Increase of Net Power Generation Of Biogas Plants By Reduction Of Heat Loss

in this work, a comprehensive mathematical model of a biogas power generation plant is exploited to investigate the advantages of heat loss reduction. The model allows simulating the whole generation process, from biological breakdown of the biomass mixture to final generation of electricity and heat by combustion of the biogas. Either a thermal sub-model of the digestors or a fluid-dynamic sub-model of ducts and heat exchangers of the auxiliary heating system have been implemented, in order to evaluate heat loss, head loss in the ducts and power absorption of the pumps. An innovative approach to the exploitation of solar gains through the gasometer domes is also evaluated, based on the use of surface coatings with high solar absorptance and low thermal emittance. The theoretical reduction of auxiliary energy need is thus predicted as a function of local meteorological data on a monthly average. The results of the analysis show that proper insulation of the digestors and coating of the gasometer domes can increase the net production of electric energy up to a few percentage points. If waste heat is also exploited externally, the net increase of heat production is much greater, especially in cold climates.