It takes an average of 42 months within the EU for wind farm planning permission to be approved, it has been revealed.
The study, which was co-ordinated by the European Wind Energy Association (EWEA), found that the UK is one of the quickest countries to make a decision, while Spain and Portugal are among the slowest.
Finland topped the table, with building consent taking an average of just eight months, followed by Austria (ten months).
Commenting on the findings, EWEA policy director Justin Wilkes said: "If Europe is serious about reaching 20 per cent renewables by 2020 some member states need to streamline their consent procedures for wind farms."
There are a number of steps that EU member states could take, such as writing clear guidelines for developers and creating a one-stop-shop approach for contacting different authorities, he added.
With over 600 members, the EWEA is the world's largest wind energy network.
Written by Joseph Hutton