Browsing by Author "Martins, A. A."
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- Comparison of allocation approaches in soybean biodiesel life cycle assessmentPublication . Morais, S.; Martins, A. A.; Mata, Teresa M.This work shows the influence of using different allocation approaches when modelling the inventory analysis in a soybean biodiesel life cycle assessment (LCA). Results obtained using mass, energy and economic based allocations are compared, focusing on the following aspects: normalised potential environmental impact (PEI) categories, total PEI and relative contributions to the total PEI from each life cycle stage and environmental impact category. Similar results are obtained either using economic and energy based allocations. However, different results are obtained when mass based allocation is used when compared with the other two. This study also illustrates that using different allocation approaches in biodiesel LCA may influence the final conclusions, especially in comparative assertions, emphasising the need to perform a sensitivity analysis in the LCA interpretation step.
- Simulation and life cycle assessment of process design alternatives for biodiesel production from waste vegetable oilsPublication . Morais, Sérgio Alberto; Mata, Teresa M.; Martins, A. A.; Pinto, Gilberto; Costa, Carlos A.V.This study uses the process simulator ASPEN Plus and Life Cycle Assessment (LCA) to compare three process design alternatives for biodiesel production from waste vegetable oils that are: the conventional alkali-catalyzed process including a free fatty acids (FFAs) pre-treatment, the acid-catalyzed process, and the supercritical methanol process using propane as co-solvent. Results show that the supercritical methanol process using propane as co-solvent is the most environmentally favorable alternative. Its smaller steam consumption in comparison with the other process design alternatives leads to a lower contribution to the potential environmental impacts (PEI’s). The acid-catalyzed process generally shows the highest PEI’s, in particular due to the high energy requirements associated with methanol recovery operations.
- Using Microalgae for Converting Solar Energy into Biofuels and other Bio-productsPublication . Mata, T. M.; Caetano, Nídia; Mendes, A. M.; Martins, A. A.It is consensual that current patterns of energy consumption and usage are unsustainable in the medium to long term, as mankind still has an overwhelming dependence on fossil fuels. Various renewable energy systems are being studied, developed and implemented, with the main goals of reducing the dependence on fossil fuels, decreasing the environmental impacts, increasing energy supply and security, among other purposes.