In moving towards a more sustainable society, hydrogen fueled polymer electrolyte membrane (PEM) fuel cell technology is seen as a great opportunity to reduce the environmental impact of the transport sector.However, decision makers have the challenge of understanding the real environmental consequences of producing fuel cell vehicles (FCVs) compared to alternative green cars, such as battery electric vehicles (BEVs) and more conventional internal combustion engine vehicles (ICEVs). In this work, we presented a comprehensive life cycle assessment (LCA) of a FCV focused on its manufacturing phase and compared with the production of a BEV and an ICEV. For the manufacturing phase, the FCV inventories started from the catalyst layer to the glider, including the hydrogen tank. A sensitivity analysis on some of the key components of the fuel cell stack and the FC system (such as balance-of-plant and hydrogen tank) was carried out to account for different assumptions on materials and inventory models. The production process of the fuel cell vehicle showed a higher environmental impact compared to the production of the other two vehicles power sources. This is mainly due to the hydrogen tank and the fuel cell stack. However, by combining the results of the sensitivity analysis for each component -a best-case scenario showed that there is the potential for a 25% reduction in the climate change impact category for the FCV compared to a baseline FCV scenario. Reducing the environmental impact associated with the manufacture of fuel cell vehicles represents an important challenge. The entire life cycle has also been considered and the manufacturing, use and disposal of FCV, electric vehicle and conventional diesel vehicle were compared. Overall, the ICEV showed the highest GWP and this was mainly due to the use phase and the fossil carbon emissions associated to the use of diesel.

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Electric mobility is playing an important and growing role in the context of sustainable transport sector development. This study presents the life cycle assessment of an electric car based on the technology of Lithium-ion battery (BEV) for Europe and compares it to an internal combustion engine vehicle (ICEV). According to a cradle-to-grave approach, manufacturing, use and disposal phases of both vehicles have been included in the assessment in order to identify the hot spots of the entire life cycles. For electric vehicles two manufacturing inventories have been analysed and different vehicle disposal pathways have also been considered. Furthermore, the environmental performances of hybrid vehicles have been analysed based on the life cycle models of the BEV and ICEV. The results of the hot spot analysis showed that the BEV manufacturing phase determined the highest environmental burdens mainly in the toxicity categories as a result of the use of metals in the battery pack. However, the greenhouse gas emissions associated with the BEV use phase were shown to be half than those recorded for the ICEV use phase. The trend of the results has also been investigated for future energy mixes: the electricity and diesel mixes for the year 2050 have been considered for the modelling of the use phase of BEV and ICEV

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This study integrates the Life Cycle Assessment (LCA) of thermal and biological technologies for municipal solid waste management within the context of renewable resource use for methane production. Five different scenarios are analysed for the UK, the main focus being on advanced gasification-plasma technology for Bio-Substitute natural gas (Bio-SNG) production, anaerobic digestion and incineration. Firstly, a waste management perspective has been taken and a functional unit of 1 kg of waste to be disposed was used; secondly, according to an energy production perspective a functional unit of 1 MJ of renewable methane produced was considered. The first perspective demonstrates that when the current energy mix is used in the analysis (i.e. strongly based on fossil resources), processes with higher electric efficiency determine lower global warming potential (GWP). However, as the electricity mix in the UK becomes less carbon intensive and the natural gas mix increases the carbon intensity, processes with higher Bio-SNG yield are shown to achieve a lower global warming impact within the next 20 years. When the perspective of energy production is taken, more efficient technologies for renewable methane production give a lower GWP for both current and future energy mix. All other LCA indicators are also analysed and the hot spot of the anaerobic digestion process is performed.

In this work we simulated the dynamics of a fluidized bed of a binary solid mixture using the isothermal multi-fluid model of the commercial CFD code Fluent 12. We focused the attention on the role of both restitution coefficient and integration methods on the dynamics of the bed, adopting a mixture of solids assorted in size (with constant density) as case study. We employed two methods of spatial discretization: first-order upwind scheme (FUS) and second-order upwind scheme (SUS). We investigated implicit versus explicit time integration methods as well. The numerical diffusion introduced by the FUS resulted in a low bubble fraction in the bed, in turn reducing solid mixing rates. Simulations carried out adopting the SUS were characterized by a reasonable bubble fraction and associated solid mixing rate. The latter method successfully predicted the transition to fully mixed, uniform fluidization conditions. The value of the restitution coefficient did not significantly affect the results of the simulations, as bubble volume fraction and jetsam concentration profiles did not show any significant change within the interval of restitution coefficient values investigated, with the exception of the nearly ideal value of 0.99. �� 2013 Elsevier Ltd

Bioenergy has an important role to play in helping the UK meet its carbon target in 2050 and the European Renewable Energy Directive objectives for 2030. There are however uncertainties associated with the use of bioenergy, and whether or how much it contributes to greenhouse gas emission reductions. In order to help identifying environmental benefits and burdens associated with biomass use for energy production, an attributional life cycle assessment has been carried out of a biomass-fired CHP plant: the Heathrow Airport energy centre. This facility burns woodchips sourced from nearby forests providing 2 MWe of electricity and 8 MWth of thermal energy which delivers heat and cooling to Heathrow Terminal 2 and low temperature hot water to Terminal 5. A hot spot analysis is conducted to identify the process steps with the largest environmental impact, starting from the harvesting of the forest residue to the disposal of the boiler ash. A scenario analysis is performed to compare the impacts of the biomass plant against fossil alternatives and to identify which renewable energy sources, between biomass and MSW, should be prioritised for development and investment. The results show a reduction in GHG emissions from using biomass, with further benefits if the bottom ash is collected and re-used as a soil conditioner for landfarming or forestry. The paper also discusses the treatment of biogenic carbon in the assessment.