Vehicle retire-and-replace subsidy programs-The Life Cycle Perspective

摘要: Environmental assessments of vehicle scrappage programs are often limited to evaluating the reduction of direct air pollutant emissions due to replacement of old vehicles with new ones exhibiting lower tailpipe emissions and higher fuel efficiencies. However, non-direct emissions (ie those associated with fuel supply, vehicle production and disposal) contribute considerably to the overall environmental impact of vehicles over their lifetimes, especially in the case of battery electric vehicles (BEV). Accounting for these indirect emissions of air pollutants, as well as greenhouse gases (GHGs), is essential to design programs providing benefits to local air quality and climate change mitigation from a more comprehensive perspective.Several generic studies determined the optimal lifetime of internal combustion engine vehicles minimizing certain life-cycle air pollutant (NOx, CO and VOC) and GHG emissions. A common finding is that a more frequent replacement of vehicles minimizes air pollutant emissions, while a long vehicle lifetime reduces GHG emissions, as fuel economy improvement rates do not outbalance emissions from vehicle production and disposal.