Better world: Top tech for a cleaner planet

There's a lot more to green technology than renewable energy. From more efficient aircraft to thread made from chicken feathers, the world is awash with ingenious ideas. So we have scoured research labs and start-ups, and made some hard choices. Here you will find our pick of the best ideas to make our planet a more energy-efficient place

Pee-n-grow

Manufacturing artificial fertiliser is a highly energy intensive process that consumes roughly 1 per cent of the world's energy supply. As odd as it sounds, using sterile, nitrogen-rich human urine instead could prevent the emission of more than 180 million tonnes of C0₂ each year. Urine collection systems with basement storage tanks have been built by the Stockholm Environmental Institute in more than 800 apartments in rural China, saving an estimated 20 tonnes of C0₂ emissions annually.

China: available now

Magnetic fridge

The two biggest consumers of electricity in the home - air conditioners and refrigerators - may soon become much more energy efficient thanks to a new method of cooling. Magnetic refrigeration subjects metal alloys to a magnetic field, causing them to cool down. Camfridge, based in Cambridge, UK, says its fridges and air conditioners will cut energy usage by around 40 per cent in comparison with conventional models.

Cambridge, UK: under development