Land-based wind refers to the energy generated by wind turbines deployed in the mainland.
Land-based wind power is a proven and mature RE technology that is being deployed globally on a mass scale. Wind turbines extract kinetic energy from moving air flow (wind) and convert it into electricity via an aerodynamic rotor, which is connected (often via a transmission system) to an electric generator. Today’s standard turbine has three blades rotating on a horizontal axis, upwind of the tower, with a synchronous or asynchronous generator connected to the grid using power electronics. Two-blade and direct-drive (without a gearbox) turbines are also available.
The electricity output of a turbine is roughly proportional to the rotor area; therefore, fewer, larger rotors (on taller towers) use the wind resource more efficiently than more numerous, smaller machines. The largest wind turbines today are 5-6 MW units, with a rotor diameter of up to 126 metres. Typical commercial wind turbines have a capacity between 1.5 MW and 3 MW.
Since 2000, cumulative installed capacity has grown at an average rate of 24% per year (%/yr). In 2012, about 45 GW of new wind power capacity were installed in more than 50 countries, bringing global onshore and offshore capacity to a total of 282 GW. New investment in wind energy in 2012 was USD 76.6 billion. Among the largest clean energy projects financed in 2012 were four offshore wind sites (216 megawatts [MW] to 400 MW) in the German, UK and Belgian waters of the North Sea, with investments of EUR 0.8 billion to EUR 1.6 billion (USD 1.1 billion to USD 2.1 billion).
Thriving markets exist where deployment conditions are right. Progress made since 2008 shows a positive trend: in 2012, wind power generated about 2.6% of global electricity while capacity and production information for wind resources around the globe show steady expansion.
Repowering, i.e. replacing “old” wind turbines with more modern and productive equipment, is on the rise. Repowering is shown to increase wind power while reducing its footprint. A 2 MW wind turbine with an 80 metre (m) diameter rotor now generates four to six times more electricity than a 500 kW 40 m diameter rotor built in 1995.
Onshore wind generation and projection
IEA, (2013), Medium-Term Renewable Energy Market Report 2013, OECD/IEA, Paris