Electric buses: more advanced than you'd think

Dr Peter Harrop, Chairman, IDTechEx



Recent IDTechEx conference presentations and webinars on the research carried out for the new IDTechEx report, "Electric Buses 2015-2025" attracted many questions. They reveal a general perception that things are moving much more slowly than is actually the case, with the exception of a few aspects such as use of fuel cells and continuous charging, both of which are failing to progress at the intended speed.

Powertrain storage winners
People ask about which powertrain storage will prevail and we answer that lithium-ion batteries will be dominant for another decade, lithium-metal being some way off even in the view of those promoting them, though the situation with supercapacitors is complex. They have come in in a big way with hybrid buses that do not plug in, replacing lithium-ion batteries because they last the life of the bus and perform better, costing less over life.
By contrast, only lithium-ion batteries can currently do the job for plug-in hybrid buses with long electric range and China now only gives subsidies for those hybrids now so there the simple hybrid bus is virtually wiped out.

Structural and hybrid supercapacitors?
There is a possibility, no more, that two new types of supercapacitor may eventually turn the tables, say in 5-10 years. They are structural supercapacitors in the form of vehicle bodywork so they effectively take no space and can store lithium-ion amounts of energy, performing better and lasting longer. Secondly, lithium-ion capacitors may grab a place as lightweighting, multiple energy harvesting and other advances mean that less electricity is needed in storage.

Lithium-ion capacitors have electrodes half way between lithium-ion batteries and supercapacitors and they currently store lead-acid/ NiCd levels of electricity with vastly superior power density (potentially acceleration/ fast charging) and supercapacitor cycle life of around one million cycles - way out of reach of battery manufacturers.
People ask about safety of structural energy storage and we answer that it can be provided. For example, there could be many cells in parallel with fuses and remember the inherently less safe batteries sometimes work with a nail through them. Anyway, we believe that structural electronics is potentially a major disruptive change in design of most electric vehicles over the coming decade. See the IDTechEx report, "Structural Electronics 2015-2025".

The two-motor trend
One asked, "How compelling is the two motor model versus mechanical CVT and only one motor", since we advise that two motors per vehicle is a strong trend for what were single motor vehicles in the past, buses being an example. Our answer is, "Very compelling but many different reasons for different types of vehicle including four wheel drive, vectored steering, redundancy, efficiency, one motor doubles as generator accepting energy harvesting inputs..." See our new report "Electric Motors for Hybrid and Pure Electric Vehicles 2015-2025: Land, Water, Air".

Pure electric buses arriving much faster than realised
Questioners note that most buses are sold via public tendering processes and ask if this is a big barrier to bringing in new innovative buses. Who should take the lead in this? We reply that the above choice of subsidies in China is very progressive as are the exceptionally stringent pollution laws kicking-in in Europe.

Government has a big role to play but local authorities buying buses also drive the programs of eliminating pollution at point of use. It all brings in pure electric buses sooner rather than later.

There is widespread under-appreciation of the status of pure electric buses. People are amazed to hear of the 1000 and 2000 unit orders being placed in China for big pure electric buses and how both articulated and double decker pure electric buses are on sale. Range is typically in the region of 170 miles/ 270 km.

Hot and cold climates
It is fair that questioners express doubts about current forms of electric buses in very hot climates however, suggesting auxiliary power units are still needed to drive air conditioning and there is some truth in this but tiny range extenders suffice and higher efficiency photovoltaics over the whole of the body capturing that powerful infrared and visible spectrum is on the way.

Tougher will be very cold climates with no sun. Here series hybrids may prevail, with new range extenders - jet engines, rotary combustion engines and, if their problems of cost of ownership, fuelling and life are overcome, fuel cell range extenders. People think that the fuel cells use affordable green hydrogen but it is almost always from fossil fuels and uncompetitive with greener electricity charging a pure electric bus.

Crossover systems
One correspondent asked, "Bratislava (Slovakia) have quiet large trolleybus network and in case of electro-buses we are thinking about combining pure electro-bus with technology to connect overhead catenary system to be able to charge ebuses during their run through the city and out of downtown to run eBus just on batteries / capacitors. What you think about this approach in content of electro-mobility?" We think it a good approach where you have existing infrastructure. Other countries are doing this. End game is pure electric buses with no catenary though.

How to compete with China
There is much debate about how bus manufacturers outside China can compete in future. The IDTechEx view is that they must innovate better than the Chinese and participate in markets that do not interest the Chinese. There is also the option of copying Daimler in forming a Chinese joint venture. Others sell them technology.

Not all innovation is guaranteed to excel of course. We are asked, "Will EV wireless charging and continuous charging road be coming up by 2025?" We reply that there will be quite a lot of wireless charging but not the majority. Continuous charging may happen in some places but not many. Cost including installation, poor standardisation and inability to do the fastest charging speed may often be an impediment in both cases.

Electric Buses 2015-2025

Electric Motors for Hybrid and Pure Electric Vehicles 2015-2025

Structural Electronics 2015-2025