How Energy Is Produced - The Renaissance of Renewable Energy - page 92

2010 this had increased up to 3 megawatts. Currently the world's largest wind turbine is
the Enercon E-126, installed in several wind parks in Germany and Belgium. It has a rotor
diameter of 126 metres, stands 198 metres tall (higher than the Great Pyramid of Giza) and
has a capacity of more than 7 megawatts, capable of satisfying the power needs of about
5,000 European homes.
Current wind turbine technology has been developed largely for onshore applications.
However, as installation technologies have improved, there has been a move towards
'offshore wind farms'. These are constructed in seas and lakes, usually a few miles from
the shore. The advantages of offshore wind farms are steady winds, absence of obstacles,
and no interference with landscape, farming or human settlement.
Small wind turbines tend not to be connected to the power grid. Indeed, these machines
are often installed in places where access to the grid is impractical or expensive. They are
therefore most commonly used to charge batteries for caravans, boats, or mobile health
centres, and to supply electricity to remote areas (isolated settlements and farms, weather
stations, etc.). Fixed small turbines are best installed in areas that receive above-average
wind (higher than 6.5 metres per second annual average), and need to be accompanied by
large accumulators (batteries) to compensate for inevitable periods of calm.
The Benefits and Costs of Wind Power
There are few technological or economic barriers to wind power. It is already considered
commercially mature, meaning that under favourable conditions it can compete with
conventional energy sources. As demand for renewable energy grows and storage
technologies improve, the wind power sector is likely to expand.
However,windenergyalsohasseveralcharacteristics thatposechallengesforelectricity
systems - mainly that output is quite unpredictable and turbines tend to be clustered in
certain locations (Wiser et al. 2011 ) . Some countries have already experienced wind energy
surpluses at certain times. Denmark has, on occasion, paid other countries to take its excess
power supply, and in west Texas surpluses of wind occasionally result in negative pricing.
According to Jens Moller Birkebaek, vice president of the Danish grid operator Energinet,
if significant changes to the electric system are not made, future supply might eclipse
demand several times a year (Kanter 2012 ). New transmission infrastructure, both on- and
offshore, will be required to access areas with higher-quality wind resources.
Though small-scale wind turbines (1-20 kilowatts in size) do not benefit from the
economies of scale that have helped reduce the cost of larger wind turbines, they can be
economically competitive in windy areas or in areas that do not have access to the grid.