Minimising the demand for fossil fuels and the greenhouse gas footprints is of high priority for sustainable development. This is true for all societal aspects – including research and development. Waste-to-Energy (WtE) networks are regarded as one of the potential contributors to solving this problem by applying a win-win strategy for simultaneously minimising the landfilled waste, fossil fuel demand and the associated footprints. A critical aspect for the success of a Waste-to-Energy network is to account for the spatial challenges posed by the distributed nature of the waste generation and the energy demands, where the size of the processing facilities and the served areas should be simultaneously optimised. The current work proposes concepts and procedure for targeting these capacities and sizes as the first step in the WtE network synthesis, employing Process Integration and P-graph. An illustrative case study is provided, illustrating the procedure and its application.