Mathematical modelling of hybrid micro-scale concentrated solar and biomass-fuelled trigeneration system for residential applications

The Sun stands as the Earth's primary source of renewable energy, offering the most promising and clean energy for future power generation. However, solar energy's intermittency compared to other renewable sources impacts grid reliability, necessitating storage advancements or hybridization. Among solar technologies, Concentrated Solar Power (CSP) systems are seen as valuable alternatives to fossil fuel-based power generation. In CSP systems, incident radiation is concentrated from a large area into a smaller one using lenses or mirrors, then converted into electric or thermal power based on users’ needs. Recent studies have explored the potential of CSP-PV and CSP-wind hybrid systems in providing cooling, heating, and power to residential buildings. The results indicate increased thermal demand coverage and reduced grid reliance compared to separate configurations. However, they also underscore the need for backup solutions to meet users’ thermal demands in winter. Thus, this study investigates the complementarity of solar energy with biomass combustion, considering a small-scale hybrid tri-generative system. The plant comprises a 440 m2 collector area of Linear Fresnel Reflectors and a 125 kWth back-up biomass boiler supplying heat to a 20 kWe / 100 kWth Organic Rankine Cycle (ORC) unit for 10 apartments. The analysis employs an advanced simulator developed in MATLAB/Simulink to evaluate the performance of the proposed hybrid system compared to the separate operation of CSP+ORC and biomass boiler, considering the inertia of the integrated system's components. On average, the CSP system supplies 62% of monthly thermal demands. while the boiler provides the remaining 38%. Hence, the results demonstrate an increase in solar energy self-consumption by leveraging low solar radiation to bring the latent heat thermal energy storage into its melting range and extend ORC operation also when radiation is poor or absent.