A ‘Minus Emissions’ car!


The Toyota Mirai takes air from outside and cleans it as it drives!
The second generation hydrogen fuel cell powered Mirai has been launched to the press and we were at an exclusive event to hear more from its creators. With a range of 650km from ‘a fill’, could this new fuel cell powered electric vehicle (FCEV) be the breakthrough in sustainable transport – after all it is fuelled by the most abundant element on the planet.

Mirai is built on a rear wheel drive Lexus platform (GA-L, used in the LS) and as a car looks very impressive. The Mirai 2 now looks every bit the definition of an executive cruiser. It has beautifully sculpted lines and a long bonnet that covers a bay stuffed to the brim with technology. It is lower than the original, the wheelbase is longer and the car’s length is an imposing 4975mm. We saw it up close last year with Toyota at a special preview in the Netherlands. The once four-seat car is now a five-seater and the level of refinement has been significantly increased. A lot of lessons from the original front wheel drive Mirai have been addressed. The new rear wheel drive layout allows for a third hydrogen fuel tank to be fitted and this along with other power-train efficiencies and improvements means the Mirai 2 can travel a respectable 650km on one fill. So a trip from Tokyo to Osaka can be undertaken with no bother! This 30% improvement in fuel efficiency in reality means nothing to most people as you could not buy the original Mirai – also it was a rarer sight than a Bugatti Veyron in shocking pink on the road. It will still be a very rare sight on Ireland’s roads for the next few years at least.

So what is the thinking behind hydrogen as a fuel source for cars. Battery electric vehicles or BEVs are ideal for shorter commutes and urban driving. Hybrids (HEVs) and plug in hybrids (PHEVs) are better at general and longer distances while hydrogen FCEVs work best in larger and heavier passenger cars, heavy-duty vehicles and public transport. As they are essentially EVs they fit in the carbon neutral narrative. On the road Toyota told us the car is incredibly refined and fun to drive with a 50/50 weight distribution and great mid range torque. The Mirai 2 even comes with a selectable two-setting sound synthesiser that generates appropriate driving noises through the speakers depending on your mood. It is clear the Mirai is a fantastic example of fuel cell technology. Hydrogen is the most plentiful element on our planet and to have a car that can utilise that and produce negative emissions is really cool – so what are Toyota’s plans for the cutting edge vehicle? Toyota says: ‘Our vision for a future sustainable hydrogen society recognises the value of hydrogen as a viable and plentiful resource for carrying and storing energy. It has the potential to deliver zero carbon mobility, not just in road vehicles but equally in trains, ships and planes, and to generate power for industry, businesses and homes. It’s also an efficient means of storing renewable energy and can be transported to where it’s needed. Toyota began development of a hydrogen fuel cell electric vehicle in 1992, successfully introducing the Mirai sedan to world markets in 2014. This breakthrough achievement was founded on the company’s world-leading experience in hybrid technology, the core technology for a wide range of different electrified vehicle power-trains.’

At the moment there are no public hydrogen filling stations in Ireland and precious few around the globe either. Toyota Ireland says it expects three filling station (built by Hydrogen Mobility Ireland’s 15 stakeholders) will be located on Dublin’s periphery initially. 10 further stations will be commissioned in the following few years. These will service the need for hydrogen of some roughly 50 vehicles in Ireland by 2023. In the intervening years we will see only a few demo models registered for use here. The Mirai three fuel tanks are arranged in a “T” configuration, the longest runs centrally beneath the vehicle floor, with two smaller tanks set under the rear seats and luggage compartment. Together they can hold 5.6 kg of hydrogen, compared to 4.6 kg in the current Mirai’s two tanks. With hydrogen priced per kilo – does that mean it is the new MPG/ L/100km we all have to learn? No, it is likely we will continue to use litres per 100 kilometres. In terms of running costs where does Mirai 2 sit next to the average diesel or BEV? Toyota said this is a complex question. In Japan the FCEV has the same running costs as a hybrid car. Fuel consumption is quoted at circa 1100yen per 100 kilometres, that’s roughly €9. As usage of hydrogen increases Toyota says the cost will come down. Perhaps as low as €6 per 100 kilometre in Europe. Presently in Europe a kilo of hydrogen fuel costs circa €10 per kilo. Toyota says it consumption is similar to a good diesel car. A drop of the hydrogen per kilo price is expected in Europe in the coming years to roughly €5-€7.

We asked Toyota Ireland will the Government tax hydrogen heavily like fossil fuels? It said the Government will most likely treat hydrogen favourably as it is for low emission use. Sadly without an abundance of hydrogen filling stations it is unlikely Joe Public will be able to (or should) get their hands on a Mirai 2. Toyota is targeting buyers/markets where companies for example could have a fleet. Ideally large transport firms could have their own hydrogen filling station and fuel on site. Toyota Ireland says the Mirai will cost under €80,000 and possible under €70,000. PCP is most likely purchase choice. Residuals are unknown as of now so why risk cash. Toyota financial services will have options and it is unlikely people will buy the Mirai outright with cash.

Toyota is on a push with the Mirai 2 and expects 30,000 sales globally. Toyota has managed to reduce production costs by 20% and like any new tech this figure will rapidly come down as the tech is developed further. The original car was a low volume machine and by upscaling production improved economies of scale have been achieved.

Nerdy technical Stuff: Toyota’s new fuel cell stack and fuel cell power converter (FCPC) have been developed specifically for use with the GA-L platform. The designers have been able to bring all the elements together in the stack frame (including the water pumps, intercooler, air conditioning and air compressors and the hydrogen recirculation pump) with each part made smaller and lighter, while at the same time improving performance. The stack case itself has been made smaller by using Friction Stir Welding, reducing the gap between the fuel cell and casing. The fuel cell stack uses a solid polymer, as in the current Mirai, but has been made smaller and has fewer cells (330 instead of 370). Nonetheless, it sets a new record for specific power density at 5.4 kW/l (excluding end plates). Maximum power has thus risen from 114 kW to 128 kW. Cold weather performance has been improved with start- up now possible at temperatures from as low as -30 ̊.
By concentrating the system connections within the case, fewer components are needed, again saving space and weight.
Focusing on innovation and improvement in every component has delivered a 50% weight reduction yet a 12% increase in power. New measures include relocation of the manifold, reducing the size and weight of the cell optimising the shape of the gas channel separator and using innovative materials in the electrodes. The unit also incorporates the Fuel Cell DC-DC Converter (FDC) and modular high- voltage parts, while achieving a 21% reduction in size compared to the current system. Weight has been cut by 2.9 kg to 25.5 kg. Advanced technology has contributed to the space-saving, with Toyota’s first-time use of a next generation silicon carbide semiconductor material in the intelligent power model (IPM) transistors. This enables an increase in output and lower power consumption while using fewer transistors, which in turn allows the FCPC to be made smaller. The same size and weight-saving approach has been applied to other parts of the FC stack. The air intake is designed for low pressure loss and contains sound-absorbing material so that noise from the air inlets is unnoticeable in the cabin. The exhaust uses a resin pipe and is designed to allow for a large amount of air and water to be discharged; a larger-capacity silencer contributes to the quieter cabin. The complete air system is almost 30% smaller than in the current Mirai and weighs more than a third (34.4%) less.
Lithium-ion battery -The new Mirai is equipped with lithium-ion high-voltage battery in place of the current model’s nickel-metal hydride unit. Although smaller in size, it is more energy-dense, giving higher output and superior environmental performance. Containing 84 cells, it has a 310.8 rated voltage compared to 244.8, and a 6.5 Ah capacity, versus 4.0 Ah. Overall weight has been reduced from 46.9 to 44.6 kg. The output has improved from 25.5 kW x 10 seconds to 31.5 kW x 10 seconds. The battery’s smaller dimensions have allowed it to be positioned behind the rear seats, avoiding intrusion in the load compartment. An optimised air-cooling path has been designed, with discreet inlets either side of the rear seats.

“It wasn’t like this when I parked it!”

The Mirai 2 is a great showcase for FCEVs but it is a substantial car so could its powertrain be ‘shrinked’ to say Yaris size? Toyota said ‘as it is a stackable technology a smaller unit with smaller power would naturally require a smaller space. Range and power have dictated the current car’s size.’ We asked will Toyota share this technology with other manufacturers? Toyota has already shared its Mirai tech with a Portuguese bus maker and is looking at sharing further – for a fee of course – its newest FCEV technology also. At the moment Toyota sells hydrogen fuel cells to BMW. Toyota is also looking at truck companies to partner up with. While also in Japan Toyota is involved in fuel cell powered trains and generators. Hybrids are in their 4th generation whereas FCEVs are only in their 2nd so Toyota expects big leaps in fuel cell improvements going forward. The elephant in the room concerns the minus emissions claim. Yes Mirai is ultra green as it runs but sourcing its fuel isn’t. At the moment the act of hydrogen fuel production is fossil fuel heavy in the main – but if the fuel can be made using green energy, then it is a win win for Toyota. Toyota Ireland’s current hydrogen bus trial uses green produced hydrogen. The new Mirai is an exciting car sadly not yet for the masses.


About Author

Michael Sheridan

Michael Sheridan is a senior and highly respected motoring journalist based in Ireland. He is a frequently heard voice on motoring, transport and mobility matters and has multiple credits on national television, national print media, national and local radio and other outlets. Michael Sheridan has been a Car of the Year Judge for more 20 years (& more recently a Van of the Year judge). Michael has produced and directed many international and national motoring TV programmes and documentaries both on cars and motorcycles - including four films on the iconic Route 66. Michael Sheridan is a former Chairperson of the Association of Professional Motoring Press (APMP).

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