Panorama - Can Tesco Save the World?

It has been blamed for concreting over the countryside, and running up endless air miles importing food and trucking it the length and breadth of Britain, but is Tesco now leading the business fightback against man-made global warming? Local communities and a new breed of business entrepreneurs increasingly see delivering a low-carbon economy as an opportunity to make money, while politicians are wary of forcing the pace of change because of its potential to lose votes.