Dozens of chimneys stretch out into the gray winter sky over Dormagen on the Rhine: Here in the chemical park, the size of 360 soccer fields, several manufacturers produce around 2000 different plastics, pesticides and rubbers. The basis for almost all operations: crude oil or natural gas. And so, above all, carbon dioxide, CO2 for short, the frowned upon greenhouse gas, escapes from all the chimneys. Residual material from the industrial economy, the cause of global warming. Only in factory building K2 in the east of the site things are a little different. Instead of escaping through the silver pipes into the atmosphere, the CO2 flows here in the opposite direction: into the factory. The line meanders over several floors, passing valves and boilers until it reaches a man-high reactor. In this, polyol is produced from the carbon dioxide in chemical reactions: a preliminary product for plastics.