Browsing by Author "Pacheco, R."
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- Biodesulphurization of fossil fuels: energy, emissions and cost analysisPublication . Alves, Luís; Paixão, Susana M.; Pacheco, R.; Ferreira, Ana F.; Silva, Carla M.In order to achieve stringent environmental and safety requirements, refineries are in search of “green” and cost-effective methods for crude oil desulphurization. Combined desulphurization technologies are being studied, including bioprocessing to upgrade fossil fuels. Using biodesulphurization (BDS), which is a biochemical process mediated by specific microorganisms, it is possible to desulphurize most of the hydrodesulphurization (HDS) recalcitrant sulphur compounds under mild operating conditions, making it a simple and eco-friendly process. In this study, two BDS process designs are compared, in terms of energy consumption, greenhouse gas emissions and operational costs by following a life cycle assessment (LCA) and life cycle cost (LCC) based methodology. The industrial HDS process is used as the reference technology for sulphur removal from fossil fuels. Different theoretical scenarios were considered and the best BDS results are scaled-up to evaluate a case study of providing ultra low sulphur diesel to an urban taxi fleet. This study exploits the potential of BDS as a cost-effective and eco-friendly alternative or complementary technology to the commonly HDS towards ultra low sulphur fuels.
- Evaluation of Jerusalem artichoke as a sustainable energy crop to bioethanol: energy and CO(2)eq emissions modeling for an industrial scenarioPublication . Paixão, Susana M.; Alves, Luís; Pacheco, R.; Silva, Carla M.ABSTRACT: An alternative to the sugar/starch-based crops bioethanol is lignocellulosic biomass, but its utilization to biofuels is still not economically viable. In this context, an increasing interest has arising on the search for specific energy crops that do not require arable lands and are not water intensive, such as Jerusalem artichoke (JA). So, this work consisted on the cultivation of JA on those agricultural conditions and its further evaluation as a sustainable feedstock towards bioethanol. Two strategies of producing bioethanol were evaluated pointing out for the consolidated bioprocessing with the Zygosaccharomyces bailii Talf1 yeast as the best approach for further scale-up, based on energy data analysis and ethanol productivity. Different industrial scenarios were outlined and compared for overall CO(2)eq emissions and energy consumption per liter of ethanol (L-EtOH), using adequate criteria on a cradle-to-gate approach. With no land-use change, no biogenic and no co-products credits, the comparison of the overall energy consumption and CO(2)eq emissions (100% process) from JA ethanol (9 MJ/L-EtOH; 679 g CO2/L-EtOH) with sugarcane/sugar beet ethanol (42/29 MJ/L-EtOH; 731/735 g CO2/L-EtOH) and with gasoline refinery (15 MJ/L-EtOH eq; 1154 g CO2/L-EtOH eq), highlights the JA as an alternative feedstock to be a focus of ethanol research for gasoline blends.
- The production of pigments & hydrogen through a Spirogyra sp. biorefineryPublication . Pacheco, R.; Ferreira, Ana F.; Pinto, T.; Nobre, B. P.; Loureiro, David; Moura, Patrícia; Gouveia, Luisa; Silva, Carla M.This paper discusses the overall energy consumption and greenhouse gas emissions when extracting pigments and producing hydrogen from Spirogyra sp. microalga biomass. The energy evaluation from the biomass leftovers was also included in this work. The influence of the functional unit and different allocation criteria on the biorefinery assessments is also shown. The study consists of laboratory tests showing Spirogyra sp. growth, harvesting, drying, pigment extraction and fermentation by Clostridium butyricum. Electrocoagulation and solar drying were tested and compared to conventional centrifugation and electrical dewatering in terms of their energy consumption for harvesting and dewatering, respectively. To discuss the biorefinery viability, the pigments and biohydrogen (bioH2) retail costs are considered against operational costs according to electricity needs. The low yield of biochemical hydrogen and the high energy requirements for the pigment extraction were identified as main topics for further research. This research hopefully contributes to highlight the importance of energy and emission balances in order to decide on feasibility of the biorefinery.