Greenhouse gas reductions and primary energy savings via adoption of hybrid plants in place of conventional ones

With the Kyoto agreement, there has been a greater emphasis on lowering energy waste and supporting low-emissions systems such as fuel cells (FC), photovoltaic (PV) systems or solar thermal systems (STS). These technologies produce environmental benefits since non-renewable energy can be preserved and environmental pollution can be drastically reduced. In addition to this, the decentralization of the electricity production plants mitigates the grid distribution losses. This paper developes a theoretical analysis focused on the environmental benefits achievable through a shift from the conventional systems, normally operating in hospitals, to different hybrid plants. The model site is a hospital located near Ferrara (Italy). At first, a numerical procedure has been adopted in order to calculate the energy requirements of the existing plant. Then several hybrid schemes have been investigated and compared: PAFCs (phosporic acid fuel cells), STS, PV systems. An energy analysis is developed for each option assuming the conventional systems, operating in the medical center, as the reference. At the same time, an economic study is developed for all the retrofit scenarios in terms of annual return, simple payback period and IRR. The results are presented with reference to the primary energy requirements and the pollutant emissions; it is demonstrated that in the case the existing conventional systems would be upgraded with these hybrid plants, overall greenhouse emissions could be abated with a significant reduction in primary fossil energy consumptions.