Comparison of CHP systems for the paper industry in the context of High-efficiency cogeneration

In January 2011, the incentive scheme for cogeneration power plants changed radically by the introduction of High-efficiency cogeneration (HEC) in Europe. As a consequence of the establishment of this directive, the techno-economic feasibility of new cogeneration plants in different areas of application (industry, service, residential etc.) and their optimal operation have been deeply modified. The previous legislation considered the entire electricity production as cogeneration electricity if two parameters, primary energy saving and thermal limit, evaluated on an annual level, exceeded specific limit values. This old incentive scheme made the sizing of Italian cogeneration power plants be focused on the maximum electricity output. According to the new incentive scheme, however, if cogeneration power plants don’t reach an established value of overall efficiency, it is necessary to split them in a CHP portion and a non-CHP portion and the incentives are proportional to the energy quantities pertaining to CHP portion only. This situation implies that cogeneration power plants designed on the basis of thermal demand are more rewarded, as opposed to what happened in the past. The main area of application of CHP systems is industry and, among the various sectors, paper industry appears the most suited to be matched with cogeneration. Given that, in industry, the choice of the most appropriate technology and the sizing are essential, the present study considers a particular industrial reality and aims at comparing different cogeneration solutions to be coupled to it. This will be accomplished thanks to the definition and analysis of energy, environmental and economic performance parameters, always bearing in mind the High-efficiency cogeneration framework and making use of GateCycle software as the main calculation tool.