Nigeria is a hot and dry country in Africa where electricity is not available(可获得的)to many fami— lies. Most people grow and sell their own fruit and vegetables. Keeping them fresh in the hot place is a real challenge. Without a fridge, most fresh food goes bad in a couple of days. Throwing away the food means losing money for poor families. Eating the bad food causes serious health problems.
A local teacher, Mohammed Bah Abba, was worried about this problem and decided to solve it. As a boy born into a family of clay pot (陶罐)makers, Mohammed knew that these traditional clay pots could keep water even when the weather was dry. In the 1990s, he used this traditional knowledge to invent a cool— ing system. It worked as a "desert fridge".
Mohammed's cooling system is made up of two pots——a small pot inside a big pot. In the space between the two clay pots, there is wet sand. People put the fruit and vegetables in the small pot, and cover it with a piece of wet cloth. Then they leave the big pot in a dry place. When water in the sand evaporates(蒸发)， the temperature in the pots will go down. In this way, the food in the small pot is cool.
Mohammed's" desert fridge" has improved the lives of thousands of people. So in 2001, he won the Rolex Award for Enterprise.
