Future Mobility Case Studies - Life Cycle Assessments of BEVs and ICVs with a Global Perspective

摘要

By 2050 the increase in mobility demand will lead to worldwide car ownership potentially triplingto around two billion vehicles. Increased demand for mobility means increased demand forenergy. To deliver this, whilst at the same time as reducing CO2 emissions and improving airquality, will require integrated smarter mobility solutions that embrace a range of smarter vehiclesand fuels, together with smarter infrastructure. In combination these help promote smarterusage. In this context Shell believes that a mosaic of mobility options will be required for roadtransport, and is actively evaluating future energy supply for future drivetrains, as part of thisintegrated solution.Apart from the further development of today’s gasoline and diesel engines powered by crude oilbasedfuels and first generation and advanced bio fuels, Shell also evaluates options from gas, in itsdifferent forms as compressed natural gas (CNG), liquefied natural gas (LNG) or gas-to-liquids(GTL), from hydrogen, and also from the energy required for electric vehicle mobility.Emissions from transport are a key factor to evaluate the best form of future energy/drivetrainoptions. The increasing challenges of global population growth, urbanisation, congestion and smogrelated emissions from traffic are also important drivers, especially for certain regions.On the other hand the road transport sector accounts for a significant portion of global energy useand energy-related greenhouse gas (GHG) emissions, and has been identified by governmentsaround the world as one of the main areas to address the challenges of sustainable mobility, energysecurity and climate change. With regards to GHG emissions in particular, policy makers in manyjurisdictions are considering and implementing measures to reduce the average GHG intensity oftransport fuels, such as policies and regulations that mandate increasing use of lower carbonintensity fuels e.g. bio fuels, or stimulate the introduction of alternative technologies e.g. electric orhybrid vehicles. In order to be effective, these measures should be based on sound scientificanalyses of the ‘life cycle’ GHG emissions of the relevant fuel/powertrain combinations (the‘mobility pathways’).To analyse the life cycle energy use and GHG emissions for a specific pathway, the researcher willnecessarily have to make methodological choices which will strongly influence the outcome of theanalysis. A universal, ‘one-size-fits-all’ methodology for conducting life cycle analysis is notfeasible – it is often necessary to allow a certain degree of flexibility in defining the boundaries ofthe system under study, and to make numerous practical assumptions. This potential ambiguityhighlights the importance of transparency in GHG emissions accounting, as well as the inherentcomplexity of life cycle assessment. Therefore, it is very important that findings from such studiesare communicated in the right context.To highlight the potential risks associated with simplification, we present a relevant case study onelectric vehicles, where the outcome of the analysis changes substantially with themethodological/system boundary choices made. Electric vehicles have increasingly gainedworldwide interest as one of the most promising potential long-term solutions to sustainablepersonal mobility; in particular, battery electric vehicles (BEVs) offer zero tailpipe emissionsenabling them not only to reduce transport GHG emissions but also to reduce other regulatedemissions (e.g. smog). However, their true ability to contribute to GHG emissions reductions canonly be properly assessed by comparing a full life cycle assessment of their GHG emissions with asimilar assessment for conventional internal combustion vehicles (ICVs). In this study, we havecarried out an analysis for vehicles typical of those expected to be introduced in 2012 in WesternEurope, the U.S. and China, taking into account the impact of three important factors: a) like-forlikevehicle comparison and effect of real-world driving conditions, b) accounting for the GHGemissions associated with meeting the additional electricity demand for charging the batteries, and c)the GHG emissions associated with the vehicle life cycle (e.g. manufacture and disposal, etc).We find that BEVs can deliver significant GHG savings compared to ICVs providing that the gridGHG intensity used to charge the batteries is sufficiently low. In particular, BEVs perform bestrelative to ICVs in terms of GHG emissions in low speed (e.g. urban) driving and when lightlyloaded with weight and auxiliaries. However, vehicle life cycle emissions are higher for BEVs thanICVs due to the GHG emissions associated with battery manufacture.Furthermore, our analysis illustrates that it is inappropriate to draw general conclusions about therelative GHG performance of BEVs and ICVs without due reference to the context – such relativeperformance depends on a wide range of factors, including regional grid GHG intensity, vehiclesize, driving pattern, loading etc., and any meaningful comparison for policy setting purposesshould take these fully into account for the specific situation being considered.