Alternative Energy

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Alternative energy news, and information about renewable energy technologies.

Sep 17

Wind Turbine Noise Solutions

Posted in Energy Inventions | Wind Power | Wind Turbines

Wind Turbine Noise Wind energy is clean energy but not without its usual baggage. Their noise disturbs those who reside in the close proximity with a wind farm. Many a time wind turbines are forced to operate under partial load so that residents and wind farms can exist in peaceful co-existence. But operating under partial load means lower energy production. Even high winds go unutilized in residential areas. The sources of the noises are many. First is the motion of the rotor blades and another is the cogwheels. Cogwheels generate noise in the gearboxes. These are transported to the tower of the wind turbine, where they are emitted across a wide area — and what the residents hear is a humming noise. This noise comes out as if mosquitoes are buzzing constantly.


If an active damping system is employed at wind farms they make this noise somewhat ineffective by producing counter vibrations. To neutralize this humming operators have to install additional damping systems or even substitute the gearbox. And these things are certainly not cost effective. If we examine closely the efficiency of the existing passive damping systems, we will find its success is limited. They operate only at certain frequencies. And it is their greatest drawback because modern wind energy converters rotate and keep changing their rotational speed according to the wind velocity to generate maximum energy. But all this leads to variations in humming sounds too and this limits the usefulness of the modern damping system. Despite noise decreasing measures, humming noises permeate the surrounding areas.

A team of researchers from Schirmer GmbH, ESM Energie – and Schwingungstechnik Mitsch GmbH and the Dr. Ziegler engineering office, IWU are developing an active damping system for wind turbines. The project is financed by the Deutsche Bundesstiftung Umwelt.

This active damping system is obviously an improvement over its predecessors. It senses the change in frequency and neutralizes the noise without affecting the speed of the wind generator. Piezo actuators are the key constituents of this system. These units transform the electric currents into mechanical motion and create “negative vibrations.” These anti-noises offset the vibrations from wind turbines. How do these piezo actuators fine-tune to the changing noise frequencies? Here the research team has devised some sensors that constantly calculate the vibrations coming out from the gearbox. These measurements of frequencies are transferred to the actuator control system. The researchers have already developed a working model of the active vibration dampers, and their next step will be to perform field trials.

  • http://www.windation.com Mark Sheikhrezai

    Large scale wind projects are a good way to harness the power of wind.

    Alternatives such as wind turbines for buildings which is made by Windation Energy systems Inc. of California are a good alternative to the large scale turbines as a distributed energy generation alternatives

    see http://www.windation.com

  • http://www.ministry-of-information.co.uk/blog/ NRT

    I can only presume noise varies with turbine type and location. I lived next to an upland windfarm – and I mean directly next to, as I lived in a tent during PhD fieldwork – for five years, and experienced less noise than produced by sheep. I just hope no-one’s saying ‘all windfarms are noisy’, since my experience proves otherwise.

    Incidentally, regarding your poll question “Do you think wind power is a feasible energy alternative?”, I’d say it is a very feasible energy supplement, but not an *alternative* to, say, nuclear.

  • ETB

    I was standing below an 80m rotor wind turbine (3 of them in the same area) to try and understand what people mean when talking about noise and turbines. These are stood up 400m away from a country road. Cars/lorries going by covered the noise of the turbines.

    Little comment for people against this “new type” of energy (new in Bracketts as wind mills are over 2000 years old, wind energy was first used by the Egyptians): being against any form of energy development is like being against the use of dish washers, washing machines, computers, etc. and they are handy…

    As mentioned above, it can’t replace existing energy sources such as nuclear but wind energy, tidal energy, wave energy, solar etc. are all complementary. As everything they just need to be used in the right way.

  • just watching

    I just visited some wind farms in Oklahoma and New Mexico. What noise are you talking about?

  • Nflight

    There is a noise that is heard at a distance from each Wind Turbine that is inaudible standing beside the large machines. This sound is what is known as Long Wave Propagation, the tone is the resonance frequency which is undetectable by the human ear. The sound is only apparent when the harmonics of the 14 rpm rotation of the turbines comes into contact with buildings farther then 1/4 mile from each turbine.

    I have attempted to contact BOSE Corporation to start a dialogue between my expertise and the ability to reduce the irritating humming sound people are hearing. Reducing the mitigation of the sub-audible irritant is the object here. Noise Canceling technology to be used at sub-audible levels will be the end result.

    Stay Tuned

  • H. Partridge

    Wind turbines are great for alternative energy. People should compromise for the world.

    If you ask me, the constant sound of mosquitos buzzing is not very pleasant. Wind turbines are not that loud.

  • Mehis Ilves

    The problem with gear noise can be solved by using another profile of gear wheels, Novikov`s gear tooth profile for example.
    Problem with noise caused by blade moving in air is solved by one japanese patent. solution can be modified to suite there.

  • krishn

    dear friends,

    I have installed a wind generator of 500w on my roof , but cannot run it because it is causing lots of noise, vibrations while winds positions changes, and a resonance (at high speed) which is transmitted to the whole building. Please suggest how to reduce or eliminate these noises.

  • Clint LeRoy

    Hello Krishn
    First off the best solution is to isolate the Pole of the wind turbine from the building. Remove the combined mounting point of the turbine and the pole and have them separate, similar to a parapet. At the point of connecting the pole/parapet to the house mount the supports with insulating material to deaden the effects of the resonance being generated by the wind turbine. If all else fails install a less noisy and better made wind turbine.

    If you mounted the wind turbine on the roof directly, this is the real problem. You need to remove the wind turbine from the roof support and place the turbine on the ground next to, or isolated away from the building.

    Wind turbines in normal use should not exude more then ambient noise levels of 68 to 72 db. If your wind turbine is producing higher pitched squeals or chips and clatters in its workings you have a bad wind turbine. The Bad wind turbine can be from design or from a lack of testing adequately to push out to the public for ownership. Please contact the manufacturer as they too may be able to help you. It is there machine producing the clatter after all.

    Hope this helps

  • Mehis

    Hello, Krishn!

    You have probably a serious problem and it is not so easy to solve. At first try to balance blades statically, it seems to be the main solution of your problem. I have no idea, how you mounted the unit on the roof and there will be the second step to do. If possible, please, some photos will be useful. How to do this job I shall explain direct to you, if you need. There will be a lot of recommendations and sketches to explain,(I have these recommendations in my native language and these needs to translate first.). And I have no idea about Your workshop`s capabilities too.

    Mail to my private and I will try to help you.
    Mehis Ilves,
    m5ilves[AT]hot.ee

  • stan francis

    Haven’t got time to make this idea up, but here goes if anyone can say how it can be done, I am no engineer of that type, just a compressed air one. Instead of using a propeller, how about fluting the air down a pipe and creating a flapper at the other end?-like a reed in a wind instrument?-this will give up and down movement, if this can be attached to a plunger of types connected to a generator, say a coil of wire and magnet? Perhaps I should get back to the moonshine… happy new year everyone and keep on experimenting whilst the UK(YUK) goes down the plug hole!

  • Lewis Wheel

    Hi.

    The problem with wind turbine noise is not the disturbance created during the day, but at night. It is not only quieter at night that during the day, but also the natural turbulence in the atmosphere is lower and the noise can travel further away with lower dissipation levels.

    It is a real problem for the people living near wind farms, and since more and more often wind turbines are installed near populated areas, it is becomming a problem for the industry, due to noise regulations.

    In order to comply with noise regulations, the rotational speed of industrial wind turbines is artificially cut off for wind speeds between 6 and 10 m/s (measured at 10m heigh above the ground). This is the most effective way to reduce the noise, since the aeroacoustic noise (the main source of noise in WTG) is proportional to the 5th-6th power of the rotational speed. Nevertheless, reducing the rotational speed reduces considerably the amount of energy production.

    Wind turbine manufacturers are working on many ways to reduce the noise, like noise-reduction-oriented blade redesign or flow control. Wind turbine noise management is receiving a lot of attention for the R&D community.

    In response to Stan Francis the only issue with your idea is the amount of energy required to compress the air. Air compressing devices are being considered by the wind turbine industry as a mean to store the energy; this means that if the energy is not used when it is produced it could be stored and then used when needed. It was found that currently only a 30% (approx.) efficiency was achieved. This means that of all the energy used to compress the air, roughly one third could be recovered.

    Regards.

  • Clint LeRoy

    Mr. Wheel
    Your comment in the first paragraph is a load of horse droppings. The noise does not change with the alteration of the suns proximity around the globe. Daytime or nighttime the sounds is persistent.

  • Stan

    “The Truth about Industrial Wind Energy” – a good presentation with major part related to noise and vibration issues.

    http://www.youtube.com/watch?v=EfPNsvbcMXk&feature=related

  • Shane Matthews

    Wind turbines will truly come into their own once super capacitors, which can be instantly charged and discharged, replace the common battery. Because batteries must be charged and discharged at certain rates, they have never been effective at storing energy from variable-output devices like solar panels or wind turbines. It’s ironic to think that the circle is now complete; the future of electricity depends on a modern equivalent of one of the oldest electrical devices, the Leyden Jar.

  • Bob Winners

    Hah! More negative alternative news generated by your local coal/natural gas powered utility. These same people who pollute our air with exhaust also attempt to pollute our minds with lies about the alternatives. Big money wants to keep power generation under their control and not have is spread to every back yard in the country. There are some benefits to large production facilities, but they should be municipally owned and operated.

  • Belacqua

    Actually Mr LeRoy, it’s not necessarily horse droppings – the conditions are in fact often different at nighttime. Stable wind conditions often arise at night, which give rise to higher wind shear and therefore lower wind noise levels at ground level for a similar wind speed at hub height. Also, temperature inversions which more commonly occur at night can also refract the sound and alter the propagation characteristics.

  • Ray

    The winds are more consistent and greater at higher altitudes. Raise wind generators to these altitudes using anchored balloons. The balloons can be kept filled with gas by running a flexible tube from the ground to the balloon.

  • bruce

    So what is the Japanese patent that will quiet these monsters?


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