In some of the world's poorest and most densely populated slums, buildings can be built so close to one another that daylight cannot find its way into the living spaces. Given the high price of electricity, many inhabitants do not use light bulbs, and thus find themselves living in light-deprived environments. According to the website inhabitat.com, a group of Massachusetts Institute of Technology students have stumbled onto a workable solution in the form of the "Solar Bottle Bulb," a very clever and cheap alternative to the electric light bulb. The bulb consists of a standard plastic bottle filled with purified water and bleach, then inserted into the roof. A clean round hole is cut into the metal roof and the is bottle inserted, with any gaps sealed up. The lower portion of the bottle hangs down into the room below, while the top of the bottle pokes up into the outside air, reports the French newspaper LePost.fr. Thanks to the principle of light refraction, the bottle produces a source of light with an intensity equivalent to a 55-watt electric light bulb. Although this system is only capable of producing light during the day, it has positively impacted the daily lives of people in the Philippines, where the solar bottle bulb has been widely installed. According to the inhabitat website, 10,000 such bottles have already been installed through Manila. The device has also been distributed all over the country by a project called "Isang Litrong Liwanag" (A Liter of Light), the latest venture of MyShelter Foundation, an NGO that aims to encourage sustainability and self-reliance through its capability-building and employment-generating projects, the site says. As well as saving money, the system is also safer than candles or potentially dangerous electrical connections, and much more sustainable, since the bleach prevents the growth of mold in the water and enables these solar bottles to last up to five years, according to the site.
