Thesis Title: Sustainability assessment of the introduction of e-bus in a Mediterranean city: Case study in the city of Rethymno, Crete

Thursday 27 September 2018, at:11:00, Venue: Hall Κ2. Α3

Examination Committee

• Professor Theocharis Tsoutsos (advisor)
• Professor Ioannis Yentekakis
• Associate Professor Dionysia Kolokotsa

Abstract:

Transportation has been amongst the crucial sectors that contributed significantly to greenhouse gas emissions and hence to local and global climate change. Current studies suggest that the incorporation of electric buses in the public transport is a crucial step towards the planning of sustainable mobility and the reduction of the environmental impacts of transportation. Nowadays, more than 1.2% of bus fleets in Europe are fully electric and that number is estimated to increase in the near future.

The market of electric buses provides a wide variety of models, with different characteristics and a constantly increased range and capacity, which can be divided into categories, based on their routes routine and their length, aiming to cover the different needs of public transport systems. However, considering the production and procurement aspects of the electric buses, some drawbacks can be easily identified, such as the big initial investment cost, their weight and CO2 emissions during production.

In order to evaluate the environmental and economic implications of the integration of e-buses in the public fleets, this research compares a fully electric battery bus and a conventional bus with a diesel-fueled internal combustion engine, by implementing an approximate Life Cycle Assessment (LCA) analysis, along with the analysis of Total Cost of Ownership (TCO) and the estimation of Payoff years on these two bus types, with similar characteristics: mini buses with 7-m length and able to serve urban routes.

The LCA analysis included all the stages of buses’ life, except for final disposal and recycling, incorporating data about the electricity mix, the seasonal fluctuation and the served routes during the summer period in Rethymno. Following a spherical approach for the assessment, the TCO analysis and the payoff time were estimated to calculate the impact per km of the vehicles for different scenarios, including 3 different urban routes in the city and the greater area of Rethymno and the peak/off-peak tourist period. In order to produce reliable results, the required data have been derived from literature reviews and from companies that produce electric and conventional buses. 

The LCA results indicate that in the case of Rethymno, the Li-ion batteries manufacturing and the production of electricity are the stages with the heaviest environmental impacts, while the economic analysis indicates that of the price of the Li-ion batteries significantly affects the TCO and the pay back period of the electric bus, which are always higher in comparison with the conventional one (ΔTCO). However, the battery price reduction will lead to a reduction of the e-bus TCO.

The study reveals that the need to identify ways to reduce the environmental impact of the batteries manufacturing and use lighter or recyclable materials is considered imperative, since this will reduce the total weight and the overall costs of the buses. These improvements will further increase the environmental and economic benefits of electric buses and facilitate their incorporation in the public fleets as a sustainable solution to address the transport needs of the local population and mitigate the impacts on energy and emissions, especially during the tourist period.