In 2002, Brazilian engineer Alfredo Moser invented a simple way to bring the sun’s light indoors: fill a clear plastic 2 liter bottle with water and two capfuls of bleach, then make a hole in the roof and secure it with a waterproof sealant.

The result: 40 to 60 watts of free, natural light.

How does it work? The bleach keeps the water from turning green, and the water refracts sunlight. To see this innovative but simple invention in action, watch the the ecoideasnet video above (with captions on). Chilean Miguel Marchand helps to install the bottle lights, or Moser Lamps, in the home of a family that lives in the Andes.

Around 1.6 billion people — 25% of the Earth’s population — live without electricity, but with this simple idea, they can enjoy sustainable light in their home for free. Moser Lamps are becoming popular solutions in the Philippines, India, Bangladesh, Tanzania, Argentina, Fiji, and other countries, and give an incredibly useful second life to plastic bottles.

If you make a Moser Lamp, please contact us by twitterfacebook, or email to let us know!

h/t BBC News.

Related watching: La casa ecológica de botellas, and more videos about sustainability.

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