Electric buses must shed weight – around three quarters of their hefty battery baggage – to earn a place on Hong Kong’s roads, says a leading bus expert who calls on the Hong Kong government to support a new concept of rapid and frequent bus charging.
Paul Bromley, a consultant with 32 years’ experience in the bus business and who led the movement to bring hybrid buses to Hong Kong back in 2007, says “range anxiety” has led to a vicious circle of cramming more batteries into buses, bogging the vehicles down in both weight and cost.
“People worry about the range of the vehicle, so they stick more batteries in. But that increases the weight, increases the cost,” he says.
According to Bromley’s analysis of a typical Hong Kong bus route, a double-deck bus needs a battery capacity of 700-800 kWh on board to get through a day on one charge. “That’s five or six tonnes of weight, and it’s going to be costing around HK$2-3 million in batteries alone,” he says, pointing out the batteries also eat into precious passenger space and make the design of the buses far from optimal. “800kWh batteries takes up about six cubic metres, you just don’t have space on the vehicle for that,” he says.
Part of the problem, he says, is that some leading Chinese bus companies are, in fact, battery makers, not bus makers. “These firms are just interested in selling the batteries, these are the high value item in the products. And that’s because people have been locked into being subsidised for running electric vehicles, rather than treating them as a commercial proposition.”
This also makes the buses notoriously expensive. The BYD single-deck buses purchased for the Environmental Protection Department’s (EPD’s) HK$180 million trial scheme came in at HK$5 million each – a huge premium on a product which Bromley says costs between HK$1.5m and HK$2m anywhere else in the world – and which, he says, is “suboptimal” for Hong Kong.
The government insists it got a good deal: “The price is comparable with those of the single-deck electric buses purchased recently by Singapore, where the land is generally flat, hence with less stringent operational conditions than Hong Kong,” says an EPD spokesman.
Bromley says a new approach is to forget vehicle range, ditch the bulk of the batteries, and get to work on charging infrastructure. Pantograph chargers, which are gaining ground in Europe, can turn an average bus stop or terminus into a rapid charging station, powering a bus with enough juice for three hours in the time it takes to brew a cup of tea. The system proposed by Bromley is OppCharge, a standard developed by a consortium of firms led by Volvo and including Iveco, Siemens and ABB.
“The bus driver pulls in, uses speed bumps to check the location, the pantograph drops down onto the bars and in ten minutes, you’ve got 75 kWh. For a single deck bus that could last four hours, for double-deck it’s three hours,” explains Bromley.
The pantograph “opportunity charge” solution is more expensive than a simple plug-in charger, costing around HK$500,000 (and possibly more depending on the site conditions), against HK$100,000 for a basic plug unit – but it becomes shared infrastructure, says Bromley. “Each bus only uses it for 10 minutes every two or three hours, you can share it between a dozen vehicles,” he says.
Building infrastructure like this, not subsidising purchase price, will be the biggest benefit to electric vehicles, says Bromley. But a problem with the concept, in Hong Kong, is government resistance to this type of scattered charging infrastructure. While pantograph concepts featured as part of the government’s HK$180 million trial, the idea was never really taken seriously as it was linked to “super-capacitor” buses, a unique EV design that requires very frequent charging – and not enough chargers were built.
“Super-capacitor buses need charging every 5 to 10 minutes, and they couldn’t get enough charging points,” says Bromley, blaming “silo” mentality thinking from the government. “If you ask Highways about pantograph installation, they say it’s a Planning issue, if you ask Planning, they say it’s EMSD [Electrical and Mechanical Services Department] issue, so you get that silo mentality from all the government departments when it really needs top-down policy-driven approach,” he says.
EPD says pantograph charging concept is still under trial, although it still sees pantographs only suitable for single-deck buses. “Whether the super-capacitor buses or fast charging bus models can be further promoted in Hong Kong depends on the availability of suitable short routes running by single-deck buses and whether the public transport interchanges or bus stops that these routes pass through can provide adequate space and power capacity for installation of top-up charging facilities,” a spokesman said.
But Bromley says the fixation with single-deck buses is wrong for Hong Kong: over 95% of Hong Kong’s buses are double-deck and, as seen in other countries, the OppCharge design also has no issues with serving a double-deck bus.
If pioneers like Bromley can overcome government inertia, the benefits of pantograph charging become very clear: under this design of rapid top-up opportunity charging, a double-deck bus would only need 200 kWh of batteries – a quarter of the weight and cost of the batteries in a “full-day range” bus, and creating a much more spacious passenger saloon. “You could stick those batteries under the stairs, or in place of the engine or the radiator, and you’ve maintained the number of seats,” says Bromley.
Bromley hopes to secure financial backing to work with an established double-deck bus provider: at the moment, he says, there isn’t a double-deck product suitable for Hong Kong. “Some manufacturers are offering fully electric double-deck buses, but my view is they are sub-optimal, they’re just putting lots and lots of batteries on. Singapore is buying 10 Yutong double-deck buses as part of its electrification programme, but I don’t know how good the production vehicles will be. I’ve seen the prototype and it’s not very good,” he says. “I don’t even believe it could do a full day’s work in Hong Kong – by my calculations they only have around 500 kWh on board,” he adds.
Aside from charging infrastructure, Bromley says there needs to be a commercial incentive to use the machines. “The second you can make the purchase cost equivalent to a fossil fuel bus, if it costs the same but costs less to run, has lower emissions, it becomes a no-brainer,” he says.
In Hong Kong, the “green” in “green minibus” refers to the colour of the roof rather than any environmental credentials – but new plans are afoot to take these busy public transport options electric, too. Some firms have tried hybrid Green Minibus vehicles under the EPD’s Green Transport Pilot Scheme, but none of these buses were popular with operators: diesel hybrids cost more to run than plain-LPG buses, and drivers complained they were noisy and unreliable. However, EPD is developing a new HK$80 million scheme to trial up to 40 pure-electric minibuses for public transport routes in Kwun Tong.
Bromley says he’s working with a European manufacturer to bring a viable contender into the race, and show the “small battery” concept to be a winner. “A green minibus does around 300 km a day,” he says. “With rapid charging, we could do that with a 90kWh battery, so again, we’re keeping the weight of the batteries off the vehicle.” With four daily recharges of around 12 minutes each, the bus can run 300 km over a 19-hour period, and the product design has already been proven in Europe.
The design is front-wheel drive, which offers a completely flat floor, as has been the case on big buses since 1997, and can have a ramp either at the side or the back to make it easy-access. The issue will be cost: a new Diesel or LPG Coaster, probably the most common Green Minibus vehicle, goes for around HK$800,000, hard to beat for a new technology at this stage, even with reduced battery and opportunity charging. But the tenders are being prepared, and Bromley is confident of getting some of these buses on the roads soon.