LONDON (Reuters) – Scottish & Southern Energy (SSE) will build the world's largest offshore wind farm and has awarded $3 billion (1.5 billion pounds) in contracts to U.S. engineer Fluor and Germany's Siemens. Despite industry doubts about the viability of offshore wind SSE said on Wednesday it would build the farm off the east coast. Work would begin on the 504 megawatt Greater Gabbard project shortly and power generation would start in 2011. The utility added it had bought Texas-based Fluor's 50 percent stake in the project for 40 million pounds. Earlier this month Royal Dutch Shell said it wanted to sell its stake in a planned 1,000 MW British offshore wind farm project called London Array, raising doubts as to whether that project would be built. London Array partner E.ON, the German utility, acknowledged that rising steel costs and a tight market for turbines had made the economics of the project challenging, despite government incentives for CO2-free generation. Falling turbine sales in the first quarter at the world's biggest turbine maker, Denmark's Vestas Wind Systems A/S, added to fears that a boom in wind energy in recent years — driven by fears of climate change — may be cooling. However, SSE spokesman Justyn Smith said that while rising costs were a feature of the wind industry the utility was confident Great Gabbard would "meet our rigorous investment criteria". Fluor will build the wind farm and the company said in a statement the contract was worth $1.8 billion.