BMW Hydrogen
7: First Look
Motoring Channel Staff - 15/Nov/2006 | 
2007 BMW Hydrogen 7
The BMW Hydrogen 7 has
two tanks, one
for gasoline, the other for liquid hydrogen
The BMW
Hydrogen 7 has a touring range of
about 200km on hydrogen and
500km on petrol
One of the hydrogen
filling stations in Germany
This is the rear-mounted
liquid hydrogen fuel tank
Hydrogen Storage - Is It Safe?What
if a truck smashes into the back of your car, which has highly volatile
compressed hydrogen in its tank - will it explode? No, says
BMW. The BMW Group
has put the Hydrogen 7 through a complete programme of crash tests
going beyond the usual legal requirements. These crash tests include
frontal offset collisions in accordance with EURO NCAP at an impact
speed of 64km/h (40mph), rear-end collisions with 100 and 40 per
cent overlap, as well as side-on collisions at the car's most sensitive
point directly on the fuel filler pipe. BMW
claims to have tested the hydrogen tanks in even more extreme accident
scenarios, where the hydrogen tanks were exposed to flames, firearm
shots and massive mechanical damage. In an additional series of tests,
tanks filled with hydrogen were fully encompassed by flames at a
temperature of more than 1,000 °C (1,830 °F) for up to
70
minutes, and even under such conditions, tank behaviour did not present
any problems, with the hydrogen in the tanks escaping slowly and almost
imperceptibly through the safety valves. Whenever
hydrogen is
able to escape into the air, it rises up quickly to higher levels,
simply because it is 15 times lighter than the ambient air around it.
And while hydrogen is neither irritating nor toxic, says BMW, it is
more easily ignitable than gasoline or diesel as soon as it forms an
appropriate mixture with air. BMW stresses that the most important
point, however, is that hydrogen is absolutely safe as long as its
characteristic features and properties are duly taken into account. As
an example, the liquid hydrogen tank comes not only with a boil-off
management system, but also with two redundant valves monitoring the
contents of the tank in the event of a significant build-up of pressure
– for example as a result of damage to the tank –
and
letting off hydrogen under controlled conditions if necessary. As soon
as the first valve opens up, hydrogen is guided up to the roof of the
car through safety pipes fitted in the C-pillars. The second valve
opening up only under higher pressure allows hydrogen to flow to the
underfloor of the car, where it is also discharged into the
air. -
Motoring Channel Staff |
|
Munich,
Germany — BMW
has just come clean (pardon the pun) with the new Hydrogen 7. It may
look and feel like BMW's large luxury car, known collectively as the 7
Series, but it doesn't sound or smell like one. This
hydrogen-powered 7 Series BMW is virtually emission-free, according to
the German automaker, and sets the company off in a bold new direction,
as it begins the long journey of refining and advancing its hydrogen
fuel ambitions. As the German marque explains, the
BMW Hydrogen 7
is powered by a hydrogen combustion engine that has gone through the
complete process of series development, using hydrogen as a source of
energy, suitable for everyday motoring as of now. The
deployment
of its first fleet of hydrogen-powered 7 Series vehicles indicates that
BMW has managed to elevate hydrogen performance to a commercially
acceptable level, and has given its hydrogen cars to high profile
members of society to test, including politicians and celebrities. While
Lexus has been the only prestige car company to offer next generation
propulsion systems in the form of hybrid (petrol/electric) vehicles,
BMW has decided against following suit, instead opting to develop
a petrol/hydrogen powered combustion engine and
storage unit. Petrol/Hydrogen EngineBMW
says the Hydrogen 7 is a revolutionary development: the engine,
suspension and body of this new model are based on the overall vehicle
concept carried over from the BMW 760i and BMW 760Li Saloons. However,
the Hydrogen 7 features a dual-mode 12-cylinder combustion power unit
able to run on both hydrogen and conventional gasoline. Interestingly,
the vehicle isn't undercooked, with the hydrogen-powered V12 engine
capable of generating 191kW of power (260hp), which is enough
to
accelerate the vehicle from zero to 100 km/h in 9.5 seconds, BMW has
revealed. The top speed of the BMW Hydrogen
7, in turn, is limited electronically to 230km/h (143mph), which should
be enough to please German drivers who frequent the Autobahns found in
the European country. It's
clear that hydrogen (at this early stage in its development) doesn't
quite yield the same power levels of petrol, yet it still offers solid
propulsion. BMW insists that its dual-mode combustion engine exhibits
no delays or changes in driving behaviour when switching between
hydrogen and gasoline fuel types, and early reports from those
who
haven driven the vehicle back up this claim. Though
this current hydrogen engine doesn't have the efficiency or the range
of some of the petrol-electric hybrid engine's on the market today, it
is a start, and BMW says that it will develop an engine that surpasses
this unit's 32kW of power per litre. The German company says it will
build a hydrogen-only engine with up to 95kW of power per litre. Hydrogen
Filling StationsOne
of the problems with such a vehicle is that hydrogen fuel is expensive
(though prices will fall as demand increases), and the refilling
stations are currently quite rare - there will be about 12 of
them worldwide in 2007. These things will be overcome
in time, and to ensure the introduction of a standardised liquid
hydrogen tank
filling system suitable for the automobile, the BMW
Group has established an open consortium in cooperation with General
Motors [Opel] and Honda as well as Linde, which is a major supplier of hydrogen,
and Walther, the manufacturer of the mechanical systems and components
for filling up the hydrogen tank. This
consortium seeks to standardise
the liquid hydrogen tank filling coupling on a worldwide level, and
will probably do so, as it is the largest endeavour of its kind. Filling
up the new BMW Hydrogen 7 has been made fairly straighforward. Lock in
place the fuel nozzle, then push a button in the cabin and the filling
process takes about 8 minutes to fill the tank. Cooled
to a
temperature of approximately -250°C, the cryogenic hydrogen is
able
to precipitate into the hydrogen tank of Hydrogen 7, explains BMW. The
process of filling the tank is co-axial, meaning that liquid hydrogen
is transported in the inner section of the tank hose (made up of two
layers) while gaseous hydrogen which has warmed up is able to return
through the outer layer after being forced out of the tank by the
liquid hydrogen and thus returning to the filler pump through the
co-axial tank coupling. The FutureBy
introducing the world's
first hydrogen-powered luxury saloon for public consumption (albeit in
an evaluation state - as all cars are monitored by BMW, and all owners
must report to BMW for feedback) BMW has attained a milestone
for
the automotive industry, and one that the German luxury car
maker will no doubt be remembered for. Introducing
this
trendsetting innovation in engine technology, BMW says it can
offer a practical and attractive solution for switching over to
hydrogen as the drive energy of the future, setting a milestone en
route to a world of individual mobility independent of fossil fuels and
free of pollutants. Liquid Hydrogen Fuel TankExperts
agree that hydrogen is the only source of energy with the potential in
the long run to replace fossil fuels in road traffic. With its chemical
symbol 'H', hydrogen is one of the components that makes up water and
nearly all organic compounds, meaning that it is part of the biological
cycle and therefore fully compatible with the environment. And as the
most common element in the universe, hydrogen is available for all
practical purposes in virtually unlimited quantities. The biggest
problem that engineers and scientists currently have with hydrogen is
it's storage. As mentioned above, BMW's filling
stations have to lower the temperature of hydrogen (normally a gas at
room temperature) to -253°C
so as to increase its energy density, and the BMW Hydrogen 7 has dual
fuel tanks - for petrol and hydrogen - that impinge on rear seat room
and boot space. But bear in mind this technology is still in its
infancy and will take many decades to refine and improve. Used
as
drive energy, liquid hydrogen
involves a particular technical challenge in the construction of the
tank. Since hydrogen under normal ambient pressure has to be cooled to
-253 °C in order to turn into a liquid, innovative vacuum
super-insulation is required to store hydrogen fuel in the car over
lengthy periods. Hence, the hydrogen tank
in BMW Hydrogen 7 has double
walls with several layers of aluminium and glass-fibre in the space in
between measuring 30 millimetres or almost 1.2 inches in thickness in
order to avoid higher temperatures entering the tank. Super-insulation
is a very effective way to minimise the intrusion of higher
temperatures and equals a 17-metre thick layer (56 feet) of styrofoam
in its insulating effect. Filling hot coffee into the tank, for
example, you would have to wait approximately 80 days until the coffee
has dropped to a temperature suitable for drinking. Though filling your
hydrogen powered limo with coffee is not advised... Those
who are wary about having significant amounts of compressed
and
volatile hydrogen sitting in a tank in the trunk of their car should
read this
addendum from BMW, and also the breakout panel
in the image column to the right. The
cruising range for the Hydrogen 7 vehicles is 500km (310 miles) on
gasoline and 200km (125 miles) on hydrogen, allowing for a total range
of about 700km (435 miles). Though the cruising range for
hydrogen
isn't huge, it's a start, and will be improved in time as BMW collects
and telemetry from its current fleet of Hydrogen 7 BMWs. Making
It User FriendlyBMW
explains that user friendliness is particularly crucial to the appeal
of any future hydrogen-powered vehicle and, accordingly, acceptance of
hydrogen as a new source of drive energy. The criterion of everyday use
was highly relevant in developing the concept of BMW Hydrogen 7:
introducing this first-ever hydrogen-powered luxury saloon built in
series production, the BMW Group is setting a most significant
milestone within the global automotive industry. The car proves that
alternative drive energy may also fulfill the greatest demands in terms
of driving dynamics and motoring comfort alike. The
development of the BMW Hydrogen 7 marks the beginning of the
industrialisation process, meaning that BMW Hydrogen 7 now comes with
the same standards and levels of perfection as any other new BMW
entering the market. BMW
Hydrogen 7 has gone through exactly the same all-round series
development process as every new model from BMW. New components such as
engine technology, the tank system and vehicle electronics for hydrogen
drive have all been developed in and through BMW’s usual
Product
Creation Process, each and every component therefore having been
examined and verified with utmost precision, ensuring that it meets all
the requirements of series development. So through
its mature
vehicle concept alone, explains the prestige automaker, the
BMW
Hydrogen 7 goes far beyond the status of previous hydrogen prototypes
and demonstration models, qualifying for full homologation and type
approval according to both German and ECE standards. BMW has also
gained approval for the car's use in the United States of America,
where it will be deployed to selected users for testing. And who knows
- maybe Australia will get a guernsey as well? As
with all BMWs,
the Hydrogen 7 is built to exacting standards: it door's feature the
automatic Soft Close function, there's laminated climate comfort glass,
BMW's high-end automatic air conditioning, electric seat adjustment
complete with memory function, auxiliary heating including remote
control, BMW's high-beam assistant, a TV function with DVB-T reception
and a monitor at the rear, the BMW Assist and BMW Online telematics
services, a separate car telephone at the rear, full preparation for
BMW Teleservice, a CD changer for six CDs, a DVD changer for six DVDs,
a smoker package as well as cupholders both front and rear. Safety
systems are well taken care of too. Head and side airbags front and
rear, interior and exterior mirrors with automatic anti-dazzle control,
as well as BMW’s Park Distance Control (PDC) and a rain
sensor
are all featured in the next generation, super low emissions vehicle.
As the world's first hydrogen-powered premium automobile to enter
series production comes as standard with highly attractive metallic
paintwork, particularly the special Blue Water Metallic colour
available exclusively on this model accentuating the unique character
of this unique car. The new BMW Hydrogen 7 is built
under regular
conditions at the BMW plant in Dingolfing (Germany) parallel to the
other BMW 7, 6, and 5 Series built at the plant. And like all of
BMW’s 12-cylinder power units, the engine is built at BMW's
Engine Plant in Munich. Clean Energy PartnershipTo
promote the development of hydrogen filling stations, the BMW Group has
been involved in the Clean Energy Partnership (CEP) Berlin ever since
its establishment in 2002. Today, leading companies such as Aral, the
Berlin Transport Authority (Berliner Verkehrsbetriebe, BVG),
DaimlerChrysler, Ford, General Motors/Opel, Volkswagen, Hydro, Linde,
Total, and Vattenfall Europe all belong to the Clean Energy Partnership
Berlin, proudly promoting one of Europe’s most important
demonstration projects and, indeed, one of the largest projects of its
kind in the world: The objective of the CEP is to further develop
hydrogen as a source of energy, demonstrating the various options to
use this innovative fuel in everyday transport. Related articles:
-
Lexus GS450h Hybrid:
Road Test
-
Honda Civic Hybrid: Road
Test
- BMW M6
- BMW 7 Series
BMW Hydrogen/Petrol
Combustion EngineThe
dual-mode combustion engine powering the first series production
luxury hydrogen saloon is the decisive, revolutionary new development
in BMW Hydrogen 7: this new engine is based on the 12-cylinder
gasoline power unit displacing 6.0-litres and featuring VALVETRONIC
technology in the BMW 7 Series. Maximum torque is 390Nm and comes at an
engine speed of 4300rpm. The V12 power
unit in the BMW Hydrogen 7 operates in two modes, meaning that the
engine
is able to burn either hydrogen or gasoline in the same cylinders.
Offering
an overall cruising range of approximately 700 kilometres or 435 miles,
BMW's hydrogen car with its dual-mode combustion engine has an even
longer range than the BMW 760i. Running
on gasoline, the engine operates with direct fuel injection, while in
the hydrogen mode the fuel/air mixture is formed in the intake
manifolds. The new injection valves developed for this purpose make the
greatest conceivable demands in engine development in terms of their
construction and integration. Conceived and designed for gaseous
hydrogen, the valves are not only larger than conventional gasoline
injection valves, but also cover a far wider variation in size and
range in terms of their volume flow, operating at different levels of
system pressure and at the same time with both very short and longer
gas injection times required for hydrogen gas. Even so, they reliably
inject exactly the right amount of hydrogen into the intake air at all
times within hundredths of a second. Since hydrogen
burns up to
ten times faster than conventional fuel, management of the dual-mode
combustion engine requires specific functions and operations. Using
fully variable VALVETRONIC valve management as well as
the variable double-VANOS camshaft adjustment, the engineers
responsible for developing BMW Hydrogen 7 had ideal tools from the
start for optimising the hydrogen combustion process, gearing the gas
cycle and mixture formation process specifically to the individual
properties and features of the hydrogen/air mixture. For
all practical purposes, BMW Hydrogen 7 emits nothing but vapour while
running in the hydrogen mode. Hence, the new model makes a very
significant contribution to the drastic reduction of emissions in
individual transport, helping in particular to reduce CO2 emissions to
a minimum. The plan for the future is to introduce a
car running
exclusively on hydrogen (single-fuel). And at the same time researchers
at the BMW Group are working on fuel cell technology, seeking to create
a highly practical solution for the automobile in the guise of the
Auxiliary Power Unit (APU), thus introducing a far more efficient and
powerful replacement taking the place of the conventional car battery. With
its dual-mode drive concept, BMW Hydrogen 7 requires not only a special
system of engine management and fuel supply, but also two different
fuel tanks integrated into the car: The hydrogen tank in BMW Hydrogen 7
takes up approximately 8 kilos (about 170 litres or 45 Imp gals) of
liquid hydrogen, the conventional gasoline tank has a volume of 74
litres or 16.3 Imp gals. Used as drive energy, liquid
hydrogen
involves a particular technical challenge in the construction of the
tank: Since hydrogen under normal ambient pressure has to be cooled to
– 253 °C in order to turn into a liquid, innovative
vacuum
super-insulation is required to store hydrogen fuel in the car over
lengthy periods. Hence, the hydrogen tank in BMW Hydrogen 7 has double
walls with several layers of aluminium and glass-fibre in the space in
between measuring 30 millimetres or almost 1.2 inches in thickness in
order to avoid higher temperatures entering the tank. The
highly
efficient insulating effect offered by the tank is also ensured by a
vacuum in the intermediate section between the two walls avoiding any
kind of airborne heat transfer. And last but not least, the mounts
holding the inner tank in position are made of carbon-fibre-reinforced
plastic bands reducing thermal conductivity to a minimum. For
physical reasons alone even vacuum super-insulation cannot totally
avoid a certain intrusion of higher temperatures, meaning that a small
amount of liquid hydrogen would inevitably boil off in the course of
time. However, this minor evaporation effect only starts after
the vehicle has been parked for at least 17 hours, whereupon the
pressure inside the fuel tank will increase to a level requiring
boil-off management of the gaseous fuel. Boil-off management
limits the inner pressure inside the tank and, when exceeding a defined
level of ideal pressure, ensures controlled removal and conversion of
hydrogen. Gaseous hydrogen released in this way is mixed with air in a
venturi pipe and oxidised into water in a catalytic converter. The
period required for purging a hydrogen tank half full in a controlled
process is approximately 9 days, the hydrogen then remaining in the
tank still be sufficient to cover approximately 20 kilometres in the
hydrogen mode. And should BMW Hydrogen 7 be driven in the meantime
in the hydrogen mode, the level of pressure inside the tank will
decrease again due to the consumption of hydrogen serving to drive the
engine. Then, when parking the vehicle again, the 17-hour parking
period without any loss of energy will start all over again from the
beginning.
|
|
