More than 230 years after a Scottish watchmaker called Alexander Cummings patented the flush toilet, Bill Gates recently handed $100,000 to a team from the California Institute of Technology who believe their invention goes one better. Flush toilets, Gates wrote in a recent blog, "are irrelevant, impractical and impossible for 40 per cent of the global population, because they often don't have access to water, sewers, electricity and sewage treatment systems". The world's richest man at the time of funding, who is also probably (as Calsberg would say) the planet's most generous philanthropist, has set inventors the challenge of developing a lavatory that will work in the most deprived and impoverished environments. To qualify, the prototypes must operate without running water, electricity or a septic system; must not discharge pollutants; and cost no more than five US cents a day to run. If they also provide a bonus in energy or other resources, even better. The challenge has ignited a volcano of ingenuity. Caltech's winning entry is based on a solar-powered electrochemical reactor which breaks down urine into hydrogen which in turn becomes a back-up source of energy. Second prize went to Loughborough University's effort, in which the waste is turned into biological charcoal which when burned produces the energy to power the system. Gates may be aiming this new loo at the Developing World, but he is far too cute and entrepreneurial not to see its potential for the west. In an era where water is becoming increasingly precious and expensive as us in Ireland shall be finding out, he says, "many of these innovations will not only revolutionise sanitation in the developing world, but also help transform our dependence on traditional flush toilets in the more wealthy nations."