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The 1% Solution:
Wind Power: Increasingly Viewed as "The Most Cost-Effective and Scalable" Renewable
March 10, 2009
The wind-power industry presently generates about 1% of all electricity worldwide. The wind turbines now in use have a typical capacity of around 1.5 to 2.5 megawatts, have rotor diameters as broad as 100 meters (see photo), and rotate around an area roughly the size of a football field.
Public opinion is divided about these devices. Many feel that they are majestic symbols of new energy sources; others reject them as an eyesore—a distraction from the beautiful landscape.
In theory, wind is so readily available throughout the world that it could meet the world’s current energy needs. Stanford University energy researchers recently found that global
wind energy potential in 2000 was about 72,000 GW—almost five times world demand.
Furthermore, wind technology is steadily getting less costly—from around 30 cents per kilowatt hour in the early ‘80’s to around ten cents in 2007. Tax credits and feed-in tariffs have made wind power as cost-efficient as gas and coal-generated electricity in many energy markets. Maria Sicilia of the International Energy Agency says that energy produced from wind could compete with gas and coal in most markets, even barring subsidies.
The European Union set a goal of getting 20% of its energy from wind and other renewable sources by 2020. America’s Department of Energy wants US wind-power to reach 20% by
2030—a far less significant goal for a country of this size. Asia’s ambitions are more grandiose than either, and it may become the world’s biggest user of wind power in the next five years.
Wind-power technology is growing and expanding at a brisk rate, but there are problems ahead. Cities are generally not near the areas where the wind blows, which means that the electricity the cities require will have to travel to them across new transmission lines that must be planned, constructed, and integrated into the existing power grid. The program is also largely dependent on subsidies, which governments could cut off at any time, depending on their priorities.
Imposing prices on carbon emissions would go a long way to eliminate this problem by funding wind and other renewable with the revenue.
Another concern for wind-power planners and advocates is that many people need to be convinced that the noise of wind farms erected close by will be tolerable.
They are much larger than you thought. Photo shows a single blade undergoing manufacture at a Vestas
plant. A Danish company, Vestas is the world's largest producer of wind machines.
A third problem is that wind power is not always available as needed. Operators of the
power grids need to make certain that alternative power is available when the wind doesn’t blow. But according to the US department of Energy’s wind advisory group,
the power reserves needed for support of wind-power that represents 20% of the total power grid are actually minimal—only a small percentage of total installed wind machine capacity.
A Short History of Wind Power
Countries began looking for alternate sources beyond fossil fuels following the first oil crisis in 1973. One of the countries most deeply affected was Denmark, which was almost entirely dependent on foreign oil sources. Wind, however, is in particular abundance there, so the country began an intensive research project on wind power to markedly reduce that dependence.
America followed suit, with funds from the government, and Boeing and NASA began creating huge, multi-megawatt wind turbines, but many of these machines were expensive to run and maintain. Entrepreneurs got into the act, although their machines were smaller and came in a wide variety. There were models with two-bladed rotors on a horizontal axis, as well as vertical axis machines. Denmark experimented with similar designs.
By the early ‘80’s, however, one design was emerging as the standard: the three-bladed wind turbine, operating on a horizontal axis. The two-blade designs were ultimately rejected because they were not as dynamically balanced as were the three-blade rotors, they were harder to design, and spun faster, which created more noise. The three-blade turbines were also more aesthetically pleasing to the eye.
Since the American machines were designed to “bend with the wind”, they were of a softer design, and did not hold structure under heavy loads. The Danish machines were rigid, and much heavier structures, that weighed almost twice as much as the American
machines.
Nevertheless, with the technology still in its infancy, in the early 1980’s California gradually installed over 1.2 GW of wind power, which was at the time nearly 90% of the total wind power capacity globally, which some called the great “wind rush”. It was fueled by federal tax credits and substantial state incentives for wind power. Large wind machine arrays began to appear, which came to be known as “wind farms”. In the mid-1980’s, the credits expired, and with it, the immediate and near future of wind power in California. American companies tied to the technology went bankrupt, as did several in Denmark, which had been largely manufacturing and servicing the California effort.
One significant result of this period, however, was the worldwide standardization on the Danish three-blade design.
Gradually, the Danish engineers developed more efficient means to deal with the stretching, bending and vibration, to reduce weight, and thus optimize the devices.
The Modern Wind Machine
These machines now achieve around 50% of the kinetic energy in the wind, with a theoretical limit of 59%. These achievements have come at a cost, however, in problems with the gearboxes, which endure considerable vibration and movement inside the turbines. A German firm, Enercon, has developed a direct-drive device with a low rotational-speed generator that does not require a gearbox. Unfortunately, these generators are generally heavier, and come at a higher cost, so there is some doubt as to the long-term viability of this approach.
The very large machines of today with their long blades capture more energy from the wind, since the blades sweep over a much larger area, which allows the turbine to produce its rated power at lower wind speeds and at a higher percentage of the time.
Other innovations are variable pitch, which allows the angle of the blades to the wind to be adjustable, so that the effect of the wind on the drive train and rotor can be minimized, and variable-speed, which enable the turbines to operate at higher efficiency over a wider range of wind speeds, thus converting more of the wind’s speed into electricity.
As a matter of interest, the worldwide distribution of working wind power as of the end of 2007 is as follows:
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Germany |
23.7% |
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Italy |
2.9% |
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United States
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18.0% |
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Britain |
2.6% |
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Spain |
15.6% |
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France |
2.6% |
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India |
8.3% |
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Portugal |
2.3% |
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China |
6.3% |
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Other countries combined |
14.4% |
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Denmark |
3.3% |
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Bigger and More Powerful
In spite of the problems of shipping, installing, and maintaining very large wind-power machines, the industry is committed to the “bigger is better” approach. Machines onshore are moving up to a capacity of 3MW, and offshore devices up to 10MW. Offshore installations are 40% more expensive than their onshore counterparts—a good reason why there are far fewer of them at present. Nonetheless, many believe that the offshore potential is very promising, since carefully selected offshore sites usually offer higher and more consistent wind speeds. Moreover, many wind farms can be situated where they can be neither seen nor heard from land, which eliminates objections from many quarters. (This has been a particularly persistent issue in America, where locals have protested wind-farm installations planned for nearby areas).
A Look to the Future
For now, at least, the most serious impediment to a more universal adaptation of wind power is the necessity of overhauling the existing power grid to accommodate it. Costly new transmission lines must be installed to transmit the power from rural, strong-wind areas to highly populated areas where the demand lies.
At present, no one can tell if the DOE group’s stated goal of 20% will be reached any time in the near future, but wind power will surely play a significant part in America’s energy future. Almost 35% of new electricity-generating power came from American wind generation in 2007. By 2030 it is predicted that 14% of all electricity generated in the European Union will come from wind power.
As Victor Abate, the vice-president of renewables for GE Energy has stated, “From a zero-fuel-cost, zero-carbon perspective, wind power is currently the most cost-effective and scalable technology available to mankind.”
Wind power is here to stay. It remains to be seen to what extent governments and their supporters will see fit to make wise use of it.
- John Burr
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