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Resource Documents: General (93 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.

Date added:  July 17, 2014
GeneralPrint storyE-mail story

Overview of problems and solutions in fire protection engineering of wind turbines

Author:  Uadiale, Solomon; Urbán, Évi; Carvel, Ricky; Lange, David; and Rein, Guillermo

The wind energy industry is one of today’s leading industries in the renewable energy sector, providing an affordable and sustainable energy solution. However, the wind industry faces a number of challenges, one of which is fire and that can cast a shadow on its green credentials. The three elements of the fire triangle, fuel (oil and polymers), oxygen (wind) and ignition (electric, mechanical and lighting) are present and confined to the small and closed compartment of the turbine nacelle. Moreover, once ignition occurs in a turbine, the chances of externally fighting the fire are very slim due to the height of the nacelle and the often remote location of the wind farm. Instances of reports about fires in wind farms are increasing, yet the true extent of the impact of fires on the energy industry on a global scale is impossible to assess. Sources of information are incomplete, biased, or contain non-publically available data. The poor statistical records of wind turbine fires are a main cause of concern and hinder any research effort in this field. This paper aims to summarise the current state of knowledge in this area by presenting a review of the few sources which are available, in order to quantify and understand the fire problem in wind energy. We have found that fire is the second leading cause of catastrophic accidents in wind turbines (after blade failure) and accounts for 10 to 30% of the reported turbine accidents of any year since the 1980’s. In 90% of the cases, the fire leads to a total loss of the wind turbine, or at least a downtime that results in the accumulation of economic losses. The main causes of fire ignition in wind turbines are (in decreasing order of importance): lighting strike, electrical malfunction, mechanical malfunction, and maintenance. Due to the many flammable materials used in a wind turbine (eg. fiberglass reinforced polymers, foam insulation, cables) and the large oil storage used for lubrication of mechanical components, the fuel load in a turbine nacelle is commonly very large. The paper finishes with an overview of the passive and active protection options and the economics (costs, revenue and insurance) of wind turbines to put in context the value of a loss turbine compared to the cost and options of fire protection. We hope that this paper will encourage the scientific community to pursue a proper understanding of the problem and its scale, allowing the development of the most appropriate fire protection engineering solutions.

SOLOMON UADIALE, ÉVI URBÁN, RICKY CARVEL, School of Engineering, University of Edinburgh, UK
DAVID LANGE, SP Technical Research Institute of Sweden, Sweden
GUILLERMO REIN, Department of Mechanical Engineering, Imperial College London, UK

Fire Safety Science 11: 200 (2014)

Download original document: “Overview of problems and solutions in fire protection engineering of wind turbines”

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Date added:  May 28, 2014
GeneralPrint storyE-mail story

Anchor cage foundations

Author:  Miceli, Francesco

Anchor cage foundations are an alternative to the embedded ring and they will be a de facto standard in the future.

Basically an anchor cage is a set of bolts, kept together by inferior and superior steel rings. It normally arrives disassembled to the site, and it is mounted by workers in a few hours.

The main advantage is a better transmission of loads to the concrete: sometimes a separation of the embedded ring from the concrete is observed, normally leading to movements of the tower and serious stability problems.

The first steps of anchor cage foundation are identical to the standard foundation: a hole is excavated into the soil with the dimensions indicated in the constructive project, and the bottom is prepared with about 20 cm of blinding concrete.



After the anchor cage is positioned in the middle. It can be assembled right in the foundation hole or somewhere nearby and than it’s moved using a small crane.





When it is in the final position, horizontality of the cage is checked and adjusted as needed (it rest on small feet). Then, reinforcement bars are placed: first radial bars, than concentric bars, shear bars and finally the superior group of bars.

When all bars are ready, concrete is poured and vibrated and the foundation is covered by soil.

Finally, the bottom section of the tower is guided into position and washers and nuts are positioned and pretensioned.

Final tensioning will be applied only when grouting is poured between the tower and the anchor cage. Grouting is a complicated operation that will be described in detail in another post.

May 11, 2012,

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Date added:  April 18, 2014
General, Impacts, Massachusetts, OrdinancesPrint storyE-mail story

Report of the Wind Advisory Committee to the Shelburne Falls Planning Board

Author:  Shelburne Falls, Mass., Wind Advisory Committee

Wind Turbine Systems for Premises Use: “Any system of turbines, whether located on the building or the ground, designed primarily to generate heat or electricity for the principal home or business located on the lot; such systems may generate a limited amount of excess electricity for resale to an electrical utility provided the system is designed principally to supply the electrical needs of the home or business on the lot.”

As written, the bylaw requires more detailed and specific interpretations for the Special Permitting Authority (now the Zoning Board of Appeals) to review, accept, or reject specific proposals for premises-use only wind turbine systems.

The WAC has been tasked by the PB to develop factual and educational material upon which it can draw when developing a more detailed premises use only bylaw. This Report summarizes that factual and educational material. When useful, the Report cites and paraphrases scientific research articles, research reported on web sites, investigations made by committee members and anecdotal evidence. Where useful, the Report makes recommendations to the PB, based upon the information that it has gathered and analyzed.

Date: October 7, 2013

Table of Contents

Part I. Operational and Technical Matters
Section 1: Technology – what devices are for sale now, what defines wind turbine?
Section 2: Small wind definition and efficiency studies
Section 3: Setbacks & height of wind turbines.
Section 4: Anticipated size of premises-use wind turbine systems

Part II. Impacts
Section 5: Impacts to climate, energy security, and economics
Section 6: Impacts to health (noise – infrasound, sound; flicker)
Section 7: Impacts to ecology (birds, bats)
Section 8: Visual nuisance impacts
Section 9: Safety considerations (ice, falling, blade throw, lightning etc.)

Part III. Legal considerations
Section 10: Robust ordinances – what are the elements of a good ordinance or bylaw?
Section 11: Complaint forms, how to manage subsequent problems if they arise
Section 12: Litigation that has arisen with premises-use turbines. Outcomes?

Section 13: Recommendations

Height Limit: The Wind Advisory Committee recommends that any premises-use turbine does not exceed 120 feet from grade to the tip of the blade.

Capacity: The Wind Advisory Committee recommends that the output of nameplate capacity be limited to 10 KW for residential and 30 KW for agricultural/business use.

Excess: In order to comply with the intent that the output be primarily for premises use, the Wind Advisory Committee recommends that the rated name capacity be restricted to the smallest unit available to cover the intended premises use.

Noise: The Wind Advisory Committee recommends that the noise limit of any wind turbine shall not exceed 5 dB above ambient at any lot line and the nearest inhabited residence. The ambient level shall be established by the applicant prior to the submission of an application by a protocol to be determined.

Flicker: The Wind Advisory Committee recommends that the By-law shall not allow any flicker affecting occupied buildings.

Aesthetics: The Wind Advisory Committee recommends to the Planning Board that they take visual impacts and property values considerations into account in the permitting process.

Setback: The Wind Advisory Committee recommends that the setback be double the height of the blade tip from any roadway, structure, or property line.

Certification: The Wind Advisory Committee recommends that any premises-use wind turbine must be an approved turbine on the list certified by the Small Wind Certification Council or other certification agency as approved by the State of Massachusetts.

One turbine per premise: The Wind Advisory Committee recommends that only one turbine be allowed per premises.

Download original document: “Report of the Wind Advisory Committee to the Shelburne Falls Planning Board”

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Date added:  December 2, 2013
General, Noise, Regulations, U.K.Print storyE-mail story

Audible amplitude modulation – results of field measurements and investigations compared to psycho-acoustical assessment and theoretical research

Author:  Stigwood, Mike; Large, Sarah; and Stigwood, Duncan

In the UK the cause of amplitude modulation (AM) and the ability to predict its occurrence is considered abstruse by many. Few have experienced or measured AM and yet conclusions are frequently made asserting that it is rare and that any action to counter its effects is limited by minimal knowledge surrounding its nature and cause. This paper aims to advance current knowledge and opinion of AM. Methods used to successfully investigate AM are confirmed. AM should be measured during evening (after sunset), night time or early morning periods. Meteorological effects, such as atmospheric stability, which lead to downward refraction resulting from changes in the sound speed gradient alter the character and level of AM measured. AM is generated by all wind turbines including single turbines. Propagation conditions, mostly affected by meteorology, and the occurrence of localised heightened noise zones determine locations that will be affected. Measurements from eleven wind farms have been presented and discussed in relation to current research and theory. Findings confirm that AM occurrence is frequent and can readily be identified in the field by measuring under suitable conditions and using appropriate equipment and settings. Audible features of AM including frequency content and periodicity vary both within and between wind farms. Noise character can differ considerably within a short time period. The constant change in AM character increases attention and cognitive appraisal and reappraisal, inhibiting acclimatisation to the sound. It is advised that those responsible for approving and enforcing wind energy development improve their understanding of the character and impact of AM. This can be achieved by attending a listening room experience which has been trialled and is discussed in this paper.

Mike Stigwood, Sarah Large and Duncan Stigwood
MAS Environmental Ltd, Cambridge, UK

Presented at the 5th International Conference on Wind Turbine Noise, Denver, 28-30 August 2013

Download original document: “Audible amplitude modulation – results of field measurements and investigations compared to psycho-acoustical assessment and theoretical research”

Presentation: Audible amplitude modulation – results of field measurements and investigations compared to psycho-acoustical assessment and theoretical research

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