Emergy evaluation of power generation systems

With the increasing demand of power sources, it is of great significance to evaluate different power generation systems and optimize the energy structure. The emergy is proved to be a comprehensive and powerful way to evaluate the sustainability of a system. In this paper, emergy is used to compare ten power generation systems by two calculation methods of emergy indices. The emergy data of integrated gasification combined cycle and wind power generation systems are gathered from the studies of life cycle assessment, while those of the other eight systems are taken from existing emergy evaluations and converted to the same baseline. The study of hydropower generation systems shows the influence of technical progress and geographical location to the sustainability. The comparison of ten power generation systems shows that the hydropower generation system has the best sustainability while the wind and solar systems demonstrate relatively low sustainability. Besides, the sustainability is relative to the carbon dioxide tax. The sustainability of wind and concentrated solar power generation systems is tend to be better than that of integrated gasification combined cycle power generation system with an increase in the carbon dioxide tax. The results indicate that the technology, investment cost and carbon dioxide emission are essential factors to sustainability of power generation systems.