“Wind is an abundant, clean, safe, secure and affordable energy source”
– Mary McCaffery – CEO RenewableUK
Wind Energy is a form of energy conversion in which turbines convert the kinetic energy of wind (air in motion) The wind generated turns the blades on the turbine (mechanical energy), which spin a shaft that connects to a generator and makes electricity (electrical energy) that can be used for power.
The major benefits of wind are that:
- The wind is free and with modern technology it can be captured efficiently. Wind energy is now one of the most cost-effective sources of new electricity generation, and utilities can lock in wind energy prices for 20 to 30 years because the fuel is free.
- Once the wind turbine is built the energy it produces does not cause greenhouse gases or other pollutants.
- Although wind turbines can be very tall each takes up only a small plot of land. This means that the land below can still be used. This is especially the case in agricultural areas as farming can still continue
At the end of 2012 there were more than 225,000 wind turbines operating around the world in about 80 countries.
Wind power currently supplies about 2.5 percent of global electricity consumption. Industry projections show that wind power will, with the right policy support, double in capacity by 2015 and again by the end of this decade. This will deliver somewhere between 8 and 12 percent of global electricity supply. Largest growing markets are in China and the USA, with India rapidly catching up.
Wind provides 30% of electricity in Denmark and also makes a double digit contribution of 16% in Portugal and Spain. It contributes more than 40% of annual electricity in three German states and 20% of South Australia’s electricity.
How Windfarms Work
Wind turbines convert the energy of the wind into electricity. The turbine blades are turned slowly by the wind, and this rotation spins a generator to produce electricity. The electricity travels through transformers and a transmission line into the local electricity network for distribution to consumers.
Almost all commercial wind turbines producing electricity consist of three blades connected to a hub that rotates around a horizontal axis. The hub is connected to the generator either directly or via a gearbox, which is located inside the nacelle, the large part at the top of the tower.
Turbines with electronic power converter technology, such as those at Windy Hill, do not have gearboxes. Instead, the electricity generated by the generator is rectified from AC into DC before being inverted back to AC suitable for distribution. The generated electricity passes through cables from the nacelle to the base of the tower. Here it is stepped up to high voltage in a generator transformer for supply to the transmission system.
Each of the turbines connects to the transmission system via the on site substation.
Wind turbines start operating at wind speeds of 2.5 metres per second (around 9 kilometres per hour) and reach maximum power output at around 13.5 metres per second (around 49 kilometres per hour). At very high wind speeds, such as gale force winds (34 metres per second or 122 kilometres per hour), wind turbines shut down to avoid damage to the equipment.
The blades rotate at 6 rpm in low wind conditions and 21.5 rpm at higher wind speeds to maximise energy production.