Flexible PVT-ORC Hybrid Solar-biomass Cogeneration Systems: the Case Study of the University Sports Centre in Bari, Italy

orc2019 Tracking Number 107

The thermoeconomic feasibility of a hybrid solar-biomass renewable cogeneration systems based on a wood-chip boiler, photovoltaic-thermal (PVT) collectors and an organic Rankine cycle (ORC) engine is investigated for combined heat and power (CHP) provision in a sports-centre application. The PVT-based CHP (PVT-CHP) subsystem, integrated with thermal energy storage, is designed to meet most of the energy demands of the facility at high solar-irradiance conditions, while the biomass ORC-based CHP (ORC-CHP) subsystem, driven by a wood-chip boiler, is used to compensate the intermittent solar energy and match the onsite energy demand. A technoeconomic model is proposed to optimise the hybrid cogeneration system design and operation. Annual energy simulations are conducted in a case study focused on the provision of electricity, space heating, swimming pool heating and hot-water supply to the University Sports Centre (USC) of Bari, Italy. The size of the ORC engine is found to be critical to the performance of the PVT-ORC cogeneration system. With an installation area of 4,000 m2 for the PVT collectors and an ORC engine size of 40 kWe/310 kWt, the hybrid solar-biomass cogeneration system can provide 100% renewable energy supply to the USC with a payback time of 11.5 years, compared to 12.3 years for the solar-only PVT-CHP system. Although the biomass-only ORC-CHP system has much shorter payback time (5.0 years), the electricity output is insufficient to match the demand, accounting for only 27% of the electricity consumed onsite. This work shows that neither the solar-only nor biomass-only systems can provide full renewable energy supply to the USC, while their hybridisation makes this target attainable, with a moderate payback on investments.