Trailblazing new power plant explained
The Toyota Mirai is a hydrogen-powered saloon which is coming to the UK in September 2015.
It looks futuristic, and could prove to be a trailblazer that signals a revolution in motoring.
The Mirai stores hydrogen – rather than petrol or diesel – in a high pressure tank.
This is transferred to a fuel stack where it is mixed with oxygen.
The resulting chemical reaction produces electricity for an electric motor that powers the wheels and secondary systems.
The benefit over a petrol or diesel powered vehicle is that there are no tailpipe carbon emissions to pollute the environment. The only output is water vapour and heat.
Furthermore, a hydrogen vehicle is more capable than an electric.
Electric cars have a limited range compared to their traditional alternatives and take hours to fully charge.
The Mirai, in contrast, travels up to 300 miles on a single tank and be refuelled in minutes.
The Mirai fuel stack produces 153bhp.
Its efficiency has been optimised using “3D fine mesh flow channels”. These – via a three-dimensional lattice structure - enhance the dispersion of air to enable “uniform generation of electricity on cell surfaces”.
The result is a unit that is physically compact and 2.2 times more efficient than its predecessor.
The tank is built from a three-layer carbon-fibre reinforced plastic.
This ensures it is strong enough to withstand the extreme pressure that hits 700bar.
Should it be compromised in a collision, valves close automatically and the motorist is warned. It is positioned outside the cabin to enable hydrogen to escape into the atmosphere (rather than into the cabin).
The Mirai incorporates other safety features too. Highlights include the pre-collision system that scans the road ahead and warns the motorist via a beep that an impact is likely.
The scenario might be that he/she has not noticed the car ahead slowing. If the driver fails to react to the warning, it brakes to avoid the impact or mitigate its severity.
The Mirai also scans lane markings and warns the motorist when it deviates from the optimum route.
This complements the blind spot monitor that reveals – via lights within the wing mirrors – when a following vehicle is hidden from view by one of the rear pillars.