Techno-economic assessment of hybrid CSP-biogas power plants

This study aims to investigate the performance and economic benefits arising from the integration of concentrating solar power (CSP) plants with anaerobic digestion processes. To demonstrate the capabilities of hybrid CSP-biogas plants, the CSP section of the Ottana solar facility (Italy) is considered as a case study. A simulation model for the performance analysis of the hybrid system is developed, and the effects of variation in the volume of the anaerobic digester and the biogas storage capacity on the main performance indexes are evaluated. Furthermore, two different operating strategies for energy storage management are compared and the possible requirements for energy curtailment are analysed. Finally, a preliminary economic analysis is carried out. The results demonstrate the benefits and improvements in plant capacity factor and efficiency arising from proper sizing of the biogas section. Conversely, oversizing of the biogas section results in significant curtailments in biogas and/or solar field energy production, due to the limited storage capacity. Consequently, the optimal configuration, even from an economic point of view, is achieved by a biogas section of a size that is able to supply part (in the range of 10%–65%) of the nominal thermal power input required by the power block.