Guardian: The world’s biggest offshore windfarm opened officially today off the UK coast but the company behind the project said that less than 20% of the £900m investment in the project has gone to British firms. The low figure will concern ministers who have portrayed green technology as a growth sector that will help drive a recovery in the UK economy. In his speech to the Liberal Democrat conference on Tuesday, the energy and climate change minister, Chris Huhne, promised a “third …