Wind power

Wind energy technology is developing fast. Wind turbines are becoming cheaper and more efficient, bringing the cost of electricity down. Europe is at the hub of this high-tech industry.

Wind turbines produce electricity by using the natural power of the wind to drive a generator. The wind is a clean and sustainable fuel source, it does not create pollution and it will never run out.

The need for clean energy:
Conventional methods of generating electricity burn fuel to provide the energy to drive a generator, usually by using the heat to provide steam to drive a turbine. These technologies may use fossil fuels, - coal, oil or gas - or nuclear fuel. Using fossil fuels creates pollution, such as oxides of sulphur and nitrogen which contribute to acid rain and carbon dioxide which contributes to global climate change.

Although conventional sources of power dominate the energy needs of European countries, wind energy is growing rapidly. Renewable energy sources currently provide nearly 5.4% of the European Union's primary energy needs and have the potential to provide much more.

How wind turbines work:

Wind turbine
Wind turbine diagram
Almost all wind turbines producing electricity for the national grid consist of rotor blades which rotate around a horizontal hub. The hub is connected to a gearbox and generator, which are located inside the nacelle. The nacelle houses the electrical components and is mounted at the top of the tower. This type of turbine is referred to as a 'horizontal axis' machine.

Wind turbines can have three, two or just one rotor blade. Most have three. Blades are made of fibreglass-reinforced polyester or wood-epoxy.

Power is controlled automatically as wind speed varies and machines are stopped at very high wind speeds to protect them from damage. Most have gearboxes although there are increasing numbers with direct drives. The turbine includes a "yaw mechanism" which turns the turbine automatically so that it always faces the wind.

Turbines range in capacity from several kilowatts to three megawatts. This means that wind power can be used for small applications like a school or farm, or for a large-scale wind farm such as the installation at Blyth Harbour, which generates enough electricity to feed 1689 homes each year.

Turbine arrangement:
Turbines in wind farms must be carefully arranged to gain the maximum energy from the wind - this means that they should shelter each other as little as possible from the prevailing wind.

Blyth Harbour
Redcar Windfarm

Wind energy production and electricity demand:
The wind is an intermittent energy resource - it does not blow all the time - but this does not reduce its value as a source of power. The variable output from wind energy poses no special difficulty for power system operation. Electricity demand is constantly fluctuating, and supply and demand have to be matched on a minute to minute basis, 24 hours of the day, every day of the year. The fluctuation caused by the introduction of wind to the system is not discernible above these normal fluctuations, and will not be until electricity generated from wind turbines reaches approximately 20% of the total system supply.

Wind energy effectively 'shaves off' some of the demand which has to be met by conventional generating plant. This is often described as having a 'negative load' effect on the electricity network. Wind energy coincides well with period of peak electricity demand. Demand often peaks on cold windy winter days - just when wind turbines are at their most productive.

Other benefits of wind power:
Apart from generating electricity without causing pollution, wind energy has numerous other advantages.

It is widely distributed - more countries have sizeable wind power potential than have large resources of hydro-power or fossil fuel reserves.

It is ideal for generating electricity at a local level - European wind schemes are typically clusters of around 10 - 40 turbines, providing enough electricity for 4,000 to 16,000 households. Some countries such as Denmark and Germany also have a high proportion of single turbines. The electricity can be fed directly into the distribution network, reducing electricity distribution and transmission losses. By contrast, electricity from larger power stations has to be transmitted on high voltage power lines and travel long distances before it gets to the point of use.

Wind energy is good for island communities - the supply can be connected to diesel or solar systems to provide back-up when the wind is not blowing.

Wind energy is low risk - the relatively small unit size of each individual wind turbine (or wind scheme) also reduces the risk of technical failure or industrial action compared with larger generating units.

Wind energy encourages energy diversity - it is sensible for any nation to have a balanced portfolio of energy technologies, rather than to rely heavily on a small number of energy sources. The energy mix among different European countries varies widely, with some countries more dependent on energy imports than others. The UK and Germany have a relatively diverse mix of fuels, whereas others are more dependent on oil (Spain and Greece), coal (Denmark) and nuclear (France and Belgium). Expanding the use of wind energy will increase energy diversity and improve the security of electricity supply. Energy diversity lessens international political sensitivity concerning fossil fuel reserves, volatility of oil and gas prices and the risks associated with nuclear power.

Wind energy capacity in Europe:
Europe is the world leader in wind energy, with more installed capacity than any other region of the world. By the end of 1999 there was over 8,500 megawatts of installed capacity - more than double figures for 1996. This growth trend is expected to continue as wind is the fastest growing energy sector worldwide.

The future of wind energy:
Improvements in wind energy technology mean that the trends which have led to the dramatic fall in the cost of wind energy are set to continue.

Glossary and References:
1 unit of electricity = 1 kilowatt hour
1,000 kilowatts = 1 megawatt

Information provided by the The voice of wind & marine energy

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