About Wind Power

Wind power could generate all global electrical requirements using only 2.5% of the wind power potentially available from economical usable locations according to a recent report by Stanford reaserchers.  Generation of electricity from wind turbines is economically competitive, less than $0.05 per kWh for new, large facilities, and the technology is reliable and well developed.  Wind power is very environmentally friendly, generating no pollutants or greenhouse gases during operation. 

If this is all true, then why do we need to use other, highly polluting non-renewable sources of electricity?  The biggest argument used by opponents is that wind power is intermittent, it doesn't blow all the time and it doesn't blow at a high enough speed all the time.  Intermittency means that on average a wind power generator is only available 25-35% of the time.  The fact is that wind power integrates into an electrical grid quite efficiently and does not require significant back-up power as claimed by some. This has been demonstrated in Spain and Denmark where about 20% of their generating capacity comes from the wind.

The second most mentioned objection is NIMBY (not in my back yard). Some people object to the aesthetics, the noise, potential erosion problems and potential hazards to birds.  These objections have generally been not the case, they are very quiet, their danger to birds is exaggerated and proper siting eliminates the aesthetic and erosion problems.  In fact some architects argue that they are a thing of grace and beauty.

Wind power is the fastest growing source of electricity.  According to the American Wind Energy Association (AWEA) the world wind capacity reached 47,000 MW at he end of 2004, a 26% increase over the previous year.  Europe and the U.S. have the most installations.

Stanford researchers found that the total wind power potentially available from economically usable locations (wind speed greater than 6.9 meters per second) over land is 72 terawatts (TW).    In comparison the total global electricity use in 2000 was 1.8 TW and the total energy use from all sources was about 14 TW.  Their map showing the wind intensity at various locations around the world can be found here.  In an earlier report the same researchers found that 24% of the U.S is suitable for wind power production.

In addition to the obstacles mentioned above, in some parts of the world wind resources are not close enough to user locations and in the U.S. their is uncertainty about the availability of the federal production tax credit.  In the U.S. wind resources are close to many population centers and additionally there is a great wind resource in the upper plains states that can be distributed to much of the country.

The controversy over wind power can be seen in these three recent instances; the Cape Wind project in the U.S., a recent study prepared for the German government recommending that wind power not be emphasized and comments in a New Zealand paper regarding a project being proposed there.  Greenwike presents the arguments for both sides of this controversy.

The intermittency problem is common to solar, wave, tidal and wind power.  My post Diversity in Renewables Smooths Output discusses this problem.  Diversity in both siting of renewable power plants and in types of renewable power goes a long ways towards mitigating this potential problem.  Planing as to which of these resources are to be used, in what quantity and where they are to be located, is key to minimizing the problems caused by intermittent operation of renewable energy plants.  Despite all the concerns about intermittent operation most experts seem to think that about 20% of electricity could be produced from wind power.  In addition there are some uses of electricity such as in the production of hydrogen and energy storage systems, such as pumped storage or compressed air energy storage, which can be used to mitigate the intermittent nature of renewable energy sources.

The following table shows the ten countries that have the largest amount of wind power installed and the percentage of their total installed generating capacity that is supplied by wind power.

Total Installed Wind Power
December 31, 2004
Country	Capacity, MW	% of Power
Germany	16,629	5%
Spain	8,263	20%
United States	6,740	1%
Denmark	3,117	20%
India	3,000	<1%
Italy	1,125	<1%
Netherlands	1,078	<1%
United Kingdom	888	<1%
Japan	874	<1%
China	764	<1%
Rest of World	4,840
Total	47,317

Wind turbines can be sited offshore, where the wind blows harder and more consistently and where larger turbines can be installed more advantageously. Many offshore wind farms are being proposed and developed today in densely populated Europe, where there is limited space on land and relatively large offshore areas with shallow water.

Offshore wind farms are being met with varying amounts of controversy.  Despite its proximity to Jones Beach, one of the largest summer recreational destinations in the New York area (with six million annual visitors), the proposed Long Island Offshore Wind Initiative (with between 25 and 50 turbines, producing up to four megawatts each) has not generated significant opposition.

Cape Wind plans to build the first offshore wind park in the U.S., in Nantucket Sound, just five miles off the coast of some of the most exclusive real estate in America.  It has generated significant opposition, although, so far, it has been able to progress through several steps of the permitting process. If the project is built, it will at least temporarily set a record as the largest wind farm in the world, its 130 turbines producing 420 megawatts of electricity.

Germany is a world leader in offshore wind, and recently finalized an agreement to build a 350-megawatt project (with 70 five-megawatt turbines) off the island of Rügen. Britain’s Crown Estate, which owns the UK’s territorial seabed, has granted approval for 13 offshore wind farms, previous post, and British utility Powergen has plans to develop a giant 500-megawatt offshore farm in the Thames estuary near London. The Irish government has approved a 520-megawatt wind farm offshore southeast of Dublin. China is building a 400-megawatt facility 60 miles from Beijing.

Technology

A wind energy system transforms the kinetic energy of the wind into mechanical or electrical energy that can be harnessed for practical use. Mechanical energy is most commonly used for pumping water in rural or remote locations — the "farm windmill" still seen in many rural areas of the U.S. is a mechanical wind pumper — but it can also be used for many other purposes (grinding grain, sawing, pushing a sailboat, etc.). Wind electric turbines generate electricity for homes and businesses and for sale to utilities.  The power available in the wind is proportional to the cube of its speed, which means that doubling the wind speed increases the available power by a factor of eight.  Currently the largest commercial wind turbine, made by Enercon, is 374 feet (114 meters) in diameter, rotates at 8 to 13 rpm, operates at wind speeds of 2.5 to 28-34 m/s and has a power rating of 4.5 MW. 

Turbine subsystems include:

• a rotor, or blades, which convert the wind's energy into rotational shaft energy;
• a nacelle (enclosure) containing a drive train, usually including a gearbox* and a generator;
• a tower, to support the rotor and drive train; and
• electronic equipment such as controls, electrical cables, ground support equipment, and interconnection equipment.

There are two basic designs of wind electric turbines: vertical-axis, or "egg-beater" style, and horizontal-axis (propeller-style) machines. Horizontal-axis wind turbines are most common today, constituting nearly all of the "utility-scale" (100 kilowatts, kW, capacity and larger) turbines in the global market.

The Advanced Wind Turbine (AWT) program initiated by the Department of Energy in 1990 to assist U.S industry to incorporate advanced technology into its wind turbine designs.  The third phase of the project explored new concepts and cutting-edge designs to develop a prototype that was to produce electricity at $0.035 /kWh or less at 15 mph (6.7 m/s) sites.  This project has contributed much to the technology, but did not meet all of its goals.  NREL is continuing development work that evolved from this program.

The five leading suppliers of wind power equipment are Vestas (Denmark, 34.1%), Gamez (Spain, 18.1%), Enercon (Germany, 15.8%), GEWind (U.S., 11.3%) and Siemans (Germany, 6.2%) based on 2004 worldwide installed capacity.

Resources used in preparing this post include:

• The American Wind Energy Association (AWEA) advocates the development of wind energy as a reliable, environmentally superior energy alternative since 1974.  Their website features, among other things, frequently updated news items, a useful wind power FAQ and a resource library. Their publication Wind Power Outlook 2005, provides a current view of wind power from the U.S. industry viewpoint.
• The State Department's International Information Programs website has a very comprehensive article about wind power, as well as similar information about other renewable energy sources.
• NREL's National Wind Technology Center has a great deal of information on the U.S. government's wind power programs.
• The recently organized Global Wind Energy Council (GWEC) was founded to unite the wind industry and its representative associations. It has links to major suppliers of equipment.  Their report, Global Wind Power Continues Expansion, GWEC, 2005, gives statistics on wind power installations as of the end of 2004. 
• The European Wind Energy Association latest news section has a good list of current happenings in the wind power world.  They also have several good reports that can be accessed from their publications page.

Technocrati tags: wind power, renewable energy

Comments

[Rucio]

Some mitigating comments in addition to those you cite.

1. In western Denmark it has been documented that 84% of its wind production had to exported, because there was no need for the extra electricity when the wind rose. So production equivalent to 20% of their electricity does not mean providing 20%. In fact it's just over 3%.

2. Siting is obviously important to minimizing the impacts you mention. But your show of concern is cancelled by the rider that the giant turbines are graceful and beautiful. You did not mention bats, which are being killed in the U.S. Appalachians at the rate of about 1/day/2MW.

3. It is always mentioned that industrial wind is the fastest growing source of renewable energy. So what? SUVs are the most popular car in the U.S. and ATV sales are booming.

4. The Crown Estate has commissioned a study of noise generated by offshore wind facilities. On Scroby Sands (off Great Yarmouth), it has recently been reported that scores of baby seals have been born dead or been abandoned by their mothers, presumably because of the disturbance caused by the wind turbines there.

[Rucio]

Very good blog, by the way!

[asil]

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