Hybridization of CSP plants with biogas boilers: A techno-economic assessment

This study aims at investigating the performance and the economic benefits coming from the integration of CSP power plants with anaerobic digestion processes. To demonstrate the capabilities of hybrid CSP-biogas power generation systems, the CSP section of the Ottana solar facility (Italy) is considered as case study. A simulation model for the performance analysis of the overall hybrid power plant has been developed on Matlab environment. The effects of the variation of the anaerobic digester volume and biogas storage capacity on the main performance indexes of the hybrid power plant have been evaluated. Finally, a preliminary economic analysis has been carried out to assess the economic benefits led by the hybridization and the optimal configuration able to minimize the energy production cost. The obtained results demonstrate the benefits in terms of improvement of plant capacity factor and plant efficiency arising from a proper sizing of the biogas section. In fact, an oversizing of the biogas section results in an important increase of the solar field energy curtailment due to the limited TES capacity with a consequent degradation of the plant performance. Consequently, the optimal configuration, even from an economic point of view, is achieved by sizing the biogas section to guarantee the continuous operation of the ORC unit at its minimum load.