ABSTRACT
The use of drop-in capable alternative fuels in aircraft can support the European aviation sector to achieve its goals for sustainable development. They can be a transitional solution in the short and medium term, as their use does not require any structural changes to the aircraft powertrain. However, the production of alternative fuels is often energy-intensive, and some feedstocks are associated with harmful effects on the environment. In addition, alternative fuels are often more expensive to produce than fossil kerosene, which can make their use unattractive. Therefore, this paper analyzes the environmental and economic impacts of four types of alternative fuels compared to fossil kerosene in a well-to-wake perspective. The fuels investigated are sustainable aviation fuels produced by power-to-liquid and biomass-to-liquid pathways. Life cycle assessment and life cycle costing are used as environmental and economic assessment methods. The results of this well-to-wake analysis reveal that the use of sustainable aviation fuels can reduce the environmental impacts of aircraft operations. However, an electricity mix based on renewable energies is needed to achieve significant reductions. In addition, from an economic perspective, the use of fossil kerosene ranks best among the alternatives. A scenario analysis confirms this result and shows that the production of sustainable aviation fuels using an electricity mix based solely on renewable energy can lead to significant reductions in environmental impact, but economic competitiveness remains problematic.
ABSTRACT
Liquid crystal display 3D printing is rapidly spreading due to the low cost of equipment and the high accuracy of manufactured parts. Particularly, this process is widespread in dental and medical fields to realise customised healthcare solutions. This study presents a parametric cradle-to-gate life cycle assessment of the liquid crystal display 3D printing process based on the part mass and building time. Specifically, the endpoint environmental impact indicators are calculated using the Recipe 2016 v 1.1 methodology with a hierarchist strategy. Also, a cost model of the process is included to assess the economic aspects of the production. This model comprises the cost of material, energy, consumables and equipment. An adaptive slicing strategy for liquid crystal display 3D printing is proposed. This algorithm starts slicing the model with the minimum layer height, then proceeds by collapsing adjacent layers so as to preserve a certain maximum imposed cusp height. The main aim of this research is to investigate the potential sustainability advantages of this strategy over traditional slicing. To this end, the life cycle assessment and cost models of the process are applied to two benchmark parts, namely a patient-specific dental model and an adapter designed to convert snorkel masks in respirators to face the COVID 19 emergency. The results demonstrate that the adaptive slicing strategy effect on part accuracy is negligible. In contrast, this method significantly increases the sustainability of the process by decreasing the building time. Specifically, the impacts on human health and resource depletion are reduced by up to 48.4% and 51.3%, respectively. Moreover, a significant reduction of the cost per part is observed. Finally, the increased productivity determines social benefits, being the produced parts intended for healthcare purposes. Therefore, the use of adaptive slicing instead of traditional strategies is strongly encouraged to advance towards the sustainability of this technology.
ABSTRACT
Medical waste (MW) has exploded since the COVID-19 pandemic and aroused great concern to MW disposal. Meanwhile, the energy recovery for MW disposal is necessary due to high heat value of MW. Harmless disposal of MW with economically and environmentally sustainable technologies along with higher energy recovery is urgently required, and their energy recovery efficiencies and environmental impacts reduction due to energy recovery are key issues. In this study, five MW disposal technologies, i.e. rotary kiln incineration, pyrolysis incineration, plasma melting, steam sterilization and microwave sterilization, were evaluated and compared via energy recovery analysis (ERA), life cycle assessment (LCA), and life cycle costing (LCC) methods. Furthermore, three MW incineration technologies with further energy recovery and two sterilization followed by co-incineration technologies were analyzed to explore their improvement potential of energy recovery and environment benefits via scenario analysis. ERA results reveal that the energy recovery efficiencies of "steam and microwave sterilization + incineration" are the highest (≥83.4%), while that of the plasma melting is the lowest (19.2%). LCA results show that "microwave sterilization + landfill" outperforms others while the plasma melting exhibits the worst, electricity is the most significant contributor to the environmental impacts of five technologies. Scenario analysis shows that the overall environmental impact of all technologies reduced by at least 45% after further heat utilization. LCC results demonstrate that pyrolysis incineration delivers the lowest economic cost, while plasma melting is the highest. Co-incineration of sterilized MW and municipal solid waste could be recommended.