Leo Marcelis at Al Jazeera on vertical farming

QATAR- The world population and the number of people living in cities are growing. At the same time, the demand for healthy, fresh and locally produced food is increasing. Vertical farming has the potential to meet this demand: by cultivating in multilayer systems which literally go up into the air, sustainable, efficient and fully controlled cultivation can be carried out in cities without taking up too much space. Professor Leo Marcelis explains to Al Jazeera the potential of vertical farming and the hurdles that still need to be taken.