Innovative earthen cooling system Northern Nigeria is an impoverished region where people in rural communities eke out a living from subsistence farming. With no electricity, and therefore no refrigeration, perishable foods spoil within days. Such spoilage causes disease and loss of income for needy farmers, who are forced to sell their produce daily. " I developed the pot-in-pot to help the rural poor in a cost-effective, participatory and sustainable way.” Nigerian teacher Mohammed Bah Abba was motivated by his concern for the rural poor and by his interest in indigenous African technology to seek a practical, local solution to these problems. His extremely simple and inexpensive earthenware "pot-in-pot" cooling device, based on a principle of physics already known in ancient Egypt, is revolutionising lives in this semi-desert area.