Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electrical power, windmills for mechanical power or sails to propel ships. Large wind farms consist of hundreds of individual wind turbines which are connected to the electrical power transmission grid. For new constructions, onshore wind is an inexpensive source of electricity, competitive with or in some places cheaper than fossil fuel plants. Small onshore wind farms provide electricity to isolated locations. Utility companies increasingly buy surplus electricity produced by small domestic wind turbines.
Offshore wind is steadier and stronger than on land, and offshore farms have less visual impact, but construction and maintenance costs are considerably higher.
Wind power, as an alternative to fossil fuels, is plentiful, renewable, widely distributed, clean, produces no GHG emissions during operation and uses little land.The effects on the environment are generally less problematic than those from other power sources.
Wind power is very consistent from year to year but has significant variation over shorter time scales. As the proportion of windpower in a region increases, a need to upgrade the grid, and a lowered ability to supplant conventional production can occur.This can destabilize the grid. Power management techniques such as having excess capacity storage, geographically distributed turbines, dispatchable backing sources, storage such as pumped storage hydroelectricity, exporting and importing power to neighboring areas or reducing demand when wind production is low, can mitigate these problems.
Almost all large wind turbines have the same design, consisting of a horizontal axis wind turbine having an upwind rotor with three blades, attached to a nacelle on top of a tall tower. In a wind farm individual turbines are interconnected with a medium voltage power collection system and communications network.At a substation, this medium-voltage electric current is increased in voltage for connection to the high voltage power grid.
Many of the largest operational onshore wind farms are located in the US.As of 2012 with capacities up to 1000 MW. In 2012 some of the largest off shore wind farms became operational in the UK with capacities in the region of 300 MW each.Worldwide there are many large wind farms under construction.
2. Wind Power Market Share
Wind power is taking an increasing share of electricity production in the energy sector in many countries in various degrees depending on the local wind conditions. As of 2011 Denmark produces more than a quarter of its electricity from wind and 83 countries around the world are using wind power to supply the electricity grid. In 2010 wind energy production was over 2.5% of total worldwide electricity usage, and growing rapidly at more than 25% per annum.The large wind farms are mainly concentrated in Europe, the US, China and India, as shown on the diagram below.
According to the GWEC, the Global Wind Energy Council,Wind energy installations totalled 240 GW globally by the end of 2011, and the industry is set to grow by at least another 40 GW in 2012. By 2020, the IEA’s scenario suggests that total capacity would reach 587 GW, supplying about 6% of global electricity.
Although the market share of windpower is increasing rapidly its market share is still relatively small in comparison with the traditional fossil fuel based facilities.
Wind power is considered a renewable source of energy since it does not directly contribute to the emission of green house gasses such as CO2. The diagram below provides a comparison of CO2 emissions per KW produced, by energy source.
3.Wind Power Economics
According to the Wind Energy Foundation (WEF) wind energy costs are now lower than the costs of most new conventional sources and are close to cost-competitive with new natural gas generation due to continuing technological innovation.The price of wind power in the USA has declined more than 90% since 1980.
This is one reason that in 2012, wind was the number1 source of new electric generation capacity in the United States, accounting for 42% of all new generation capacity. In Australia, wind energy is now cheaper than coal and natural gas.
According to the WEF in 2011 and 2012, the price of wind under long-term power purchase contracts in the United States averaged just 4 cents per kilowatt hour, which is 50% lower than in 2009.
A good way to compare the cost of producing energy from various sources is to consider the cost of installation per KW production capacity.The second factor is the Capacity Factor, which is the percentage of time that wind turbines are actually producing electricity.
For wind energy various information sources indicate that the installed cost for onshore wind farms is about 1500-2000 US$ per KW. For off-shore installations this is between 2500-4000 US$ per KW installed capacity. The capacity factor ranges from 25-35% depending on local weather patterns.
The effective wind energy cost is the cost of installed capacity divided by the capacity factor.Taking into account an average capacity factor of 30% for wind energy, the cost of effective onshore wind energy is 5000-6600 US$/KW.
For offshore wind energy installations the cost of effective capacity is 8300-13300 US$/KW.
This compares favorably with the cost of solar energy. The installed costs of solar energy is about 3000-4500 US$/KW and the capacity factor is about 20-25%.Therefore the effective solar energy cost is between 15000-18000 US$/KW.
4. Summary and Conclusions
Wind power is growing rapidly in the world, because it is considered a renewable and economic way of making energy. Windpower can compete with power derived from fossil fuels and has virtually no GHG emissions.
Many people consider wind farms a form of horizon pollution because they can interfere with the landscape.Also bird life is considered to be negatively effected by the presence of large wind farms.Although wind farms use the energy provided by nature, windfarms also interfere with nature.
Local small scale wind energy is a lot more expensive and not economical, although much innovation is taking place to make small scale wind energy more economically attractive.