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Abstract: The use of numerical models for estimating fuel consumption and emission of HC, CO, NO x and CO2 of gasoline vehicles, under urban driving conditions, is examined. Three models were selected for evaluation: EcoGest, CMEM and ADVISOR. The models were used to simulate a sample of 14 urban trips for two 1999 Ford Taurus vehicles. Trip statistics were monitored on-board of the passenger vehicles across a variety of traffic conditions, using a portable emissions measurement device (PEMS). A key conclusion is that the tested models can be used with relatively high confidence to predict fuel consumption and CO2 emissions. However, results must be viewed with greater caution when it comes to predictions for other pollutants. [Copyright &y& Elsevier]

Abstract: Currently, oil based fuels are the primary energy source of road transport. The growing need for oil independence and CO2 mitigation has lead to the increasing importance of alternative fuel usage. CO2 is produced not only as the fuel is used in the vehicle (tank-to-wheel contribution), but also upstream, from the fuel extraction to the refueling station (well-to-tank contribution), and the life cycle of the fuel production (well-to-wheel contribution) must be considered in order to analyse the global impact of the fuel utilization. A road vehicle tank-to-wheel analysis tool that may be integrated with well-to-tank models was developed in the present study. The integration in a demonstration case study allowed to perform a life cycle assessment concerning the utilization of diesel and natural gas fuels in a specific network line of a bus transit company operating in the city of Porto, Portugal. [Copyright &y& Elsevier]

Several environmental rating methodologies are available worldwide to evaluate and compare the environmental performance of vehicles, which can be useful for consumers decisions and for organizations in the promotion of less pollutant technologies and fuels. This paper presents an overview of vehicle environmental rating methodologies available worldwide. Four of them adopt a life-cycle perspective: Green Score (US), Ecoscore (Belgium), Green Car Rating (UK) and EcoTest (Europe), while VCD (Germany), Eco vehicles rating (Mexico) and Green Vehicle (Australia) only consider the fuel in-use stage. Fuel in-use stages methodologies are good indicators of air quality rankings but would rank a fuel cell hydrogen vehicle on top along with the electric vehicles which does not reflect the carbon footprint of the overall fuel pathways and side effect pollutants. Therefore life cycle based methodologies are worth being further explored. Between the more complete life cycle based methodologies, Green Score and Ecoscore differ in terms of the impact categories considered, stages of the life cycle taken into account, weighting system and geographical application, but both use environmental economics and translate the results into a single indicator 0–100 (best). For this relevant variability of aspects they were selected to be applied to a set of seven real vehicles, comprising internal combustions engines and alternative vehicles, including the alternative fuels hydrogen and biodiesel. The application of methodologies shows that the position of the commercial vehicles obtained in the ranking for both methodologies differs. Internal combustion engine (ICE) has the higher impact in the environment and electric vehicle (EV) scores between the best positions; the position of the fuel cell hybrid electric vehicle (FCHEV) and the biodiesel ICE vary significantly. A sensitivity analysis shows that the US rating has high sensitivity to variations, namely in damage costs and fuel pathway. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the life cycle inventory (LCI) of hydrogen production by Clostridium butyricum fermentation of Scenedesmus obliquus hydrolysate. The main purpose of this work was to evaluate the potential of H2 production from microalgal biomass and the respective energy consumption and CO2 emissions in the bioconversion process considering the microalga production, acid hydrolysis of S. obliquus biomass, preparation of the inoculum and culture media, and fermentation. The scale-up to industrial production was not envisaged. The hydrogen yield obtained in this work was 2.9 ± 0.3 mol H2/mol sugars in S. obliquus hydrolysate. Results show that this process of biological production of hydrogen can achieve 7270  of energy consumption and 670 . The microalgal culture is the stage responsible for 98% of these total final values due to the use of artificial lighting. All stages and processes with the highest values of energy consumption and CO2 emissions were identified for future energetic and environmental optimisation. [Copyright &y& Elsevier]