Zoom on wind power

Wind power , renewable energy , offshore , primary energy

Research on electricity generation sometimes improves age-old techniques: wind power is a very good example of this. Wind itself originates in the sun heating up vast amounts of air in the atmosphere, setting them into a motion we refer to as wind. It is thus an endlessly renewable source of energy, albeit little exploited worldwide (3% of global electricity generation in 2009) and whose potential remains to be tapped. How is electricity made from wind? What trends can be expected in terms of electricity production?

Wind’s energy converted into electricity

A wind turbine or “aerogenerator” is made of blades (mostly three, spanning a diameter of 5 up to 110 metres for the largest), a propeller on top of a mast on which the blades spin, and a generator transforming mechanical energy into electrical energy. A wind turbine requires winds between 14 and 90 km/h to function. Below, the blades and the propeller they drive cannot reach the minimum pace of ten revolutions per minute required to generate power. Above, there is a risk that the blades might exceed 25 revs per minute, weakening the system, which leads the turbine to shut down automatically. Betz’ law allows to calculate the amount of electricity produced depending on the wind.

Non-polluting, easy to install and relatively affordable: the most efficient energy source?

A wind turbine requires no fossil fuel to function. Contrary to most thermal power plants which require heating up water and turning it into steam before releasing it into the environment, wind turbines have no calorific impact on the surroundings. Another of its assets is the little space it requires. Although wind mills must be at least 200 metres apart from one another, 98% of the land on which they are built remains farmable. Besides, since the wind blows harder in wintertime, turbines are naturally responsive to higher electricity consumption. Last but not least, wind power is already relatively cheap, on average twice cheaper than petrol-based electricity. Its cost should go on decreasing as turbines are manufactured on a larger scale.

Wind power is intrinsically intermittent and heavily dependent on local weather conditions. It is thus impossible to design an energy mix massively reliant on wind, although some ambition to strengthen its role as a complementary source, especially thanks to the more powerful off-shore turbines. Besides, wind farms are often frowned upon by nearby residents who see them as an eyesore. They also disturb bird migrations. Finally, today the total power of a wind farm remains limited compared to other sources. It would take almost 10,000 large turbines to generate as much electricity as a nuclear plant.

Promising perspectives in Europe

In 2011, installed wind power in Europe amounted to over 80,000 MW. Germany has already been betting on this tool, with 29,060 installed MW (7% of its total electricity production), followed by Spain with 21,674 MW (15% of the total) and Italy with 6,737 MW. France is the fourth largest user with 6,684 MW (1.7% of its energy mix), but at the same time the third most dynamic country in terms of new installations with 1,086 MW installed in 2010.

The European Wind Association (EWEA), the umbrella group for the wind power industry, is lobbying to have 230 GW installed by 2020 so as to produce 600 TW, which would meet the needs of 135 million households. This amount of production would cover 14% of the EU’s total energy requirement (4.8% today), which is in harmony with and in support of the target of 20% renewables by 2020 the EU set for herself. However, such a large scale installation requires an investment which is difficult to assess, given the current trends of the wind power market. Despite all that, such an investment would be quite profitable in the middle and long run, according to Jean-Louis Bal, head of the department of Renewable Energies at the ADEME (French Environment and Energy Management Agency) in 2010. Besides, a report issued by the EWEA in April 2012 makes it clear that the sector could generate 520,000 jobs by 2020, on top of the 192,000 already existing.

All this will only succeed with the support of off-shore turbines, which are still at an early stage of development. In 2030, the off-shore wind power generation capacity could reach 150 GW, compared with 40 GW today, for instance thanks to better technology enabling more efficient connection to distribution grids. If such forecasts are accurate, the environment could be spared 315 million tons of CO2.

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