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Honda’s FCX Concept will be on display
at the Tokyo Motor Show this week, and in order to inform, educate and
dispel some of the myths associated with hydrogen fuel, we’ve put
together the following fact sheet, which compares just two ways in which
hydrogen can be employed.
Hydrogen will fuel the
next generation of global vehicles. It’s a fact accepted by the entire
industry. And given that it’s the most commonly-occurring element in the
universe, supply is not an issue.
A future of cars powered by hydrogen is
an exciting prospect to consider. Not only can hydrogen help cars to
emit zero CO2 emissions, but the development of technology to
use the fuel promises to change the ways cars are designed, built and
run forever.
However, there are different ways of
using hydrogen as a fuel for a car. For example, it can be burned within
an internal combustion engine or it can be used in a fuel cell to
produce electricity to power a motor.
But while the initial fuel is the same,
the way that the fuel is used, the technologies employed to use the fuel
– and not least the benefits and disadvantages of the ways in which it’s
used – are totally different.
We hope our fact sheet proves useful
and clears some of the fog surrounding the issue.
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Hydrogen-fuelled fuel cell technology (as used by Honda FCX
Concept) |
Hydrogen-fuelled internal combustion engine (as used by BMW
Hydrogen 7) |
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Concept |
Honda’s V-Flow FC Stack combines hydrogen fuel with oxygen to
create electricity via a chemical reaction. This powers an
electric motor, that delivers drive to the car’s wheels |
Hydrogen fuel is burned in an internal combustion engine, which
creates power to drive the car. It’s a tried and tested
technology that’s been around for 100 years. We know it works |
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Fuel |
Uses
only hydrogen as fuel |
The
BMW H7 can switch between petrol and hydrogen fuel – but that
means it is impossible to optimise the engine for petrol or
hydrogen, so therefore the engine is never working at its
optimum. Also it can run solely on petrol – meaning the user can
run the car on petrol the entire time (with CO2
levels of up to 327g/km) |
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Reliability |
Relies on a chemical reaction, not moving parts – but technology
is new and further testing needs to be carried out |
Continues to use moving parts, but technology is proven |
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Emissions |
A
true zero harmful emissions vehicle (only water vapour is
emitted from the exhaust) |
Zero
CO2 emissions, but emits nitrogen oxides (NOx) –
albeit low levels) – created by the hydrogen and air mix burned
in the engine |
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Storage |
Hydrogen stored as a compressed gas (at 35 MPa in a 171 litre
tank) |
Hydrogen stored in liquid form stored at -253 Celsius |
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Storage qualities |
The
drawback of compressed gas is that energy is used in the
compressing of the gas, and in-car storage tanks have to be
fairly large in order to carry sufficient amounts of hydrogen |
Liquid hydrogen is highly energy intensive as it has to be
cooled down to -253 Celsius and therefore it has some storage
problems. For example, if left for a period of time without
using the car (currently estimated to be 9-14 days), ‘boil off’
takes place, meaning the liquid hydrogen warms up, is vaporised
and escapes from the tank. As well as draining the fuel, this
also means the car cannot be stored in a contained area for any
length of time |
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Efficiency |
When
employed as part of a car’s powertrain, fuel cell technology is
incredibly efficient at using energy. The V-Flow FC Stack in the
Honda FCX Concept is 60 per cent efficient at using the energy
value of its hydrogen fuel. To put that into perspective, a
petrol-fuelled hybrid is 28 per cent efficient, while a petrol
internal combustion engine is just 18 per cent efficient at
using the fuel (all when measured on the LA4 cycle) |
Not
nearly as efficient as a fuel cell, but we do not have the exact
data to provide an exact comparison. It is likely that a
hydrogen internal combustion engine is half as efficient as a
fuel cell, but that cannot be proven at this time |
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Range |
Due
to their excellent efficiency, fuel cells generally have a
longer range. Honda’s FCX Concept has a range of 354 miles with
a full tank. With only half of the amount of hydrogen that can
be carried by the BMW Hydrogen 7, the FCX can travel 250 miles |
The
range of the BMW’s hydrogen tank is 125 miles |
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Technology |
Totally new way of powering a vehicle with innovative technology
– the ultimate alternative fuel solution |
An
evolution of the combustion engine |
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Design |
Could
revolutionise the car design industry: fuel cell cars do not
have to accommodate a sizeable and heavy combustion engine, and
the associated cooling components. Plus, the FC Stack can be
housed anywhere in the vehicle, allowing for a better centre of
gravity and improved weight distribution |
Based
on existing car design |
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Infrastructure |
Requires development of a new hydrogen refuelling infrastructure |
Circumvents the problems of lack of infrastructure (as the
internal combustion engine can run on petrol – but of course
environmental benefits are lost) |
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Safety |
Honda’s FCX cars are in commercial use in America and Japan,
which means they have to go through the same stringent crash and
safety tests as any other vehicle. As well as protecting
occupants from front, side and rear impact, the FCX also
features special impact-absorbing framework around the fuel cell
system and high-pressure hydrogen tanks, to shield them during a
collision |
Should still meet current safety/crash test regulations, as
hydrogen is stored within tanks in existing car design |
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Timing |
FCX
to be launched as production vehicle in US and Japan during 2008 |
There
are cars in limited production, with fleets of test cars being
used to raise awareness |
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