Abstract
The aim of this work is the energy efficiency assessment of cogeneration systems based on biomass gasification for residential applications, using a multistage modelling approach. The gasification stage has been modelled through an enhanced (i.e., gas-solid) thermodynamic approach using the Cantera solver and the Gri-Mech thermodynamic properties. Several values of temperature and amounts of gasifying agent have been taken into account for the simulations. The efficiency of the whole CHP system has been evaluated supplementing the simulation of the gasification stage with the energy balance of the cogeneration set (i.e., internal combustion engine) and implementing the developed routines in the Matlab-Simulink environment. The CHP plant is considered to supply thermal energy to residential buildings. Dynamic simulations by means of EnergyPlus 7.1 code have been performed considering three main building configurations given by three different thermal resistances for the opaque building envelope. The building-system interactions have been performed for the climate of Milan. Domestic hot water consumption has been chosen in agreement with EN 15316-3-1:2007. The resulting building-system scenarios have been compared with a conventional scenario of separated production by means of PES (primary energy saving). The paper shows the system size range for the chosen residential applications and the optimal operating conditions. The economic return of a such power plant has been discussed. The results of this work confirm the gasification-based CHP technology allows energetic and economic benefits. It can have substantial room for improvement with respect to conventional separated generation systems at the same size.