Strategic selection of future EV technology based on the carbon payback period

Abstract

The British Low Carbon Vehicle Technology Project (LCVTP) has developed technologies for future plug-in vehicles. Simulation results indicate significantly lower tailpipe CO2 emissions when compared to conventional internal combustion engine technology, but how good are the CO2 savings on a life cycle basis? Do these technologies have higher embedded CO2 from vehicle production? If so, can this be paid back within the lifetime of the vehicle? To help answer these questions, building on work completed within LCVTP, Ricardo conducted a life cycle top-down review of hybrid and EV technology architectures to estimate the CO2 emissions associated with each phase of the vehicle's life. Results showed that these technologies have the potential to reduce the life cycle CO2 footprint of passenger cars, compared to today's conventional technology. However, the higher embedded CO2 from vehicle production has to be paid back before these savings can be realised. This carbon payback period is highly dependent on the CO2 emissions resulting from electricity generation and transmission. This implies that the commercial role out of plug-in vehicles must happen in tandem with decarbonisation of the electricity to ensure CO2 emissions are really reduced. Ensuring future low carbon vehicles are truly low carbon will require a shift in focus from tailpipe CO2 to considering the environmental impact of the whole vehicle life cycle and the energy it uses. By adopting a life cycle philosophy and considering the carbon payback, vehicle manufacturers, policy makers and consumers can select the appropriate low carbon technology for their situation.