Wind Power

Wind Power Renewable Energy *

The main renewable energy resources that you know about are sunlight (solar energy) and wind energy and perhaps to a lesser extent tidal energy systems and geothermal energy systems. All of these are in some way or another connected to the sun, which is the ultimate life giver on this planet.

The Earth-Atmosphere system is in equilibrium such that heat radiation into space is equal to incoming solar radiation, the resulting level of energy within the Earth-Atmosphere system can roughly be described as the Earth's "climate." The hydrosphere (water) absorbs a major fraction of the incoming radiation. Most radiation is absorbed at low latitudes around the equator, but this energy is dissipated around the globe in the form of winds and ocean currents. Wave motion may play a role in the process of transferring mechanical energy between the atmosphere and the ocean through wind stress. Solar energy is also responsible for the distribution of precipitation which is tapped by hydroelectric projects, and for the growth of plants used to create biofuels.

The IEA explains it like this:  "Renewable energy is derived from natural processes that are replenished constantly. In its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, and biofuels and hydrogen derived from renewable resources."

* Let's first examine wind power as a source of green alternative energy.

A wind turbine needs air, lots of it. A modern wind turbine ranges from 600 KW to 5 MW of rated power, although for commercial use the output range is typically 1.5-3 MW.

Since wind speed is not constant, a wind farm's annual energy production is never as much as the sum of the generator nameplate ratings multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. Typical capacity factors are 20-40%, with values at the upper end of the range in particularly favourable sites. For example, a 1 megawatt turbine with a capacity factor of 35% will not produce 8,760 megawatt-hours in a year, but only 0.35x24x365 = 3,066 MWh, averaging to 0.35 MW. Online data is available for some locations and the capacity factor can be calculated from the yearly output.

Globally, the long-term technical potential of wind energy is believed to be five times total current global energy production, or 40 times current electricity demand. This could require large amounts of land to be used for wind turbines, particularly in areas of higher wind resources. Offshore resources experience mean wind speeds of ~90% greater than that of land, so offshore resources could contribute substantially more energy. This number could also increase with higher altitude ground-based or airborne wind turbines.

Wind power is renewable and produces no greenhouse gases during operation, such as carbon dioxide and methane.

Wind Power Market

At the end of 2008, worldwide wind farm capacity was 120,791 megawatts (MW), representing an increase of 28.8 percent during the year, and wind power produced some 1.3% of global electricity consumption. Wind power accounts for approximately 19% of electricity use in Denmark, 9% in Spain and Portugal, and 6% in Germany and the Republic of Ireland. The United States is an important growth area and installed U.S. wind power capacity reached 25,170 MW at the end of 2008.

Horse Hollow Wind Energy Center, in Texas, is the world's largest wind farm at 735.5 MW capacity. It consists of 291 GE Energy 1.5 MW wind turbines and 130 Siemens 2.3 MW wind turbines. A proposed 4,000 MW facility, called the Pampa Wind Project, is to be located near Pampa, Texas.

In the UK, a licence to build the world's largest offshore windfarm, in the Thames estuary, has been granted. The London Array Windfarm, 20 km off Kent and Essex, should eventually consist of 341 turbines, occupying an area of 230 km². This is a £1.5 billion, 1,000 megawatt project, which will power one-third of London homes. The windfarm will produce an amount of energy that, if generated by conventional means, would result in 1.9 million tonnes of carbon dioxide emissions every year. It could also make up to 10% of the Government's 2010 renewables target.

Wind Farms

Wind power is one of the most environmentally friendly sources of renewable energy

A wind farm, when installed on agricultural land, has one of the lowest environmental impacts of all energy sources:

* It occupies less land area per kilowatt-hour (kWh) of electricity generated than any other energy conversion system, apart from   rooftop solar energy, and is compatible with grazing and crops.
* It generates the energy used in its construction in just 3 months of operation, yet its operational lifetime is 20–25 years.
* Greenhouse gas emissions and air pollution produced by its construction are low and declining. There are no emissions or pollution produced by its operation.
* In substituting for base-load coal power, wind power produces a net decrease in greenhouse gas emissions and air pollution, and a net increase in biodiversity.
* Modern wind turbines are almost silent and rotate so slowly (in terms of revolutions per minute) that they are rarely a hazard to birds.

Studies of birds and offshore wind farms in Europe have found that there are very few bird collisions. Several offshore wind sites in Europe have been in areas heavily used by seabirds. Improvements in wind turbine design, including a much slower rate of rotation of the blades and a smooth tower base instead of perchable lattice towers, have helped reduce bird mortality at wind farms around the world. However older smaller wind turbines may be hazardous to flying birds. Birds are severely impacted by fossil fuel energy; examples include birds dying from exposure to oil spills, habitat loss from acid rain and mountaintop removal coal mining, and mercury poisoning.

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