Resource Library Category: Europe (20 items)
Documents presented here are not the product of nor are they necessarily endorsed by National Wind Watch. This resource library is provided to assist anyone wishing to research the issue of industrial wind power and the impacts of its development. The information should be evaluated by each reader to come to their own conclusions about the many areas of debate.
Renewable energy: vision or mirage?
Source: Sharman, Hugh; Leyland, Bryan; and Livermore, Martin
— As renewable energy sources produce power intermittently, they cannot replace gas, coal and nuclear generation, even with further development.
— Solar and wind energy have no prospect of becoming economically competitive in an unrigged market. Government intervention will lead to higher energy costs and jeopardize energy security.
— Increased investment in wind turbines will do little to reduce carbon emissions and fossil fuel consumption.
The report ‘Renewable Energy: Vision or Mirage?’, released today by the Adam Smith Institute and Scientific Alliance, reveals that the government’s focus on renewable energy sources is misguided. The UK’s plans for renewables are unrealistic, and these technologies cannot provide the secure energy supply the country needs. Present policies will lead to an energy crisis by the middle of this decade. The key points from the report are detailed below:
- Wind and solar power do little to reduce carbon emissions, as they need large-scale back up generating capacity to compensate for their intermittency.
- With the decommissioning of many of the UK’s coal-fired stations – and nearly all existing nuclear reactors – over the coming decade, energy security is now a priority for policymakers alongside the drive to reduce carbon dioxide emissions. However, even ignoring cost issues, problems of intermittency mean that renewable technologies are incapable of making a major contribution to energy security.
- The Renewable Energy Roadmap for 2020 is hugely overambitious. Renewable energy generation is currently 28% below its already reduced target. Subsidising renewable energy also comes at a cost to consumers who pay for it through higher electricity prices. Nuclear and gas are the most viable energy sources to avoid a capacity crisis in the near future.
Wind turbines are not the solution
- To achieve current targets for wind turbines for 2020, almost 5 wind turbines must be installed every working day, with the majority of them offshore. This is unrealistic.
- No matter how much wind capacity is added, there is no way of storing the energy long enough to avoid the need for backup generators. It cannot ensure the lights stay on, so there can be little reliance on it.
- Experience in other countries shows that a large investment in wind turbines must be matched by large-scale conventional back up generating capacity, which makes any reductions in CO2 emissions quite modest.
- Wind farms in the UK have a capacity factor of only 25%; investment in these farms would not be a commercial proposition without subsidies, even ignoring the intermittency problem.
- Wind power operators in the UK get a higher subsidy per MWh than in other countries in the EU and yet many approved wind farms never get built due to problems connecting to the Grid. Onshore wind turbines face much opposition from the public and off-shore turbines are more expensive to install.
- The operational life for wind turbines is just 20 years. This is much shorter than for coal, gas or nuclear and is another factor making wind power an expensive option.
- Planned high investment in wind power up to 2020 will preclude the possibility of investment in diversified and efficient generating capacity. Wind power is an inefficient of use of taxpayers’ money, is not as green as commonly perceived, and will not provide for the energy needs of the UK.
Solar power
- This is high cost and inefficient at our high latitude.
- The focus of subsidies has been on small scale, domestic installations which are intrinsically less cost effective.
- As there is no technology for long-term, high capacity storage of electricity, this technology cannot help to meet Britain’s energy needs.
- Large solar farms are difficult to build as they need a large land area. This acts as a financial disincentive – nuclear and coal-fired power stations need much less land.
It is difficult not to conclude that the official enthusiasm for renewables has more to do with the power of the green lobby than economics and energy security. Martin Livermore, joint author of the report, adds:
“For too long, we have been told that heavy investment in uneconomic renewable energy was not only necessary but would provide a secure future electricity supply. The facts actually show that current renewables technologies are incapable of making a major contribution to energy security and – despite claims to the contrary – have only limited potential to reduce carbon dioxide emissions.”
“Consumers have a right to expect government to place high priority on a secure, affordable energy supply. It seems that ministers have not yet realised the need to invest in more nuclear and gas generating capacity if the electorate is not to be badly let down.”
Download original document: “Renewable energy: vision or mirage?”
Den Brook Amplitude Modulation Noise Condition
Source: Moroney, Lee; and Constable, John
The noise most commonly associated with wind farms, and frequently complained of, is the repetitive swishing beat occurring at turbine blade rotation frequency, which is known as Amplitude Modulation (AM) of the aerodynamic turbine noise.
In 2007 the Government commissioned the University of Salford and the Hayes McKenzie Partnership (HMP) to investigate AM noise by means of a survey of wind farm noise complaints lodged with local authorities. At the time of publication the resulting Salford report1 did not reveal the names of any of the wind farms with noise problems nor the specifics of the noise complaints.
The Renewable Energy Foundation (REF) submitted a Freedom of Information request to the University of Salford to obtain this data, and following a ruling by the Information Commissioner, this data was ultimately disclosed. The survey data was published in 20092 and revealed that a significant number of noise complaints were potentially attributable to AM noise.3
There has been an increasing debate, including those at Public Inquiries into proposals for specific wind farms, about the need for an AM noise condition to protect wind farm neighbours from excessive AM noise, which has been blamed for sleep disturbance.
Of particular interest is the case of the Den Brook wind farm application. This project was consented in December 2009 following a second public inquiry during which noise issues were extensively discussed. The Inspector accepted that a planning condition to prevent excessive AM noise was both necessary and reasonable, and included a new AM condition as part of the consent.
Unfortunately, the Inspector’s drafting of the terms surrounding enforcement of this AM condition was ambiguous, resulting in an appeal to the Courts, essentially for clarification. An Appeal Court decision provided that clarity by stating that the AM limits defined in Condition 20 of the Inspector’s decision must be complied with for the 25 year lifetime of the planning permission.4
The Den Brook AM condition
The Den Brook AM condition, Condition 20 of the decision, states:
20. At the request of the local planning authority following the receipt of a complaint the wind farm operator shall, at its expense, employ a consultant approved by the local planning authority, to assess whether noise immissions at the complainant’s dwelling are characterised by greater than expected amplitude modulation. Amplitude modulation is the modulation of the level of broadband noise emitted by a turbine at blade passing frequency. These will be deemed greater than expected if the following characteristics apply:
a) A change in the measured L Aeq, 125 milliseconds turbine noise level of more than 3 dB (represented as a rise and fall in sound energy levels each of more than 3 dB) occurring within a 2 second period.
b) The change identified in (a) above shall not occur less than 5 times in any one minute period provided the L Aeq, 1 minute turbine sound energy level for that minute is not below 28 dB.
c) The changes identified in (a) and (b) above shall not occur for fewer than 6 minutes in any hour.
Noise immissions at the complainant’s dwelling shall be measured not further than 35m from the relevant building and not closer than within 3.5m of any reflective building or surface, or within 1.2m of the ground.
At first glance this condition appears complex and it has excited controversy, in part because it has been argued that it is difficult to distinguish wind farm AM noise from other noises in the environment.
We believe that it would be a useful contribution to the understanding of the potential application of the Den Brook noise condition if it were used to assess actual, i.e. real and empirical, wind farm noise data.
However there is little useful wind farm noise data in the public domain. We are fortunate in that we have recently obtained data collected by the Hayes McKenzie partnership as part of a Government contract in 2005 to investigate low frequency noise at wind farms. 5
That this raw noise data has come into the public domain is testament to the determination of an individual who, with the assistance of the local MP and advice from the Campaign for Freedom of Information and the Information Commissioner, succeeded in obtaining the data from the Department of Energy and Climate Change in spite of a surprising unwillingness on the part of DECC officials to facilitate its release. 6
Applying the Den Brook Noise Condition to Real Wind Farm Data
In order to demonstrate the Den Brook noise condition in application to wind farm noise data we have extracted a sample subset from the Hayes McKenzie data. This consists of noise levels (LAeq) measured at 100 millisecond (ms) intervals, where the overall level exceeds 28dB as dictated by condition 20(b). This measurement frequency is a finer level of granularity than required by the condition and a good match for the LAeq, 125 milliseconds measurements defined in 20 (a) of the condition.
The following graph shows a one minute period of this data, a time interval chosen because it is that which is specified in condition 20(b).
Figure 1: Period 10: One minute of LAEq (100ms) wind turbine noise levels from 14 May 2005, 03:09:00. The dots above the general noise level line show AM peaks in noise level where the rise and fall exceeds 3dB.
For this one-minute period, a breach of the AM condition requires, firstly, that the overall level exceeds 28 dB(A): the minimum level is 37.3dB(A) in this period so that requirement is met. Secondly, it requires that AM peak-to-trough changes in LA(eq) exceed 3 dB ‘(represented as a rise and fall in sound energy levels each of more than 3 dB) occurring within a 2 second period’. A dot has been placed above every peak in Figure 1 that exceeds 3 dB.
The following chart displays a six-second period extracted from Figure 1 that demonstrates more clearly the levels of rise and fall in each two-second period. It can be seen that in each of the three two-second periods there is at least one example of a rise and fall in noise level of more than 3 dB. These changes demonstrate a breach of the condition under the terms of 20 (a). Counting the number of similar amplitude peaks in Figure 1 (marked with a dot above the line of the turbine noise level), it can be seen that there are at least 16 in that one-minute sample. This demonstrates that this particular minute is in breach of the AM condition as described at 20 (b).
Figure 2: Period 10: The six-second period from 8–14 seconds taken from Figure 1, demonstrating the rise and fall in noise levels.
The final stage necessary to demonstrate breach of the condition is described at 20(c) and requires that there are at least six minutes in an hour demonstrating the defined level of AM. In Appendix 1 of this report we give a further five charts of one-minute periods within the same hour that also display the features typical of AM in breach of the condition.
We therefore conclude that this dataset indicates a breach of the Den Brook AM Condition 20.
It is also relevant to this discussion to consider if the amplitude modulation displayed here is attributable to wind farm noise or perhaps arises from some other noise in the environment. There are a number of ways of ensuring that the noise measured is wind farm noise, the obvious one being a simultaneous audio recording.
However, we can also inspect the noise levels displayed in the various graphs for any characteristic signature or structure, and in this case we observe that there are periods of clearly regular beats. If the wind farm is the source of the noise then the frequency of the beats will agree with the blade passing frequency of the turbines. The data in Figure 1 indicates beating approximately once per 0.7 second, corresponding to a blade passing frequency of 1.4 per second or 28 revolutions per minute, which is a plausible rate of rotation for this wind turbine. This conclusion could be verified against the SCADA (Supervisory Control and Data Acquisition) data automatically accumulated at each turbine, but unfortunately we do not have access to this information.
Conclusion
We believe that this exercise demonstrates that the Den Brook condition is straightforward and that it is possible for this condition to be employed in a transparent and objective manner to demonstrate the existence of excess AM in wind turbine noise.
The point of the current analysis is simply and solely to demonstrate the technical application of the key elements of the Den Brook noise condition to real wind farm noise data and we have shown that this is possible and can be conducted in a clear and objective manner. It should be noted, however, that we have not set out in this paper to prove that the particular wind farm in question would breach the Den Brook AM noise condition in a legal sense and indeed this AM condition does not apply to that windfarm. To do so would require evidence demonstrating that the noise measurements were compliant with the final part of the condition, namely that the measurements were taken not closer than 3.5m to any reflective building or surface, or within 1.2m of the ground, and we have no information on this matter, but if such evidence were available then legal breach of the condition could, in principle, be demonstrated.
These findings should be welcomed by both wind-farm neighbours, developers, and decision makers in the planning process. AM noise provokes complaints and heated debates, and an enforceable, objective, condition to cap such noise gives all parties clarity, as well as sparing neighbours and developers the trouble, expense, and uncertainty of private nuisance actions. The Den Brook condition appears to be a readily workable solution to this very real problem.
Dr Lee Moroney
Dr John Constable
References
1. Moorhouse, Hayes, von Hunerbein, Piper, Adams, “Research into Aerodynamic Modulation of Wind Turbine Noise” (NANR233) July 2007. Available from: http://webarchive.nationalarchives.gov.uk/+/http://www.berr.gov.uk/files/file40570.pdf
3. G. P. van den Berg, ‘Why is wind turbine noise noisier than other noise?’, Euronoise (2009).
4. See Hulme v SoS for Communities & Local Government & Ors 2011 EWCA Civ 638. Available from: http://www.richardbuxton.co.uk/v3.0/node/520
5. ‘The measurement of low frequency noise at three UK wind farms’, DTI 06/1412 Hayes McKenzie Partnership Ltd, 2006, http://webarchive.nationalarchives.gov.uk/+/http://www.dti.gov.uk/energy/sources/renewables/publications/page31267.html
6. The private individual who received the data from DECC has kindly given REF a copy. The released material consists of approximately 70 GB of data on a hard drive in a format only readable using proprietary software. We have extracted some of the 100ms LAeq wind turbine noise data and would be happy to provide that as a text file on request for others to analyse.
Appendix 1
Figure 3: Period 9: One minute of LAEq (100ms) wind turbine noise levels from 14 May 2005, 03:08:00. The dots above the general noise level line show AM peaks in noise level where the rise and fall exceeds 3dB.
Figure 4: Period 2: One minute of LAEq (100ms) wind turbine noise levels from 14 May 2005, 03:01:00. The dots above the general noise level line show AM peaks in noise level where the rise and fall exceeds 3dB.
Figure 5: Period 13: One minute of LAEq (100ms) wind turbine noise levels from 14 May 2005, 03:12:00. The dots above the general noise level line show AM peaks in noise level where the rise and fall exceeds 3dB.
Figure 6: Period 3: One minute of LAEq (100ms) wind turbine noise levels from 14 May 2005, 03:02:00. The dots above the general noise level line show AM peaks in noise level where the rise and fall exceeds 3dB.
Figure 7: Period 6: One minute of LAEq (100ms) wind turbine noise levels from 14 May 2005, 03:05:00. The dots above the general noise level line show AM peaks in noise level where the rise and fall exceeds 3dB.
Download original document: “The Den Brook Amplitude Modulation Noise Condition “
Damage Limitation
Source: Markieta, Michael; and Carver, Steve
Regular visitors to the Scottish hills cannot have failed to notice the increasing environmental influence of renewable energy in recent years. Windfarms now feature prominently in views from many of our most iconic ‘wild’ mountains, a trend likely to accelerate with the Scottish Government’s tight timetable to generate all of Scotland’s power needs with low carbon technologies. If many more large onshore windfarms now look inevitable, then the question of how best to minimise their environmental impact arguably gains greater urgency. Is it possible both to develop and to conserve the large areas of scenic wild landscape for which Scotland is notable in a European context? Where are the areas which if developed would minimise the extent of intrusion on the remaining uninfluenced landscape? A new study by Steve Carver and Michael Markieta of the Wildland Research Institute at the University of Leeds aims to address this question.
The team summarise their work for UK Hillwalking here, with links to the interactive mapping they’ve been using to determine landscape impacts.
Windfarms beyond the National Park boundary will soon be prominent in this view from Braeriach
No High Ground – mapping out the landscape and renewable energy conflict
We’ve all seen the headlines. We’ve all seen them sprouting up across the mountain landscape, cluttering the horizon as we look out from our favourite hill. We’ve all had those well-worn debates with friends and colleagues across the dinner table or down the pub over a pint as to why they are a good or a bad thing. We all know we have to do something about our insatiable demand for electrical energy, but what we don’t know is just how much impact wind turbines have and will have on our landscape. What we do know is that wind energy is having a significant impact on the Scottish landscape and that this is set to increase over the next few years as more wind farms are constructed. The SNP are firmly committed to increasing investment in the renewable energy sector and have set a target for Scotland to generate 100% of its energy requirements from renewable sources by 2020. Although the renewable mix is likely to include hydro, wave and tidal power it is likely that the bulk of the burden in reaching this ambitious target will fall on the shoulders of wind, both onshore and offshore, because this is where the engineering challenges are better understood and the investment:returns ratio is most profitable. This can only mean one thing… more turbines on the hills and along our coasts.
‘The area of the Scottish countryside that is free from visual influence caused by built development declined from 41% in 2002 to 28% in 2009′
A recent analysis carried out by Scottish Natural Heritage (SNH) showed that the area of the Scottish countryside that is free from visual influence caused by built development declined from 41% in 2002 to 31% in 2008. More recently still, this figure has now declined to 28% in 2009. While this figure is based on all built structures (airports, roads, railways, pylons, urban areas, etc. and importantly existing wind turbines) it is an alarming trend and one that potentially masks the contribution to this erosion of landscape character and values that is due to wind energy developments. Earlier work by SNH showed that in the central Highlands the amount of land free from impacts caused by road and rail access, plantation forestry, hydro power and electrical transmission lines declined rapidly between 1860, 1950 and 2000. Government claims that “Scotland has the potential to become the Saudi Arabia of renewable” backed by the 100% renewable target has surely given a green light to further expansion of wind energy over the next few years. Such a trend is not without its detractors and questions have been raised in Parliament by the John Muir Trust on this.
Meanwhile, other aspects of the Scottish economy depend heavy on tourism with estimates ranging from £5-10billion from 15million visitors per year with figures set to increase by almost two fold by 2020. Of course, some of this revenue is from people visiting cultural centres like Glasgow and Edinburgh, but many of Scotland’s visitors come for the landscape whether it’s to walk, climb, sail, play golf, fish, shoot or just enjoy the magnificent countryside from bus or car. A key characteristic of the Scottish countryside is its wildness; the qualities of which are most strongly expressed in those areas that are dominated by natural or near-natural vegetation, lack of human intrusion from built structures and the rugged, challenging and remote nature of the land. Recent surveys on behalf of SNH in 2007 and 2010, respectively, have reported that 91% of Scottish residents think that it is important to have wild places and 98% thought that wild land in Scotland should be protected.
‘Where are the areas which if developed would minimise the extent of intrusion on the remaining uninfluenced landscape?’
It would seem that 2020 is a significant date here in both respects; as an ambitious target for renewable energy generation and a hopeful one for tourism revenue. However, there seems to be an obvious conflict, one that implies that more wind turbines will mean a bigger impact on the landscape and potentially, therefore, less tourism. Research currently underway at the Wildland Research Institute at the University of Leeds is attempting to provide some of the answers as to exactly how existing and planned wind farms are impacting on Scotland’s landscape. The work attempts to provide greater information about the cumulative effects of wind turbines in the Scottish landscape, such as how many turbines are visible, how much of them can be seen given the terrain and exactly big they look . As already discussed, the extent of Scotland’s landscape that is unaffected with a view of modern human artefacts is decreasing rapidly and the effect of wind turbines needs to be accurately monitored. Our analysis takes into account all turbines in the various stages, including those already built as well as those in approved, planned and scoping stages. The basic aim of this study is to identify areas where further development of Scotland’s wind energy potential will not mean further erosion of the landscape quality and further reduction of the 28% figure.
Figure 1
Figure 2
See Figure 2 as an interactive map on Maptube here.
To do this we make extensive use of computer mapping techniques and digital map data together with a technique known as “viewshed” analysis to map the turbines’ zone of visual influence (ZVI). Generally, a viewshed analysis is performed to identify the areas from where a turbine can be seen or not seen. The results show the areas that are within or outwith the ZVI as a map like the one shown in Figure 1. With modern computing techniques, a viewshed for over 4200 wind turbines in Scotland can be computed in a matter of hours, rather than days or weeks or even months. Currently, 71% of Scottish countryside is without a view of an installed turbine. However, if all the wind turbines that are currently approved or in the planning or scoping phase are built, then this figure will fall to 49%. Added to the existing visual impact from other human artefacts reported in the SNH work, then it is unlikely that many areas of the Scottish landscape will be free from visual influence by the 2020 date. However, logic dictates that there must be some places where a wind farm could effectively be hidden from view, so that those areas currently without a view of a turbine or other human artefact are either not adversely affected or reduced further still. By utilizing careful application of the viewshed analysis, we can reverse engineer the primary outputs (where you can and can’t see a wind turbine) to check if there are any areas which can be further developed so as to not further reduce the amount of the remaining uninfluenced landscape.
Early indications are that there are very few areas that can be further developed without reducing the remaining uninfluenced landscape. This begs a further question: where are the areas which if developed would minimise the extent of intrusion on the remaining uninfluenced landscape? Inherently, the question is rooted in humanistic perception of acceptable levels of cumulative impacts. For discussion’s sake, the top 10% lowest impact zones are shown above (Figure 2). These are located mainly around existing wind farms, such as Whitelee Wind Farm, as well as various offshore areas.
Figure 3
Figure 4
Figure 3 interactive version here.
Figure 4 interactive version here.
We have also run a similar analysis for areas in Scotland that are protected for their exceptional biodiversity or landscape value. The total land area protected for its biodiversity (including Natura2000 sites, National Nature Reserves, etc.) is actually very large and consequently the analysis reports that there are very few areas (Figure 3) that do not have a view of these protected areas. However, fewer areas of Scotland are covered by landscape designations (National Parks and National Scenic Areas) and therefore the viewshed analysis reveals much larger regions (Figure 4), mainly in Aberdeenshire, which do not have a view of a protected landscape.
‘Further renewable energy developments in Scotland need to be carefully sited to avoid conflict with landscape policy and tourism potential’
While the results for the biodiversity and landscape areas are different, there is an important point to be made here, namely that the biodiversity areas are often quite fragmented whereas the landscape areas are not. Biodiversity can be found across a range of scales from your local pond to whole landscapes, but in the long run the resilience and sustainability of that diversity depends on the connectivity and unfettered state of natural ecosystems and processes, and that these require large areas to be natural in. So, in the long run it is actually quite difficult to separate biodiversity from landscape as logic dictates that high biodiversity tends to produce beautiful and natural looking landscapes, while large, unmodified landscapes gives nature room to flourish, such that the two remain mutually inclusive. The important take home message here is that policy and decision making on wind energy in Scotland needs to take into account the cumulative impacts of not only the wind turbines on the Scottish landscape, but also the protected areas for their exceptional biodiversity or landscape characteristics and values. The problem here is that while the area within protected high value landscapes is remarkably beautiful, the viewshed from within and into the protected landscape area extends way beyond the boundary. In essence, the value of the National Park or NSA is detracted by any tall wind turbines outside of boundary that are visible, but also within the viewshed of the protected area. Results suggest that 58% of the installed wind turbines are visible from a designated protected landscape and if wind turbines in all stages of development are taken into consideration, this figure may well increase to something like 62%.
Interactive map of Wildness Quality here.
It is our opinion that further renewable energy developments in Scotland need to be carefully sited to avoid conflict with landscape policy and tourism potential. There is no perfect solution, so we will probably have to accept some level of compromise both from a landscape and biodiversity perspective. While what we are doing here attempts to provide a technical response to a complex social (landscape values and climate change) and economic (energy vs tourism) problem, it is clear that the answer is essentially a spatial one and the kind of methods described can provide the information base on which better informed decisions and policy can be made.
Michael Markieta and Steve Carver
Wildland Research Institute, University of Leeds
June 2011
Effect of a common wind shear adjustment methodology on the assessment of wind farms when applying ETSU-R-97
Source: Stigwood, Mike
Executive summary
This research paper has been commissioned by MAS Environmental Ltd. It challenges many of the commonly accepted assumptions on the influence of wind shear on wind turbine noise introduced by an article published in 2009. The article outlined changes to the assessment of wind shear reasoning that by altering background noise levels for wind shear, permitted turbine noise limits would be lowered.
The 2009 article method for assessing wind shear was not based on research and was developed following some widely stated, but now shown to be incorrect, assumptions about the effects of wind shear.
This paper investigates the differences in turbine noise assessment as recommended in the article method and as recommended in ETSU-R-97, the current UK guidance for assessing wind farm noise. Using data measured at a number of wind farm sites around the country comparison is made between the difference in margin between predicted turbine noise level and associated limits as calculated by the article method and by the application of ETSU-R-97 as written. This paper explores whether there are any benefits to using the article method, however small, and reviews the consequences for local communities in adopting this change.
The study concluded that the desired benefit using the article method at all wind speeds, and especially at 5-7m/s where the article method was expected to perform best, is not realised. Where standardised wind shear conditions as implemented by the article, which do not relate to those conditions causing complaint, were substituted for the actual wind shear conditions likely to cause complaint more turbine noise was allowed. Further, the comparison showed that in all cases analysed there was a loss of community protection when adopting the article method.
