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Tag Archives: wind turbines

Goodbye to FiTs

By Dave Elliott

A shift away from Feed-in Tariffs (FiTs) to project auctions as a way to support renewable energy seems to be underway across the EU. The UK government certainly has cut FiT levels and recently warned that the FiT system might be wound up entirely – and soon. Although it seems to have won a last minute partial reprieve, with the level of cuts being reduced from 87% to 64%, after something of an outcry, it is just a matter of time before it goes. Is this a good idea?


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Wind power around the world

By Dave Elliott

Wind power is booming globally, with over 370GW of electricity generation capacity installed so far. It could jump to 2,000 GW, more than five times its current level by 2030, supplying up to 19 % of global electricity, the Global Wind Energy Council says, although that would require ‘unambiguous commitment to renewable energy in line with industry recommendations … [and] the political will to commit to appropriate policies’. (more…)

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Nuclear – not the answer to climate change

By Dave Elliott

Although there are exceptions, as I noted in my last post, the UK being one, nuclear power seems to be in decline globally and this has led to what some might see as last ditch attempts to revive its fortunes. One such is the recent Open Letter to environmentalists, originating in Australia and backed by over 70 academics globally, though nearly half from Australia:   (more…)

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Renewable Impacts

By Dave Elliott

It has been an eventful year for renewables. While progress continues apace, with renewables now supplying around 15% of electricity in the UK and 22% of global electricity, in this pre- Xmas post, rather than spelling out all the good news, I will look at some of the less good stories from the year- concerning wind power and CSP. (more…)

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Renewables vs shale gas

By Dave Elliott
As a parting shot, after standing down as DECC’s Chief Scientific Advisor at the end of July, Prof David MacKay produced a comparison of renewables (wind and solar) and shale gas:

The headline figure (as picked up by the Telegraph: was that wind farms cover around 700 times more land area /kWh of energy produced at the site than shale gas wells. However, as usual with renditions of MacKay’s approach to land-use comparisons, this simple statistic is arguably a little misleading. As he admits, the actual area covered by wind turbine bases and access roads is very much less that the area covered by the wind farm, most of which can be farmed as usual. So, using his figures, the wind turbine /gas well land use ratio falls from 700:1 to 18:1

There are also other aspects that need to be considered in the comparison, some of which he covers in side notes. The energy content of the shale gas emerging from the well isn’t the same thing as the electricity output of a wind farm (or solar farm)- the gas has to be burnt in a power plant to generate energy (at 50% efficiency at best) and that also takes up room. This might reduce the wind turbine /gas land use ratio from 18:1 to perhaps 9:1 or less. And unless we condone the release from the gas-fired power plant of CO2 to the air, there will also have to be a carbon capture plant and a CO2 gas storage system- taking up a large area somewhere, and reducing the efficiency of the gas plant. That might add another factor of 2 or more, so maybe we are down to a ratio of 4:1 or less.

Hydraulic fracking also uses very large amount of water– that has to come from somewhere. It also creates large amounts of contaminated water, which has to be stored and/or treated, presumably somewhere else. It’s hard to know how to take these factors into account in land use terms. Another factor of 2? In the final analysis, overall, there might not be that much in it, if the land-use comparison is done fairly, at least for on-land wind, depending on location. And of course the whole land-use comparison collapses if we are talking about offshore wind. Or for that matter, offshore shale wells.

MacKay also looks at ground-mounted solar farms. Certainly solar farms (as opposed to roof-mounted PV arrays) do take up land space, on MacKay’s figures, around 8.5 times more than for wind turbines/kWh, although less than the total equivalent wind farm area. But, rebalancing the comparison, the Solar Trade Association has pointed out that much of this land can be grazed and most (perhaps 95%) of it can be used for wild flower growth, aiding biodiversity:

MacKay also looks at the truck movements associated with each option. His figures for solar and wind (nearly all during construction) seem high, those for shale gas low: he assumes all water is piped to and from the shale gas well site, but surely some water, and certainly fracking chemical fluids, would have to be tanked in throughout the operation, while some wastes would have to be tanked out. As for visual intrusion, his choice, for comparisons sake, of 10 temporary shale gas-drilling towers, may well be perceived as uglier but less invasive overall than his choice of 87 much taller 2MW wind turbines, though it will surely depend on the location. Some people positively like the look of wind turbines, seeing them as elegant symbols of low-impact energy extraction. It’s hard to see drilling rigs like that, although we have yet to have major shale gas projects in the UK to test that out. If, as it has been suggested, the UK may have 1000 wells started each year, attitudes may harden, as projects attempt to go ahead and impacts become apparent. My favorite unknown is whether excess gases will have to be flared off. That would make for quite a spectacle in rural areas…

At it stands, DECC’s most recent public opinion survey found that 79% of those asked backed renewables like wind and solar (82% backing solar, 67% on-land wind) while only 24% supported shale gas extraction:

There are also wider strategic issues: an emphasis on shale gas could undermine the development of renewable energy and efforts to respond to climate change. Scientists for Global Responsibility (SGR) and the Chartered Institute of Environmental Health (CIEH) have produced a report reviewing current evidence associated with shale gas extraction. SGR Director and report co-author, Dr Stuart Parkinson, said: ‘The evidence we have gathered shows that exploiting yet another new source of fossil fuels such as UK shale gas is likely to further undermine efforts to tackle climate change. We need to focus on low carbon energy sources, especially renewables, together with concerted efforts to save energy.’ The report calls for rethink, arguing not only that impacts may be high and regulatory oversight insufficient, but also that on-land wind power may be cheaper than shale gas.

The governments current decarbonisation policy envisions fossil gas being replaced as a heating option by green electricity from wind and solar and by nuclear electricity, used to power heat pumps. See my next post. That could make for a huge saving in gas – and emissions. And it would reduce the need to import increasingly expensive gas as north sea reserves dwindle. There will still of course be a need for gas to run electricity generating gas turbines, with some of those being used at times to balance variable renewables like wind and solar. However, although some new more flexible gas plants may be needed as old ones retire and renewables expand, the extra gas required for balancing, over and above what is used by the gas CCGT units at present, will be relatively small. And, as the Pugwash 2050 scenario explored, using the DECC calculator, if UK renewables expanded to 70% and alternative supply and demand side balancing options were developed, the need for gas for power generation would fall, so that, with proper commitment to energy saving, by 2050 well under 10GWof gas fired capacity would be needed. And increasingly it could use green gas- from biomass/waste AD and also possibly via surplus wind/PV to gas conversion, some of this also being use at high efficiency in CHP plants feeding district heating networks. There are disagreements about how much biomass could be available and used, but the Tyndall Centre says that by 2050, 44% of the UK’s energy requirements could be met by the increased utilisation of biomass, including household waste, agricultural residues and home-grown energy crops i.e. with no imports:

It is possible than gas could find a new market in transport, assuming the governments plan to see that electrified via a shift to electric vehicles is not successful. Certainly SNG/CNG could play a helpful role in fuelling trucks and large vans. But, as the Tyndall report suggests, much of this could be green gas. So why exactly do we want all this shale gas? Perhaps, with, tragically, renewable expansion already being constrained by government policies, it’s to compensate for that and also in case the nuclear expansion programme fails to materialize.

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Flights of fancy: airborne wind turbines

By Dave Elliott

Airborne wind turbines are now being considered as a serious new energy supply option. “Flying-wind” technology is still of course only at development stage, with various kite and aerofoil wing designs being tested. However, the resource is very large and the US government has indicated interests. A US Lawrence Livermore Lab study noted that there was around four times more power available in high altitude winds than in ground level flows- in all around 1600TW globally. (more…)

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More wind

By Dave Elliott

With 175 turbines, the first 630 MW stage of the huge 1GW London array offshore wind farm is now open, taking over from the 500 MW Greater Gabbard project off the East Anglian coast as the largest offshore wind farm so far globally. In parallel, revised plans for the 240 turbine Atlantic array off the Welsh/Devon coasts have been put forward  and Galloper have been given permission to construct a 504 MW 150 turbine wind farm off the coast of Suffolk and related infrastructure at Sizewell to connect it to the electricity grid system,while Triton Knoll Offshore Wind Farm Limited has been granted permission to construct a 1200 MW wind farm with 288 turbines off the coast from Lincolnshire and Norfolk.


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Animal stories 2 – birds, bats and wind turbines

Wind farms can reduce local bird numbers by up to half, according to a new study by the Royal Society for the Protection of Birds in conjunction with the Scottish Natural Heritage. It looked at 12 upland wind farms in the UK during the breeding season for a dozen common species including rare species such as hen harriers and skylarks. The research, published in the Journal of Applied Ecology, found 7 species showed ‘significantly lower frequencies of occurrence close to the turbines.’ The breeding population of buzzard, hen harrier, golden plover, snipe, curlew, wheatear and meadow pipit were reduced by up to half within 500 m of the turbines. It suggested that the most likely cause of the decline is the fact that birds are less likely to live and breed near wind farms because of the noise and development. Collisions with turbines was also suggested as a possible cause, but was thought to be less likely.

The British Wind Energy Association concurred with that: “This study shows there is a potential problem with displacement, but it is not yet proved that there is a problem with bird mortality rates.” It added ‘Wind farms and turbines are the most benign form of energy generation and the industry has found that wind farms simply do not pose a threat if they are properly sited and follow procedure. The threat of global warming could be a far greater threat to the population of birds than wind farms’.

The RSPB have recently backed wind farms as long as they are properly sited, and recommended a spatial planning approach as used elsewhere in the EU.
The Daily Telegraph (26/9/09) however claimed that RSPBs pro-wind stance had caused ‘many members to leave in protest because of concern about the developments ruining the view in remote areas and contributing to the decline of birds’.

Nevertheless, James Pearce-Higgins, senior conservation scientist with RSPB Scotland and lead author of the study, told them that it still supported wind farms. But developments should not be put in the wrong area – where they can harm birds. ‘There is an urgent need to combat climate change, and renewable energy sources, such as wind farms, will play an important part in this. However, it is also important to fully understand the consequences of such development, to ensure that they are properly planned and sited. Our results emphasise the need for wind farms to avoid areas with high densities of potentially vulnerable species such as curlews and golden plover, and help offer a way forward by informing the likely extent of positive habitat management which may help to offset the impacts of development.’

It’s not just birds though, it’s also bats that can have problems and it seems in larger numbers. But researchers at Aberdeen University, funded by the People’s Trust for Endangered Species ( are currently making good progress on using radar to deter bats from colliding with in the turbine blades.

But collisions may not actually be the problem. A study of bat deaths at a local wind farm by the University of Calgary reported by Science Daily found that the majority of migratory bats in this location were killed because a sudden drop in air pressure near the blades caused injuries to the bats’ lungs known as barotrauma. Although the respiratory systems in birds can withstand such drops, the physiology of bats’ lungs does not allow for the sudden change of pressure.

TransAlta, Canada’s largest publicly traded provider of renewable energy, initiated a follow-up study at the same site to determine what could be done. They tested a revised operating procedure   slowing turbine blades to near motionless in low-wind periods significantly reduces bat mortality. Prof. Robert Barclay, who led the University of Calagary study, commented “Biologically, this makes sense as bats are more likely to fly when wind speeds are relatively low.” It was found to reduce bat deaths from wind turbines by up to 60% without significantly reducing the energy generated from the wind farm.

Ref: Baerwald et al. 2009 ‘A Large-Scale Mitigation Experiment to Reduce Bat Fatalities at Wind Energy Facilities’. Journal of Wildlife Management 73 7 ; 1077 DOI: 10.2193/2008-233

Science Daily.


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Sounding off on Wind turbines

In a book to be published in Oct, Dr Nina Pierpont, a New York paediatrician, says she has identified a ‘wind turbine syndrome’ (‘WTS’) due to the disruption or abnormal stimulation of the inner ear’s vestibular system by wind turbine infrasound and low-frequency noise, the most distinctive feature of which is a group of symptoms which she calls ‘visceral vibratory vestibular disturbance’, or VVVD. Evidently this can cause problems ranging from internal pulsation, quivering, nervousness, fear, a compulsion to flee, chest tightness and tachycardia – increased heart rate. Turbine noise can also trigger nightmares and other disorders in children as well as harm cognitive development in the young. However, Dr Pierpont made clear that not all people living close to turbines are susceptible.

That might explain why, as the British Wind Power Association (BWEA) noted in an initial response, ‘an independent study on wind farms and noise in 2007 found only four complaints from about 2000 turbines in the country, three of which were resolved by the time the report was published’.

Nevertheless, it’s wise to be cautious. Some small domestic scale machines, which being small have very high rotation speeds, can be noisy, but audible noise from large modern wind turbines is nowadays hardly an issue, with gearless, variable speed turbines being very quite, since the blade rotation speed is better matched to the changing wind speed, thus increasing energy transfer efficiency and reducing aerodynamic noise. But low frequency sound might conceivably be a problem for some people. The only way to find out if this is this case and then to assess it’s significance, is to carry out research on a large scale – Pierpont’s sample was tiny, evidently based mostly on interviews with just 10 families living near wind turbines – 38 people!

In 2006 DTI published a study by Hayes McKenzie, which investigated claims that infrasound or low frequency noise emitted by wind turbine generators was causing health effects. The report concluded that there was no evidence of health effects arising from infrasound or low frequency noise generated by wind turbines. But the report noted that a phenomenon known as Aerodynamic Modulation (AM) was in some isolated circumstances occurring in ways not anticipated by ETSU-R-972, the report which described the method of assessing the impact of the wind farm locally. So the Government commissioned Salford University to conduct a further work. This study concluded that AM is not an issue for the UK’s wind farm fleet. Based on an assessment of 133 operational wind projects across Britain, the study found that, although the occurrence of AM cannot be fully predicted, the incidence of it from operational turbines is low. Out of all the working wind farms at the time of the study, there were four cases where AM appeared to be a factor. Based on these findings, the Government said it did not consider there to be a compelling case for more work into AM, but it would keep the issue under review.

Pierpont’s views have attracted significant media attention, with for example, the normally pro-wind Independent even suggesting that ‘there is a prudential argument for postponing the commissioning of land-based wind farms until they are shown to be safe’. A bit less radically, Pierpont has called for a 2 km safety zone.

The NHS website stepped in with a short critique, which noted that “The study design was weak, the study was small and there was no comparison group. There is also no information on how the group was selected in the first place and some uncertainty as to which countries these people come from.” It concluded ‘it is physically and biologically plausible that low frequency noise generated by wind turbines can affect people’ but, ‘this study provides no conclusive evidence that wind turbines have an effect on health or are causing the set of symptoms described’.

The BWEA, in a special Factsheet, then went on the offensive, noting that ‘Dr Pierpont is a known anti-wind campaigner’. And it pointed to a peer reviewed study by Geoff Leventhall which had refuted the allegations about infrasound, concluding that they were ” irrelevant and possibly harmful, should they lead to unnecessary fears”.

The Pierpont study does sound very weak but, to clear the air, it seems that the issue has to be resolved once and for all by an authoritative independent study.


Geoff Leventhall ‘Infrasound from Wind Turbines – Fact, Fiction or Deception?” Canadian Acoustics Vol. 34 No.2 (2006)


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