The e-nova took place on November 21st and 22nd at the University of Applied Sciences Burgenland. At this congress on sustainable technologies for energy supply, for buildings and the environment in general, Dr. Johannes Fresner introduced Circular Economy as a principle of the production of the future. Examples of closing the cycle in plastics and food processing were presented, as well as advice for companies: replacement of problematic chemicals that make recycling difficult, optimization of design, layout and internal recycling, as well as examples of new collaborations on the use of by-products and waste-to-energy.