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Wind Power

 

The «mature» renewable energy

Wind has been always used by man to provide mechanical power for various purposes – water pumping, grain grinding etc. Modern wind machines or wind turbines convert wind energy into electricity. Their highly sophisticated design allows more efficient "capture" of wind energy even in medium wind velocities.

The produced electricity is either consumed locally (remote sites, low capacity), or injected into the grid (grid connected wind turbines). Grid connected installations (or large wind parks) represent almost the entire market today. In order to address the sitting problem and land availability as well as to capture the high wind energy potential of the open sea, offshore wind parks have recently been constructed and commissioned.

The unit power of wind turbines in constantly increasing: there are already up to 4 MW onshore turbines and 8 MW offshore wind turbines are being developed. There are two main categories of wind turbines: vertical axis machines and horizontal axis machines. For large wind parks horizontal usually three blade machines are used. The horizontal axis are more efficient mainly in terms of aerodynamic performance. Generators, control equipment and other auxiliary may vary from one type of machine to another.

Wind power development

In 2009 the sector had a turnover of 50 billion. On the same year nearly 550.000 people were employed in the wind industry worldwide while by 2012, the number is expected to increase to 1 million jobs. In 2009 Europe had a share of nearly 48% of global installed capacity with more than 76GW of wind power installed. Investments in the same year exceeded 10GW or 13 billion Euro, 23% more than 2008. At the same time 99% of the offshore wind turbines are found in Europe.

 

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Figure 1. Typical horizontal axis wind turbine

 

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Figure 2. Onshore and offshore wind parks

 

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Figure 3. Various types of vertical axis wind machines

 

 

A decreasing growth rate in the Mediterranean regions due to a strong territorial impact

After an initial period (2005-2010) of rapid growth of installed power, the development of wind energy is slowing down in many Mediterranean regions of Europe. In Tuscany for example, no more than 5 wind mills parks have been installed so far, representing on overall installed power of 44,5 MW. In the PACA region as well, the number of facilities is still very modest. Since almost 1 year, no new Eolian Development Zone (ZDE) has been authorised by local authorities. In Slovenia, the development of wind energy is still under discussion and has not yet began.

One of the reasons for such a « backlash » is the perception of a strong territorial impact of wind energy. Modern wind turbines have nothing in common with old rustic windmills or early 20th century machines. They can be up to about 150 meters high, and their blades can be more than 30 meters long. In the coastal and mountainous Mediterranean regions, wind energy is thus often accused of damaging the landscape and thus jeopardizing tourism and local economic development. Therefore local authorities express strong reluctance to host wind parks.

The ENERMED project allowed to identify « success stories ». The Autonomous Community of Valencia enjoys 992 MW of installed power (or 20 times the power installed in PACA). In the island of Crete, 168MW have already been installed while the installation of more parks is currently under development.

 

The promisses of off shore wind energy

Alongside the development of onshore wind, offshore wind power is an important sector for development of wind energy. Offshore installations have several advantages: lack of space limitations allows for bigger machines (the blades can be extended up to 120 m in diameter), which consequently raises the unit power of the machine, better wind availability increases the capacity factor to about 40%. Ath the same time, development of offshore wind is currently limited by technical constraints, resulting in additional economic costs: demanding installation process, anchoring difficulties reduce the applicable depths, the towers have to withstand waves and currents, sufficient protection against corrosion, difficult electrical connection via submarine cables, demanding maintenance etc.

In this perspective, the most envisaged solution today consists in floating offshore wind turbines. Anchoring wind turbine in the submarine ground indeed requires to be installed in shallow water (maximum depth 50 meters) which means in Mediterranean regions to be very close to costal areas thus representing a potential damage for landscape.

 

 

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