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Note: This is a work in progress and more myths and facts will be added later.
13/05/08 Added myth 5.
24/06/08 Added Whalepower info.
Myth 1: More energy is required to build a wind turbine than it will ever produce in its life time.
Much research has been done around the world into wind turbine 'Energy Balance' and 'Energy Pay Back Times'. They all generally show that large wind turbines positioned in appropriate locations actually out perform or at least equal almost any fossil fuel source of energy.
Typically a large 1MW or greater turbine (the biggest offshore turbine to date is 7.5MW) will produce between 11 and 30 times more energy than would be used to build and maintain it. By comparison other sources have energy payback ratios of:
1. Coal - between 7 and 34
2. Gas - between 5 and 26
3. Hydro - between 43 and 205
4. Wind - between 11 and 30
What these figures mean is that large wind turbines will produce far more energy than was ever used to make and maintain them.
Note: these comments may not apply to small microgeneration wind turbines.
References:
Royal Institute of Technology, Sweden.
Barbara Batumbya Nalukowe, Jianguo Liu, Wiedmer Damien,Tomasz Lukawski,
Life Cycle Assessment of a Wind Turbine, 22 May 2006
Kansas Geological Survey
White, Scott,
Net Energy Payback and CO2 Emissions from Three Midwestern Wind Farms: An Update. December 2006
The World Nuclear Association - Energy Analysis of Power Systems.
Other respected sources of information not used here:
Gagnon, Belanger and Uchiyama,
Life Cycle Assessment of Electricity Generation Options: the Status of Research in year 2001.
Lenzen and Munksgaard,
Energy and CO2 Analysis of Wind Turbines - Review and Applications.
Myth 2: Renewable Obligation Certificates are a form of subsidy.
The government doesn't actually give out money in the form of subsidies for this scheme. The only money that is provided by the government is to manage the scheme to make sure there isn't any cheating.
What happens is that electricity companies that do not produce enough electricity from renewables have to buy certificates from those that produce to much electricity from renewables. If an electricity company does not have enough certificates (eg. they didn't produce enough electricity from renewables) then they are effectively fined and the money obtained is allocated to those companies that hold certificates.
It is basically an incentive scheme to produce renewable energy and to cut carbon emissions.
Myth 3: All the steel and concrete used to produce and install a wind turbine means its carbon footprint is no better than other energy sources, such as coal or gas.
A lot of research has been done on this subject.
The carbon footprint of a system is normally calculated based on the complete life cycle of the system. That means from the point of acquiring the materials to decommissioning and recycling the materials used to produce the system.
The carbon footprint of large wind turbines is tiny compared to that of coal, gas and oil fired power station. The industry recognised method of comparing carbon footprints is to calculate grammes of carbon dioxide equivalent per kilowatt hour of electricity produced (gCO2eq/kwh).
Using figures for each source of fuel we can see that wind energy has a very low carbon footprint:
1. Coal - between 894 and 975
2. Gas - between 450 and 519
3. Hydro - between 3 and 11
4. Wind - between 5 and 30
Note: units used in the list are gCO2eq/kwh, also these figures do not apply to small microgeneration wind turbines.
Coal has by far the biggest carbon footprint of any energy source.
References:
Kansas Geological Survey
White, Scott,
Net Energy Payback and CO2 Emissions from Three Midwestern Wind Farms: An Update. December 2006
Uwe R. Frische
Oko-Institut, Darmstadt
Comparison of Greenhouse-Gas Emissions and Abatement Cost of Nuclear and Alternative Energy Options from a Life-Cycle Perspective.
January 2006
The World Nuclear Association - Energy Analysis of Power Systems.
Myth 4: The wind is to intermittent and unpredictable to be of use as a reliable energy source.
There are some issues with intermittent wind, however there are technologies used now and many more being developed that will make this less of an issue. For most of the time the wind is blowing at various locations around the UK, this variability can be used to balance the output of the whole wind farm system across the UK to a certain extent, especially when combined with modern technologies and real time software analysis of the system.
There are many technologies being developed that are capable of 'load levelling'. Such systems could allow wind farms to provide a more constant output or to provide energy on demand, they include:
Compressed Air Energy Storage (CAES)
In this system air is pumped and compressed into a suitable underground location. Compressed air being a form of energy storage. This means that the energy from the wind can be stored when the electricity demand is low, then it can be recovered later when demand increases. There are two existing systems operating in the US and Germany, with a third under development in Iowa.
More recently Prof. Seamus Garvey at Nottingham University with a grant from E.ON proposes to develop a prototype system that pumps the air into large bags deep under the sea so that it can be stored at great pressures.
Iowa Stored Energy Park
US Department of Energy article about CAES
Vanadium Redox Flow Batteries
This is a relatively new technology and looks quite promising, although there is uncertainty about the availability of Vanadium. Currently they are marketed as a system for remote locations, providing battery backup. However the first large scale systems have been installed in Ireland at the Sorne Hill wind farm and at King Island, Australia, this enables the farm to deliver a smooth constant output of electricity.
The batteries themselves differ from standard batteries that we are familiar with. The liquid used in them is 'charged' and pumped into storage tanks. The 'charged' liquid is pumped in the opposite direction to release the energy as electricity. This means to increase the capacity more liquid and storage tanks are added.
VRBpower
Sustainable Energy Ireland article
Hydrogen
This option is more experimental and probably requires improvements in the efficiency of producing hydrogen from water using electrolosys. However a company called Wind Hydrogen is working on some major projects that will hopefully solve many of the technical issues.
Wind Hydrogen Ltd
Hydrogenics provide Hydrogen wind energy storage (added 31 May 2008)
Flywheel Energy Storage
These systems have been around for a while and are used in some large scale uninterruptible power supply systems. The US government is financing some large systems as a way of stabilising grid fluctuations.
Beacon Power
Vycon
Whalepower turbine blade technology
Inspired by the flippers of a humpback whale, Dr Frank Fish has developed new wind turbine blades that are more efficient at low wind speeds. This isn't exactly an energy storage system, but these new blades can be retro fitted onto existing wind turbines, improving their overall performance and reducing some of the need for energy storage.
Whalepower
Myth 5: Small domestic microgeneration wind turbines would be better than the big mega-watt wind turbines.
Comparing small microgeneration wind turbines with large scale wind turbines isn't particularly easy. The design, the materials used and methods of manufacture can differ greatly. Small turbines tend to be managed manually (if at all), where as large wind turbines have automated control systems that govern what the turbine does.
However there is a fundamental rule that applies to all 'horizontal axis' wind turbines which means that the power output is directly proportional to the area swept by the blades (basic science and engineering).
In practice what does this mean?
Basically as the blade diameter is increased, the area swept is far greater (Pi x r2), so if the blade diameter is increased by 10 times, the power output is increased by approx. 100 times.
The basic equation looks like this:
Power = 0.5 x Betz Efficiency Factor x Swept Area x Air Density x Velocity3
The obvious outcome of this basic natural rule is that the bigger the turbine is, the more economical it will be and the smaller the carbon footprint.
To produce the same energy as a single large turbine, thousands of small turbines would have to be installed, the total of which would probably have a much larger carbon footprint and cover a larger area than the single large turbine.
Buildings tend to cause gusting and interfere with wind flow, this can affect the performance of a small wind turbine. If a microgeneration wind turbine doesn't produce much power because of the poor local wind conditions then it's carbon footprint will rise.
There isn't a great deal of research into the carbon footprints of microgeneration wind turbines, so just how good or bad they are compared to the large turbines is not certain.
What is certain is that large scale turbines are inherently more efficient and economical.
More information about small turbines and the growing standards to regulate the industry can be found at the British Wind Energy Association web site:
BWEA Small turbine page
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