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BMW to Display Liquid Hydrogen Storage System and Bi-fuel Engine at NHA 2006

BMW’s liquid-hydrogen fueled V12 from the H2R. Click to enlarge.

Of the major automakers working with hydrogen as a fuel, BMW holds a unique position—not only has it settled on hydrogen-fueled combustion engines as the interim step to a longer-term fuel-cell future (a stance Ford also takes), the German automaker focuses on liquid hydrogen fuel, rather than gaseous.

Liquid hydrogen offers a higher volumetric density (0.070 kg/liter) than gaseous (0.030 kg/liter @ 10,000 psi)—an important consideration when faced with a limited storage volume in a vehicle.

There are, however, several critical practical issues with using liquid hydrogen in a vehicle, including:

  • Hydrogen boil-off. Boil-off impacts cost, efficiency and vehicle range, not to mention safety consideration for vehicles parked in confined spaces. Insulation is needed to keep the temperature ultra-low, and this reduces gravimetric and volumetric capacity.

  • A high energy requirement for liquefaction of the gas—around 30% of the heating value of the hydrogen.

A liquid hydrogen storage tank from Linde. Click to enlarge.

BMW is bringing to NHA a liquid hydrogen storage system that is double-walled. Between the two walls, there are approximately 70 layers of aluminum-coated synthetic foil under high vacuum. According to BMW, a 17-meter (50-foot) layer of polystyrene would be necessary to achieve the same insulation effect.

In September 2004, BMW demonstrated the power potential of its approach by setting nine international speed records for hydrogen-driven vehicles with the BMW H2R research vehicle. This unique prototype is powered by a 6.0-liter V-2 engine that develops approximately 285 hp; among the records it set was 186.11 mph for the flying-start kilometer. (Earlier post.)

On a slightly more practical level, the company is developing a limited-production 7 series bi-fuel model capable of burning either gasoline or liquid hydrogen. At the National Hydrogen Association’s annual conference in Long Beach this week, BMW will display its current work on a bi-fuel hydrogen-gasoline engine as well as the in-vehicle liquid hydrogen storage system.

During the development of these bi-fuel engines, BMW has hit output levels of more than 170kW (230hp)—with more potentially available, according to the company.



Ron Fischer

But, if you leave the car parked in a garage for a week most of the fuel boils off (hopefully through a good ventilation system).

Lawrence Livermore proposed "pressurized LH2 storage" but the cost of a tank that withstands pressure cycling while super insulating is far too high.

Note how in that 2003 report they conclude with "It is difficult to see how the 2015 or even the 2010 targets can be met."

LH2 might work for fleet use where the time between filling and driving is well known, but that's not what BMW is demonstrating. This almost appears to be a spectacular (personal driving) and impractical diversion from more sound implementations (fleet use).

Paul Berg

Rafael Seidl

BMW is pushing this concept because almost all of the R&D had already been done in co-operation the now-defunct German Space Agency DFVLR in the 70s and 80s. This includes the adaptation of the engine, the construction off the fuel tank as well as filling stations. See:;/site=a4e/lng=en/do=show/alloc=3/id=2216;/site=a4e/lng=en/do=show/alloc=3/id=2298

The advantage of using H2 to fuel an ICE is that it is much cheaper and viable in series production today/soon compared to switching everything to a FC in a single step.

The advantage of LH2 over CH2G is increased range, as there is limited space for a fuel tank on board a vehicle.

Fundamental problems with BMW's approach are:
(a) very high cost of LH2G production & distribution (well-to-wheels GHG ratio of 1.2 relative to gasoline)
(b) very high cost of LH2 vehicle fuel tank (extremely low temperatures)
(c) continous boil-off of LH2 in all storage vessels (for safety)
(d) crash safety of LH2 tank
(e) exergy losses due to H2 combustion in ICE (as opposed to electrochemical reaction in fuel cell)
(f) significant NOx production in a certain lambda range (but no CO or HC to reduce it to N2 in a catalyst)

My take: this is BMW's way of having an H2 story without having to commit massive additional engineering resources.

Rafael Seidl

Paul -

the link you provide highlights the many adverse factors that have to come together before producing hydrogen from renewable sources makes economic - as opposed to ecological - sense in present market conditions. Anywhere you have a grid connection it's better to arrange for buffer storage in existing hydroelectric dams. Providing you avoid short circuits etc., you could even deploy floating arrays of solar panels on the reservoirs to avoid having to use land for the purpose.

A single-minded focus on switching just the transportation sector away from oil is wrong-headed. Both energy security and CO2 reduction goals are equally well served by reducing the use of oil for e.g. space heating and electricity production.


This is a sick and unfunny joke.

Liquid hydrogen requires 60% of its energy content to produce and liquefy it in the first place. Overall wind farm to wheels efficiency? Something like 20% I think - terrible anyway. Direct charging of EV batteries from windfarm - overall efficiency of 70% plus.

Hydrogen is terribly dangerous stuff - with the attitude people have to safety, this can never be made idiot proof enough. Range of this car with liquid hydrogen? Will never be more than 250 miles for a reasonable sized European car. You want near absolute zero cryogenics in your car? Think stratospheric cost and space program safety issues. Robotic refilling - billions and billions in infrastructure costs to equip filling stations, set up delivery pipelines, brittle steel, H2 leaks - total pie in the sky. We'd have a Hindenberg downtown every week.

Pure propaganda to make the uninformed think that BMW are doing something useful. The ultimate driving machine - one you can't take out of the garage.

Robert Schwartz

The question is whether liquifying hydrogen takes less energy than can be derived from burning it.


"This is a sick and unfunny joke."

Couldn't agree more. What a waste of time and resources. The worst part of this is that it wouldn't ween us off of petroleum anyway. For years, we'd still be using fossil fuels to derive H2. Let's see....a less powerful car with half the range that costs 3x as much. Sounds like it should be really easy to market this one....I really would have expected more common sense from a company like BMW.

Rafael Seidl

FWIW, I rather suspect that BMW is doing this purely as a technology demonstration to placate the California Air Resources Board. Remember, it is CARB that is forcing every major carmaker in the world to figure out a way to produce and sell "zero emission" vehicles. This diverts scarce R&D funds from more mundane approaches that would yield much greater aggregate emissions reductions.

CARB's original ambition, the all-electric vehicle, would have greatly benefitted certain CA/US battery manufacturers; however, EVs were a massive commercial flop. To save face, CARB started advocating fuel cells and regular hybrids. Now, there is a lot of hype about plug-in hybrids, which are really just EVs lugging around an ICE as well.

To underscore how little sense the ZEV legislation actually makes, consider this: virtually all harmful emissions (other than the GHG CO2) from a lambda=1 engine with a three-way catalyst are generated during the warm-up phase. For SULEV certification, the critical time is the first 20 seconds (!) after starting a cold engine. A 500 mile trip on the freeway generates fewer tailpipe emissions than a twice-daily 5 mile commute to work. Stating emissions in g/mi or km for lambda=1 engines is a completely misleading anachronism (does NOT apply if lambda>1!)

If you want to further reduce the emissions of a lambda=1 vehicle, you need to heat up the three-way catalyst before starting the engine. BMW actually did this in their 7 series Alpina variant a while back using an electric coil powered by a second battery.

So careful who you bash here. Carmakers are just jumping through the hoops CARB is putting in front of them.


I believe that H2ICE is the best path to take. Fuel cells are at least a decade from actual middle-class affordability, and you would be a fool to believe the "available in '09/'10/'11" timeframe BS. There is no reason to believe such comments from the motor companies; fuel-cell technology is only marginally than when GM et al were were spouting the same blatantly deceptions back in 2000 about there "2005 availability". The main barrier to fuel cells is still there ridiculous materials cost! Maybe in a decade those relatively pathetic R&D dollars will yeild a non-platinum FC, or other such breakthrough. H2ICE challenges are relative childs-play compaired to the FC challenges.

The other half is of course the hydrogen. Liquid storage needs just as much R&D a FCs. Gaseous storage is definately the only storage option that would get hydrogen vehicles with petrol characteristics. And THATS practically ready to role.


...marginally BETTER...


Why push any form of H2 before we have a means to use it properly? One of the primary reasons for creating an H2 infrastructure is because the tank-to-wheel efficiency of a fuel cell is twice that of an ICE. Without the fuel cell, the only noteworthy benefit is the lower emissions (as compared to gasoline), and even that is suspect after you factor in how much energy goes into extracting/compressing/storing it. It's like putting the cart before the horse.

So, as we will be dependent on the ICE for the foreseable future, why even bother using H2 in them? Biofuels present a much better option with the infrastructure we have. The least advantageous option, corn-based ethanol, is still better for our environment and our economy (the latter being an often overlooked fact).

I am not trying to totally discount the idea of a hydrogen economy. Realizing there could be many advances in the areas of production and storage over the years, it doesn't make sense to stop investing into the R&D. However, you just do not deploy something of that magnatude before it is ready, and it clearly is not. You can't go halfway on this stuff.


I just want to know how do you lubricate an H2 powered ICE without burning any oil that will end up in the exhaust.

Rafael Seidl

Justin -

you still have to lubricate an H2-powered ICE with oil, and a small fraction of that is burnt. It`s just that the concentration of the associated emissions are well below the accuracy of the measuring equipment.

Barry R. Guthrie

I have a question about using Liquid H2 abd compressed H2 in the combustion process.

From what I understand the operating temperature is -253 to +85 degrees C @ a pressure of 0.0 to 0.7. To use the fuel in the engine it will have to be pumped and pressurized for direct injection into the combustion chamber.

Does anyone know what the direct injection pressure may be?

What would be the H2 injection temperature as it is pressurized by a pump and direct fuel injector?

I was just thinking about what this chamber temperature might be and how close it would be to the autoignition temperature of 583 degrees C.

The closer the H2 can be pressurized the less combustion heat enthalpy lost in heating the H2 to ignition and more heat energy can go into work.

If the H2 is injected as a liquid it needs to change phase to a vapor to combust and require heat. This heat enthalpy is parasitic to work.

I say this in comparing to a compressed H2 system at 10,000 psi. As the H2 goes from the tank to the direct fuel injector what is the potential fuel injection pressure?

This is a strange condition because the H2 expands from a higher pressure to a lower direct injection pressure. This is create an endothermic expansion reaction where the H2 absorbs heat from the suround as it expands from a higher pressure to a lower pressure. The gas is injected under some pressure that increases the gas temperature. If the H2 is injected as a gas it does not need additional heat to change phase from a liquid. However, the H2 gas injection temperature may still be too low and require too much additional heat enthapy before before combustion.

Which system requires more heat energy to condition the H2 for combustion?
Which system requires more pumbing energy to pressurize the direct injection?
Which system provides the total combustion system best net energy heat work benefit?


Hello Sir,

We read U'r information We are intersted to know the information regarding the stoarage of hydrogen
such as
cost of h2 storage tank of 10 to 35 MPa
different manufacturers of h2 storage tank
cost of the h2 fuel per liter

Sorry for the trouble

thanking U

abhishek gautam

Respected Sir,,

i am a student of mechanical engineering at
IIT Bomnay in India.
Sir i wanted to know the detail about type of liquid hydrogen cars and what are the difficulies in its implimentation apart from its high cost.

thanking you
Warm regard

sean costello

piston-based hydrogen ICE is massively inefficient as compared to a matching turbine, it would then be self-lubricated and cooled by the hydrogen fuel itself and the turbine could operate oil-free. not only that, but efficiency would go from 25-30 to over 90%. plus, the energy required to liquify the hydrogen is regenerated in the vehicle itself as the liquid hydrogen is heated by ambient air, with about 60-70% round-trip efficiencies, this is also why most liquid nitrogen and lox air seperation plants run quite efficiently as whatever isn't supplied as liquid powers turbines up to ambient temperature recovering some of the energy used to liquify and seperate the air.


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sean costello

you know i find it interesting that all the people complaining about how the hydrogen is derived are forgetting that they can buy their own photovoltaics and produce their own hydrogen for about the same cost per kWh "wells to wheels" efficiency as gasoline. not only this, but power plants produce 2 kWh of electricity to the grid AFTER transmission losses (at your house's plug) for every 1 kWh delivered for the same amount of petroleum - not to mention the energy savings that the oil is pumped to the power station via pipe instead of trucked to the gas station. So 50% efficient hydrogen production is equivalent to gasoline use. Furthermore, the energy used to liquify the hydrogen is then recouperated by the car via ambient heating - increases pressure and eliminates engine losses associated with compressing the gas. Same help that a turbine gets from running off a pressurized source instead of having the compressor producing a drag on system operation. not only that, but most car engines can be reconfigured to run on a hydrogen/water injected mix if gasoline no longer became available. so whoever posted earlier that you have to mix it with gasoline was wrong.

sean costello

what we really need is for the automakers to get their head out of their asses and make our vehicles more efficient. the only way to do that is drop the piston-based engines and go to turbines, only way turbines dont guzzle gas just as bad as the piston-based would be hybrid turbine to electricity with direct high speed high voltage (300-1000 volts 3 phase AC) generators which power high voltage motors. my company did a financial feasibility study. for about $40-50k mass produced price (10k+ units or more) if the car companies used about 300 pounds of carbon fiber to lighten the vehicle (structural and non-structural components) would result in about 1200 pounds of steel weight reduction increasing fuel mileage (whatever the fuel is). not to mention thermodynamic efficiency would be 2.5 times better, with LH2/LOX at about 1/5 the volumetric energy density this increases volume of fuel tank 2x, but the fuel is lighter, and if derived from renewable resources, cost averages down rather than the price of oil historically going up.

Robert Galloway

Ladies and/or Gentlemen:
The problem of boil off of hydrogen from vehicle fuel tanks during periods of non-use seems to beg for the solution of piping this boil off into the natural gas distribution system. The practicality of this is beyond my level of knowledge but I'd like to know it's been considered and whether there are absolute contraindications or merely surmountable obstacles.


Robert Galloway

The only reasonable source of H2 is nuclear. And, as for the extreme hazard of H2, I'd rather be involved in a collision that releases forty gallons of H2 as forty gallons of gasoline. The cryogenic hazard is real enough as far as being frozen to death in your auto after a collision. Being burned to death ain't so great either. Dispensing at the filling station is being demonized beyond reason. Working in research for a number of years with LN2, it isn't that big a deal. The only questions that really matter are those regarding energy in versus energy out. Is the process sufficiently "efficient" to be worth doing? If the energy to produce and liquify equal the energy back out, it looks like a practical way to get nuclear power into the gas tank. Connect the auto in the garage to the present natural gas distribution system and capture ALL of the boil off.

Robert Galloway

Somebody help me. Most of you have been looking into this far longer than I. Who has the numbers from start to finish on the cost of using electricity from a nuclear power plant to produce hydrogen, energy (I'd think directly rather than with an intermediate electric step) from said nuclear plant to liquify the hydrogen and then the cost per mile to move a mid sized automobile to the grocery or to work every day? Everybody discusses this with so much emotional overburden. "Just the facts, Mam. All I want are the facts, Mam".


We need nukes (a billion years of fuel on earth) to generate electriciy for electric cars for short range and hydrogen for long distance vehicles and phase out fossile fuels or the economy and the earth will end........

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