Wind Power Turbines
General Overview
This article is designed to provide a basic understanding of the nature and operation of Wind Turbines. For answers to any questions not answered here, please contact our office.
Global Warming
The growing concern about Global Warming and Greenhouse gas production has lead Governments worldwide to consider clean alternatives to Coal and Diesel for the production of electricity. Australians are the worst greenhouse gas emitters in the world. 43% of Victoria’s emissions are produced by the burning of brown coal for the production of electricity. The Australian Government has set a requirement that by 2010 Renewable Energy will provide 9500 gigawatt hours of electricity per year. This equates to approximately 4000 megawatts of installed capacity of Renewable Energy sources or the equivalent of two Loy Yang A power stations. Renewable Energy is clean energy and is as close to greenhouse gas neutral as it is possible to achieve.
Why Wind
What about Solar Power, Hydropower and Biomass. Solar electricity is currently very expensive (about $13 per watt installed) And there is no sign of solar getting any cheaper, in fact all suppliers of solar panels have recently increased their prices. While well suited to applications such as remote homes, remote communications and navigation aids for instance, the cost and payback period for grid connected solar is not viable without government grants.
- Hydro electricity is by far the most cost effective form of Renewable Energy, however Government policy is that no new dams will be built for Hydro, so the only opportunities are to install Hydro Turbines on existing infrastructure or dams, these opportunities are few and far between and will not be enough to meet the requirement.
- Biomass covers a wide range of energy sources and technologies, from burning household rubbish to make steam for the generation of electricity to growing crops to burn or to produce oil (i.e. Canola oil) which when treated can be used as a Diesel substitute. The economies of these technologies have yet to be proven.
Wind Energy is Proven Technology
Some European countries have had Wind Turbines in operation for over 20 years. Wind Energy production costs in Europe are now competing with coal fired power stations. Since 1990 the Wind Energy Industry has been the fastest growing sector of the power generation industry and continues to be so. Large scale Wind Turbines can be installed for about $2.00 per watt or about two million dollars per megawatt. A typical Wind Farm will use about 1% of the area where it is constructed leaving the rest for normal farming or grazing practices. Wind Turbines have a designed working life of 20 to 25 years and require very little maintenance during this time. Wind Turbines are safe, there has been no recorded injury to a member of the general public anywhere in the world.
Wind Turbines
Wind Turbines will typically be installed in small groups of 2 to 5 units connected to the existing utility grid, or in larger groups of 10 to 30 units with a dedicated transmission line to a suitable connection point at a nearby high voltage cable or switchyard. The Turbine consists of a large set of 3 blades which drive a generator via a large gearbox, this is installed in a nacelle which is mounted on a powered turntable at the top of a tall tower. (see fig 1) When the wind speed increases above a certain speed , known as the cut in speed typically about 3 to 4m/s (meters per second) The Turbine will begin to generate electricity, and will continue to do so until the wind speed reaches the cut out speed, (about 25m/s) at this point the turbine will shut down, rotate out of the wind and wait for the wind speed to drop to a suitable speed to allow the Turbine to start again. The Turbine will have an optimum operating wind speed at which maximum output will be achieved, this is typically about 13 to 16m/s During operation the generator ensures that the blades maintain a constant speed of about 20 revolutions per minute, which the gearbox transforms into 1500 revolutions per minute. Higher wind loads acting on the blades result in increased power production but not a higher number of revolutions per minute.
How Big
Wind Turbines are big (see fig 3) a typical Turbine of the size to be used in Australia will be installed on a tower which is between 50 meters (150 feet) and 80 meters (240 feet) tall. The rotor diameter (blade span) will be between 50 meters (150 feet) and 80 meters (240 feet).
Turbine towers are constructed from rolled steel plate and are normally about 4 to 5 meters (12 to 15 feet) diameter at the base and about 2 to 3 meters (6 to 9 feet) diameter at the top. Turbines are installed on concrete foundations that are buried well below ground level with a pedestal to mount the tower on so the landholder can work the land right up to the base of the tower.
Noise
Wind turbines are not noisy; a typical 1.5 megawatt (15,000,000 watt) Turbine, similar to the Turbines installed at Codrington and Toora will produce 45dB(A) or less at 300 meters. This noise level is about the same noise level you will hear sitting in your kitchen listening to your fridge. The average noise level in a typical home is 50dB(A). However this is only the noise produced by the Turbine, the natural wind rush noise is heard as well and this is normally about 40dB(A) so the end result at a typical exclusion distance of 300 to 400 meters is that the Turbines are almost inaudible. Some Turbines produce up to 100dB(A) but this is measured at the gearbox at the top of the tower. The fact is that with the turbine running at its rated speed a normal conversation can held at the base of the tower. This can be proven quite easily by visiting one of the existing Wind Farms and hearing for yourself.
Embodied Energy
A typical large Wind Turbine will recover the energy used to manufacture and construct it; (embodied energy) in 4 to 5 months of operation in a reasonable wind regime. It should be remembered that a coal fired power station never recovers the energy used to construct and operate it as these power stations have a continuing requirement for very large amounts of energy to operate.
Wind Turbines will not replace Coal Power Stations
Wind as we all know is neither constant or consistent but society requires an electricity supply that is, so base load power stations will always be required.
What Wind and other Renewable Energy sources can do is supplement these base load power stations and reduce the consumption of coal and therefore emissions. Wind Turbines have never caused an existing power station to close down, but it has meant that in countries like Denmark, Holland, Spain, Italy and Germany new coal fired power stations do not need to be built. Germany is oneof the largest users of Wind Energy with 6113megawatts of Wind Turbines installed, this is assisting the German Government to close its nuclear power stations. The Danish Government has determined that Wind Energy will provide 50% of the countries energy requirements by 2030; this means a 50% reduction in greenhouse emissions if this Energy was sourced from coal power stations.
In Victoria the brown coal power stations of the LaTrobe Valley produce almost 10% of Australia’s
CO2 emissions or 2kg of CO2 for every kilowatt hour of electricity produced.
Birds
Wind Turbines pose little threat to birds, there is little real evidence here or overseas that bird strikes on Wind Turbines present any real problem providing the Turbines are placed with care and thought. The Americans who in the 80’s built several Wind Farms in California have largely caused the concern regarding bird strikes. These Wind Farms were built without consideration of aesthetic or environmental issues and caused many problems including bird kills. The Wind industry worldwide has learnt from this experience and no reputable Wind Farm Developer would consider the wall to wall Wind Turbine option. It is unlikely that any Council or State Government would allow this type of development. If we are really concerned about the plight of Birds perhaps we should be looking at Cats, Cars and power lines.
Capacity Factor
Capacity factor, sometimes called load factor is the amount of time an energy production source is able to produce electricity. A coal power station will have a capacity factor of 65 to 85% that is, it will be able to produce output for 65 to 85% of the time, it will be out of action the rest of the time due to maintenance, labor strikes, breakdowns etc. A typical Wind Turbine will have a capacity factor of 25 to 40% depending on the available wind resource. Currently in Australia a Wind Farm will need a capacity factor of 32% or better to be viable.
What does having Wind Turbines on your property Mean To You
For some people the greatest benefit of having Wind Turbines on their property will be the contribution to reducing greenhouse gas emissions and for others it will be the guaranteed income for the life of the Turbines (20 to 25 years) Currently you could expect up to $3000 per megawatt installed (or part there off) per annum with no outgoings at all. The process of establishing Wind Turbines can be a drawn out affair and may take 2 to 3 years from first contact to construction and commissioning. The following steps will need to be undertaken prior to construction.
Land holder agreements and contracts.
This usually means you will be asked to commit to allow your site to be monitored for Wind with the option to negotiate a contract to proceed to construct Wind Turbines If the results of the monitoring prove satisfactory. These initial agreements are usually for 3 to 5 years. The agreements are flexible and allow the land holder to apply conditions to the agreement.
I.e. prior notification of a visit, gates must be closed, cars must follow tracks etc.
Site Monitoring
This normally requires:
The installation of a temporary mast the same height as the proposed Turbines hub, (known as hub height)
This will be between 50 and 80 meters (150 to 240 feet) This mast will be equipped with one or more wind monitoring instruments, these will relay data to a recording device (logger) at the base of the mast.
The stored data will be down loaded about once per month. No input is required from the land holder. The mast is normally guyed and as long as the guy anchor points are fenced to avoid cattle rubbing and stretching the guy’s, the mast should not interfere with normal use of the land.
Monitoring will most often take 12 months but may only be 6 months if there is a reference point nearby.
Operation and Maintenance
Once the Wind Turbines have been commissioned it will operate with little human intervention. All monitoring and adjustments can be made remotely via a computer, staff will visit the Turbine to perform routine maintenance as required.
Permits, Statutory Requirements and Common Sense
Once a site has been proven a number of statutory requirements will need to be undertaken as well as matters of common sense and common courtesy. These will include but may not be limited to the following.
- Consultation with neighbors and nearby residents.
- Consultation with local community.
- Consultation with local indigenous groups.
- Consultation with the Council.
- The undertaking of an environmental effects study.
- A study into Flora and Fauna (birds) issues.
- Native title issues.
- Planning and permitting.
This process may take up to 2 years or more but is likely to be 12 to 18 months.
Construction
When a permit is issued, construction will commence. Soil testing will be undertaken to determine the type of foundation required for the Turbine towers and in consultation with the land holder access tracks will be formed to allow heavy construction equipment to enter the site. These tracks and earthworks can be left when construction is complete for farm use or the ground reinstated to it’s original state. Once the foundations have cured construction is quite rapid and a Turbine can be erected in 1 or 2 days with another 2 or 3 days for commissiong a small area will be required for the installation of the transformers and switchyard. This area will be fenced with chain wire and present no hazard to man or beast.