Toyota Mirai: at the forefront of environmental sustainability
- Today's environmental challenge and Toyota's response
- How can a Fuel Cell Vehicle contribute to a better environment?
- Popularising Fuel Cell Vehicles to pioneer a Hydrogen Energy Society
Today's environmental challenge and Toyota's response
The continuing growth of the world's population — estimated to reach 9.6 billion by 2050 — will certainly lead to a further increase in the global production of vehicles and a resulting massive consumption of fossil fuels. This will exacerbate problems such as climate change, global warming and air pollution.
Two strategies are being taken to address environmental problems caused by the mass consumption of fossil fuels.
One is to use less petroleum. Combining high thermal efficiency, low fuel consumption engines and a host of advanced technologies, hybrid vehicles are a textbook example of how to use less petroleum.
The second strategy is to diversify energy sources. Energy diversification is a broad field, and Toyota has been working for decades to diversify the use of automobile fuels and powertrains. Each alternative fuel has its characteristics, and Toyota is confident that hydrogen is one of the technologies that brings the promise of a cleaner future. Hydrogen is an environmentally friendly energy vector that can be produced from a variety of raw materials including solar and wind power, biofuel, and natural gas. The company is therefore investing heavily in Fuel Cell Vehicles powered by hydrogen.
How can a Fuel Cell Vehicle contribute to a better environment?
A Fuel Cell Vehicle runs on hydrogen instead of gasoline or diesel. To be more specific, it runs on a motor powered by electricity generated by a chemical reaction between hydrogen and oxygen in a fuel cell. The only by-product of a Fuel Cell Vehicle in operation is water vapour. It does not emit any harmful substances such as CO2 (a major cause of global warming), or SO2 and NOx (causes of atmospheric pollution). In addition to producing zero emissions when driven, Fuel Cell Vehicles are also highly practical. They have an ample cruising range and can be refuelled very quickly.
Because of their simultaneous achievement of zero emissions and high practicality, Toyota positions Fuel Cell Vehicles as the ideal eco-cars.
Popularising Fuel Cell Vehicles to pioneer a Hydrogen Energy Society
Fuel Cell Vehicles (FCVs) are highly energy efficient, have ample driving ranges with short refuelling times and only discharge water when driven. They are an environmental technology with great potential, truly worthy of being called the "ideal eco-car."
Toyota has been working on the development of the FCV for three decades. While global attention is just beginning to turn towards the creation of a hydrogen-energy based society, Toyota's journey dates back to 1992 when it first started development of Fuel Cell (FC) technology. The core technologies (the FC stack and hydrogen tanks) were both independently developed, and over time these development and manufacturing technologies became strong points for Toyota. Now, after developing and fine-tuning the necessary technologies, Toyota is bringing its first FCV to market. It's called the Mirai, which is a Japanese word meaning "future".
Introducing Toyota's first Fuel Cell Vehicle: the Mirai
- Toyota is bringing innovation greater than that of the first-generation Prius to market
The Mirai is a core component of Toyota's dream for a sustainable mobility society. This is one that allows us all to move freely in comfort and safety in an environmentally friendly, sustainable manner.
With a focus on the next 100 years of automobiles, Toyota has proceeded with the development of a vehicle that offers a new, unique value. The Mirai is a pioneering vehicle that will contribute to a Hydrogen Energy Society. In addition to its superior fuel cell technology and environmental performance, the Mirai is fun to drive, has a futuristic design that clearly marks it as an FCV, and offers a quiet and comfor-table ride.
In order for green technology to contribute to the environment, the technology needs to become widespread. Toyota has already taken the initiative in popularising Hybrid Vehicles (HVs). With the Mirai, Toyota is bringing innovation greater than that of the first-generation Prius to market, and will do all it can to popularise the Mirai and the associated FCV technology.
As to who will buy the Mirai, it will be particularly attractive to business leaders aiming to personally start an "energy revolution" to change the world. In other words, pioneers who will create a revolution affecting the world for the next century. These could be individuals who place great importance on environmental performance and the necessity of FCVs high-income innovators who admire advanced technology and originality and of course automobile-fans.
Organisations interested in the Mirai could be public companies wanting to do their part for the environment, and public agencies/local governments keen to promote low-carbon technology.
Hydrogen under the microscope
- Environmentally friendly energy source
- Hydrogen station infrastructure is needed
- A safe automotive fuel
- Working towards a Hydrogen Society
Environmentally friendly energy carrier
The hydrogen that powers the Mirai can be generated using a wide range of natural resources and man-made by-products, such as sewage sludge. It can also be created from water using natural renewable energy sources like solar and wind power. When compressed, it has a higher energy density than batteries, and is relatively easy to store and transport. Consequently it also carries expectations for potential future use in power generation and a wide range of other applications. FCVs are able to generate their own electricity from hydrogen, meaning they can help make a future hydrogen-based society a reality, and are therefore expected to further contribute to accelerating energy diversification.
The need for a hydrogen station infrastructure
Obviously, a hydrogen refuelling infrastructure is necessary, and this will be via hydrogen stations, which are purpose-built facilities for supplying hydrogen to FCVs. Hydrogen stations can be either stationary or mobile. Stationary hydrogen stations can be on-site or off-site. With the on-site type, raw material (kerosene, LPG, natural gas, bio-gas etc.) is reformed in the hydrogen station to produce hydrogen. The station can also use an electrolyser electrically fed by wind power or solar panels. With the off-site hydrogen station, hydrogen produced at a factory is transported to the station, as we do today with the fuel from refineries to retail.
A genuinely safe automotive fuel
Hydrogen is as safe as any other fuel used in a car. It's been used as an energy carrier for decades, and there is a vast amount of cumulative know-how and experience in Toyota and elsewhere to handle it safely. Safety aspects are discussed in detail further down.
Working towards a Hydrogen Society
The Hydrogen Society or Hydrogen Economy refers to the vision of using hydrogen as a decarbonized and efficient energy source that can replace conventional fossil fuels. Hydrogen is attractive because it can be stored, transported and transformed into energy (water and heat), with water as the only emission.
However, hydrogen is not found in pure form on Earth. It has to be produced from other compounds such as water, natural gas or biomass — processes which of course involve energy to convert these into pure hydrogen. For that reason, it's more accurate to describe hydrogen not as an energy source but an energy carrier or storage medium. The environmental impact of using hydrogen therefore depends on the carbon footprint of its production path.
One of the most potentially useful ways to use hydrogen is in electric cars or buses through a fuel cell which converts the hydrogen and air into electricity. Hydrogen may also be useful as a means of storing renewable energy from intermittent sources — for example, when the wind is blowing but there is not high demand for electricity. In this context, it's a great alternative to large-scale batteries or other storage systems, especially as intermittent sources are ramping up in EU grids. Currently, Hamburg is proving that Hydrogen-based storage of excess energy, also called power-to-gas, is a smart choice, through the example of ''Power to gas for Hamburg'' project*. Another possibility is to use hydrogen as a heating fuel in our homes and buildings, either blended with natural gas or by itself.
It is the flexibility that hydrogen offers that makes it so potentially useful within future low-carbon energy systems. It can be produced from a wide variety of resources and can be used in a wide range of applications. In addition, hydrogen is already used extensively in the chemical industry so industry is familiar with its production, handling and distribution on a large scale. For all these reasons, many experts see hydrogen as a key enabler of the lowest-cost low-carbon energy system.
HYDROGEN IN A FEW WORDS
- The lightest gas on earth. Colourless, odourless and non-poisonous
- During generation of electricity, hydrogen binds with oxygen to form water. Therefore, there are no CO2 emissions
- In contrast to CO2, hydrogen does not adsorb infrared radiation, which means it does not have any effect on global warming
- Is liquefied at approx. -253°C
The Mirai: The innovative eco-car that is convenient and easy to use
- An up-to-date, high-value eco-car
- A Fuel Cell Vehicle (FCV) that uses the Toyota Fuel Cell System (TFCS)
- More energy efficient than internal combustion engines
- Ample cruising range and short refuelling time
- Emits only water
- Innovative design
- Packed with comfort features
The Mirai is positioned as the most up-to-date, high-value eco-car in the world today. It is free from any sense of inconvenience. Its ease of use is comparable to any conventionally powered vehicle. A driving range comparable to that of gasoline vehicles is possible with a short refuelling time of about 3-5 minutes.
The Mirai offers the kind of exceptional value drivers would expect from a next-generation car: distinctive exterior design, excellent acceleration performance and unmatched quietness thanks to motor propulsion at all speeds, in addition to enhanced driving pleasure due to a low centre of gravity and outstanding handling stability.
The new Toyota Mirai signals the start of a new age of vehicles. It's a Fuel Cell Vehicle (FCV). An FCV is a vehicle that takes in hydrogen and oxygen into its Fuel Cell Stack (FC stack) to generate electricity that is used to run the motor and produce driving power for the vehicle. Using hydrogen — an important future energy source — as fuel to generate electricity, the Mirai achieves superior environmental performance with the convenience and driving pleasure expected of any car.
The Mirai uses the Toyota Fuel Cell System (TFCS), which features both fuel cell technology and hybrid technology, and includes Toyota's new proprietary FC stack and high-pressure hydrogen tanks.
The FC stack can be described as a small power generation station. It differs from a regular dry cell in that it generates the electricity by the chemical reaction between hydrogen and oxygen. It can continue to produce electricity without loss of power, as long as oxygen and the hydrogen fuel are continuously supplied. The FC stack performs the role of the engine in a hybrid vehicle. Both a hybrid vehicle engine and the FC stack of an FCV are devices that produce energy by the intake of ''fuel'', even if a Fuel Cell does not burn it. The efficiency of the conversion from fuel to energy is double that of gasoline vehicles.
The Mirai delivers everything expected of a next-generation car: a recognisable and highly innovative design driving exhilaration stemming from superior handling stability achieved by a low centre of gravity quiet but powerful acceleration provided by the electric motor and comes packed with comfort features. It is a quiet car, with few vibrations, and can reach a maximum speed of 178 km/h.
A closer look at the Mirai
Ultimate driving pleasure and comfort
- Powerful and smooth acceleration
- Unmatched quietness
- Outstanding stability, controllability and ride comfort
With the Mirai, there's absolutely no compromise when it comes to driving pleasure and comfort. An unprecedentedly smooth, gliding drive feel goes hand in hand with a high level of cornering performance on winding roads.
Powerful and smooth acceleration
High FC stack output and battery power assist is transformed into drive power by the motor. The maximum torque is provided imme-diately at the first press of the accelerator, and powerful and smooth acceleration achieves comfortable and steadily increasing driving performance. Superior acceleration offers standing start acceleration (from 0 to 100 km/h) of 9.6 seconds.
Besides being free from engine vibration or noise, outstanding quietness is achieved by full sealing of all body parts and the use of sound-absorbing and sound-insulating materials, optimally placed around the cabin. Other measures for improving quietness include:
- Acoustic glass is used for the windshield glass and front and rear door windows.
- Foam type sound-insulating materials are optimally placed inside body frames.
- Sound-absorbing materials are used around the engine hood and fender.
- Optimally placed outer mirrors and optimally shaped front pillar help reduce wind noise.
Outstanding stability, controllability and ride comfort
The Mirai has a low centre of gravity. Its FC stack, hydrogen tanks and other power unit components are placed under the vehicle floor. The low centre of gravity ensures superior handling stability and produces a comfortable driving experience by reducing changes in vehicle position.
By locating the FC stack, hydrogen tank and other parts at the centre of the vehicle, front-rear weight distribution is ensured to produce a midship feel. As a result, agile cornering performance and appealing handling lets drivers enjoy driving the car as intended.
A number of features contribute to the Mirai's high-rigidity body. Enhanced rigidity around the suspension achieves outstanding stability and controllability. Both high rigidity and light weight are achieved by using aluminium and ultra-high strength sheet steel for the engine hood and body structural parts. This ensures rear wheel grip feel, steering wheel response and superior stability and controllability.
Aerodynamics is up there with the best. Since the vehicle does not emit heated gases, the floor was able to be fully covered. Air resistance is reduced to boost fuel efficiency. The design of the clearance lamps contributes to the aerodynamics, while aero stabilising fins are positioned on the side of the rear combination lamps.
MacPherson strut suspension is mounted at the front of the car while torsion beam suspension is mounted at the rear. Both the front and rear suspensions have been tuned to help achieve superb handling stability and smooth ride comfort.
But that's not all. Other details have been tailored to ensure driving pleasure and comfort. One of these is "Br mode", which is equivalent to engine braking on an ICE vehicle. In this mode, regenerative braking is most effective and slightly stronger deceleration can be obtained when the driver wishes to reduce speed, such as when negotiating long downhill sections of road.
FCVs of course do not have a conventionally sounding engine, so to further heighten driving pleasure, the operation sound of a tuned air compressor reinforces the feeling of acceleration. Likewise, a sense of security is instilled in the driver's mind thanks to a deceleration sound that is emitted so that the driver can sense the feeling of deceleration such as in engine braking.
Finally, the Mirai comes with two selectable drive modes. The ECO mode switches the powertrain to control the priority given to fuel consumption, while POWER mode changes the characteristics of the powertrain for a sharper response to accelerator pedal input.
An eco-car experience
in a practical package
- Good visibility
- Optimum driving position
- Wide, easily accessible trunk storage space
- Functional, easy-to-use storage spaces
The Mirai is an eco-car experience in a practical package that is achieved by placing the FC stack and other power unit components under the vehicle floor.
A number of features contribute to good visibility. Thin wiper blades are used that do not obstruct the driver's view. Consideration is also given to wiper mounting positions. Excellent forward visibility is afforded by an optimised pillar shape and outer mirror attached to the door panel. By adopting a frameless automatic anti-glare inner mirror, the mirror unit has been made smaller while the mirror surface has been enlarged, ensuring rearward visibility.
Customer-fitted driving position is a key priority. Power tilt and telescopic steering, 8-way adjustable power seats and a motorised lumbar support function are used on both the driver's and passenger's seats. Also provided is a memory function that can store and reproduce the driving positions (steering, seat, outer mirror) for two people.
A power easy-access system on the driver's seat enhances driver's seat accessibility. When entering and exiting the vehicle, the driver's seat automatically slides back in unison with the steering wheel's auto tilt away and return function. The result is smooth entry/exit.
The cleverly designed battery layout achieves a wide, easily accessible trunk storage space of 361 litres (VDA standard).
The Mirai is packed with functional, easy-to-use storage spaces. These include a centre console box, which turns into an armrest (with slide function) when closed front door pockets capable of holding a 500 ml plastic bottle or A4-size documents horizontally an overhead console for storing small items seatback pockets on the back of the driver's and front passenger's seats a push-open sliding cup holder between the rear seats and a rear seat console box underneath the armrest. Other storage space includes a cup holder in the front, rear door pockets, and a glove box.
Advanced exterior design
- "Air to water" side profile
- Bold side grille design
- Innovative headlamps
- Aluminium wheels
The advanced exterior and interior design of the Mirai will capture early adopters. It comes with a next-generation exterior that leaves the impression of future mobility, while its sophisticated interior embodies a look of "immediately distinguishable new value" appropriate for such a leading edge vehicle.
The car's front view clearly expresses state-of-the-art technology. Its front face underscores the originality of FCVs, and a bold and clear three-dimensional structure brings out the grilles on the left and right to their maximum. These are also functional, as they have been designed to ensure maximum air intake.
The Mirai's stand-out "air to water" side profile expresses the uniqueness of FCVs by symbolising the flowing shape of a droplet of water. Its rear view achieves both a powerful stance and clean impression, thanks to a bold shape and wide bumper top. The result gives an agile and clean impression of air passing through and under the bumper.
The bold side grille design expresses the vehicle's technology of drawing in air and generating water. The side grilles are emphasised by metallic plating and side bars to create an original front view. The rear bumper shape leaves a strong impression of the rear view. An innovatively designed red inverted triangular fog lamp and fin-shaped spoiler combine to make the unique shape of the bumper stand out.
Toyota's RandD engineers have been busy in the structure and design of the Mirai's innovative headlamps. The front turn signal lamps and clearance lamps are separate from the headlamps, and are designed to merge with the side grilles. The headlamps exhibit high-tech and sophisticated luxury through a novel design that presents an ultra-thin profile with an inline arrangement of four LED lights plus visible heat sinks and other optical equipment.
The power retracted, remote controlled, coloured outer mirror is equipped with a high visibility LED side turn signal lamp and an effective rain clearing function. The auto-retract function is handy for parking.
The Mirai's 17-inch aluminium wheels have been made lighter by a Toyota-first engraving process. This manufacturing process (metal is shaved from the intersecting line between the disk and the rim) reduces the weight of each aluminium wheel by approximately 500 grams.
Sophisticated interior design
- Innovative interior design
- Solid quality feel and soft touch materials
- Centre combination meter cluster
- Multi-information display
- Capacitive air conditioning and seat heating control panel
- High-quality comfort
- "Form In Place Method"
As with the exterior, the interior design of the Mirai subtly shouts innovation and value, and will attract the attention of early technology adopters.
A feature of the Mirai's innovative interior design is its seamlessly flowing cabin space, created by the shape continuing from the combination meter hood to the front pillar and rear window. The structure that is enveloped by the slim centre panel from upper and lower parts makes the innovation of the overall interior stand out.
The contrast between the solid quality feel and soft touch materials has been accented by high-brightness silver ornamentations throughout the interior and the use of soft-to-the-touch pads in door trim, instrument panel, centre console, and other parts. A refined interior has been achieved through the sophisticated harmony between contrasting combinations. Glossy, geometric switch panels and pull handles with a firm grip contrast with the clean, solid jet-black of the centre console panel.
The cockpit is surrounded by advanced devices that allow the driver to feel future mobility. The centre combination meter cluster is designed to appear to be raised, expressing innovation. By locating the centre combination meter cluster at the top centre of the instrument panel, information can be read effortlessly without diverting the driver's gaze considerably from the road ahead.
A 4.2-inch high-definition TFT liquid crystal display is used for the speedometer and multi-information display. It features large, easy-to-understand indications of a wide range of information clearly visible on the colour screen. The information to display is selected from six tabs (drive information / navigation system link / audio link / driving system operation support / warning messages / settings).
The speedometer features a large, easy-to-view vehicle speed display. Two screen modes can be set: a split mode that displays a sub-screen, and a standard mode. Pressing the 4-direction switch on the steering wheel displays the FC system indicators in the split screen.
The capacitive air conditioning and seat heating control panel is reminiscent of tablet-like digital devices. Operations can be performed by lightly touching the screen. Also provided are capacitive temperature adjustment switches that allow the temperature to be easily set simply by sliding switches up and down with your fingertip. LED-lit lettering and switches are illuminated in white during the daytime and clear blue at night. The display indicates set temperature, air volume and other information in the centre of the air conditioning control panel.
Everyone riding in the vehicle can experience high-quality comfort. The refined cabin fuses premium with modern. Seats are designed in modern art-like shapes that embody the comfort and functionality of a luxury vehicle. Detailed attention has been paid to the level of ride comfort and sitting comfort to achieve body fit and hold that is less likely to cause fatigue, even on long drives.
Beautiful design, body fit and ride comfort is achieved by a "Form In Place Method". This refers to the process of injecting urethane raw materials into a seat cover, which is pre-loaded into a mould, and causing it to foam to take its final form. This is in contrast to conventional methods where moulded pads are covered. Form In Place allows seats to be formed faithfully to the design, and the ideal concave cross-sectional shape wraps the entire body to achieve a superior body fit and hold.
Eight-way adjustable power seats for achieving the optimal seat position and a motorised lumbar support function are installed as standard on the driver's and passenger's seats. Two-stage temperature adjustable seat heaters are provided as standard on all of the Mirai's seats. Soft materials have been added to pad surfaces or seat backs and cushions. A pleasant level of comfort while seated with a high degree of body fit is achieved by forming seat cushions to conform to the shape of the hip.
A high quality feel and aesthetic sense is pursued right down to the details. Soft pads on the meter hood, instrument panel, console, door trim and door armrest achieve a pleasant tactile sensation.
Outstanding cold start performance
- Improved power generating performance immediately after starting below freezing point
- Improved warming up performance
One of the drawbacks associated with cars powered by hydrogen is that maintaining good power generation from a fuel cell requires water — and in environments where the temperature regularly drops below freezing point, excess water freezes. This impedes the flow of air (oxygen) and hydrogen and causes a decrease in power generation performance.
Toyota has addressed this challenge by ensuring that it is possible to start the Mirai at -30°C and to achieve output at levels satisfactory for practical use immediately after starting. This was done in two ways:
1) Improved power generating performance immediately after starting below freezing point:
&bull Higher cell flow channel and electrode performance: Exclusion of generated water and air diffusion were improved.
&bull Establishment of intra-cell water content control technology: The content of water is measured and controlled at a level suitable for power generating performance below freezing point.
2) Improved warming up performance:
&bull Lower thermal capacity as a result of higher fuel cell stack output density.
&bull Establishment of fuel cell rapid warm-up control technology: Heat generated by the fuel cell is controlled to drastically reduce warm-up time.
The Mirai has been extensively tested in extremely cold conditions in Alaska, Canada, Finland and Northern Japan. Fuel cell stack output performance was evaluated after starting the car after it had been parked outdoors overnight for 17 hours at temperatures as low as -30°C. 100% power output was obtained 70 seconds after starting.
Active safety, passive safety, and comfort features
- State of the art safety
- Comfort features:
- ECO HEAT/COOL mode switch
- Automatically retractable outer mirrors
- Handy smartphone charging area
- Steering wheel and seat heaters
- Top-of-the-range audio equipment
The Mirai's safety equipment is the one we expect from for the very latest eco-car.
The Mirai incorporates a Pre-Collision System with superior performance. The system detects a vehicle ahead or obstacles on the same route by means of a millimetre wave radar and helps prevent collisions through alerts and brake control, if it is judged that there is a high possibility of collision.
If the driver depresses the brake pedal after an alert, the pre-collision system powerfully aids braking power. Even if the driver has not depressed the brake pedal, the pre-collision brake is activated and the car brakes autonomously, reducing the speed by up to 30 km/h to prevent collision or reduce damage and possible injuries.
The Blind Spot Monitor (BSM) is useful to check behind the vehicle. It detects vehicles running in adjacent lanes. When the vehicle enters a blind spot area that cannot be viewed from the outer mirror, the LED indicator mounted on the outer mirror is illuminated. At this time, the side-turn signal lamp is made to blink and the LED indicator also blinks to call the driver's attention.
The car is equipped with the Rear Cross Traffic Alert (RCTA) function. When starting out in reverse, vehicles travelling behind are detected by radar. Like BSM, an LED indicator blinks and a buzzer sounds to warn the driver's attention.
An additional active feature is Lane Departure Alert (LDA) which warns of unintended departure from lane. The white/yellow lines on the road are recognised by a camera. When the vehicle might deviate from the lane without the driver performing a turn signal operation, the driver is alerted to this by the sounding of a buzzer and an indication on the display.
Drive-start Control reduces damage of sudden start accidents during gear-shift operation and reversing. For example, after a collision when in reverse, the driver might hurriedly move the shift lever from R to D while the accelerator pedal is still depressed. At this time, the driver is warned by an indication on the display, and motor output is suppressed to limit sudden starting off or sudden acceleration.
Automatic High Beam automatically switches between low and high beam. During night-time driving, the sensor of the cabin camera detects the brightness of the surrounding area and automatically switches between high beam and low beam to assist the driver's forward visibility. When lights from vehicles ahead, oncoming vehicles or street lights are detected, the headlamps are automatically returned to low beam. This prevents the driver from forgetting to operate the headlamps and reduces the inconvenience of manual operations. This function can also be turned off by operating the switch.
Other preventive safety functions are:
- Adaptive Cruise Control.
- Vehicle Stability Control (VSC) and Traction Control (TRC).
- Anti-lock Braking System (ABS) with Electronic Brake-force Distribution (EBD).
- Hill start assist control.
- Emergency brake signal.
- Automatic anti-glare inner mirror.
- Parking assist sensor system.
- Rear view monitor system.
A total of eight Supplemental Restraint System (SRS) airbags are equipped as standard:
- Dual-stage SRS airbags (driver's seat, passenger's seat).
- SRS knee airbag (driver's seat).
- SRS seat cushion airbag (passenger's seat).
- SRS side airbags (driver's seat, passenger's seat).
- SRS curtain shield airbags (front and rear seats).
The car body is designed to reduce pedestrian injuries in the event of an accident. Impact absorbing structures are used for parts such as the engine hood and cowl to reduce and absorb impact to pedestrians' heads and other parts of the body.
Other impact safety functions include a 3-point seat belt with pre-tensioner and force limiter on all seats, and a general-purpose ISOFIX compatible child seat securing bar and a top tether anchor bar for the rear seat.
The Mirai is equipped with comfort items for improving user's comfort.
The ECO heat/cool mode switch enables fully automatic left and right independent temperature control air conditioning. The set temperature can be changed smoothly by sliding the metal switches on the driver's or passenger's seat.. An ECO mode switch exclusively for air conditioning is provided to prioritise fuel economy by controlling air conditioning performance without any change to driving feel. The ECO mode is operated by turning the switch on and off or by holding it down. In ECO HI mode, air conditioning control is performed with even higher priority given to fuel economy than in ECO mode.
Especially handy in parking lots are the automatically retractable outer mirrors, which are retracted and returned interlocked when locking and unlocking the doors.
Smartphones that are compatible with the Qi wireless charging standard or have Qi compatible accessories can be charged simply by placing them in the handy smartphone charging area provided in the centre console box.
Steering wheel and seat heaters on all seats provide instant heat while greatly reducing power consumption. This comfort equipment affects fuel consumption and cruising range less than even air conditioning and allows drivers and passengers to feel warmth immediately. The steering wheel heater warms the steering wheel once the switch is turned on and is automatically turned off after about 30 minutes. Two temperature settings (Hi/Lo) are used on the seat heaters for all seats.
Top-of-the-range audio equipment in the Mirai includes a display system with a 7-inch VGA TFT display as standard. It incorporates AM/FM radio, CD, Bluetooth, navigation system and DAB. The car is equipped with a JBL® premium sound system featuring 11 speakers, and USB and AUX terminals are provided as standard in the centre console box.
Other comfort features include Smart Entry & Start System theft prevention systems (immobilizer system + automatic alarm) rain sensing front wiper and an accessory power outlet socket (12 V DC).
How the world-leading TFCS works
- TFCS (Toyota Fuel Cell System) combines Hybrid and FC technologies developed by Toyota over many years
- Two energy sources — FC stack and battery — are optimally selected to drive the motor
- How the FC stack generates power
TFCS combines Hybrid and FC technologies developed by Toyota over many years
The Toyota Fuel Cell System (TFCS) adopts the latest compact, high-performance FC stack.
The Mirai was developed around Toyota's long-cultivated core technologies of energy recovery during braking, and high-performance, high-efficiency hybrid technology to assist during engine starting and acceleration. Two energy sources, FC stack and battery, are adequately selected to drive the motor to achieve more environmentally friendly and powerful running.
Two energy sources — FC stack and battery — are smartly selected to drive the motor
The Mirai is a hybrid that combines an FC stack with a battery. Hybrid originally means a combination of two different types. Generally, a hybrid car refers to a vehicle that runs efficiently by a combination of two drive sources: an engine and a motor. An FCV such as the Mirai differs slightly from general hybrid vehicles in that it is a hybrid that uses a combination of an FC stack and a battery as the energy sources to be transmitted to the motor. The battery provides power support during acceleration as it does for other hybrid technologies used to achieve more powerful and efficient running.
How the FC stack generates power
The smallest unit of a fuel cell (a cell) is comprised of an electrolyte membrane, a pair of electrodes (negative and positive) and two separators. Though each cell has a small voltage of 1 V or less, large power output for running a vehicle can be obtained by connecting a few hundred cells in series to increase the voltage. These cells combined together are called an FC stack, and this FC stack is usually what is referred to when talking about fuel cells.
In a fuel cell, electricity is made from hydrogen and oxygen. Hydrogen is supplied to the negative electrode, where it is activated on the catalyst causing electrons to be released. The electrons freed from the hydrogen move from the negative electrodes to the positive electrodes, generating electricity. The hydrogen which releases electrons convert to hydrogen ions that move to the positive side while passing through the polymer electrolyte membrane. At the positive electrode catalyst, oxygen, hydrogen ions and electrons combine to form water.
Safety: The car, the refuelling process and the gas
- The car: Tough fuel tanks and highly sensitive hydrogen sensors
- The refuelling process: International safety standards in place
- The gas: Using the lightest element in the universe has its benefits
Over the last decade, hundreds of FCV test cars have been thoroughly road tested, and safety tested. They have racked up millions of kilometres over all sorts of demanding terrains. They have been put through their paces in the cold of northern Finland and the heat of southern Spain. Their hydrogen fuel tanks have even been shot at by high-velocity weapons. The result is that the Mirai has passed all the tests with flying colours. It's as safe as any other Toyota vehicle. The fact that it is powered by hydrogen has absolutely no effect on its inherent safety. Three aspects of the Mirai that relate to safety are the car, the refuelling process, and the gas itself.
The car: Tough fuel tanks and highly sensitive hydrogen sensors
The hydrogen that powers the Mirai is stored at a high pressure of 700 bar in two compact, ultra-resistant tanks. Toyota has been working on their design in-house since 2000 and are more than satisfied with their strength and safety levels.
Their main source of strength originates from the carbon fibre shell. Over that is a glass fibre layer. Should the car be involved in an accident, any resulting damage to the hydrogen tank will be clearly visible on this layer. Tests can then be carried out to evaluate if the carbon shell itself is compromised. The glass fibre does not contribute to rigidity of the tank, but gives absolute confidence of its integrity. The whole tank is lined with plastic to seal in the hydrogen.
As mentioned above, the tanks have been subjected to extremely severe testing. They are designed to withstand up to 225% (GTR standard*) of their operating pressure, which is clearly a very comfortable safety margin.
In the improbable event of a leak, the Mirai contains highly sensitive sensors that detect minute amounts of hydrogen. These are placed in strategic locations for instantaneous detection of hydrogen. In the extremely unlikely event of a leak in the fuel system, the sensors immediately shut down the safety valves and the vehicle itself.
As a third layer of safety, the cabin is strictly separated from the hydrogen compartment to prevent penetration of any leaking hydrogen, which would instead gradually disperse into the atmosphere.
The refuelling process: International safety standards in place
Refuelling is a critical process because it involves human action, which unfortunately can lead to unforeseen and unsafe scenarios, like trying to drive off while the fuel nozzle is still connected to the car. For this reason a number of safety precautions have been put in place.
First, the nozzle at the end of the hydrogen dispenser's flexible hose contains a mechanical lock to ensure optimal connection with the car's filling inlet. Unless this mechanical lock clicks into place securely, filling will not commence.
Secondly, a pressure impulse checks for any leakage in the system between the filling station and the car. If a leak is detected, refuelling is aborted.
Thirdly, the rate of filling is carefully regulated, to avoid overheating during transfer. Temperature sensors located in the car's hydrogen tanks, the nozzle and the pump constantly communicate with each other by infrared to control the rate of flow of hydrogen into the car so that the temperature rise is not excessive. Probably the smartest refuelling that any driver's ever experienced.
The internationally applicable standards SAE J2601, SAE J2799 and ISO 17268 establish safety limits and performance requirements for gaseous hydrogen fuel dispensers. The criteria include maximum fuel temperature at the dispenser nozzle, the maximum fuel flow rate and the maximum rate of pressure increase.
Should a driver attempt to drive off in a Mirai while the fuel nozzle is attached to the car, they will not succeed. The car's ignition is disconnected until the nozzle has been replaced in its holster and the car's fuel cap is closed. To be absolutely sure, a redundant safety system is embedded in the hose and locks the pump if a car would pull the hose too hard when driving off in the middle of refuelling.
The gas: Using the lightest element in the universe has its benefits
Hydrogen gas is the lightest thing known to man and considerably (14x) lighter than air. The consequence is that should a leak occur, the hydrogen will rise into the atmosphere. And thanks to its status as smallest molecule in the universe, it disperses quickly in air and any gas.
Finally, the Mirai's tanks have a pressure relief device that releases the hydrogen gradually in case the temperature should rise abnormally (like in a fire). This prevents any overpressure or explosion far from the stereotype of a hydrogen explosion. Moreover, the resulting fire leaves much of the car undamaged.
Summary of safety aspects
Hydrogen is as safe as any other fuel used in a car. It's been used as an energy carrier for decades, and there is a vast amount of cumulative know-how and experience in Toyota and elsewhere to handle it safely. Furthermore, it is a carbon-free, non-hazardous energy source that can be produced from many renewable resources and emits no greenhouse gases when used as a fuel.
Environmental considerations: From production to disposal
- Vehicle production
- Hydrogen production
By generating only water as a by-product during the driving phase, the Mirai significantly reduces the overall impact of a car on the environment. Depending on the way hydrogen is produced, an overall CO2 reduction of 40-70% can be achieved compared with a conventionally petrol powered vehicle. In future, when hydrogen will be massively produced by renewable energy, the CO2 emissions from well to wheel will be even more drastically reduced, bringing us close to our ultimate goal of zero emissions.
The Mirai is being manufactured at a sustainable Toyota plant which aims to fully utilise natural resources while operating in harmony with the natural environment. There are three aspects to this approach:
- Effective energy generation, through the utilisation of exhaust heat from the plant or renewable energy such as solar.
- Elimination of energy waste: development and introduction of low CO2-emitting production technologies and step by step improvements.
- Community involvement and ecosystem conservation: tree planting activities in the grounds of the plant.
Hydrogen can be produced from various primary energies, depending on the most suitable method for each country. It can also play a major role in the spread of renewable energy. Solar and wind power are intermittent sources, resulting in unstable generation, which requires an adequate storage system. However, one way to store these renewable energies is to convert them to hydrogen, which is more appropriate than batteries for large storage, thanks to a higher energy density. The society of the future must utilise renewable energy, and smartly integrate the electricity grid with the hydrogen grid for effective use.
Resource efficiency plays an important role at Toyota. The recoverability rate of the Mirai exceeds 95%. As the Mirai's fuel cell stack uses the precious metal platinum, Toyota created the world's first stack collection and recycling network.
Especially for the industrial battery, Toyota in Europe has set itself the challenging target of aiming to collect 100% of the batteries. In 2010, Toyota succeeded to establish the world's first battery to battery recycling operation in Japan. Furthermore, as of 2013, batteries are reused in stationary energy storage applications. Realising that our raw materials are finite, Toyota is continuously stepping forward to a resource efficient economy.