A youth group in one of Nairobi's many teeming slums has found a brilliant way to light up dark houses. Drawing upon an innovation from Brazil, the young people have installed so-called "water bulbs" in homes and schools. The "bulb" is made from everyday materials and can produce as much light as a 60-watt conventional bulb.
Abbass, 11, can barely read what is in his book. In the middle of the day, the family's windowless tin shack feels like the darkest night.
But a few blocks away, members of a youth group called Koch Hope are preparing to change that. First, they fill a two-liter bottle of water, add a little bleach and, with the water, bleach, a caulking tube, and some tools, make their way to Abbass's house.
Next, they cut a hole in the tin roof as a mesmerized Abbass watches.
The bottle containing the bleach is passed through the hole, the hole is sealed with caulking, then tested for leakage, and
Voila! Abbass and his family are now able to read, learn, and do things that they had struggled to do in the dark.
Abbass' mother, Madina Muhsin, says she will be saving almost half of her weekly income spent on kerosene now that her home is receiving the equivalent of around 50 to 60 watts of light.
"I'm very happy," said Muhsin. "I can see the light. Before it was all dark, dark, dark. Now I am happy - I am very happy."
The Muhsins are the latest family in the Nairobi informal settlement of Korogocho to receive the so-called "water bulb," in which water and bleach refract sunlight. The bulb also works under a full moon.
Most people living in Korogocho and other Nairobi informal settlements do not have access to electricity, and earn somewhere between $1-$2 a day.
Community worker Matayo Magalasia grew up in a dark house in Korogocho. His family was too poor to afford kerosene.
As a young adult, Magalasia stumbled onto a YouTube demonstration of the technology, first discovered in Brazil.
"I started thinking, can I get the two-liter bottle? Yes, I can get the two-liter bottle, there is the Dandora dumping site on the other side of the slum. Can I get water? Yes, I have water. Can I get the bleach? That one I can buy. Can I get the silicon? Yes, I can buy that," Magalasia said.
His early struggles motivated him to approach Koch Hope with a plan to spread this innovation around.
Koch Hope picked up the challenge and had installed water bulbs in about 100 Korogocho homes during 2011.
One of those homes belongs to Veronica Wanjiru and her two children. She says her eldest son had to repeat a grade at school, because he was not keeping up with his homework.
"I have seen a big difference, especially with my children's education," said Wanjiru. "If they are given homework, they can finish it on time. They do not have to wait for me to come and light the candle or go outside and do their studies outside so that they can finish their homework."
Koch Hope wants to expand the project to other areas, but says it needs help to pay for the relatively expensive caulking materials that seal the hole.