Union Science and Technology Minister Harsh Vardhan today launched a low cost solar lighting device which can be used in slums. The device is “leak proof” and works for almost 16 hours at a stretch, Vardhan told a press conference. This device has the potential of being used in some 10 million households and, if this happens, it would result in saving of 1,750 million units of energy. This would also lead to reduction in emission of 10 million tons of carbon dioxide,” he said. This can be typically used in slums,” said Y S Chowdary, Minister of State for Science and Technology, adding that it was used in the slums of Lal Bagh in the national capital as a pilot project.Explaining the working of the device, Vardhan said the micro solar dome captures sunlight through a transparent semi-spherical upper dome and concentrates it inside a dark room. The light passes through a sun-tube having a thin layer of highly reflective coating on the inner wall of the passage. It also contains a low dome having a shutter at the bottom that can be closed if light is not required in the daytime. A scientist associated with the project said there was a flaw in the project when it was initially started but it was rectified after it was pointed out by DST Secretary Ashutosh Sharma.