"CNN's Ian Lee goes to Egypt to meet Faris Farrag, a former banker who now farms plants and breeds fish with an "aquaponic" system. Aquaponic systems rely on recirculation, meaning there is little waste and better efficiencies. On Farrag’s farm, gases exhaled by his fishes are pumped into the greenhouse, while oxygen produced by the plants is circulated back to the fish farm." (Quoted from article)