This editorial introduces and provides an overview of a Special Issue dedicated to the 9th conference of Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction-PRES 2006. It contains 11 selected papers covering various fields of energy related issues focusing on recent developments and includes energy resources, management and use, heat integration, heat pumps, emission treatment and waste to energy. The selected papers include interesting applications in the power generation, food industry, building materials production, oil refining, district heating, waste treatment and hydrogen production. (C) 2008 Published by Elsevier Ltd.