The wood-burning Drax power station in Yorkshire provides 12 per cent of the UK's renewable energy. It has already received £6 billion in green energy subsidies from the government. But are the wood pellets the power station burns really as sustainable as the company claims? Reporter Joe Crowley investigates where the wood comes from and uncovers an environmental scandal. He reveals how Drax is chopping down trees and taking logs from some of the world's most precious forests.