Spatially differentiated life cycle assessment of Thailand's transport: The implications from country-specific factors and alternative technologies

This study proposed country-specific characterisation factors (CFs) for Thailand by modifying the Thai Spatially Differentiated Life Cycle Impact Assessment (ThaiSD) method and introducing monetary conversion factors to express environmental impacts in Thai Baht. Five impact categories were fully parameterised, including fine particulate matter formation (PMF), human toxicity (both cancer and non-cancer) (HT_c and HT_nc), freshwater ecotoxicity (FET), and water scarcity (WS). Other spatialised CFs were selected from regionalisation models in ReCiPe2016 and IMPACT World+. When comparing the use of country-specific CFs with global average, the impact scores for PMF, HT_c, HT_nc, FET, photochemical ozone formation and terrestrial acidification demonstrated notably different levels, ranging from ±25 to ±50 %. The developed method was then applied to assess environmental impacts and costs of Thailand's transport sector, encompassing freight and passenger transport across roadway, railway, waterway, and aviation. Climate change (CC) was significantly attributed to human health and ecosystem quality impacts, while the major contributor to resource scarcity impact was fossil resource scarcity (FS). In some scenarios, non-exhaust emissions, particularly from freight trucks, accounted for 40–60 % of the total PMF impacts. Environmental costs of freight and passenger transport in Thailand were 0.08–3.64 Thai Baht per tonne-kilometre and 0.01–0.81 Thai Baht per passenger-kilometre, respectively. Among transport modes, trains were found to be the most environmentally favourable option for both passenger and freight transport, while aviation had the highest environmental impact for freight transport. In contrast, passenger aviation had a comparable environmental burden to passenger cars due to optimised occupancy rates. Despite the efficiency of modern internal combustion engine vehicles (ICEVs), particularly Euro 5 and 6, employing blended biodiesel was less effective in comparison to conventional diesel. Battery electric and fuel cell electric vehicles offered advantages in mitigating CC, PMF, and FS compared to ICEVs, although trade-offs remained across other impact categories.