Trash to Gas - World Challenge 

Food waste from restaurants in the heritage town of Mamallapuram in South India had become a big problem, leaving the tourist destination covered in rubbish and increasing the risk of disease. Indian NGO 'Hand in Hand' set up a project with local people to collect food waste from households, hotels and restaurants, and turn it into biogas - which is then used to generate electricity via a 10kW power station. The project now consumes about a ton of food waste every day - waste that would once have found its way into landfill. The project is self-sustaining, providing training and employment for locals to become 'Green Friends' - town wardens whose job is to keep the streets clean and the lights on.