British Gas owner Centrica has agreed to sell a 50% equity stake in its 270 megawatt (MW) Lincs offshore wind farm for £50m in cash.The buyers, Danish state-controlled oil and gas group DONG Energy and Siemens Project Ventures, part of Germany's Siemens Financial Services, are expected to complete the deal in January.Centrica also announced that Lincs has entered into a turbine supply agreement with Siemens Wind Power for 75 offshore wind turbines of class SWT-3.6-120. These are an upgrade from the class SWT-3.6-107 originally envisaged for Lincs and are expected to generate more power through higher load factors, enhancing project returns. Once the deal is done, DONG Energy and Siemens Project Ventures will reimburse Centrica for half the development costs incurred to that date. Total investment is expected to be about £750m, with Centrica's share being £375m. Construction of the Lincs wind farm is due to begin in 2010 with first power expected in the second half of 2012. 'DONG Energy brings substantial experience of offshore wind projects,' said Centrica boss Sam Laidlaw.