The final turbines to be installed at Europe's biggest onshore wind farm, the 322 MW Whitelee facility, have been switched on by Scotland's First Minister, Alex Salmond. The 140 Siemens 2.3 MW turbines cover an area of 55 square kilometres just 15 kilometres from Glasgow. At the switch-flipping, Salmond announced Scottish government approval for a 130 MW extension to the wind farm. Developer ScottishPower is also developing plans for a second extension for a further 140 MW to bring total capacity to nearly 600 MW -- as big as wind farms in Texas, China and India. ScottishPower, owned by Spain's Iberdrola, expects to submit an application for consent for the extension this summer. It points out that Whitelee is one of the first major wind farms to be built close to large population centres. A £2 million visitor centre is currently being built and the site will be open to the public later this summer with tours of the wind farm available and plans to introduce eco-friendly buses powered by electricity from the site.