Access to clean water is taken for granted in the developed world, but lack of clean water is actually killing or negatively affecting billions of people. It is one of the prime challenges of modern society. A US physicist born in India clearly has not eradicated the problem, but he has developed a system that has saved and helped countless lives.
2012 Zayed Future Energy Prize Lifetime Achievement Winner Dr Ashok Gadgil invented UV Waterworks, which "uses UV light emitted by a low-pressure mercury discharge... to disinfect drinking water." The key, aside from genuinely cleaning the water, is that the system is able to do so very cheaply. Using this system, WaterHealth International is able to sell clean drinking water to underprivileged people in developing countries for 2 cents per 12 liters. This is critical in places where people make under $1 per day.
When Dr Gadgil won the Zayed Future Energy Prize 2½ years ago, WaterHealth was serving clean water to over 4 million people a day in India, Mexico, the Philippines, and Ghana.
But this is far from Dr Gadgil's only achievement. He also invented the Berkeley-Darfur stove, "which cuts firewood use by 55% and is benefitting 20,700 households in the Darfur refugee camps." And he has pioneered energy-efficient light bulb programs at over 100 utilities that bring energy-efficient bulbs to low-income families. This cuts their costs, a huge benefit to low-income families, and it also cuts global warming emissions considerably. This program has been rolled out through utilities in North America, Europe, Asia, and Africa!
Of course, this is not an exhaustive list of Dr Gadgil's many achievements. But these are some of his most famous, and they clearly show that his useful, inventive, humanitarian ideas have had a profound impact on millions and millions of people.