The Pot-in-Pot system consists of a smaller earthenware pot nestled within another pot with sand and water in the space in between. When that water evaporates, it pulls heat from the interior of the smaller pot, where produce can be kept. In rural Nigeria, one of their biggest problems farmers face is the inability to preserve their crops. With the Pot-in-Pot, tomatoes last for twenty-one days, rather than two or three days. Fresher produce can be sold at the market, generating more income for the farmers.