Well-to-wheel nitrogen oxide emissions from internal combustion engine vehicles and alternative fuel vehicles reflect real driving emissions and various fuel production pathways in South Korea

Abstract

South Korea is suffering from high concentrations of particulate matters in the air caused by domestic and foreign influences, and the government is attempting to reduce nitrogen oxide (NOx) emissions in the transportation sector, which could be causing secondary generation of these emissions. This paper presents a life cycle assessment (LCA) on the six base fuels and finally produced results for WTW NOx emissions for internal combustion engine vehicles (ICEVs) (gasoline), ICEVs (diesel), battery electric vehicles (BEVs) and fuel-cell electric vehicles (FCEVs) through LCA based on electric power generation sources and hydrogen production methods. For the tailpipe emissions of ICEVs, the real driving emission (RDE) NOx emission data from previous studies supported by the Ministry of Environment in South Korea were considered, in addition to the NOx emissions based on the New European Driving Cycle (NEDC) test procedure. As a result, the WTW NOx emissions of ICEVs (gasoline), ICEVs (diesel-euro6), and ICEVs (diesel-euro6d-temp) were calculated at 0.113, 0.776 and 0.154 g/km, respectively, when considering the RDE NOx emissions. In addition, for BEVs, coal, natural gas and power generation mixes were calculated at 0.113, 0.059, 0.065 g/km, respectively, depending on the power generation source. In the case of FCEVs, naphtha cracking (NC), steam methane reforming (SMR with natural gas), SMR (with landfill gas), electrolysis, and production mixes were calculated as 0.088, 0.080, 0.030, 0.254, 0.088 g/km, respectively, according to the hydrogen production method. It was noted that the WTW NOx emissions from the most recent diesel-fueled ICEVs (euro6d-temp) was similar to those of FCEVs and ICEVs (gasoline), although pre-euro6d-temp diesel vehicles suffer from significantly high WTW NOx emissions, mostly from tailpipe emissions under real driving conditions. In this study, it is possible to analyze the life cycle from the actual operational data in a uniform perspective for all vehicle types. In addition, it is able to derive WTW results for alternative fuel vehicles according to various power generation sources and hydrogen production methods and to understand the effect of upstream energy sectors. © 2022