The ridiculous BMW 7 Series Hydrogen hybrid

[Mr Gus]

Who was that Stinsy? (your name is hell to shorten you devil)

[Stinsy]

Who was that Stinsy? (your name is hell to shorten you devil)

I can’t remember the name. And probably would probably be shy to say if I did remember. (Some turned out to be litigious fiends once the roof fell in).

Anywho. Some facts recanted there that got me banned:

1) If you’re burning anything in air, you’re going to get NOx. Air is more-or-less 80% Nitrogen/20% Oxygen. If you’re doing any oxidising reaction involving air, some of the “O” is going to combine with some of the “N”, that’s just a given. In a high-temperature, high-pressure environment of an ICE, you’re going to get loads of NOx. This isn’t GCSE chemistry fellas this is the real world!

2) Hydrogen Peroxide. You’re trying to combine H with O to get H2O. However if you think you’re going to get no H2O2 you’re dimmer than you look! In fact if you WANT to make H202 you burn Hydrogen in air, that is how they manufacture hydrogen peroxide!

[Oldgreybeard]

I’ve just remembered: I got kicked off the old forum for a few weeks of explaining that “the the only product of burning Hydrogen in an ICE is water” is a completely false statement! It turns out one of the “mods” owned a hydrogen burning ICEV and didn’t want the truth to see daylight!

The old place seemed to me the be the personal fiefdom of one or two moderators. I never understood why the owner put up with it, as it undoubtedly lost them business. I had requested a quote for around £12k worth of kit for this house when I was summarily dismissed, not for anything contentious, but just passing on my experience (in a balanced way) of using NiFe cells for many years. Seemed that touched a nerve with one of the mods. Needless to say I cancelled the planned order and told them exactly why I had done so. They seemed not to be bothered by it.

[AE-NMidlands]

1) If you’re burning anything in air, you’re going to get NOx. Air is more-or-less 80% Nitrogen/20% Oxygen. If you’re doing any oxidising reaction involving air, some of the “O” is going to combine with some of the “N”, that’s just a given. In a high-temperature, high-pressure environment of an ICE, you’re going to get loads of NOx. This isn’t GCSE chemistry fellas this is the real world!

But isn't the "A" level bit of chemistry that there are differing speeds of reactions and thresholds which have to be passed for differing reactions to start? Maybe it is first-year degree level...

My understanding is that N₂ is a stable well-bonded molecule, so has to be pushed to get involved whereas O₂ is hanging around just looking for things to react with. Hence the reason that petrol spark-ignition engines don't emit much N₂ but in the diesel/compression ignition cylinders it gets over the temp / pressure threshold and lots of N₂ is formed. Hence the big difference in exhaust quality and health effects (not that I am recommending breathing petrol exhaust...)
A

[Moxi]

There are many variables to determine the actual exhaust products and even the test data will change over time as an engine wear's and becomes less efficient.

I think the point that was being made is that despite the sales blurb that only water vapour is emitted by an engine combusting Hydrogen its categorically untrue and some of the harmful pollutants are still evolved as part of the process.

I think the other side of the Hydrogen debate, that most industrial Hydrogen is still derived from cracking natural gas, is also a big factor in the reasons for NOT adopting this technology for mass transit.

If Hydrogen has a place surely its got to be as a storage medium to convert excess wind in to "clean" hydrogen (rather than cracked hydrogen) for later re-use in CCGT generator sets ?

Moxi

[openspaceman]

My understanding is that N₂ is a stable well-bonded molecule, so has to be pushed to get involved whereas O₂ is hanging around just looking for things to react with. Hence the reason that petrol spark-ignition engines don't emit much N₂ but in the diesel/compression ignition cylinders it gets over the temp / pressure threshold and lots of N₂ is formed. Hence the big difference in exhaust quality and health effects (not that I am recommending breathing petrol exhaust...)
A

The health effect is that NOx can react with sulfates in the atmosphere to create PM2.5, also forming nitrates in rainfall and affecting drinking water. More a problem in dry hot places I would have thought.

Anyway the reason diesel engines emit more NOx is that they always take a full gulp of air, as NOx are favoured when there is high temperature, high pressure and spare oxygen and these conditions exist higher power levels, but not so much at low power as the temperature is low, or at full power when there is not much spare oxygen. Hence adblue is injected into the exhaust at certain power levels to react with NOx in the catalyst and produce N2 and water.

SI engines never have much excess oxygen.

I would like a BEV but I am running a few hand me downs, not having bought a car since 1993.

[AE-NMidlands]

My understanding is that N₂ is a stable well-bonded molecule, so has to be pushed to get involved whereas O₂ is hanging around just looking for things to react with. Hence the reason that petrol spark-ignition engines don't emit much N₂ but in the diesel/compression ignition cylinders it gets over the temp / pressure threshold and lots of N₂ is formed. Hence the big difference in exhaust quality and health effects (not that I am recommending breathing petrol exhaust...)
A

The health effect is that NOx can react with sulfates in the atmosphere to create PM2.5, also forming nitrates in rainfall and affecting drinking water. More a problem in dry hot places I would have thought.

Anyway the reason diesel engines emit more NOx is that they always take a full gulp of air, as NOx are favoured when there is high temperature, high pressure and spare oxygen and these conditions exist higher power levels, but not so much at low power as the temperature is low, or at full power when there is not much spare oxygen. Hence adblue is injected into the exhaust at certain power levels to react with NOx in the catalyst and produce N2 and water.

The health effect is that NOx (acid gases) dissolve in the moisture/water in your lungs (and your eyes) to make liquid acid. I have spent enough time in tunnels monitoring exhaust from big diesel engines to know about this. Hot and dry is irrelevant.
To me "NOx are favoured when there is high temperature, high pressure " says that a threshold has been passed, I don't think it is just linear - and what I was taught too.

[Mart]

I think the other side of the Hydrogen debate, that most industrial Hydrogen is still derived from cracking natural gas, is also a big factor in the reasons for NOT adopting this technology for mass transit.

Moxi

Yep, first use green H2 to displace existing hydrogen demand such as fertiliser. Maybe steel and cement production, if direct leccy isn't suitable. But aiming for road transport when BEV's are so, so much better is crazy.

My maths may be a bit questionable but I think we'd need 4+ times as much leccy for HFCV's than BEV's.

After losses from the powerstation to the wheels, a BEV puts about 75% of the energy through the wheels, whereas a HFCV vehicle is about 25%, so 3x more than a BEV.

But, changing the UK car fleet to leccy would add about 17% gross to our leccy demand, with a net figure of around 10% after refinery savings, plus transportation etc.

But those savings (which I may be exagerating, sorry) are a one off, so the HFCV's would require 3x 17% = 51% and if the savings apply (they may not), then the net figure is 44%.

So HFCV's would require roughly 4.4x as much additional leccy generation as BEV's will.

........ I think?

[Stinsy]

1) If you’re burning anything in air, you’re going to get NOx. Air is more-or-less 80% Nitrogen/20% Oxygen. If you’re doing any oxidising reaction involving air, some of the “O” is going to combine with some of the “N”, that’s just a given. In a high-temperature, high-pressure environment of an ICE, you’re going to get loads of NOx. This isn’t GCSE chemistry fellas this is the real world!

But isn't the "A" level bit of chemistry that there are differing speeds of reactions and thresholds which have to be passed for differing reactions to start? Maybe it is first-year degree level...

My understanding is that N₂ is a stable well-bonded molecule, so has to be pushed to get involved whereas O₂ is hanging around just looking for things to react with. Hence the reason that petrol spark-ignition engines don't emit much N₂ but in the diesel/compression ignition cylinders it gets over the temp / pressure threshold and lots of N₂ is formed. Hence the big difference in exhaust quality and health effects (not that I am recommending breathing petrol exhaust...)
A

My point was that the much-repeated story that "the only output from a Hydrogen-burning ICE is water" is a lie.

[JC_UK]

Hi all,

Back in the 1990's BMW did a trial in Munich for their Hydrogen technology.

They converted a fleet of 7 series limos to run off a Hydrogen tank in the boot and there were used to shuttle VIPs from Munich Airport to the Munich central (Ringroad - MittlerRing) BMW offices. Hydrogen fuelled, not fuel cell.

Aral (part of BP?) branded Hydrogen 'pumps' were shown as part of the demo/trial.

Performance of the BMW engines running on Hydrogen was not dis-similar to the petrol/diesel versions.

The only negative I could see in the demo was where the Hydrogen was going to come from to get to the garage forecourts.....

Maybe I dreamt it?

Cheers
JC