JAn AgriTower is a Greenhouse with multiple stories. This way we can multiply the amount of food we can grow, while using the same amount of ground. In the AgriTowers there should be room for livestock ánd crops. We could experiment with this,building some on Earth first. Favourably in a 'hostile' environment,like the desert or near the polar circle. Besides focusing on 'old' food,we should also have an eye for 'new' food,like insects. These foods contain a lot of proteins and energy. They are also far easier to 'breed' and take significantly less space than cows and chickens for instance.