Resource Documents: Safety (47 items)
Documents presented here are not the product of nor are they necessarily endorsed by National Wind Watch. These resource documents are 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.
Author: Sarlak, Hamid; and Sørensen, Jens
Figures 4 to 6 show the results for different-size blade pieces from different-size turbines at different wind speeds and blade tip speeds. For normal tip speeds (figs 4 and 5), the potential blade throw distance for a 2.3-MW turbine was calculated to be ~500 m (1,640 ft) and for a 5-MW turbine ~900 m (2,953 ft). At “extreme” tip speeds (fig 6) the corresponding distances were 800 m (2,625 ft) and 1500 m (4,921 ft).
[ABSTRACT] This paper aims at predicting trajectories of the detached fragments from wind turbines, in order to better quantify consequences of wind turbine failures. The trajectories of thrown objects are attained using the solution to equations of motion and rotation, with the external loads and moments obtained using blade element approach. We have extended an earlier work by taking into account dynamic stall and wind variations due to shear, and investigated different scenarios of throw including throw of the entire or a part of blade, as well as throw of accumulated ice on the blade. Trajectories are simulated for modern wind turbines ranging in size from 2 to 20 MW using upscaling laws. Extensive parametric analyses are performed against initial release angle, tip speed ratio, detachment geometry, and blade pitch setting. It is found that, while at tip speeds of about 70 m/s [157 mph] (normal operating conditions), pieces of blade (with weights in the range of approximately 7-16 ton) would be thrown out less than 700 m for the entire range of wind turbines, and turbines operating at the extreme tip speed of 150 m/s [336 mph] may be subject to blade throw of up to 2 km from the turbine. For the ice throw cases, maximum distances of approximately 100 and 600 m are obtained for standstill and normal operating conditions of the wind turbine, respectively, with the ice pieces weighing from 0.4 to 6.5 kg. The simulations can be useful for revision of wind turbine setback standards, especially when combined with risk assessment studies.
Hamid Sarlak and Jens N. Sørensen
Section of Fluid Mechanics, Department of Wind Energy, Technical University of Denmark, Lyngby, Denmark
Wind Energy 2016; 19:151–166. DOI: 10.1002/we.1828
Download original document: “Analysis of throw distances of detached objects from horizontal-axis wind turbines”
See also: : “A method for defining wind turbine setback standards” by Jonathan Rogers, Nathan Slegers, and Mark Costello, Wind Energy 2012; 15:289–303
Author: Neville, Tania
There is a growing body of information, data, opinion, litigation and complaint surrounding the proliferation of industrial wind turbine developments worldwide. Governments have been quick to adopt the purported clean energy benefits of such development but slow to advance and implement appropriate guidelines, enforcement mechanisms and a means to examine what appears to be a growing public health issue related to noise.
This paper reviews case law to date and current health and independent noise data that indicate litigation in common law for private nuisance and negligence may succeed based on the common complaints associated with living near industrial wind turbines, that is, noise, health problems and property devaluation.
Planning and guidelines in relation to these developments now offer certainty to developers but have reduced the input of locals and local government. It is considered that the global view cannot override well established common law principles and that those impacted by these developments locally, should be able to seek redress in the courts.
Government responses to global problems should not result in harm or damage to individuals or small communities.
Download original document: “Industrial wind energy: When planning & guidelines fail the locals; Is common law an instrument to protect neighbours? A discussion on nuisance and negligence actions relating to noise and health”
Author: Wiser, Ryan; Yang, Zhenbin; et al.
[section 220.127.116.11 (pp. 575-576), “Wind Energy,” IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation, 2011]
A variety of proximal ‘nuisance’ effects are also sometimes raised with respect to wind energy development, the most prominent of which is noise. Noise from wind turbines can be a problem, especially for those living within close range. Possible impacts can be characterized as both audible and sub-audible (i.e., infrasound). There are claims that sub-audible sound, that is, below the nominal audible frequency range, may cause health effects (Alves-Pereira and Branco, 2007), but a variety of studies (Jakobsen, 2005; Leventhall, 2006) and government reports (e.g., FANM, 2005; MDOH, 2009; CMOH, 2010; NHMRC, 2010) have not found sufficient evidence to support those claims to this point. Regarding audible noise from turbines, environmental noise guidelines (EPA, 1974, 1978; WHO, 1999, 2009) are generally believed to be sufficient to ensure that direct physiological health effects (e.g., hearing loss) are avoided (McCunney and Meyer, 2007). Some nearby residents, however, do experience annoyance from wind turbine sound (Pedersen and Waye, 2007, 2008; Pedersen et al., 2010), which can impact sleep patterns and well-being. This annoyance is correlated with acoustic factors (e.g., sound levels and characteristics) and also with non-acoustic factors (e.g., visibility of, or attitudes towards, the turbines) (Pedersen and Waye, 2007, 2008; Pedersen et al., 2010). Concerns about noise emissions may be especially great when hub-height wind speeds are high, but ground-level speeds are low (i.e., conditions of high wind shear). Under such conditions, the lack of wind-induced background noise at ground level coupled with higher sound levels from the turbines has been linked to increased audibility and in some cases annoyance (van den Berg, 2004, 2005, 2008; Prospathopoulos and Voutsinas, 2005).
Significant efforts have been made to reduce the sound levels emitted by wind turbines. As a result, mechanical sounds from modern turbines (e.g., gearboxes and generators) have been substantially reduced. Aeroacoustic noise is now the dominant concern (Wagner et al., 1996), and some of the specific aeroacoustic characteristics of wind turbines (e.g., van den Berg, 2005) have been found to be particularly detectable (Fastl and Zwicker, 2007) and annoying (Bradley, 1994; Bengtsson et al., 2009). Reducing aeroacoustic noise can be most easily accomplished by reducing blade speed, but different tip shapes and airfoil designs have also been explored (Migliore and Oerlemans, 2004; Lutz et al., 2007). In addition, the predictive models and environmental regulations used to manage these impacts have improved to some degree. Specifically, in some jurisdictions, both the wind shear and maximum sound power levels under all operating conditions are taken into account when establishing regulations (Bastasch et al., 2006). Absolute maximum sound levels during the day (e.g., 55 A-weighted decibels, dBA) and night (e.g., 45 dBA) can also be coupled with maximum levels that are set relative to pre-existing background sound levels (Bastasch et al., 2006). In other jurisdictions, simpler and cruder setbacks mandate a minimum distance between turbines and other structures (MOE, 2009). Despite these efforts, concerns about noise impacts remain a barrier to wind energy deployment in some areas.
In addition to sound impacts, rotating turbine blades can also cast moving shadows (i.e., shadow flicker), which may be annoying to residents living close to wind turbines. Turbines can be sited to minimize these concerns, or the operation of wind turbines can be stopped during acute periods (Hohmeyer et al., 2005). Finally, wind turbines can shed parts of or whole blades as a result of an accident or icing (or more broadly, blades can shed built-up ice, or turbines could collapse entirely). Wind energy technology certification standards are aimed at reducing such accidents (see Section 7.3.2), and setback requirements further reduce the remaining risks. In practice, fatalities and injuries have been rare (see Chapter 9 for a comparison of accident risks among energy generation technologies).
Author: Mabbott, Bruce
Due to the sound concerns regarding the first wind turbine installed at the wastewater treatment facility, the manufacturer of the turbines, Vestas, is keen for the Town of Falmouth to understand the possible noise and other risks associated with the installation of the second wind turbine.
The Town has previously been provided with the Octave Band Data/Sound performance for the V82 turbine. This shows that the turbine normally operates at 103.2dB but the manufacturer has also stated that it may produce up to 110dB under certain circumstances. These measurements are based on IEC standards for sound measurement which is calculated at a height of 10m above the base of the turbine.
We understand that a sound study is being performed to determine what, if any, impacts the second turbine will have to the nearest residences. Please be advised that should noise concerns arise with this turbine, the only option to mitigate normal operating sound from the V82 is to shut down the machine at certain wind speeds and directions. Naturally this would detrimentally affect power production.
The manufacturer also needs confirmation that the Town of Falmouth understands they are fully responsible for the site selection of the turbine and bear all responsibilities to address any mitigation needs of the neighbors.
Finally, the manufacturer has raised the possibility of ice throw concerns. Since Route 28 is relatively close to the turbine, precautions should be taken in weather that may cause icing.
To date on this project we have been unable to move forward with signing the contract with Vestas. The inability to release the turbine for shipment to the project site has caused significant delays in our project schedule. In order to move forward the manufacturer requires your understanding and acknowledgement of these risks. We kindly request for this acknowledgement to be sent to us by August 4, 2010, as we have scheduled a coordination meeting with Vestas to discuss the project schedule and steps forward for completion of the project.
Please sign in the space provided below to indicate your understanding and acknowledgement of this letter. If you have any questions, please do not hesitate to call me.
Bruce Mabbott, Project Manager
Solaya, a Division of Lumus Construction
August 3, 2010
Mr. Gerald Potamis
Town of Falmouth [Mass.] Public Works
Sumul Shah, Lumus Construction, Inc.
Stephen Wiehe, Weston & Sampson
Brian Hopkins, Vestas
Download original document: “RE: Falmouth WWTF Wind Energy Facility II ‘Wind II”, Falmouth, MA – Contract No. #3297”