In the early stages of his research, professor Jo Dewulf concentrated on environmental analytical methodologies and on advanced oxidation technologies as end-of-pipe techniques. Now for about 20 years, he heavily focuses on clean technology, i.e. searching for preventive actions within production processes themselves. To do so, he makes thorough analyses at the process, plant and overall industrial system level, based on life cycle thinking and thermodynamic principles in order to find out opportunities for improvement (techniques: Exergy Analysis: EA; (Exergetic) Life Cycle Analysis: (E)LCA). Apart from methodological improvements, implementations and collaborations with industrial partners have been put in practice in three areas: fine chemicals and pharma, agro/bio/food, and raw materials.