Abstract
Despite the massive electrification of the energy sector, combustion-based technologies will continue to play a key role for decades to come. Therefore, to meet the ambitious target of decarbonization of the energy sector, adapting current technologies to alternative energy sources, like biofuels, is a must. The proposed work aims at investigating the role of biomass producer gas in compression ignition (CI) engines, as a substitute of diesel fuel. A micro combined heat and power generation system (CHP) consisting of an open-top downdraft gasifier, a single-cylinder water-cooled CI engine and a waste heat recovery circuit have been set-up with the aim to investigate emissions and performance at several Diesel Substitution Rates (DSR), up to 50 %. Maximum substitution levels – which occur due to knocking limitations and combustion instabilities - have been also identified. The main results show: i) a decrease of thermal and electrical efficiencies in the range of 10–30 %; ii) strong NOx and smoke opacity reductions (with peaks close to 80 %); iii) an increase of CO emissions (above 50 %); iv) the assessment of a decreasing maximum DSR as the power load increase (98 % at the lowest load, up to 46 % at full load). Such findings offer quantitative results through which multi-objective optimization procedures could be implemented. Moreover, experimental results indicate the need for a diesel injection timing optimization strategy to mitigate CO emissions.