In the context of the energy transition and climate objectives, more and more renewable electricity production is being installed worldwide. This production capacity is non-controllable and has an intermittent character because it is dependent on the availability of wind and sun. However, the electricity grid must always remain in balance, which requires coordination of production with consumption or vice versa. This PhD delves deeper into the chemical process industry's ability to maintain this required balance by providing flexibility. The chemical industry is a major consumer of energy, and electricity in particular. It is also characterized by continuous business operations, extensive energy integration and operational limitations dictated by safety. This means that flexible processes cannot be taken for granted. A thorough analysis of chemical processes shows that flexibility can be found in some specific chemical processes as well as in more general supporting processes. Aggregating or clustering different processes and industrial sites may further increase the flexibility potential. An industrial cooling process, an electrolysis installation and a hybrid steam production system are developed as applied case studies in the light of the possibilities on the various electricity and reserve markets.