Electrification of public transport
TSL has developed a stochastic mathematical model that designs city-wide wireless charging infrastructure.
The transport industry contributes over a quarter of all UK greenhouse gas emissions in the UK, with most of it produced by road vehicles. Therefore, it becomes paramount to modernise and electrify the UK’s road transportation to reach UK’s Net Zero target by 2050.
While the UK has made important progress in electrifying public transportation, there are some limitations in their use. Electric buses, for instance, have limited driving range and long recharge times that translates to requiring large fleets. To resolve this issue, TSL proposes the use of Wireless Charging Lanes, which recharges buses while on the move.
To date, the studies carried out to estimate the infrastructure requirements to implement WCL have severe limitations that preclude their realistic application. For example, a common assumption is that energy is independent of traffic congestion, vehicle speed, passenger load, and weather. Neglecting these relationships may lead to serious operational consequences, such as buses running out of electricity, or requiring shutting down on-board services such as heating and air conditioning.
The aim of this study is to optimize the deployment of wireless charging infrastructure for the electric bus system. We develop a two-stage stochastic programming model has been established to identify the best location of the WCL along with the optimal on-board battery size for every bus route while also considering all the possible energy consumption scenarios. The objective of the model is to minimize the total cost requirements of the WCL set up, which is composed of the following:
- The cost of building the WCL,
- The cost of on-board battery for the entire bus fleet
- A penalty attributed when the battery level falls below the designated threshold
Using this mode, we analyse the central bus routes in London, which constitutes a total of 22 routes. We compare the implementation of WCL against using stationary charging at the end of the bus route.
|Length of WCL||45.6 km||-|
|Battery costs (£)||1,422,500||1,969,000|
|Charge cable costs (£)||60,794||-|
|Power transmitter costs (£)||142,002||-|
|Battery repair costs (£)||1,874||3,180|
|Total costs (£)||1,627,170||1,972,180|
We also monitor the battery charge level to ensure a safety margin is maintained throughout the operation.
An extensive sensitivity analysis is carried out for a single bus route (Line 43) to jointly determine the optimal operational requirements in terms of battery size, WCL infrastructure, and bus fleet size. WCL could reduce annual costs for the operation of this route by 24% during the 10-year period considered.
The techniques developed in this study have been applied to city-wide simulations.
We capture worst case scenarios based on weather, passenger load, speed and traffic conditions.