An online tool for guiding bus fleet decarbonisation through green hydrogen and electrification
Cummins, Tadgh
Cummins, Tadgh
Loading...
Publication Date
2023-12-18
Type
Thesis
Downloads
Citation
Abstract
The transition to zero emission bus (ZEB) fleets is accelerating, and bus fleet operators are faced with no choice but to plan their decarbonisation approach now. Two prevalent ZEB options are battery electric buses (BEBs) and fuel cell electric buses (FCEBs) fuelled by green hydrogen. Hydrogen is labelled as green when it is produced by electrolysis powered by renewable electricity. It can often be unclear which combinations of BEBs and FCEBs are most suitable in terms of cost, emission reduction, and capability to maintain regular operation of the bus fleet. Additionally, as governments implement incentives to make public transport more appealing than using a car, fleet sizes and number of routes will grow, increasing the demand for ZEBs. This work develops the Enabling Support Tool (EST), an easy-to-use Microsoft Excel-based model that can assess the trade-offs between BEBs and FCEBs in terms of their technical performance, required infrastructure, cost, and emissions reduction potential. The novel aspects of this work are as follows. Firstly, the EST model was transferred to an online webpage featuring an interactive graphical user interface allowing stakeholders to interact with the model directly. Additionally, the model features a novel input process that minimises data collection and preparation time while requiring less training to use than previous models of similar purpose. This work is also novel in that it quantifies the effect of road gradient and passenger weight on the specific fuel consumption of BEBs and FCEBs using a regression analysis method. This model enables users to quickly explore the feasibility of different combinations of BEBs and FCEBs and thus guide cost-effective full fleet decarbonisation. Using the EST model, decarbonisation case studies were performed on existing bus fleets in Galway, Ireland and Saarland, Germany. The case studies envision the transition of the entire bus fleet from conventional diesel-fueled buses to ZEBs. The aim of the case studies was to determine the optimal combination of BEBs and FCEBs in a mixed fleet and to compare the total cost of ownership and emissions reduction achieved when switching to a mixed fleet, a BEB-only fleet, and an FCEB-only fleet. The main results of the case studies are as follows. For the Galway city fleet consisting of 31 double-deck buses, 15 additional buses would be required to maintain fleet operations if transitioning to an all-electric bus fleet due to the relatively short range of double-deck BEBs. This increases the total cost of ownership (TCO) by 0.21 €/km, leading an overall TCO of 1.37 €/km. A fleet comprising of FCEBs only would not require any additional buses but would be much more expensive due to the high cost of FCEBs and hydrogen. For a hydrogen price range of 2 €/kg – 12 €/kg, the calculated TCO is 1.06 €/km – 1.62 €/km. At a hydrogen price of 7 €/kg, the mixed fleet of BEBs for shorter routes and FCEBs for longer routes has the lowest predicted TCO out of the ZEB fleets, at 1.10 €/km. For Saarland, results show that BEB fleets are currently more economically attractive than FCEBs in the region due to a lower price of electricity and higher average range of single-deck BEBs which are used in the area. Sensitivity analysis of the key outputs of the EST shows that the parameters with the largest impact are fuel and electricity prices, bus price, and hydrogen infrastructure costs. Using prediction trends for the evolution of these parameters over time, scenarios were developed to investigate the changing roles of BEBs and FCEBs in bus fleets from 2023 to 2030. In the 2030 scenario featuring pessimistic cost reduction trends, ICEB technology remains the most cost effective. In the scenario featuring optimistic trends, the FCEB fleet is the most cost effective with a TCO of 0.84 €/km.
Funder
Publisher
NUI Galway