Ceramic membranes are considerably more stable and durable than polymer membranes and allow due to their excellent materials properties the use of high temperature and pressure. This enables an efficient operation and effective use of waste heat. Perowskite membranes are high-temperature membranes for separating oxygen from air. For this purpose membranes are developed in different geometries, membrane modules and systems. Affordable oxygen makes it possible to increase the efficiency of combustion reactions. At the same time, the fuel consumption and thus the emission of greenhouse gases is reduced.