* SSE, RWE Innogy developed 500 MW wind farm
* World's biggest offshore wind farm opened month ago in UK
LONDON Aug 7 (Reuters) - The world's second-largest offshore wind farm, capable of generating enough electricity to power over half a million homes, was opened officially off England's east coast on Wednesday.
Energy and Business Minister Michael Fallon opened the 500 megawatt Greater Gabbard wind farm off the Suffolk coast, a 1.3 billion pound ($2 billion) project that is a 50-50 joint venture between SSE Plc and RWE Innogy.
Britain is banking on offshore wind technology to help it reach legally binding targets to cut carbon dioxide emissions. It aims to develop 18 gigawatts of power from wind by 2020. The addition of Greater Gabbard pushes the total so far to about 3.6 GW, according to RenewableUK.
Greater Gabbard has 140 turbines, which were manufactured by Siemens, and it is expected to double in size when an extension, called Galloper, is completed in 2017.
It was launched just a month after Prime Minister David Cameron opened the world's largest wind farm, the 630 MW London Array project, also off the south-east coast.
The UK government says offshore wind could provide enough power for 11 million homes by the end of this decade.