Placing wind turbines offshore only increases the environmental gains as the turbines can produce an energy output which is up to 25% higher than for comparable turbines onshore. To help combat climate change, the Government has set a target of 15% of electricity supply from renewable energy by 2015. In March 2007 the 27 nations of the European Union agreed to a legally binding target of 20% of all energy to be supplied from renewable sources by 2020. Increasing the amount of energy generated from renewable sources also increases the diversity and hence the security of supply. It is anticipated that wind power will play a dominant role in terms of contributing to the European target.