ISAB refinery is part of the biggest and most complex European petrochemical centre that includes the municipalities of Priolo Gargallo, Melilli and Siracusa. In all likelihood, it is also the youngest petrochemical industrial site in Italy. Beside the two actual refineries, it also consists of a thermoelectric plant and an I.G.C.C. (integrated gasification combined cycle) plant realized with the aim of reducing the impact on the environment. Cleaned gas is, then, used to produce electricity and steam. During years the centre has be modernized thanks to new plants construction and their integration to the existing ones to improve the production efficiency. For some years a new plant producing hydrogen from gas has been built.