The German Sustainability Award, sponsored by the Federal Ministry of Education and Research, has also announced the topic of food in cities in the bio-economy year 2020 / 2021. In the discussions, it has become clear that metropolises are a "sink" for regenerative raw materials such as food. Together with Forschungszentrum Jülich and the consulting company mfm - menschen für medien, the Global Food Summit has developed an idea concept for how existing grey, rain and yellow water treatment systems can be further developed for urban agriculture. Algae production can play a major role here as a "game changer". Our contribution has been submitted. Now we have to wait until September to see whether we are in the three competition finalists.