Cooking with the sun.

When Dr. Robert Metcalf first used a solar cooker, the future changed for thousands--maybe millions--of Africans.

"It was a transforming experience for me when I lifted the lid from my first solar-cooked food and watched the steam roll out," he said.

He knew that billions of poor people around the world depend on the use of wood for cooking. And as they take more and more firewood from wild areas, they are destroying habitats around the world. Wood collection is one reason why many animals have become endangered and even extinct.

"But sunshine can be an alternative to tire," Dr. Metcalf says.

Since his first solar-cooked meal, he has helped people around the world to use simple new technologies to cook their food and make their water safe to drink--without burning wood.

Villagers Hard at Work

Each morning in villages across East Africa, small children and their mothers wake up and walk several miles to collect firewood to cook their food. Their journey takes much of the day, and the heavy bundles they carry home on their heads last only a few days.

This is why Dr. Metcalf spends each summer in Africa. He teaches women and children in villages and refugee camps how to cook with the sun.

He knows the importance of cooking to make food safe. He is a scientist who studies germs. He wanted to help answer two important questions: How can more people cook without fire? And how can they make sure their drinking water is safe?

To find answers, he helped create Solar Cookers International. It's an organization that introduces solar cookers to developing countries and teaches people how to use them.

Technology That's Easy

In the district of Nyakach in Kenya, women use sunlight to cook their traditional meals of ground white corn, or ugali, which is mixed with rice, beans, and vegetables.

Instead of building a fire, they mix the food in a dark pot, put the pot into a clear plastic bag, and place the pot and bag in a solar cooker. The cooker is an open box, lined with aluminum foil and shaped to reflect sunlight onto the pot. The dark surface of the pot absorbs much of the light, turning the light energy into heat, which cooks the food.

"The women are very excited because it's easy, it works, and the food tastes great," says Dr. Metcalf.

So far, more than thirty thousand African families now have solar cookers, and new programs will introduce solar cookers to millions of families.

Making Water Safe

To find water, women and children may have to walk long distances to dig holes in dry riverbeds or to gather water from streams and shallow wells.

They fill their buckets and carry them home on their heads. The buckets often weigh as much as forty pounds. Not only is finding water hard work, but the water is often contaminated with germs that make people sick.

Dr. Metcalf and others developed a simple, reusable device that people can use to make sure their water is sale to drink. The device is called a WAPI, which stands for "WAter Pasteurization Indicator."

The pasteurization process is named after Louis Pasteur, who developed it in the 1800s. In this process, harmful germs in water are killed by heating the water to 149 degrees Fahrenheit for one minute. That's not boiling, but it's too hot to touch.

But many people in Africa do not have thermometers. They can use a WAPI instead. It's a closed plastic tube with a ball of hard wax stuck inside one end.

To pasteurize a pot of water, anyone can lower a WAPI into the pot and slowly heat the water in a solar cooker. When the ball of wax melts and drops to the bottom of the tube, the water has reached a temperature that kills the bacteria. To use the WAPI again, the user turns it over so that the wax is in the upper end of the tube.

According to Dr. Metcalf, "The women in Nyakach say, 'The Sun is shining in a different way in East Africa.' The relentless Sun is now an ally in two of the most important activities humans share--cooking food and making water safe."

There is much more work to be done. But thanks to Dr. Metcalf and Solar Cookers International, the lives of many East Africans are becoming safer and easier, one village at a time.

How a Solar cooker Works

A simple solar cooker is made of cardboard or foam panels covered with aluminum foil. The cook must use a dark-colored pot, which absorbs more light than any other surface. He or she places the solar cooker in direct sunlight, then puts the covered pot of food in a clear plastic bag and sets it in the middle of the cooker.

Over a few hours, the reflecting panels direct sunlight onto the pot. The dark surface absorbs the light, which changes from light energy into heat. The plastic bag holds in the heat. The temperature can reach about 250 degrees Fahrenheit--hot enough for cooking and baking.

A solar cooker turns sunlight into heat.