of a large wind fleet in Britain,” said energy and transport analyst Andrew Smith of consultant London Analytics. One banker with experience of funding wind farm projects disputed the economic basis of the REF report.

“In general, that report makes no distinction between power capacity and its rate of use: keeping fossil-fuel burning power plants available for those times wind does not blow does not mean that they will emit at high rates, as they will be used only very rarely,” said Jerome Guillet, head of energy at Belgian bank Dexia. Guillet also said the report can be read as being in support of a major roll-out of wind power capacity because back-up power can be sourced from elsewhere in the national grid.

“That argument suggests that wind can easily be integrated if other capacity exists or can be connected to, and that is the case in the UK,” he said.

Power swings

REF also funded a second piece of research, also used by Parsons Brinckerhoff when producing its report. Will British weather provide reliable electricity? by James Oswald and others was published in August 2008 in the journal Energy Policy .

This study modelled the output of 25GW of wind power against Met Office data and concluded that: “Power swings of 70% within 12 hour periods are to be expected in winter, and will require individual generators to go on or off line frequently, thereby reducing the utilisation and reliability of large centralised plants.

“These reductions will lead to increases in the cost of electricity and reductions in potential carbon savings.

“It is shown that electricity demand in Britain can reach its annual peak with a simultaneous demise of wind power in Britain [due to calm weather] and neighbouring countries to very low levels. This significantly undermines the case for connecting the UK transmission grid to neighbouring grids.”

“Oswald used real data from the Met Office, but used just single points and extrapolated from there.”

Robert Gross, UK Energy Research Centre

UK Energy Research Centre co-director Robert Gross questioned the methodology used. “Oswald used real data from the Met Office, but used just single points and extrapolated from there, imagining that the data sets from those points powered large wind farms. Real wind farms can be several kilometres long, and may not necessarily be situated where you would place a Met Office weather station.

“But my main criticism is that he does not do a systematic detailed analysis, but uncovers certain scary scenarios which are very unlikely to happen.” He said that it was generally accepted that wind energy had to be replaced in calm weather but that using wind energy was still a useful way to reducing carbon emissions. Parsons Brinckehoff ‘s report said that 30GW of installed wind power would need 10GW of faststart gas-fired back-up plants, and that this would undermine wind power’s green credentials.

Wind developers expect the Crown Estate to reveal which groups will win 10 concessions to build a total of 25GW of capacity before Christmas. This will be the next stage of Britain’s offshore wind development programme. Willson added that there was a dearth of information on the performance of wind power.

He cited a second study, the All-Ireland Project run by the Republic of Ireland’s Commission for Energy Regulation and the Northern Ireland Authority for Utility Regulation, which he said highlighted the intermittency problem.

“Ireland is ahead of us, with 20% of installed power in wind, and they needed fast-starting plants, for 80 to 100 hours per year.” These plants do not reach full generating capacity for two hours, he said.

He said that building extra wind capacity was undermining efforts to make other types of power plant more efficient. “Wind undermines the economic case for building efficient plants,” he said.

Persistent concerns

REF policy director John Constable said the research used by Parsons Brinckerhoff was “highly regarded work” and that it used verifiable data from the Met Office. He also said allegations his organisation was anti-wind were “rubbish” and slammed the BWEA as “irrationally pro-renewable”.

But he admitted that his organisation - founded by TV presenter Noel Edmonds - had “persistent concerns” that a large wind fleet would place technical and cost burdens on the UK electricity system, as well as limiting market access for other clean technologies. “Wind has a suppressing effect on the rest of the renewables sector,” he said. “There are very high margins for developing wind.”

ICE director general Tom Foulkes said problems with intermittency can be overcome.

“Although intermittency of wind flow has been posed as a problem, according to recent research it doesn’t present a major issue.”

Tom Foulkes, ICE

“Wind turbines are a proven low carbon source of energy that should be scaled up without delay to decarbonise the energy sector and ensure security of supply. Although intermittency of wind flow has been posed as a problem, according to recent research it doesn’t present a major issue. There has been a lot of progress in demand-side management and wind forecasting which will reduce uncertainty further,” he said.

“However wind energy cannot be considered in isolation. Decarbonising the entire energy sector, which is crucial for reducing emissions on the scale needed, will require development of other low carbon technologies such as marine renewables, carbon capture and storage, and deployment of new nuclear.”

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