Saturday, November 22, 2014
BBN AUTO! The Future is here: Toyota to launch hydrogen-powered car
-Jahmiu Tewogbade Add BBN on 2BAFB965
Toyota will launch its
all-new Mirai hydrogen fuel cell vehicle in Japan on 15 December before
introducing it in the UK and other selected European markets in September 2015,
with that date dictated by getting a refueling infrastructure rolled out.
Fuel cells, which
produce electricity directly as they combine fuel with oxygen (as opposed to
producing mechanical power from heat which is then turned into 'leccy by a
generator) have been the power of the future for nearly 100 years, and even
provided some fizzy drinking water as a by-product of powering the Apollo
landers (the Space Shuttles also used fuel cell exhaust as drinking water).
Mirai uses the Toyota
Fuel Cell System (TFCS), which brings together fuel cell and hybrid
technologies. It includes Toyota’s new, proprietary fuel cell stack and
high-pressure hydrogen tanks. Toyota claims this is more energy efficient than
internal combustion engines and emits no CO2 or pollutants when
the vehicle is driven. That is Toyota dodging the issue of where the
hydrogen comes from – it is normally made industrially from natural gas, which
involves considerable carbon emissions, though Toyota prefers to speak of
getting it from sewage* – and what is needed to pressurize it. Fuel cells
combine the hydrogen with oxygen, hence the gaping vents in the front for
breathing and cooling.
Toyota points out that
there are distinct advantages over other forms of electric power as the system
has a range of 300 miles and a hydrogen refueling time of around three minutes.
But with a top speed of just 111mph and a 0-62 time of 9.6 seconds, it’s way
behind a Tesla S, let alone a Tesla D. This is clearly not helped by the Mirai
having a kerb weight of 1,850kg.
The limiting factor on
performance is the maximum power output and for the stack in the Mirari that’s
153bhp (114kW) at 650 volts. Toyota is proud of this as it has been improved by
using 3D fine mesh flow channels which ensure uniform generation on the cell
surfaces.
The
amount of water on the fuel cell electrolyte membranes has a substantial
influence on electricity generation efficiency. The amount of water is
controlled using an internal circulation system to carry water produced in the
electricity generation process. This makes the Toyota FC Stack a world-leading
system that, unlike those used in all other previous Toyota fuel cell vehicles,
doesn’t require a humidifier.
Filling a car with
something as explosive as petrol is pretty dangerous, but pressurized, to
700bar, hydrogen poses an additional level of risk so the car has two carbon
fiber-reinforced plastic tanks well inside the wheelbase and mounted low.
There are leak detection
and stoppage systems, and tanks and other hydrogen-related parts are all
outside the cabin, so that if there is a leak, the hydrogen will disperse
easily. Putting major parts such as the FC stack and high-pressure hydrogen
tanks centrally beneath the vehicle floor gives improved handling stability and
ride comfort, as well as a low center of gravity and good front/rear weight
distribution.
A pre-collision system
with millimeter-wave radar could help prevent collisions, or reduce damage in
an impact by triggering driver alerts and (if a high collision risk is
detected) brake control.
An
interesting design feature is to make the heat sinks for the LED headlights
visible. Mirai runs on 17-inch aluminum wheels which have been made lighter by
the use of an engraving process. This manufacturing process to reduce the
weight of aluminum wheels involves shaving metal from the intersecting line
between the disc and rim. This reduces individual wheel weight by approximately
500g
BBNA learnt that Toyota Mirai is released only in Japan ... for now.
Culled from The Register
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