Life Cycle Assessment of Electric Road Systems - Climate impact in comparison with battery electric vehicles, biogas vehicles and fuel cell electric vehicles

Abstract: One third of Sweden's total annual greenhouse gas emissions originate from the transport sector today and great changes are thus needed in order to reach the net zero emission target by 2045. One of the most important measures discussed is an increased electrification of the transport sector and a solution with potential to contribute to this transition is electric road systems (ERS), where vehicles are charged dynamically. A conductive ERS technology is currently being developed by the company Elonroad, offering a solution involving four main components: rail, pick-up, on-board charger and feed-in station. This study investigates climate impact from Elonroad's ERS solution by conducting a life cycle assessment of the four components. Results from the life cycle assessment are also combined with findings in previous studies on fuel cell electric vehicles, battery electric vehicles and vehicles fuelled with biogas for both heavy-duty vehicles and passenger cars. This in order to compare climate impact between the renewable transport solutions from a life cycle perspective. Lastly, the results from the life cycle assessment of the ERS are used in a case study on the public transport bus line 4 in Stockholm. It is found that one rail contribute to emissions of 2 590 kg CO2-eq, one pick-up of 200 kg CO2-eq, one OBC of 1 370 kg CO2-eq and one feed-in station of 153 000 kg CO2-eq, with hotspots being aluminium used in the rail and DC/DC converter used in the on-board charger. In the comparison between the propulsion systems it is seen that the ability for the ERS vehicles to downsize the battery reduces life cycle emissions from vehicle production significantly. The variable influencing the climate performance the most is the utilisation rate, determining how many vehicles sharing the environmental burden. For heavy-duty vehicles assessed in gram CO2-eq per tonne kilometre, it is seen that above a utilisation rate of 428 vehicles/day the ERS vehicles have the lowest climate impact amongst the studied propulsion systems. Fuel cell electric vehicles using hydrogen from steam methane reforming of natural gas have the highest impact, followed by biogas vehicles using liquefied biogas and then battery electric vehicles. Lowest impact after ERS vehicles with a high ERS utilisation rate has fuel cell electric vehicles using hydrogen from electrolysis. For passenger cars assessed in gram CO2-eq per vehicle kilometre, a utilisation rate of 4 780 vehicles/day is required for ERS vehicles to perform the best. The highest impact is seen for fuel cell electric vehicles using hydrogen from steam methane reforming of natural gas, followed by the corresponding but with hydrogen from electrolysis and then vehicles fuelled with compressed biogas. Lowest impact after ERS with a high utilisation rate has the battery electric vehicle. In the case study of Stockholm bus line 4 it is seen that ERS can reduce annual emissions from 1 480 tonne CO2-eq/year with today's system of biogas and biodiesel buses to 480 tonne CO2-eq/year with ERS. If instead transitioning to stationary charged electric buses a reduction to 802 tonne CO2-eq/year is seen.