Waste: don't just take it away

Born out of a failed methane experiment comes a water-treatment system that uses 90 percent less energy than conventional sewage system and cost 50 percent less to operate. Dean Cameron – the creator of the Biolytix Water – harnessed worms, beetles and billions of microscopic organisms to turn human waste into water suitable for irrigation.

The low cost (a small version for four people could cost $175) and its minimal energy use hold a promise for 2.5 billion people around the world who can't afford proper sanitation. So far there are 3000 biotanks installed in homes and businesses across the Pacific.