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Model-based optimization offers the appealing opportunity of interpolating performance of a physical system between settings and of inferring its behaviour from previously unobserved areas of the parameter space, up to the optimal one. Application of this technique to micro-Combined Heat and Power (m-CHP) generation based on biomass gasification allows better exploiting the potential of this renewable energy source (RES) and of the specific technology for thermo-chemical conversion. A numerical model of a real CHP plant of the micro-scale of power, the ECO20 manufactured by the Italian Company Costruzioni Motori Diesel S.p.A., is presented in this paper as coupled with an optimization algorithm for the search of the best performance in terms of electric power output. The considered m-CHP system, made of a gasifier, a syngas cleaning system and a spark ignition Internal Combustion Engine (ICE) working as a co-generator, is fueled by woodchip. The plant model is realized by schematizing the whole biomass-to-energy chain within the Thermoflex™ environment and, simultaneously, by improving the prediction of the ICE performance through a properly developed and validated one-dimensional (1D) model in GT-Suite®. Simulation of the combustion process is specifically customized for syngas use, namely to account for the extreme variability of this fuel that strongly depends upon the kind of processed biomass and the gasifier operating conditions. The system model is validated on the ground of experimental data collected on the real plant and is coupled with the modeFRONTIER™ software for the optimal choice of the main operating parameters. The final purpose of the work is the assessment of a framework for the energetic and environmental optimization of biomass-powered cogeneration systems suitable of being used under various conditions and for various purposes. The here reported case study consists of the optimization of the electric power output by the considered m-CHP unit as a function of the equivalence ratio at the gasifier and of the ICE spark advance. Starting from an electric output of 17 kW, measured during the experimental campaign, it is demonstrated that an improvement of 6% on the electric power can be reached by acting only on the system parameters settings, without changing the system components.

This work aims to present the results of an energetic and economic analysis of a biomass fueled CCHP system operating according to different design configurations. The investigated system consists of a biomass-fueled cogeneration unit, an absorption chiller, a thermal energy storage system and a cold one, providing electricity, heat and cooling to an Italian cluster of buildings. For each simulated configuration, the feasible investment cost of the CHP unit is evaluated considering the economic savings obtained with respect to separate generation of electricity, heat and cooling. The best configuration from the economic point of view is indicated, and the incidence of the variation of the absorption chiller and storage systems sizes on the feasible investment cost of the CHP unit is evaluated and discussed as well. Results indicate that the most influencing parameter is represented by the absorption chiller power. © 2017 The Authors.

In this work, an operation strategy for a biomass-fired combined cooling, heating and power system, composed of a cogeneration unit, an absorption chiller, and a thermal energy storage system, is formulated in order to satisfy time-varying energy demands of an Italian cluster of residential multi-apartment buildings. This operation strategy is adopted for performing the economical optimization of the design of two of the devices composing the combined cooling, heating and power system, namely the absorption chiller and the storage system. A sensitivity analysis is carried out in order to evaluate the impact of the incentive for the electricity generation on the optimized results, and also to evaluate, separately, the effects of the variation of the absorption chiller size, and the effects of the variation of the thermal energy storage system size on the system performance. In addition, the inclusion into the system of a cold thermal energy storage system is analyzed, as well, assuming different possible values for the cold storage system cost. The results of the sensitivity analysis indicate that the most influencing factors from the economical point of view are represented by the incentive for the electricity generation and the absorption chiller power. Results also show that the combined use of a thermal energy storage and of a cold thermal energy storage during the hot season could represent a viable solution from the economical point of view. © 2017 Elsevier Ltd

The increase in energy prices and the stagnation of sales prices of the main agricultural commodities required a rethinking of farm production strategies. Since during the last years, thanks to a series of policies aimed at promoting renewable sources it has been a rapid diffusion of lignocellulosic biomass species, this paper aimed at evaluating the economic feasibility of the introduction of eucalyptus (Eucalyptus spp.) as energy crop for farmers of Southern Italy, by comparing it with traditional crop rotations. In particular, economic analysis has been carried out in a representative case study located in the Sicilian hilly hinterland where, in 2013, it has been built a biomass plant for energy production. However, results showed that introduction of eucalyptus for biomass production is less profitable for farmers than traditional crops, considering the incompressibility of production costs and the actual market price of woodchips.