The idea of wind power as a sustainable energy source and a renewable replacement to the current method(s) of energy generation manages to divide opinion almost evenly. Due to the realisation of the damage being caused to our planet there has been a major emphasis on exploring new ways of acquiring energy or a source of energy. There will inevitably be pros and cons of wind energy to consider, more specifically wind turbine energy and with the aid of research and data analysis to illustrate arguments for both sides it will be become comprehensible that there are feasible reasons as to why I am somewhat sceptical.
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Wind power is an environmentally friendly and natural alternative form of energy that can be conserved and made useful by wind turbines. Wind turbines convert this energy into electricity, an energy by which the majority of human being as a race has become entirely dependent on. Whilst the reliance on electricity has increased, so too has the recognition of the possible affects current methods of energy generation has on the planet. Wind turbines are being looked at as a possible replacement for fossil energy for example. We know for sure that one day methods like burning fossil fuels will no longer be available. There is no doubt that alternatives are to be found for the sake of the future of the planet. These alternatives must be renewable and if possible inexhaustible. The question is, are wind turbines the answer?
Personally I feel that without a dramatic progression wind power may not have enough to maintain its challenge against the diminishing cheap natural gas and Middle Eastern Oil. However as we consume the final remaining years of the natural gas and oil the apparent affects on the Earth and therefore the necessity for a replacement is there for all to see.
Wind power is certainly an issue that divides people. Globally the underlying support has begun to surface but there is still a lack of concern amongst those who don’t feel there is much to worry about with regard to the current state of affairs or at least that’s the way it seems
The quality of wind turbine has progressed as the technology has been explored; one only has to look at the windmill which is an early example of today’s wind turbine. With any debate like this though you must identify and evaluate the advantages and disadvantages. There are a number of issues that fall into both categories and I by assessing these issues in the context of importance I will portray my point of view
Above is the Does burger windmill. Windmills like these were used primarily to grind grain, although they were also used to pump water from low-lying land. Modern Wind turbines have evolved from this idea and usually consist of three blades. They are designed in such a way that the tip speed is high but torque ripple is low, thus giving it high reliability. An example is the turbine below in Denmark.
The world’s first automatically operated wind turbine was built in Cleveland in 1888 by Charles F. Bush. It was as high as 60 feet, had a 12 kW turbine and weighed in excess of four tons. (Taken from: http://en.wikipedia.org/wiki/File:Wind_turbine_1888_Charles_Brush.jpg )
If you study the history of the wind turbine there are obvious trends of development. Initially the Persians light devices driven by drag proved to be pioneering and the majority of turbine ideas today are adapted in some way from this early interpretation.
persian.bmp (27790 bytes)(Figure 4)
It is clear that despite the lack of effectiveness due to the amount of the rotor that does not interact with the wind the idea however is a good on taking into consideration the times and resources.
As you look further along in time you recognise the increased use of materials for drag devices. Go forward again and the modern era designs revert back to light efficient aerodynamic lift devices.
Early windmills consisted of vertical sails which were an adaptation of the earliest use of wind power, sail boats. There were no drawings or documentation detailing the very first designs, but below is an example of a Persian design that was then copied by the Americans in the 19th Century.
The earliest known use was for grain grinding and later for water pumping, and even as living quarters. The most modern have been the three blade design but the vertical designs have not been abandoned.
The initial windmills found in Europe had the horizontal-axis configuration. Realising that structurally the efficiency would increase, they evolved to vertical-axis. This dealt with the problem of losing up to half of the rotor collection area.
Over time there was an incremental improvement in efficiency of the windmill sail. The most advanced windmill sail shared the same characteristics of a wind turbine blade.
The mills were almost like the electric motors of their time. Their applications ranged from irrigation, grain-grinding, the common water-mill, saw milling of timber, and even the processing of other commodities such as cocoa, paints and tobacco.
In the 19th century the use of large tower mills in Europe declined as the popularity of steam engines increased. Further wind power development came from America where they introduced much smaller systems. An example of this is the steel-bladed water pumping windmill made in the Mid West of America in the late 1800s.
“Most of these mills had tails to orient them into the wind, but some were weather-vaning mills that operated downwind of the tower. Speed control of some models was provided by hinging sections of blades, so that they would fold back like an umbrella in high winds, an action which reduced the rotor capture area to reduce thrust. The most important refinement of the American fan-type windmill was the development of steel blades in 1870. Steel blades could be made lighter and worked into more efficient shapes. They worked so well, in fact, that their high speed required a reduction (slow-down) gear to turn the standard reciprocal pumps at the required speed.” (Darrell Dodge: http://www.telosnet.com/wind/early.html )
Figure 6 and quote above is an illustration of how the mills evolved and were getting ever closer to the turbine designs of today.
It was from these types of designs and applications that in the late 19th sparked the idea of using these multi-blade windmill designs to generate electricity.
Thus bringing about Charles F Bush’s design shown in Figure 3. Despite its success for more than twenty years, there were limitations in its ability to produce electricity. The low speed and high solidity of the rotor failed to reach the output potential of a modern design.
One of the main arguments a cynic such as myself will bring to the table is the initial outlay required to erect a wind turbine. Although costs such as maintenance, subsequently may not be excessive the cost to build and put up just one can be. Professor Tony Day of London South Bank University provided an enlightening ‘Costs Chart’ that highlights just some of the initial costs one faces when you think about installing a residential wind turbine.
This chart was taken from a presentation given by Tony Day. It demonstrates the costs that were endured in an example project he undertook.
This chart was also from the same presentation. These are typical costs that are to be expected for the installation of some wind turbines. These are ball park figures and an example of only some of the costs. It is likely that there are many more to consider which will only increase the outlay.
The more productive in terms of power output turbines will cost a lot more. A large Megawatt wind turbine can cost up to 1 million US dollars and gets much more expensive when to consider a wind farm.
One of the most important elements to consider is how much power we can create and make useful from a wind turbine or wind turbine farm. At present the reward maybe isn’t as satisfying as the initial cost would demand. Aside from cost though to ensure optimum opportunity to produce high levels of energy the following must be regarded:
High wind sites – it is important to situate a wind farm in an area where it is very windy. An average minimum wind speed of 12-13 miles per hour (6 meters per second) is mandatory.
Proximity of existing infrastructure – High voltage lines can be extremely expensive to establish so it is important to consider their proximity to the turbines.
Access – Whether onshore or offshore you need to be able to access your site, initially to set it up but also subsequently to maintain it.
Wind power is renewable, plentiful and much less affects the planet than power generated by fossil fuels. It is currently the UK’s leading renewable energy source overtaking hydropower and currently accounts for around 2% of the UK’s electricity supply. There are no waste products and wind is naturally, readily available.
If a small home wind turbine was installed in an ideal location, you could be less dependent on fossil fuel energy and wind power could be a replacement, even if it is just boiling your kettle!
Electricity that is generated by wind bares no CO2 emissions and cannot be exhausted and due to the simplicity of their mechanical processes, a wind turbines running cost can be next to nothing. Depending on where you seek your information it is suggested that in a prime location, position and if installed accurately a turbine designed to power a house can potentially provide about 30% of a household’s electricity. It will probably take up to ten years though for them to pay from themselves. Widen the scope to a large scale wind turbine farm and the potential is there for it to be a big player within energy generation game, unfortunately it isn’t there yet.
The unpredictability of the wind is a major issue. Many think that the world’s weather is changing and becoming more unpredictable. If the areas that are high in wind become less so once wind farms are erect what would happen? A backup energy source would require a traditional polluting method of energy generation and would rather defeat the object!
Apart from the initial costs already discussed you have to consider the planning permissions also. It isn’t always straight forward for a wind farm to spring up. Even home wind turbines will require permission from the council.
How much electricity generated is dependent on the speed and direction of the wind which isn’t something that we can control. Location is vitally important but not always available and depending on the location you need to consider, obstructions and the height of the turbine.
There are many groups who feel that wind turbines cause damage to habitats and can be dangerous to birds. There are also those who despise their appearance and what they do to the environment aesthetically. Noise pollution is also an issue although there are wind turbines that seem to have minimised if not eradicated this problem.
There aren’t as many sites available as initially thought and those people who wish to have a personal wind turbine are required to test the wind speed for 3 months with an anemometer.
“To calculate the amount of power a turbine can actually generate from the wind, you need to know the wind speed at the turbine site and the turbine power rating. Most large turbines produce their maximum power at wind speeds around 15 meters per second (33 mph). Considering steady wind speeds, it’s the diameter of the rotor that determines how much energy a turbine can generate. Keep in mind that as a rotor diameter increases the height of the tower increases as well, which means more access to faster winds.
Rotor Size and Maximum Power Output
Rotor Diameter (meters)
Sources: Danish Wind Industry Association, American Wind Energy Association
At 33 mph, most large turbines generate their rated power capacity, and at 45 mph (20 meters per second), most large turbines shut down. There are a number of safety systems that can turn off a turbine if wind speeds threaten the structure, including a remarkably simple vibration sensor used in some turbines that basically consists of a metal ball attached to a chain, poised on a tiny pedestal. If the turbine starts vibrating above a certain threshold, the ball falls off the pedestal, pulling on the chain and triggering a shut down.”
This information from howstuffworks.com shows how the rotor dimensions and its proportionality to power out.
It portrays that an ideal wind speed is 33 mph. This is before it becomes dangerous. As already discussed a wind speed of about half of this is mandatory before you even think about building a wind turbine.
When monitoring or calculating power output you must consider the correlation between it, the wind speed and the frequency of the wind speed. Below is a chart taken from Professor Tony Day’s presentation on wind turbines:
The blue graph illustrates how the frequency and value of wind speed and what it means for power output. It confirms that at an average wind speed of about 6-8 metres per second, you can produce about 300 300kW of power. At this specific location you only get this about 8-9% of the time. And in that lies a problem. For wind power to be considered a major alternative you need a more frequent and reliable wind speed to ensure high levels of power is generated all the time. More to the point, the power that would be generated by wind farm for example given turbines of this specification; it would be a struggle to power a city let alone a nation.
There is clearly some way to go if the future of wind turbines is to overcome some people’s turbulent views. There are ideas in the pipeline and future design which will go some way to harnessing the energy more effectively to produce more power. Whilst residential wind turbines take the best part of a decade for you to see pay back on an investment the American Wind Energy Association suggest that payback can been seen a lot earlier with regard to wind farms.
” Overall, wind farms cost in the area of $1,000 per kW of capacity, so a wind farm consisting of seven 1.8-MW turbines runs about $12.6 million. The “payback time” for a large wind turbine … is about three to eight months, according to the American Wind Energy Association.”
If this information is to be believed this payback time is reasonable but this does not take into consideration the initial cost of land, transmission lines and other infrastructure that are crucial to wind power systems.
As time has gone on there have been some quite dramatic falls in the costs of wind energy. As technology improves the trend will continue it is just a question of how quickly.
New ideas and designs are coming to light now also, for example the vertical axis turbine which seems to bare some advantages over its older brother is being reinvented all the time despite being a fairly new idea. Its design allows you to place the gear box and generators closer to the ground and there is no need to orient them in the direction of the wind. Also they can be kept closer together as they do not have a slowing affect on the air that a horizontal turbine would which means more can be build within a given space.
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Every Government wants to increase the amount of power generated by wind but the major stumbling block is always economic. Especially right now, cost of steel and turbines has increased immensely following the economic downturn so initial costs of a wind turbine are even higher. Even though wind will never run out, this makes it very difficult to budget for big plans to be implemented.
Whilst wind turbines present a great argument for clean reusable energy, there are issues that are positioned on the ‘odds against’ category. It is widely believed that despite signs showing a change in the planets eco system the promotion of wind turbines has come about because of lobbying by industrialists as opposed to straightforward economics or science. Have we really caused as much damage as the ‘green’ amongst us have suggested? Or has there been an overreaction? One issue you cannot ignore is that fossil fuel is exhaustible, maybe not in our life time but we certainly owe it to those who will inherit our planet to ensure they enjoy energy in the same way that we have.
Costs of these machines are initially very high and many are only designed to last 25 years which adds a sting to an otherwise acceptable running cost. At the moment when running wind turbines coal generated power still has to be available as a backup which begs the question, are we really reducing our carbon emissions?
Also the power generation from traditional methods is high and whilst it lasts is constant. There are no ‘off days’ that can come about where the weather is concerned. Many also despise the look wind turbines and are against the damage visually that a wind farm can cause.
There is also a very real danger to birds and the migration of birds as many have been injured by this ‘new phenomenon’.
In an ideal world if wind power was to take over all wind farms will need to operate at 100% capacity 100% of the time which just cannot happen. The realistic operating maximum is about 50% and many wind farms fall below that now based on data from Ofgem, the energy regulator.
Wind power is certainly one option we can turn to on a small scale its attributes will come in handy to an extent. But unless there are vast improvements in the technology and power output turbines will remain an entity that is perceived as useless by many because it produces derisory amounts of electricity at monumental cost. One could say, “Too much wind and not enough puff!”.
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