Process systems engineering (PSE) is a discipline that delivers tools for guided decision-making in the development of new processes and products. Proven successful in the pharmaceutical-, food- and water sectors, it has also breached the field of energy systems. The future energy systems aim to be more efficient, cost-effective, environmentally benign, and interconnected. The design and operation is extremely challenging for decision-makers, engineers, and scientists and here lies a crucial role for the process systems engineer.