Hybrid Biomass/Solar Micro-CHP System with ORC

The continual increases in global energy demand and the worsening pollution from greenhouse gas emissions call for more and more utilization of sustainable energy sources, such as biomass and solar energy. Biomass or solar driven combined heat and power (CHP) systems are continuously phasing in the energy market due to their cleanness and sustainability. Biomass-fuelled or solar driven micro-scale CHP (1-10kWe) suitable for domestic applications has yet to be demonstrated or commercialized. This paper presents the design of a hybrid biomass-fired and solar compound parabolic concentrator (CPC) driven micro-CHP system with organic Rankine cycle (ORC). Combustion of biomass in the biomass boiler converts biomass chemical energy and the solar CPC transforms solar radiation into thermal energy which is used to drive ORC for power generation. The hybrid biomass/solar driven ORC-based micro-CHP system can increase its stability, continuity, flexibility and environmental protection. As solar energy becomes available, biomass boiler may be shut down and alternative concentrating solar thermal energy may be utilized to save biomass fuels and reduce combustion emissions. The barrier to developing a micro-scale organic Rankine cycle (ORC) system has been the suitability and availability of micro expanders for household applications. An air motor has been used as an expander in the biomass-fired ORC-based micro-CHP system developed by the authors which has generated 937W electricity. A test facility of a compound parabolic concentrator (CPC) with an evacuated tube absorber has been constructed and will be examined. The CPC performance is theoretically evaluated to be very effective. Further testing, accurate simulation and economic analysis about the hybrid biomass/solar ORC-based micro-CHP system will be carried out in the next phase of the research.