sojen copestake's been to visit a world —first project where the aim is to create more food but causee environment. one word — sewage. yes, sewage. every year we produce1 million tonnes of it in the uk. and it produces its own waste — heat. interest is growing on how to use this waste heat as a sustainable energy source, and here in east anglia it's being used in the building of a unique greenhouse project which could revolutionise our country's farming industry. this will be the world's first greenhouse that is using heat from a water treatment plant, and that has the benefit of not only reducing the impact on the environment but also reducing the uk's need to import produce. in the uk we consume over 500,000 tonnes of fresh tomatoes every year. 80% of this, around 400,000 tonnes, is imported. the same goes for cucumbers and peppers. we import 75% of our cucumbers and 90% of peppers. these new greenhouses could not only help make the uk self—sufficient in produce, but also reduce carbon emissions by 75%. so ben, we're now walking into the greenhouse, blimey, it's really, really big.