The study was initiated in the context of the review of the Integrated Pollution Prevention and Control (IPPC) Directive. This report presents the results of a study that assesses the theoretical potential to reduce air emissions of SO2 and NOX that might have occurred had the best available techniques (BAT) and associated emission levels (AELs), as described in the large combustion plant best available techniques reference document (LCP BREF), been fully introduced in a set of electricity-generating large combustion plants (LCP) within the European Union (EU-25) in 2004.