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Abstract The growing demand for energy and the accelerating threats from climate change call for innovative and sustainable solutions to decrease dependency on fossil fuels. Biomass-based, small-scale Combined Cooling, Heating and Power (CCHP) systems are one of these solutions, because they can satisfy the energy demands of the consumer with enhanced flexibility, lower losses, less costs and less environmental pollution as compared to centralized facilities. Due to recent advances in several scientific subfields with relevance to small-scale CCHP, a rapidly increasing amount of literature is now available. Therefore, a structural overview is essential for engineers and researchers. This paper presents a review of the current investigations in small-scale CCHP systems covering biomass-fired concepts and solar extensions. To this end, critical system components are described and analysed according to their specific advantages and drawbacks. Recent case studies have been collected and key findings are highlighted according to each type of prime mover. The results indicate a scientific bias towards the economic viability of such systems and the need for real-life and experiment system data. However, the potential of biomass-fired CCHP systems and of such systems with solar extensions has clearly been recognised. Based on the results, future policy implementations should focus on fostering such systems in areas with high energy costs and to increase energy resilience in developed regions. Additionally research and industry applying novel prime mover technologies should be financially supported. Highlights • Small-scale, biomass-fired CCHP is gaining interest in science and industry. • Summary on biomass conversion, prime mover and cooling technologies. • The findings are put into context with current and future technology trends. • Entrepreneurial bias of scientist towards feasibility of CCHP systems. • Policies should promote CCHP in areas with high energy costs and low grid stability. [ABSTRACT FROM AUTHOR]

• Cost-optimal design method for CCHP-assisted HP systems for varying climate scenarios. • Numerical transient model for demand and CCHP/HP system analysis. • Techno-economic analysis of Montjuic Castle, Barcelona, based on the model. • Small CCHP leads to more sustainable autonomy without unreasonable extra costs. • Climate change has a relatively small effect on comparative economic performance. An innovative modelling approach for the design of biomass-based, solar-assisted combined cooling, heating, and power (CCHP) and heat pump (HP) systems for various climate scenarios is proposed in this work. The modelling approach is comprised of three sub-models (a demand sub-model, a supply sub-model, an economic sub-model) allowing for cost-optimal sizing of the system components based on net present cost (NPC). Subsequently a transient optimization model has been developed, which computes the technical and economic performance for each component size and for each ambient temperature of the different climate scenarios. Additionally, the model provides data on energy efficiency, exergy efficiency, and CO 2 -emissions of a given CCHP/HP system. The model has then been employed in a case study in order to analyse the performance of a CCHP/HP system for a tourist, museum, and guest accommodation structure located at the Montjuïc castle in Barcelona, Spain. The results show that the smallest simulated biomass-based CCHP system using a 25 kW e syngas-fuelled engine would reduce lifetime costs by 7% compared to an only-HP system while operating with a high total energy efficiency of over 60%. The combined CCHP/HP system would operate with an exergy efficiency of 18%. However, larger CCHP systems cannot offset the much higher capital costs despite increasing electricity sales. The findings also reveal that for the high climate change scenario the overall project costs drop by up to 2.5%, however the effects have little impact on the optimal CCHP/HP system sizing. Even the smallest CCHP system would reduce emissions already by 75% with an increasing trend for larger systems. Although CCHP/HP systems would lead to lower NPC and emissions, the high investment costs and the complexity of the combined system remain considerable obstacles. [ABSTRACT FROM AUTHOR]

Energy services are especially expensive on remote islands due to longer and more unstable fuel supply chains. In this paper, different renewable energy systems utilizing locally available biomass and solar energy are proposed as alternatives for a hotel resort on Neil Island, India. Based on local demand data, commercial information, and scientific literature, four cases are modelled with the simulation software HOMER and their economic, energetic, as well as ecological (3E) performances are compared. The robustness of each case configuration is tested with a sensitivity analysis. The results show that a biomass-based, solar-assisted combined cooling, heating, and power (CCHP) system offers an economic saving potential of more than 500,000 USD over twenty years and could decrease CO2 emissions by 365 t per year. When not applying CCHP measures, system performance is significantly worsened. A solar and battery-assisted diesel generator system shows similar economic outcomes as the CCHP system but worse ecological performance. Implementing the biomass-based CCHP system could improve the ecological footprint of the island, substantially decrease expenditure for the hotel owner, and generate a new source of income for surrounding farmers through biomass selling. [ABSTRACT FROM AUTHOR]