Millions of poor homes could soon be brightened by sustainable, safe and inexpensive light bulbs made from one-litre plastic bottles containing purified water, salt and bleach. The MyShelter Foundation hopes to distribute the “solar bottle bulb“, developed by MIT students, to one million homes throughout the Philippines by 2012.
The bottles are sealed within holes cut in the metal roofs of homes, with their lower halves emerging from the ceiling. The clear water disperses light around the room through refraction, salt slows evaporation, and bleach prevents mold growth, allowing each solar bottle bulb to last up to five years.
Even though the solar bottle bulb, equivalent to a 55-watt electric light bulb, only works during daylight hours, it provides a significant benefit to poor people in cities like Manila, whose homes are close together and barely allow in any light. MyShelter is promoting the bulbs (paid for by the city of Manila) through the Isang Litrong Liwanag (“A Liter of Light”) project, and training residents to make and install them.