An initiative in the offing is to operate Electric Buses (EBs) for the feeder services of the Metro. The intent is to finance partly the investment of 30 EBs which would be shared between Bus Operators NTC, UBS and RHT. The EBs would moreover be energised by Solar Power.

EBs would eventually be further introduced on longer bus routes. The public bus transport in the country needs a much-required revamping. The bus fleet is not being adequately renewed.  Currently, more than a third is above 10 years old and a quarter being more than 15 years old. The bus system looks anachronistic against a modern metro. Besides, the present generation is shunning the bus and is more attracted to shared taxis, van services and private transport. The EBs, offering an opportunity for a transformation in the bus transport system, could galvanise an about-turn towards public transport.

In two earlier papers*, we upheld that Electric Vehicles, of which the EBs form part, play a significant role in the context of climate change and sustainable development. They exemplify a new ‘clean’ technology using batteries as the power source. The EB releases no tailpipe emissions, has less vibration and less noise and is much cheaper to operate. The downside is that they tend to be expensive in addition to requiring large investment in charging infrastructure.

In this paper we explore the implications and challenges of introducing EBs.

The feeder and long route EBs

Buses for feeder connectivity to the Metro would generally operate on routes of less than 10 km. These could be 9m length midi EBs capable of running on narrow sub-urban routes. Powered with a 130-150 kWh battery, they would have sufficient range with full battery charging to cover ten trips totalling some 100 km per day.  

EBs for long route operation require some more complex consideration. The battery capacity should have sufficient range to cover the distance and flexibilities of longer route operations. 11-12m lengths EBs with 300-350 kWh are best suited here. However, these latter battery capacities could be economically not attractive. Batteries in the range 200-240 kWh could make do but would result in a loss of flexibility in operation. The EBs should then be on fixed route scheduling and cannot diverge from route allotments in view of limitations of range of the battery. En-route boost charging at bus stations is an option but such fast chargers are prohibitively expensive. 

Current 12m long diesel bus has seating capacities of 46-52 seats, their EBs counterpart are generally limited to less than 40 seats. Even with some 12 standees allowed, the carrying capacity is less, thus requiring many more buses to provide for the same capacity requirements.  Revenue earning potentials per bus are thus also reduced

Battery capacity of the EBs

EB batteries are expensive although the price tends to fall with development and scale production. At current price of about $200 per kWh, a 300kWh battery serving a long route could alone cost some Rs 2.4 m.

In operation, to avoid likelihood of the bus being stranded, the battery is generally not let to discharge below 15%.  As well to avoid battery degradation, batteries are recommended to be charged only to 80% capacity. Factoring these in, a rated 200 kWh battery would only give some 136 kWh of useful energy. This may give a maximum driving range of some 170 km. That could be lesser still if the bus is air-conditioned.

Charging the EBs with solar power

The EBs could be charged overnight from the electricity grid. With a 125-kW charger, that could take some 5-6 hours to charge a bus.
However, simultaneously charging several EBs in the evening at a depot will have potential impact on the electricity grid of the neighbourhood. It could require significant grid infrastructure upgrades. CEB would typically charge this cost over to the bus operator.

If as intended, the EBs would be charged through a mixture of Solar Energy and CEB grid electricity, a proper charging station that could charge 3 EBs at a time may be set up. That complete station infrastructure could cost some Rs 3m.  For a bus fleet of some 10 EBs, the investment in depot chargers could represent some Rs 9m. It could be more if the buses are split up at more than one depot due to operational exigencies.

In addition to capital investment on the solar panels, the bus depots would need to be redesigned to accommodate both refuelling of existing diesel buses and charging of EBs. Space could be an issue in view of the large turning radius of buses.

Financing the EBs

A mini EB with adequate battery capacity for the feeder connectivity with the Metro could cost about Rs 8m each. For each of UBS, RHT and CNT, the investment could represent some Rs 90m for 10 buses with associated chargers.

Based on other countries’ practices, a capital subsidy of up to 40% upfront cost of the EB plus a partial subsidy on the Photo Voltaic based chargers could be expected from Government. 

Notwithstanding, that could still leave NTC, UBS and RHT to each mete out some Rs50m - 60m as investment. Can these companies financially support such procurement?  Government can increase its capital subsidy. Alternatively, one avenue that may be investigated is having recourse to asset leasing institutions. These could be local banks or financial institutions or even the EB manufacturing company. EB leasing model would be new to the country.  Still, this would represent an additional cost to be integrated into the bus companies’ business models and involves high risks owing to inadequate experiences in this new venture. 

Management of EB Infrastructure

The bus companies, new to electric bus and charging technologies would face two challenges at least. One is to manage the operations having a watchful eye on battery range capacities so that the bus does not get stranded for want of battery charge. More importantly is the management and maintenance of the charging infrastructure.

The authorities are committed to have the buses charged with solar power. The solar panels would be energised during daytime, to be dispensed to the EBs at night. Thus, in addition to investments in solar panels, additional ones would be needed in battery storage capacities. Alternately, the energy from the solar panels could be sold to the CEB and purchased again at night. Another alternative would be charging through a combination of solar power and from the electricity grid. Either ways require energy management and charger operation and maintenance competencies, which the bus companies do not have.

To address this issue, a management split could be considered here. The bus companies managing the en-route operation of the EBs and having the CEB (or a separate company) managing and maintaining the charging infrastructure. Still then complications would arise for the CEB. The charging infrastructure would not be at one company, but three companies, which may be further split into different depots of each company. CEB could find this fragmentation difficult to manage.

Hand over the feeder EBs to Metro

It is considered that the best suited means to avert the above complexities would be to hand over the whole management of both the feeder EBs and the associated charging infrastructure to Metro Express Ltd (MEL). There could be compelling reasons for this. First, MEL has an interest in this as the very raison d'être of the EBs is to feed in passengers to the Metro. Second, by virtue of its operation, the Metro already has strong expertise in electric motion and power management. Third, it would avoid the complications of operating the EBs from three different companies with additionally different depots. Fourth, the Metro would be the one to bear the brunt if the feeder services are not managed properly by the bus companies. Fifth, the EBs are principally meant to service the Metro and there would be synergies between both Metro and feeder bus schedules and operation. Sixth, this would satisfy the requirement of having a single integrated fare collection system for both the Metro and the feeder buses. Seventh, perhaps more importantly, MEL would not be shackled with the legacy practices as in the bus companies and being a greenfield company may set up fresh proper systems. 

There could remain the issue of lost revenues to the bus companies. These may be addressed through some compensating methods such as an operating lease formula. In such cases, this would allow the bus companies time to also learn the intricacies of the EBs before they launch the longer route EB services.

* https://www.lexpress.mu/node/383132
* https://www.lexpress.mu/idee/384617/transitioning-towards-electric-cars