Resource Documents: Denmark (36 items)
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Author: Teilmann, Jonas; and Carstensen, Jacob
Offshore wind farms constitute a new and fast growing industry all over the world. This study investigates the long term impact on harbour porpoises, Phocoena phocoena, for more than 10 years (2001–12) from the first large scale offshore wind farm in the world, Nysted Offshore Wind Farm, in the Danish western Baltic Sea (72 × 2.3 MW turbines). The wind farm was brought into full operation in December 2003. At six stations, acoustic porpoise detectors (T-PODs) were placed inside the wind farm area and at a reference area 10 km to the east, to monitor porpoise echolocation activity as a proxy of porpoise presence. A modified statistical BACI design was applied to detect changes in porpoise presence before, during and after construction of the wind farm. The results show that the echolocation activity has significantly declined inside Nysted Offshore Wind Farm since the baseline in 2001–2 and has not fully recovered yet. The echolocation activity inside the wind farm has been gradually increasing (from 11% to 29% of the baseline level) since the construction of the wind farm, possibly due to habituation of the porpoises to the wind farm or enrichment of the environment due to reduced fishing and to artificial reef effects.
Environmental Research Letters, 2012, Vol. 7, No. 4, 045101
Author: Renewable Energy Foundation
1. Onshore wind turbines represent a relatively mature technology, which ought to have achieved a satisfactory level of reliability in operation as plants age. Unfortunately, detailed analysis of the relationship between age and performance gives a rather different picture for both the United Kingdom and Denmark with a significant decline in the average load factor of onshore wind farms adjusted for wind availability as they get older. An even more dramatic decline is observed for offshore wind farms in Denmark, but this may be a reflection of the immaturity of the technology.
2. The study has used data on the monthly output of wind farms in the UK and Denmark reported under regulatory arrangements and schemes for subsidising renewable energy. Normalised age-performance curves have been estimated using standard statistical techniques which allow for differences between sites and over time in wind resources and other factors.
3. The normalised load factor for UK onshore wind farms declines from a peak of about 24% at age 1 to 15% at age 10 and 11% at age 15. The decline in the normalised load factor for Danish onshore wind farms is slower but still significant with a fall from a peak of 22% to 18% at age 15. On the other hand for offshore wind farms in Denmark the normalised load factor falls from 39% at age 0 to 15% at age 10. The reasons for the observed declines in normalised load factors can not be fully assessed using the data available but outages due to mechanical breakdowns appear to be a contributory factor.
4. Analysis of site-specific performance reveals that the average normalised load factor of new UK onshore wind farms at age 1 (the peak year of operation) declined significantly from 2000 to 2011. In addition, larger wind farms have systematically worse performance than smaller wind farms. Adjusted for age and wind availability the overall performance of wind farms in the UK has deteriorated markedly since the beginning of the century.
5. These findings have important implications for policy towards wind generation in the UK. First, they suggest that the subsidy regime is extremely generous if investment in new wind farms is profitable despite the decline in performance due to age and over time. Second, meeting the UK Government’s targets for wind generation will require a much higher level of wind capacity – and, thus, capital investment – than current projections imply. Third, the structure of contracts offered to wind generators under the proposed reform of the electricity market should be modified since few wind farms will operate for more than 12–15 years.
Author: Danish Society for Occupational and Environmental Medicine
DASAM [the Danish Society for Occupational and Environmental Medicine] has with interest read the proposal for a new executive order on noise from wind turbines. DASAM welcomes that low frequency noise from wind turbines are now being subjected to the same limits as low frequency noise from other industries during the night.
DASAM believes however, that the executive order not sufficiently protects against health risks due to noise and therefore recommends:
- The noise limits should be lowered from 39dB (A) to 35 dB (A).
- A health based assessment on the effects of introducing up to 1000 wind turbines in Denmark should be performed.
Based on current knowledge about the relationship between noise from wind turbines and effects on humans, and the raised critic on the quality of the proposed noise measurements, for example from researchers from Aalborg University, we are concerned whether the proposed noise limit values for wind turbines will sufficiently protect the Danish citizens against annoyance of living close to wind turbines.
A number of original papers and several reviews show that between 10% and 40% of citizens living close to wind turbines feel annoyed or extremely annoyed by the noise, and it is shown that the number of annoyed people rises sharply when the noise exceeds 35 dB [1-7]. Generally, it has not been possible to distinguish between nuisances from noise and low frequency noise respectively. Some of the studies also suggest that living near a wind turbine affect sleep quality and the most recent review concluded that “Wind turbine noise is causing noise annoyance and possible also sleep disturbance, which means that one cannot completely rule out effects on the cardiovascular system after prolonged exposure to wind turbine noise, despite moderate levels of exposure” .
Some case studies describe vibroacoustic disease and wind turbine syndrome in persons living close to wind turbines, but these findings have not been confirmed by more systematic studies.
The current noise limits that are unchanged in the new revised proposal is 44 dB(A) at 8 m/s (open land) and 39 dB(A) at 8 m/s (noise sensitive land use). Actually, the noise load can be considerably higher, due to 1) no enhanced noise limits in the night, even though it is well documented, that the noise reduction can be lowered 3-15 dB at night [8,9] and 2) that the noise level can increase at higher wind speeds.
As something new, an indoor noise limit value of 20 dB for low-frequency noise is proposed, but it is accepted, that the noise limit value will be exceeded in 33% of households living close to wind turbines. Basically DASAM finds this approach unacceptable. The Environmental Protection Agency’s calculation of the insulation capability of houses against low frequency noise – including the acceptance of the large number of exceedings – and the controversial use of measurement variability in the control measurements for noise has been strongly criticized by international experts in noise and acoustic . In the proposed executive order the noise insulation numbers are increased compared to earlier, resulting in calculated indoor levels of low frequency noise below 20 dB, despite the fact that the real levels are well above 20 dB. We refer to  and to the statement on the executive order from Aalborg University for further details.
We estimate that with the current noise limit values for wind turbines, an unacceptable proportion of citizens in the vicinity of wind turbines will be annoyed or strongly annoyed by the noise. In the suggested noise limit values it has not been taken into consideration that susceptible subjects due to e.g. pre-existing disease can be more sensitive to noise compared to the general population .
No studies so far have investigated the magnitude of the problem in Denmark, but based on studies from mainly Sweden and Holland DASAM recommends that the noise limit value is decreased from the current 39 dB (A) so in the future no more than 35 dB is allowed at residences at a wind speed of 8 m/s. It is also recommended to use 35 dB as the noise limit value in noise sensitive land use – today it is covered by the 44 dB noise limit value. By doing this the Danish noise limit values will become comparable to the Swedish  and the New Zeelandic  noise limit values. Based on present knowledge, this means that less than 10% of citizens living close to wind turbines will be annoyed by the noise.
DASAM finds it relevant that a health-based assessment is made of the effects of introducing as planned up to 1000 wind turbines in Denmark. DASAM can propose a person capable of performing the task, including suggestions on how effects of wind turbines may be monitored and estimated in the future.
Chairman, Danish Society for Occupational and Environmental Medicine
Associate Professor, MD, specialist in occupational medicine
Department of Public Health, Section for Environmental and Occupational Medicine
Aarhus University, Denmark
Tlf: +45 8617 8022 / +45 2899 2499
- Sammenhæng mellem vindmøllestøj og helbredseffekter. DELTA, marts 2011
- Infrasound and low frequency noise from wind turbines: exposure and health effects; Environ. Res. Lett. 6 (2011) 035103 (6pp)
- Health aspects associated with wind turbine noise – results from three field studies. Noise Control Eng J 59(1) 2011
- Perception and annoyance due to wind turbine noise—a dose–response relationship; J. Acoust. Soc. Am. 116 (6), December 2004
- Wind turbine noise, annoyance and self-reported health and well-being in different living environments; Occup Environ Med 2007;64:480–486
- Response to noise from modern wind farms in The Netherlands; J. Acoust. Soc. Am. 126 2, August 2009
- Evaluating the impact of wind turbine noise on health-related quality of life; Noise & Health, Sept-Oct 2011; 13:54,333-9)
- Effects of the wind profile at night on wind turbine sound; Journal of Sound and Vibration; doi:10.1016/j.jsv.2003.09.050
- Schneider, C.P. Accuracy of Model Predictions and the Effects of Atmospheric Stability on Wind Turbine Noise at the Maple Ridge Wind Power Facility, Lowville NY.2007
- Henrik Møller, Christian Sejer Pedersen, Steffen Pedersen, ”Miljøstyrelsens mystiske beregninger”, Kronik, Berlingske, 15. juni 2011
- New Zealand Standard. Acoustics – Wind farm noise DZ 6808. REPORT DRAFT
Author: Engel, Ditlev
Dear Karen Ellemann,*
Following previous correspondence, I am writing this letter to express my concern regarding the limits for low frequency noise from wind turbines now being proposed.
Back in January 2011 we applauded your announcement of the new regulations regarding low frequency noise and the fact that you also then emphasised that those regulations would not be tightened and that it was a question of improving the security in connection with the installation of wind turbines. Accordingly, the reaction from the industry branch back in January 2011 was positive, although as an industry we were uneasy about having heavier demands imposed on us than other industries.
When the new regulations were then published on 26.05.2011, we were of course convinced of your initial point of view. As a result, we were extremely surprised to find that the proposed new regulations do in fact include a significant and severe tightening of the previous noise regulations.
In fact, according to our analyses, the most economical turbines, the 3 MW category, are the ones that will be strongly affected by the new rules. This applies to open terrain in particular, where in future low frequency noise will dictate and increase the distance requirements to neighbours for close to half of the projects that we are already aware of over the next 2 to 3 years.
In a small country such as Denmark this means that a significant number of projects will not be viable as the increased distance requirements cannot be met whilst maintaining a satisfactory business outcome for the investor.
The Danish market for wind turbines is of minor importance for Vestas in terms of sales, typically less than 1% of our sales per year. However, the Danish market provides a number of other functions for Vestas which are of considerable value from a business point of view. By means of its high wind penetration, 24% in 2010 – still a world record – Denmark has a role as a forerunner country and a full scale laboratory for conversion to renewable energy.
This means that other countries often look to Denmark when adjusting their legislation regarding wind energy. We are therefore concerned – justifiably so as history shows – that the proposed Danish regulations for low frequency noise from wind turbines will spread to a large number of other markets with much higher commercial impact for Vestas and consequently for employment in the business.
The Danish wind turbine industry employs approx. 25,000 people in Denmark and boasts an export which is about 8.5% of total Danish exports. Such “over-proportional” presence has become possible because Denmark has been able to create the conditions for good correlation between demonstration, education and industry research and development. In reality we fear that the demonstration element will suffer irreparable damage as a result of the new regulations regarding low frequency noise. When combined with the imminent danger that important markets will copy the new Danish regulations, I consider the new regulations to be extremely damaging to the prospects of further popularisation of land-based wind energy.
At this point you may have asked yourself why it is that Vestas does not just make changes to the wind turbines so that they produce less noise? The simple answer is that at the moment it is not technically possible to do so, and it requires time and resources because presently we are at the forefront of what is technically possible for our large wind turbines, and they are the most efficient of all.
In the light of this it seems strange that the wind turbine industry is being discriminated against compared to other industries. All other industries are subject to differential noise requirements regarding low frequency noise for night and day (20 and 25 dB, respectively), whereas the wind turbine industry are subject to requirements of 20 dB 24 hours a day.
The proposed low frequency limit values may hinder the development of onshore wind in Denmark, including meeting our commitments in relation to the EEC. Ultimately, we consider there is a danger that the regulations will be copied by other countries and accordingly this will provide an obstacle to the popularisation of wind energy at a global level. Both issues will damage Vestas as a business, including affecting Danish activities.
Vestas Wind Systems A/S
Chief Executive Officer
Alsvej 21, DK-8940
Dir. +45 9730 0000, www.vestas. com
A copy of this letter was sent to Lykke Friis, Minister for Climate and Energy
*Karen Ellemann, Minister of Environment
Department of Environment
Højbro Plads 4
1200 Copenhagen K
Randers, 29 June 2011/erlgs
Translated from Danish by Bente H. Sorensen, Translationz.com.au
[See Danish news story about subsequent lax rules: Miljøstyrelsen anklages for at fifle med vindmøllestøj]