Winds of change

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A typical onshore turbine has 30-40-m long blades.

Wind power is one of the fastest growing renewable technologies.

Energy efficiency is often neglected in times of low oil and gas prices. But since the turn of the century the rising cost of hydrocarbons has driven energy-poor countries to look at developing diversified and independent energy supplies.

As a result, there is growing interest in exploiting renewable sources of energy, in particular wind and solar power.

According to the Global Wind Energy Council (GWEC), more than 20 GW of wind power was installed across the world in 2007, led by the US, China and Spain, bringing the total installed wind energy capacity to 94.1 GW.

Last year, the global wind market was worth some US $36 billion in new generating equipment.

"The growth rates we are experiencing in wind energy continue to exceed our most optimistic expectations," says GWEC secretary-general Steve Sawyer.

"Globally, wind energy has become a mainstream energy source and an important player in the world's energy markets. It now contributes to the energy mix in more than 70 countries.

League leaders

Germany leads the world in the use of wind power, with 22.3 GW installed or 23.6% of the world's total wind power capacity. The US and Spain follow on 16.8 GW and 15.1 GW respectively.

Wind energy still only accounts for around 1% of global electricity generation, but this figure is expect to rise in the years ahead.

"Emissions-free wind power can be brought online quickly, and must play a major role in meeting climate protection targets," adds Sawyer.

This is especially the case in the critical period between now and 2020 when greenhouse gas emissions must peak and begin to decline if we are to avoid the worst impacts of climate change."

The GWEC estimates that Europe's wind power capacity of 57.1 GW saves around 90 million tonnes of carbon dioxide each year, producing 119 TWh of electricity in an average wind year.

It predicts that by the end of this decade the cumulative capacity of all wind installations will reach 149.5 GW.

Suitable sites

Of course, not all locations around the world are suitable for wind power. A minimum wind speed of 5 m per second is needed for harnessing the energy to become worthwhile.

To generate sufficient power, a large number of wind turbines are needed: statistics says a 1 000 MW wind farm would occupy an area of 50-150 km².

Wind turbines capture energy from the wind using their blades, which turn. When there is no wind the blades remain at a 45-degree angle so that the turbine can draw maximum energy from gentle winds.

Turbines begin to produce energy when wind speeds reach about 4 m per second. The blade gradually rotates towards an angle of zero degrees with the broad surface facing the wind.

When the wind strikes the blade, it creates positive pressure on the front of it and negative pressure behind it.

In other words, the wind pushes against the front edge and creates a suction effect behind the blade, which makes the rotor turn. At maximum rotational speed, the blade tips reach a speed of 250 km per hour.

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I agree
Posted by Mohammed, Baghdad, Iraq on Monday 5 May 2008 at 17:05 UAE time


I agree with this idea that people should use renewable energy to guarantee that they'll have electricity for extra some years.
I think because the relentless price of oil, wind farms will be more expensive few years later, so UK and other rich countries should think of that and prepare to pay large amount of money to invest in this kind of projects.

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