Mohammed used skills he had learned as a boy making pots. And He used his knowledge of biology, chemistry, and geology. He knew that evaporating water would cool the pots. He knew that the area in Jigawa had a lot of clay. And he knew that bringing these facts together could produce a very useful thing for many people.
In nineteen ninety five Mohammed had a wonderful idea. He began to develop a system that could keep vegetables cool and fresh for a long time.
For two years Mohammed worked on this project. He made the design better and better. He called his system "The Pot-In-Pot Refrigeration Cooling System. " It kept vegetables cool and fresh just like a refrigerator. It worked very well. It did not need electricity. It was very easy to make. And it did not cost a lot of money!
Mohammed's Pot-in-pot design works like this. First, he puts a smaller pot inside a larger pot. Then, he puts wet sand in the space between the two pots. This sand must always stay wet for the Pot-In-Pot to work. Then he places a wet cloth or cover on top of the two pots.
The temperature inside the smaller pot drops when the water from the sand evaporates into the air. Outside the pot it may be twenty eight degrees. But inside the pot it would only be fifteen degrees!
Mohammed knew that he had found the substitute for an electric refrigerator. But thousands of people needed this cooling system. How could he give it to them?
Well, Mohammed decided to spend his own money.
