Environmental Life Cycle Analysis of an Ammonia-Ethanol Fueled Internal Combustion Engine (ICE) for Power Generation

Climate change and other environmental impacts have been an enormous worldwide concern in recent decades. Decarbonizing strategic and economic industries is mandatory. Using carbon-free fuels such as ammonia (NH3) has been promoted as a promising solution for decarbonizing both energy and industrial sectors. The use of biofuels has also been encouraged as an attractive alternative to replace conventional petroleum-based fuels in transportation. Therefore, the present study evaluates the environmental profile of using ammonia-ethanol blends in internal combustion engines (ICE) for power generation systems through a life cycle assessment (LCA) framework using the OpenLCA v1.10.3 software. The experiments were conducted in a single-cylinder spark-ignition engine that employs direct injection using three different fuel compositions (in mole fraction) of ethanol/ammonia (75/25, 50/50, and 25/75), with two different intake pressures (0.5 and 1 bar) at 1000 rpm. The functional unit (FU) was set at 1 kWh. The GWP results for 0.5 bar of intake pressure are between 0.07 and 0.95 kg CO2/kWh. The scenario running on Brazilian ethanol and green ammonia is the most environmentally friendly case. The carbon footprint for ethanol/ammonia-based ICE at 1 bar fluctuates between 0.052 and 0.68 kg CO2/kWh. Similarly, regarding GWP, there is a slight difference in Fossil Depletion Potential (FDP) when using ethanol from Brazil and ethanol from Ecuador due to the lack of circular economy strategies in Ecuador's agriculture, compared to Brazil. Regarding the contribution analysis, for a 50% green ammonia – 50% ethanol scenario for power generation, ethanol production has the highest contribution for global warming, fossil depletion, and freshwater eutrophication potential impacts. Compared to the analysed environmental impacts, some of our proposed scenarios depict better performance than the average electricity production in the United Kingdom, France and Europe. Therefore, ethanol-ammonia fuel-based for power generating systems could be an important option to contribute to the decarbonization of the electric sector.