Fausto Freire

Uncertainty Analysis in Biofuel Systems An Application to the Life Cycle of Rapeseed Oil

Summary This article evaluates the implications of uncertainty in the life cycle (LC) energy efficiency and greenhouse gas (GHG) emissions of rapeseed oil (RO) as an energy carrier displacing fossil diesel (FD). Uncertainties addressed include parameter uncertainty as well as scenario uncertainty concerning how RO coproduct credits are accounted for (uncertainty due to modeling choices). We have carried out an extensive data collection to build an LC inventory accounting for parameter uncertainty. Different approaches for carbon stock changes associated with converting set-aside land to rapeseed cultivation have been considered, which result in different values: from −0.25 t C/ha.yr (carbon uptake by the soil in tonnes per hectare year) to 0.60 t C/ha.yr (carbon emission). Energy renewability efficiency and GHG emissions of RO are presented, which show the influence of parameter versus scenario uncertainty. Primary energy savings and avoided GHG emissions when RO displaces FD have also been calculated: Avoided GHG emissions show considerably higher uncertainty than energy savings, mainly due to land use (nitrous oxide emissions from soil) and land use conversion (carbon stock changes). Results demonstrate the relevance of applying uncertainty approaches; emphasize the need to reduce uncertainty in the environmental life cycle modeling, particularly GHG emissions calculation; and show the importance of integrating uncertainty into the interpretation of results.

Energy and Environmental Benefits of Rapeseed Oil Replacing Diesel

In this paper the benefits of rapeseed oil (RO) replacing petroleum diesel in transportation are evaluated, demonstrating that RO use displaces greenhouse gas (GHG) emissions and saves fossil energy. A systemic description of the RO chain in France has been implemented and GHG emissions and energy used throughout the life cycle have been calculated using alternative co-product credit procedures, namely a replacement method, three allocation approaches (mass, energy, economic) and ignoring co-product credits. The results show that the cultivation stage is particularly important, being responsible for 68% of the primary energy requirements and 87% of the GHG emissions of the RO “well-to-tank” system, mainly due to the use of fertilizers and related N2O emissions. Considerable reductions in fossil fuel depletion and GHG emissions can be achieved by replacing petroleum diesel with rapeseed oil (0.9 MJ and 62 g CO2eq per MJ of fossil diesel replaced), but optimum use of co-products is needed.

Life cycle activity analysis: logistics and environmental policies for bottled water in Portugal

Abstract. An innovative mathematical programming decision support model –Life Cycle Activity Analysis (LCAA)– is presented, integrating considerations of optimal allocations of resources and impacts upon the environment during the life cycle of products. LCAA is based on the classical formulation of activity analysis and on the life cycle assessment framework. The concept of linear activities is extended to embrace mass and energy fluxes over the entire life cycle of products including their environmental impacts. Special attention is given to the presence of loops in the product chains, such as those occurring when materials/products are recovered (reused, recycled.). An application brought from the Portuguese bottled water industry is described. The model features alternative activities for production technologies and product recovery strategies and permits the joint consideration of monetary costs and environmental burdens. The results obtained under five scenarios, including distinct disposal strategies and environmental constraints, are discussed.Zusammenfassung. In diesem Beitrag wird ein innovatives mathematisches Entscheidungsunterstützungsmodell – die Life Cycle Activity Analysis (LCAA) – präsentiert, welches die optimale Allokation von Ressourcen und Auswirkungen auf die Umwelt während des Lebenszyklusses eines Produktes beinhaltet. LCAA basiert auf der klassischen Formulierung der Aktivitätsanalyse und auf dem methodischen Gerüst des Life Cycle Assessments. Das Konzept der linearen Aktivitätsanalyse wird erweitert, um Massen- und Energieflüsse während des gesamten Produktlebenszyklusses sowie deren Auswirkungen auf die Umwelt einbezogen. Eine besondere Aufmerksamkeit wird auf bestehende Zyklen in Prozessketten gelegt, die bei der Wiederverwendung / Verwertung von Materialien/Produkten auftreten. Es eine Anwendung aus der portugiesischen Flaschenwasser-Industrie vorgestellt. Das Modell zeichnet sich durch verschiedene alternative Aktivitäten für Produktionstechnologien und Wiederverwendungsstrategien aus und erlaubt die gleichzeitige Betrachtung von monetären Kosten und Umweltbelastungen. Die Ergebnisse, die aus fünf Szenarien zu verschiedenen Entsorgungsstrategien und Umweltschutzrestriktionen gewonnen werden, werden diskutiert.

THERMAL ANALYSIS AND DRYING KINETICS OF OLIVE BAGASSE

ABSTRACT The slow thermal decomposition of olive bagasse at temperatures ranging from 25 to 900° C, with particular stress on the moisture evaporation phenomena, is analyzed making use of thermogravimetry, derivative ihermogravimelry and differential scanning calorimetry. The results obtained demonstrate that Thermal Analysis techniques contribute for the characterization of iniernai moisture transfer processes. “ Drying curves” obtained from Thermal Analysis experiments were compared with thin-layer drying curves of olive bagasse at relatively high temperatures. The existence of a critical moisture content, which distinguishes two types of water liaisons, was demonstrated, and its value quantified at 17-18%.

Stochastic comparative assessment of life-cycle greenhouse gas emissions from conventional and electric vehicles

PurposeElectric vehicles (EVs) are promoted due to their potential for reducing fuel consumption and greenhouse gas (GHG) emissions. A comparative life-cycle assessment (LCA) between different technologies should account for variation in the scenarios under which vehicles are operated in order to facilitate decision-making regarding the adoption and promotion of EVs. In this study, we compare life-cycle GHG emissions, in terms of CO2eq, of EVs and conventional internal combustion engine vehicles (ICEV) over a wide range of use-phase scenarios in the USA, aiming to identify the vehicles with lower GHG emissions and the key uncertainties regarding this impact.MethodsAn LCA model is used to propagate the uncertainty in the use phase into the greenhouse gas emissions of different powertrains available today for compact and midsize vehicles in the US market. Monte Carlo simulation is used to explore the parameter space and gather statistics about GHG emissions of those powertrains. Spearman’s partial rank correlation coefficient is used to assess the level of contribution of each input parameter to the variance of GHG intensity.Results and discussionWithin the scenario space under study, battery electric vehicles are more likely to have the lowest GHG emissions when compared with other powertrains. The main drivers of variation in the GHG impact are driver aggressiveness (for all vehicles), charging location (for EVs), and fuel economy (for ICEVs).ConclusionsThe probabilistic approach developed and applied in this study enables an understanding of the overall variation in GHG footprint for different technologies currently available in the US market and can be used for a comparative assessment. Results identify the main drivers of variation and shed light on scenarios under which the adoption of current EVs can be environmentally beneficial from a GHG emissions standpoint.

Electric vehicles in Portugal: An integrated energy, greenhouse gas and cost life-cycle analysis

Electric vehicles are been proposed as a more sustainable option for transportation; however, the life-cycle environmental and economic performance of electric vehicles (EVs) relatively to conventional internal combustion vehicles (ICE) is controversial. This paper presents an integrated energy, GHG and cost life-cycle analysis of electric vehicles for Portugal. A life-cycle model and inventory has been implemented for 2 EV technologies: 100% electric battery (BEV) and plugin (PHEV40 and PHEV20) vehicles, which have been compared with conventional ICE vehicles (gasoline and diesel), for two types of vehicles (subcompact and compact). Primary energy requirements, GHG emissions and costs per km have been calculated and compared for the various technologies and scenarios. Life-cycle costs have been calculated using the equivalent annual cost method, assuming two alternative interest rates (5% and 10%) and two prices for electricity. The results show that, for energy and GHG emissions, the most important life-cycle phase is vehicle operation; however, for life-cycle economic costs it is the acquisition price of vehicles. Concerning climate change, it has been found that the evolution of the Portuguese electricity generation mix is critical in the identification of the vehicle technology with lower impacts.

Development and Application of Competencies for Graduate Programs in Energy and Sustainability

Educational competencies represent learning objectives and are used to plan educational programs, develop curricula, and assess existing programs, among other functions. After reviewing the literat...

Significance of mobility in the life-cycle assessment of buildings

While most life-cycle assessments of buildings have focused on construction and use phases, the location of a building can significantly affect the transportation demand of its inhabitants. The life-cycle energy and greenhouse gas (GHG) emissions of two representative buildings in Lisbon, Portugal, are compared: an apartment building in the city centre and a semidetached house in a suburban area. An integrated approach is used to conduct a life-cycle analysis that includes building construction, building use and user transportation. Sensitivity analyses are used to evaluate impacts for multiple locations. For the apartment, building use accounted for the largest share of energy and emissions (63–64%), while for the house, most (51–57%) of the energy and emissions were associated with user transportation. Energy and GHG emissions for suburban locations were significantly higher (by 55–115%) than those in the city-centre locations, largely due to individuals commuting by car. The analysis demonstrates the significance of transportation and highlights the importance of residence location in urban planning and environmental assessments. These results are likely to apply to other southern European cities that have expanded with significant growth in car ownership and use. To improve urban sustainability, development strategies should consider the transport infrastructure in addition to building efficiency.

EXPERIMENTAL ANALYSIS OF THE DRYING KINETICS OF A FOOD PRODUCT

ABSTRACT A laboratory system allowing for the characterization of the thin-layer drying kinetics of olive bagasse at relatively high temperatures was designed and constructed. The system, which permits a wide range of operating velocities and temperatures, up to 700°C, allowed the weight loss of the sample to be monitored continuously. Constant drying conditions were maintained using an on-line computer. The drying conditions investigated in this study included combustion products of atmospheric air and propane with dry-bulb temperatures ranging from 125°C to 250°C, relative humidity lower than 1% and gas velocities ranging from 0.5 to 2.0 m/s.

Life-cycle greenhouse gas assessment of Nigerian liquefied natural gas addressing uncertainty.

Natural gas (NG) has been regarded as a bridge fuel toward renewable sources and is expected to play a greater role in future global energy mix; however, a high degree of uncertainty exists concerning upstream (well-to-tank, WtT) greenhouse gas (GHG) emissions of NG. In this study, a life-cycle (LC) model is built to assess uncertainty in WtT GHG emissions of liquefied NG (LNG) supplied to Europe by Nigeria. The 90% prediction interval of GHG intensity of Nigerian LNG was found to range between 14.9 and 19.3 g CO2 eq/MJ, with a mean value of 16.8 g CO2 eq/MJ. This intensity was estimated considering no venting practice in Nigerian fields. The mean estimation can shift up to 25 g CO2 eq when considering a scenario with a higher rate of venting emissions. A sensitivity analysis of the time horizon to calculate GHG intensity was also performed showing that higher GHG intensity and uncertainty are obtained for shorter time horizons, due to the higher impact factor of methane. The uncertainty calculated for Nigerian LNG, specifically regarding the gap of data for methane emissions, recommends initiatives to measure and report emissions and further LC studies to identify hotspots to reduce the GHG intensity of LNG chains.