Clean water with free energy is the goal of German scientists who are using the sun’s rays to power small water treatment plants for developing countries. The system is designed for arid areas of Africa and Asia where a lack of electricity makes it impossible to use large industrial plants for the desalination of seawater, like those in the Middle East. ‘The regions have a very poor infrastructure. Quite often there is no electricity grid, so conventional desalination plants are out of the question,’ says Joachim Koschikowski. The engineer and his team at the Fraunhofer Institute for Solar Energy Systems (ISE) have developed small decentralised units with their own solar power supplies that can transform salt water or brackish water into pure drinking water. ‘Our plants work on the principle of membrane distillation,’ says Koschikowski, comparing the technology to that used in breathable, waterproof fabrics, where the membrane prevents rainwater from penetrating through to the skin, while allowing water vapour to pass through to the outside. ‘In our plant, the salty water is heated up and guided along a micro-porous, water-repellent membrane. Cold drinking water flows along the other side of the membrane,’ he says. […]