BUSES that use plug-in hybrid technology were introduced in Singapore in July 2024, and there were 11 such buses on the roads as at September, going by data from the Land Transport Authority (LTA).
Plug-in hybrid buses are a type of plug-in hybrid electric vehicle (PHEV). With their sizeable onboard battery charged, they can run for around 100 km on battery power. When the battery is flat, they rely on their onboard diesel engine for longer range.
Fully-electric vehicles can only be charged using an external source. The batteries of existing conventional hybrids are not charged this way; instead, they are charged on the go, while running on a fuel source – petrol or diesel.
PHEV technology is already used in passenger cars here, but PHEV buses – from China manufacturers Zhongtong and Yutong – made their debut on Singapore’s roads only this year.
Zhongtong was the first to offer a PHEV bus in 2023, with the first unit registered to Chitson Transport Service in July 2024.
LTA’s data states that as at September, eight Zhongtong and three Yutong PHEV buses were registered here to private transport operators.
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Zhongtong is distributed by Cycle & Carriage Singapore, a subsidiary of mainboard-listed Jardine Cycle & Carriage, and Yutong by Think One EV, a subsidiary of Think One Group.
Yap Eng Cheng, a director at Chitson which now has three of the buses, told The Business Times that the company chose the plug-in hybrid buses based on environmental concerns, charging infrastructure and running costs.
Speaking in Mandarin, he noted the government’s plans to have cleaner buses by 2040 to protect the environment. However, fully-electric buses are considerably more expensive, and chargers for such heavy vehicles and buses are still hard to find.
The diesel plug-in hybrid, on the other hand, runs 4.5 km per litre and is twice as efficient as a diesel-only bus, he said. On electric power, it can run for up to 100 km. The company has thus cut its fuel costs considerably.
While conventional diesel-electric hybrid buses exist, the PHEV buses are more efficient because they use a new technology that gives them extended range.
Unlike in conventional hybrids, the engine charges the battery, which runs the electric motor that drives the wheels. This allows the engine to operate in its optimal range more of the time, delivering better fuel efficiency.
Neo Tiam Ting, chairperson of Think One Group, told BT that while the PHEV bus costs more, the improved efficiency means an operator can recoup the difference over the vehicle’s lifetime.
Without a Certificate of Entitlement, Yutong’s plug-in hybrid bus costs around S$285,000, compared to S$195,000 for the diesel equivalent and S$428,000 for the fully-electric version.
Unlike light goods vehicles, buses are not eligible for the Commercial Vehicle Emissions Scheme, which gives rebates to cleaner vehicles and penalises more polluting ones.
LTA plans to electrify half of the public bus fleet by 2030; there are now 70 electric buses in public passenger service in Singapore. The government owns public bus assets and infrastructure, and operators such as SBS Transit and SMRT Buses are paid to operate the bus routes.
Under the Land Transport Master Plan 2040, Singapore is to gradually replace all existing diesel buses with cleaner-energy buses by 2040.
As at September 2024, there were 17,677 diesel, 315 electric, 50 conventional diesel-electric hybrid and 133 petrol buses in Singapore.