Exergetic, economic, and environmental life cycle assessment analyses of a heavy-duty tractor diesel engine fueled with diesel–biodiesel-bioethanol blends

Highlights: • A biofueled tractor diesel engine was exergetically, economically, and environmentally studied. • Biodiesel could improve the exergetic, economic, and environmental indicators of the system. • There was no clear pattern of the effects of bioethanol on the investigated indicators. • Biofuel blends were exergetically, economically, and environmentally superior to diesel. • The best results were found for the blend containing 10 vol% biodiesel and 4 vol% bioethanol. This study aimed to analyze a heavy-duty tractor diesel engine operating on diesel-biodies-bioethanol blends using exergetic, economic, and environmental life cycle assessment analyses. Diesel was mixed with biodiesel and bioethanol with volumetric ratios of 5–15% and 2–6%, respectively. Nine diesel–biodiesel-bioethanol blends and one baseline fuel were tested at different PTO shaft speeds ranging from 800 to 1000 rpm under full load operating conditions. Various exergetic, economic, and environmental indicators were computed to facilitate decision-making on fuel composition and PTO shaft speed. In general, increasing biodiesel concentration in the fuel blend could improve the exergetic, economic, and environmental indicators of the system. However, there was no clear pattern of the effects of bioethanol on the investigated indicators. Interestingly, most of the prepared fuel blends were exergetically, economically, and environmentally superior to diesel. The lowest weighted environmental impact (52.1 mPts/GJ) and PTO shaft power generation cost (0.18 USD/kWh) were found for the fuel blend containing 10 vol% biodiesel and 4 vol% bioethanol at the PTO shaft speed of 1000 rpm. This fuel blend also showed the highest resource utilization efficiency (29.3%) and environmental sustainability (26.1%) at the PTO shaft speed of 1000 rpm. The weighted environmental impact and PTO shaft power generation cost of the selected fuel blend were 44.3% and 46.2% lower than those of diesel, respectively. The resource utilization efficiency and environmental sustainability of the selected fuel blend were 97.3% and 99.8% higher than those of diesel, respectively. Overall, substituting a portion of diesel with biodiesel and bioethanol was proved to be an attractive strategy from the exergetic, economic, and environmental perspectives. The results obtained can be valuable in practical applications to enhance the sustainability and viability of power production in agricultural activities. The applied exergetic, economic, and environmental methodologies appear to be reliable and comprehensive tools for assessing the whole-life sustainability and viability of mineral-biofuel blends.