Q2. What have the authors stated for future works in "Impact of bus electrification on carbon emissions: the case of stockholm" ?
Future research should focus on lifecycle impacts of batteries and charging stations ( for both fast and slow charging ) required for electrification which could be subject to sensitivity analysis under various lifecycle lengths.
Q3. What is the key to achieving decarbonization and energy efficiency in the transport sector?
Electrification of road transport in combination with a modal shift towards public transport can be key to achieving decarbonization and energy efficiency improvement of the sector (Creutzig et al., 2015).
Q4. What is the main reason why the battery emissions are higher?
Higher battery capacities could support the electrification of larger parts of the bus network and therefore reduce emissions associated with fuel consumption.
Q5. What is the attractive fuel option for public bus fleets?
Electricity is one of the most attractive fuel options for Swedish public bus fleets, according to a survey among environmental managers of the Public Transport Authorities (PTAs) (Xylia and Silveira, 2017).
Q6. How many GWh of energy savings can be obtained from electrification of the bus?
If the electric bus energy consumption is assumed to be, on average, 1.5 kWh/vehicle-km and the biodiesel (HVO) bus consumption is 4.5 kWh/vehicle-km, the electrification of these routes leads to energy savings equivalent to approximately 44 GWh/year.
Q7. How can battery electric buses reduce emissions?
More specifically, battery electric buses can reduce WTW emissions of NOx and Volatile Organic Compounds (VOC) by 60e80%, compared to a EURO IV diesel bus (He et al., 2018).
Q8. Why was the literature prioritized for selecting the parameter values?
When available, Swedish literature was prioritized for selecting the parameter values due to higher relevance to this case study.
Q9. How much is the battery weight that is taken into account in the sensitivity analysis?
With the assumed battery capacity of 60 kWh, energy density of 80Wh/kg, and one battery change perbus, the total battery weight that is taken into account in the sensitivity analysis is 390 tons.
Q10. What is the effect of heavier batteries on emissions?
the resultsof this analysis show that heavier batteries could not only lead to higher battery-related emissions, but also to higher fuel-associated emissions, as the energy consumption increases.
Q11. What is the impact of the electricity mix on emissions of electric buses?
The authors conclude that, under current conditions and considering charging and distribution losses, electric bus emissions would exceed emissions of conventional diesel buses.
Q12. What is the expected effect of technology improvements on the environment?
It is expected that technology improvements in batteries shall lead to reduced environmental impact, as well as an improved ratio for the battery weight and its capacity.
Q13. What is the difference between energy optimized and power optimized batteries?
The power optimized batteries have lower energy density but can withstand higher charging power, and they also have a longer life than energy optimized batteries.