On top of all of this, more and more cities are lining up to transition their bus fleets to BEBs. In October 2017, within the frame of C40 (Cities Climate Leadership Group) mayors from a dozen global cities, including London, Paris, Los Angeles and Mexico City, signed the Fossil-Fuel-Free Streets Declaration, pledging to procure zero-emission buses from 2025 and “ensure a major area of (their cities are) zero emission by 2030”.
TOWARDS A VIABLE FUTURE
For the time being, BEBs cost twice as much as diesel buses. In effect, the excess expense today comes from the high prices of batteries – whether it’s the initial investment or the cost of replacing them (although public transport operators can usually benefit from rental opportunities from manufacturers, if buying the batteries proves too costly). However, prices of batteries have plummeted up to 90% in the last decade and are expected to continue to fall, with projections indicating BEBs will become commercially viable between 2020 and 2025 (Source).
Though urban bus fleets have yet to be replaced by electric buses, it is important transit authorities adopt a transition period and carry out trials. This will help ensure the energy transition is being carried out in line with the different environmental guidelines and targets. It will also enable authorities to take into account the local expectations, contexts and challenges by creating models and evaluating the technical and economic impacts.Moreover, this approach will enable operators to provide the best possible quality and deliver the optimum cost in the long run.
Recharging the batteries efficiently is the key to running successful trials. There are two ways this can be achieved. The first is charging along the line. This is done by fast charge, i.e. when the bus stops, a pantographic system connects to an overhead fast-charger for a few seconds to a few minutes. This provides a large enough charge for the vehicle to continue until the next charge. This can either be at every station, every few stations or at the end of the line. Helsinki, Finland, currently has several fast-charging BEBs in service.
The second charging solution takes place by plugging during 6 to 8 hours, when the bus is at the depot. For BEBs, this consists of an overnight charge. Of course, the type of solution opted for depends on factors such as the topology of the route, the distance between stops, climatic conditions, time spent at stops and the number of passengers.
INTEGRATING ECO-BUSES INTO A GLOBAL URBAN POLICY
Replacing fleets of diesel buses will certainly help unclog congested cities by reducing GHG emissions as well as fine particules and nitric oxide. But their ability to drive down emissions is much greater when the whole system is taken into account. In other words, quiet cutting-edge BEBs can very likely foster a modal shift, getting people to leave their personal vehicles at home. And this is where the significant impact will be.
According to calculations by the World Bank, if buses carrying 150,000 passengers per day on a simulated 30-km transit corridor were to shift to 100% electric, annual emissions would be cut by 27%. However, if 10% of passengers have made a modal shift – i.e. they leave their cars at home – this would be equal to a full 48% drop in emissions.
China clearly appears to be leading the way when it comes to this shift. As mentioned before, the city of Shenzen is a case in point, with its more than 16,000 fully-electric buses. Taking the long view, the transition to alternative energies in transport is more than simply a change in motorisation – it’s the emergence of a new mode of transport, which poses numerous interconnected challenges. Despite these challenges, electromobility is here to stay and electric buses are without a doubt a driver for bringing more sustainable transport to urban areas around the world. In short, they are certain to reshape both how we perceive and experience public transport across the urbanising world of the 21st century.