A review of studies on the LCA of electric vehicles is included in this section. The review has been conducted for understanding how some LCA studies for automotive application have been assessed, what are the parameters included such as functional unit, the weight of vehicles, battery types, and recycling which shall be used for understanding and choosing the right approach for the LCA and understanding the impact via the results. Based on the bibliometric analysis by Lucarelli et al. (2020), the research rate within the transport sector has tripled in the last five years, which shows the increased attention of academia in the transportation sector.
Life cycle assessment is a widely used application for assessing the environmental impact in automotive applications. Several comparative LCA studies between ICEV and BEV were found in the literature. Nonetheless, only few life cycle studies were focused on the HEV, specifically for the on-road vehicles.
Based on the findings from different search tools such as Scopus, and google scholar, most of the LCA studies conducted for the transport sector entail private cars, due to which the scale of the environmental impact from the CHE might differ compared to the available studies. However, the LCA studies for private cars are taken as a guideline for how the study needs to be conducted. In most of the comparative LCA studies between BEV and ICEV, the use phase has been given relatively higher importance which deals with only the tailpipe emissions (Samaras & Meisterling, 2008; Boureima, et al., 2009). However, some studies have focused on the vehicles' overall life cycle, including the manufacturing of the battery and the energy generation for the vehicles in the system boundary. Pero et al. (2018) and Hawkins et al. (2012) have investigated the energy production parts and presented it in their findings. Based on their results, the use phase is the dominant phase for GHG emissions.
Battery usage for electric vehicles also has several sustainability issues, and this has captured avid interest from several areas, including the LCA community. Studies focusing mainly on battery analysis for automotive applications are Ellingsen et al. (2013) and Dai et al. (2019).
The study by Ellingsen et al. (2013), is one of the most transparent studies on different lithium-ion batteries (LiFePO4 and LiNCM). Based on Hawkins et al. (2012), battery production contributes to 35% to 41% of the studied electric private cars during the production phase global warming potential impact while the electric engine contributes 7%
to 8%.
There are few LCA studies for heavy-duty electric vehicles and CHEs compared to private cars. The reason might be because drivetrain electrification of heavy-duty vehicles has not taken widely in the market. Also, LCA studies for the cargo handling equipment in the ports have not caught massive attention in academia. Though few LCA studies are conducted on heavy vehicles and non-road mobile machineries, some research results have been published
and referred to the life cycle study of the CHE studied here. Rupp et al. (2018) conducted a comparative study of conventional and hybrid heavy-duty trucks where mainly the drivetrain was compared, and the functional unit of 1-ton cargo transportation over a 1 km distance was chosen. The study also considered several factors, such as battery replacement and the effect of the driving profile. The study concluded that the hybrid truck could save around 4.34g CO2eq emissions per transported ton and kilometer during use. Based on the findings impact from the product manufacturing is roughly 10%, while the main effect in the overall life cycle is associated with the use phase, which is 90% of total GHG emissions. (Rupp et al., 2018)
Zrnic et al. (2013), conducted an LCA on CHE, which aimed to analyze the performance and CO2 reduction potential of the electric Rubber Tired Gantry (RTG) compared to the conventional RTG and electric Utility Tractor Rigs (UTR) compared to the conventional UTR. The RTG studied by Zrnic et al. (2013) has similar attributes to the SC that will be explored in this thesis. The mass of the RTG is around 70 tons, and emission from the product manufacturing of the RTG based on the CML Method is 335,000 kg-CO2 equivalent for the diesel-based RTG and 344,000 kg- CO2 eq. for the electric RTG. Similarly, for 5,000 operating hours, the environmental impact of the diesel RTG was 60,017 kg CO2-eq, and the electric RTG was 1,462 kg-CO2 eq. The result for the product manufacturing being similar mass can be comparable with the results from the studied straddle carriers.
Similarly, Schwarzenberg et al. (2018) conducted an LCA on straddle carriers where the main aim was to assess the impact of battery-electric straddle carriers compared to the diesel-electric straddle carriers where 100% steel was recycled for the end-of-life, and the rubber would be incinerated. The result was difficult to interpret in terms of scaling, but based on the observation, the use phase was the dominant phase when recycling was credited.
Based on the overall observation, it has been found that there are very few life cycle studies on cargo handling equipment and most of the studies lack transparency. Therefore, this thesis shall guide for understanding the life cycle impact of CHE and contribute to the research field. Also, it would shall be a baseline to analyze the climate change mitigation potential of the CHEs in terms of the criteria set in the EU Taxonomy Regulation in future researches.
5 METHODOLOGY
The LCA methodology can be assessed in four distinct and mutually dependent phases: goal and scope definition, life cycle inventory, life cycle impact assessment, and interpretation (International Organization for Standardization, 2006).