Life cycle assessment of battery electric vehicles and hydrogen fuel cell vehicles
Creators: Khanna, Dipankar
Publisher: name: University of Alberta Library
Year: 2023

<p>The global road transportation sector is a major greenhouse gas (GHG) emitting sector. In 2021, the sector generated 28% of the world’s GHG emissions, mainly due to the direct burning of fossil fuels. In order to reduce the adverse impacts of climate change caused by human activities, the global community aims to cut GHG emissions from 2005 levels by 2030. A significant GHG emission contributor, the transportation sector has a crucial role to play in achieving this target. Decarbonizing the sector by fuel switching (replacing conventional diesel vehicles [CDVs] with battery electric vehicles [BEVs] and hydrogen fuel cell vehicles [HFCVs]) can make it more sustainable and environmentally friendly. BEVs and HFCVs are emerging as important options as they can significantly reduce GHG emissions, especially when coupled with a decarbonized power sector. The GHG emission savings of BEVs and HFCVs have been estimated in many studies. However, the environmental benefits of BEVs and HFCVs rely considerably on driving behavior and the climatic conditions of a given location. The global use of BEVs and HFCVs increased by 70% in 2018 from 2017 and is projected to increase further in the coming decades. Several studies have evaluated the environmental performance of BEVs and HFCVs, but few consider the impact of the key parameters that affect performance: climatic condition, drag coefficient, rolling coefficient, speed, acceleration, and road type. Nor is the environmental impact of lightweight materials such as carbon fiber reinforced plastic (CFRP) manufactured from bitumen-based asphaltene included in the studies. Mass can be reduced significantly by substituting conventional materials (steel, aluminum, copper, etc.) with lightweight CFRP. That said, CFRP brings its own set of production and economic challenges. This study, therefore, explores the impacts of these parameters on the overall life cycle performance of BEVs and HFCVs. Nine operational scenarios for BEVs and two for HFCVs were established based on prevalent road types and climatic conditions. The life cycle GHG emissions for BEVs range from 93 g CO2 eq/km (city in summer scenario) to 258 g CO2 eq/km (highway in severe winter scenario) for conventional BEVs, and for CFRP BEVs, from 72 g CO2 eq/km (city in summer scenario) to 163 g CO2 eq/km (highway in severe winter scenario). The life cycle GHG emissions for HFCV range from 107 g CO2 eq/km (city in summer scenario) to 382 g CO2 eq/km (highway in severe winter scenario) for conventional HFCVs, and for CFRP HFCVs, from 85 g CO2 eq/km (city in summer scenario) to 254 g CO2 eq/km (highway in severe winter scenario). <br>
Often, considerably more energy is required to produce CFRP than to produce conventional raw materials such as steel, aluminum, etc. The operation phase is the largest GHG emissions contributor among the life cycle phases (manufacturing, assembly, maintenance, end of life). The operation emissions for the considered scenarios range from 50 g CO2 eq/km (city in summer) to 175 g CO2 eq/km (highway in severe winter scenario) for conventional BEVs and for CFRP BEVs, from 32 g CO2 eq/km (city in summer scenario) to 102 g CO2 eq/km (highway in severe winter scenario). The operation emissions for conventional HFCVs range from 78 g CO2 eq/km (city in summer scenario) to 353 g CO2 eq/km (highway in severe winter scenario), and for CFRP HFCVs, from 54 g CO2 eq/km (city in summer scenario) to 223 g CO2 eq/km (highway in severe winter scenario). However, the environmental performance of both CFRP BEVs and CFRP HFCVs depends highly on the CFRP production method. For HFCVs, the hydrogen production process and the efficiency of the fuel cell highly influence production. For all the considered scenarios, however, the life cycle GHG emissions decreased significantly when conventional raw materials were replaced with CFRP for both BEVs and HFCVs. The GHG savings from the use of CFRP were highest in the highway in severe winter scenario and lowest in the city in summer scenario for both BEVs and HFCVs. This information is beneficial to those making investments and policy decisions related to BEVs and HFCVs. </p>