Invitation to Topical Expert Meeting on NOISE REDUCTION TECHNOLOGIES

Transcription

1 April 2013 Invitation to Topical Expert Meeting on NOISE REDUCTION TECHNOLOGIES At Executive Committee meeting 70 in Tokyo it was decided to arrange a Topical Expert Meeting on Noise Reduction Technologies. VTT Technical Research Centre of Finland is the host of the meeting Date and venue for the meeting is as follows: June 11 and 12 (2013) VTT House, Tekniikankatu 1 Tampere, Finland The meeting will begin at on Tuesday and will end around on Wednesday. This invitation is for 2-4 people per IEA country who will be able to discuss the subject in detail and give a short presentation relevant to the topic. An introductory note to the meeting has been prepared, see attachment. Proceedings from the meeting will be distributed soon after the symposium. Participants are urged to bring along one copy of the material they want to have included in the documentation. Details on travel and accommodation can be found on the following pages. The contact persons at VTT Technical Research Centre of Finland are: Hannu Nykänen (program and other details of the meeting) hannu.nykanen@vtt.fi Pirkko Tulijoki (travel to and accommodation in Tampere) pirkko.tulijoki@vtt.fi Attachments: 1. IEA background and meeting format 2. Practical arrangements 3. Introductory note

2 1. IEA BACKGROUND AND MEETING FORMAT The objective of IEA RD&D Wind Task 11 is to promote wind turbine technology through cooperative activities and information exchange on RD&D topics of common interest. The Topical Expert Meetings are workshops, where information is presented / discussed freely in an open manner. See the following web page for more details: and click on General description and meeting format. More information can be obtained from: IEA RD&D Wind general IEA official home page There is no cost for participation in the meeting, except for your personal expenses for travel and accommodation. The national representatives of the countries participating in Task 11 cover meeting costs. 2. PRACTICAL ARRANGEMENTS Date and venue: Meeting date: June 11 th 09:00 17:00 - June 12 th 09:00 15:00 Meeting place: VTT House, Tekniikankatu 1, Tampere, Finland Meeting location: Meeting room Neula (A129) Tel.: s: (Hannu Nykänen) (Pirkko Tulijoki) hannu.nykanen@vtt.fi / pirkko.tulijoki@vtt.fi Web site: To see more information of TAMPERE you can visit:

3 Hotel accommodation Cumulus Koskikatu Hotel Koskikatu 5, TAMPERE Tel Fax: Please book your hotel accommodation directly with the hotel Central Booking Office: Tel , my.reservation@restel.fi and indicate code IEA RDD Noise for the application of the special prices: Rates: EUR/night/single standard room and EUR/night/twin standard room. Rates are net and per night inclusive of buffet breakfast, sauna and service charge. Terms of payment: Cash or credit card. The room allotment will be released on Travel Instructions Tampere can be reach by air, bus or by train. Below you can see how to get to Tampere. BY AIR There are several daily connections to Helsinki from major cities in Europe: From Helsinki-Vantaa Airport (HEL) there are frequent daily flights to Tampere-Pirkkala Airport (TMP). The flight time is about 30 minutes. Note a long walk when you change flight to Tampere. There are also direct flight to Tampere-Pirkkala from Copenhagen by SAS. Note a long walk when you change flight to Tampere. The easiest route to Tampere by SAS ( direct flights from Sweden, Stockholm (STO) to Tampere-Pirkkala Airport (TMP). A low fare airline Ryanair operates to Tampere-Pirkkala from London, Stansted (no Heathrow). Tampere-Pirkkala Airport is located 17 kilometres southwest from Tampere city centre. Regular buses and taxis operate between the airport and Tampere. Bus number 61 is operating between Pirkkala airport and Tampere city center. Time table can be found in the following web site: The one-way bus ticket cost 4,60, you can buy it from the driver (with cash). Please note that the bus leaves near the terminal 1; Ryanair uses the terminal 2.

4 Also in Tampere city centre, you have to leave from bus at stop called Koskipuisto (next stop after bus station stop and before central square stop ). There is approx. 100m walk to hotel Cumulus Koskipuisto. Other option is take the taxi from Pirkkala airport directly to hotel, the taxi will cost approx BY BUS from Helsinki-Vantaa airport to Tampere There is also a direct express bus connection to Tampere from Helsinki-Vantaa airport. Buses leave at regular intervals at all hours. The travelling time is about 2 hours 30 minutes and costs some BY TRAIN from Helsinki to Tampere Helsinki railway station located 18 kilometres from Helsinki-Vantaa airport. There are excellent and reliable train connections between Helsinki and Tampere city centre. Trains depart every hour (except for the night time) and the travelling time is under 2 hours. Travel from the hotel to VTT House (8 km) From hotel to VTT you can use the bus number 13 or 20. The nearest bus stop is on the main street Hämeenkatu name Koskipuisto. Please find the timetables here: number 13: number 20: Click a stop name to show a timetable for a specific stop: Koskipuisto. The end stop is Hervannan valtaväylä for both buses where you have to walk about 50m to VTT house. You can find the journey planner here: One-way ticket prize is 2,50. You can buy it from the driver with cash.

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6 INTRODUCTORY NOTE BACKGROUND Thriving towards a more carbon free energy production has led to large wind power exploitation, that is on-going and growing also to new countries. For acceptance of this exploitation, careful account must be taken of how humans perceive the environmental changes incurred. Noise immission from wind turbines is one such change. The wind turbine market is very international. A substantial number of common rules and guidelines have been developed over the years. This is true also for the noise generation and emission issue: important examples being the development of the existing IEC standards. Wind turbines generate noise from multiple mechanical and aerodynamic sources. As the technology has advanced, wind turbines have gotten much quieter, but noise from wind turbines is still a public concern. The problems associated with wind turbine noise have been one of the more studied environmental impact areas in wind energy engineering. Noise levels can be measured, but, similar to other environmental concerns, the public's perception of the noise impact of wind turbines is in part a subjective determination. Noise reduction of wind turbines has recently become more important due to increasing large-scale turbine developments, stringent noise regulations, and installation of wind power plants near residential areas. At the present time, the noise produced by wind turbines has diminished as the technology has improved. As blade airfoils have become more efficient, more of the wind energy is converted into rotational energy, and less into acoustic noise. Vibration damping and improved mechanical design have also significantly reduced noise from mechanical sources. NOISE REDUCTION TECHNOLOGIES Several projects are ongoing with the target of development of technologies for noise reduction. Possible ways to reduce or mitigate noise include low noise turbine design (like blade design and avoiding resonances from tower structures) and using wind turbine control during operation. Wind turbine noise is mainly caused by broadband noise from the blades and can be reduced using noise prediction technologies. Efforts to reduce aerodynamic sounds have included [Wagner, et al., 1996] the use of lower tip speed ratios, lower blade angles of attack, upwind rotor designs, variable speed operation and most recently, the use of specially modified blade trailing edges. Turbines can be designed or retrofitted to minimize mechanical sound. This can include special finishing of gear teeth, using low-speed cooling fans and mounting components in the nacelle instead of at ground level, adding baffles and acoustic insulation to the nacelle, using vibration isolators and soft mounts for major components, and designing the turbine to prevent sounds from being transmitted into the overall structure. Recent improvements in mechanical design of large wind turbines have resulted in significantly reduced mechanical sounds from both broadband and pure tones. Today, the sound emission from modern wind turbines is dominated by broadband aerodynamic sounds [Fégeant, 1999].

7 On the other hand, according to legislation from the EU the sound emissions from the installation of wind power plants at sea must be reduced so the threat to the marine mammals are minimised. Traditionally, the water borne noise from driving monopiles into the seabed has not been reduced, but with a new and innovative technology developed by Lo-Noise in Denmark, it is now possible to reduce the noise with up to 25 db in a radius of 750 m. Other example of projects ongoing is the project that began in 2010 in the Maine Technology Institute (USA), to find out whether noise-cancelling technology, can be applied to help with the problems some people have with turbine noise leaving near to Fox Islands wind farm. The concept for the project is that the sounds from the turbines would be measured, and a specific waveform derived from that sound would be transmitted to speakers inside the home. These speakers would produce a sound that cancels the turbine noise. In order to test this concept, the sounds the turbines make must be recorded from inside the home. Once the recording is finished, engineers will study the data and determine if this technology can be applied to turbine noise. Another issue of relevance for judging the effect of a certain immission from wind turbines is the possibility to estimate masking from background noise. In this field the procedure in many countries seem to be based on empirically determined background noise curves. An alternative is to try to develop general models. Concerning vegetation noise a model was suggested by Fégeant (1999). Recently this model has been improved and validated by further measurements Bolin (2006). Concerning noise from breaking waves an effort to find a scaling law is described by Appelqvist et al. (2006). TOPICS TO BE ADDRESSED 1. Challenges from low frequency and amplitude modulated noise 2. Noise reduction options through turbine design to minimize mechanical sound 3. Noise reduction options through turbine design to minimize aerodynamic sound 4. Operational strategies through turbine controls to reduce noise emission, and wind farm design 5. Modelling and Experimental investigations on long range sound propagation in the atmosphere: 6. Background noise (wind driven) 7. Masking of wind turbine noise INTENDED AUDIENCE The target audience for this meeting is turbine manufacturers, authorities responsible for defining and enforcing legal product requirements, researchers and consultants. A short presentation, of their experiences in the field, is expected from participants. Title of presentation can be chosen freely in line with the intention in the Introductory Note. The allocated time is minutes including questions and discussion. However, the time is dependent on the number of presentations that will be given.

8 INTENDED AUDIENCE The target audience for this meeting is government policy makers, authorities responsible for defining and enforcing legal product requirements, researchers and consultants. A short presentation, of their experiences in the field, is expected from participants. Title of presentation can be chosen freely in line with the intention in the Introductory Note. The allocated time is minutes including questions and discussion. However, the time is dependent on the number of presentations that will be given. TENTATIVE AGENDA The tentative agenda covers the following items: 1. Introduction by host 2. Introduction by Operating Agent, Recognition of Participants 3. Collecting proposals for presentations 4. Presentation of Introductory Note 5. Individual presentations 6. Discussion 7. Summary of meeting 8. OUTCOME OF MEETING The outcome of the meeting is the proceedings including a short summary of the presentations and a compilation of topics that are crucial for calculation of sound propagation around wind turbines. FURTHER READING Anthony L. Rogers and James F. Manwell, 2002, Wind Turbine Noise Issues Anthony L. Rogers and James F. Manwell, 2002, Wind Turbine Acoustic Noise Kentaro Hayashi, 2012, Low-noise Design for Wind Turbine Blades Fégeant, O Wind-induced vegetation noise. Part 1&2. Acta Acustica, 85. Bolin, K Masking of wind turbine noise by ambient noise, Lic. Tech. thesis, KTH, TRITA-AVE-2006:86. Appelqvist, P., Almgren, M, Bolin, K. and Åbom, M Masking of wind turbine noise by sea waves. Proc. BNAM.