Why JCB thinks that hydrogen is the best alternative to diesel for heavy machinery.

[Countrypaul]

Mart,

When comparing weights for the BEV vs HICE there is no mention of the engine/motor and transmission weights. If the HICE is based on a diesel engine - and for heavy machinery a heavy lower revving engine would be logical for longevity/reliability/servicing the the weight of the engine could easily be 100Kg /L - not sure how to compare that power wise 25KW/L ? Then we need to add transmission and exhaust weights. An electric motor & transmission weighs around 100kg for a 250kW Tesla motor. I suspect 400Kg of batteries +100Kg electric motor & transmission might well weigh less that HICE engine lus transmission pls hydrogen storage tanks. Probably requires a little more research to get reasonably comparable figures though...

[Mart]

Hiya CP, I'm of a similar thought regarding weight. For cars I'm not convinced the batts are such an issue. Yes the vehicle currently weighs more than a comparable ICEV, but not to the extent that LB was suggesting. In fact our Hyundai IONIQ 28kWh is only about 50kg more than the HEV option, and about 50kg lighter than the smaller battery PHEV option.

I'm wondering if weight is an issue for heavy plant, so it didn't concern me too much, until LB and Harry both started BEV bashing over battery weight - people in glass houses perhaps?

Not sure how useful this comparison is, but our TMY LR weighs ~1,930kg, I think the TM3 LR weighs ~1,900kg. For comparison the Toyota Mirai weighs 1,900kg. I believe it has 3 H2 fuel tanks.

Weight for trucks is more of an issue, though the majority of loads are volume limited, not weight limited. Also,most trips are shorter range, so, for example, if the weight penalty of a Tesla semi 500 mile model is too much, then there's the option of the lighter 300 mile model. [Also EU BEV trucks get a 2,000kg max weight bonus, and in the US +2,000lb.]

[openspaceman]

Mart you have thought a lot more about this than I, interesting points.

Started off well, I found the first half interesting. Wasn't sure about the casual way H2 was being talked about, but I'll come back to that. They addressd the NOx issue. I don't pretend to understand it, but the suggestion didn't seem to be managing NOx levels lower, but implied little NOx through appropriate combustion ..... I suspect I was mis-understanding that.

This was the interesting bit for me; he seems to be implying that they make use of the fact hydrogen burns over a much wider range of fuel to air ratios. It also has a high octane rating, i.e. it will not detonate when the weak mixture is highly compressed until sparked when a flame front moves smoothly through the mixture. So the temperature of combustion is lower than it would be from a stoichiometric mixture. Expanding the charge from a high compression but lower temperature would not favour NOx even though excess air is present but it would also be nearer a diesel cycle with regard to volumetric efficiency.

I still think we will import a liquid fuel made in sunnier places where biomass also grows quickly but JCB must have irons in the fire to need a solution for ICE.

I wonder what fuel LB uses in the vehicle he commutes to work with. Not to mention I don't think he'll get far with hydrogen in his yacht, and no it has no sails.

[Moxi]

Thought I would chuck a few more things into the conversation:

Because of the flame propagation speed and the volume of exhaust gases the HICE needs a larger crank shaft, stronger valves heavier stronger cylinder head etc etc and general consensus appears to be that it would be 1.5 times the weight of the equivalent diesel ICE.

Then theirs the question of hydrogen embrittlement, by the time they have identified and selected suitable materials the cost of an HICE engine could be prohibitively expensive, to give an indication hydrogen rich natural gas pipelines in the gas fields can suffer stress fatigue embrittlement failure in weeks if joints are not prepared and jointed correctly and even when they are they become physically fragile to movement after little more than 6 months - how this translates to a multi component machine with close tolerances and expansion and contraction cycles, moving parts and repetitive cycling will be anyone's guess. I'm sure they can build concept units but how long they will last and how they can translate these into commercial derivatives ?

Moxi

[openspaceman]

Yes it is interesting that burning hydrogen creates twice the volume of steam but the nitrogen remains the same so not that big an effect overall.

I guess the higher temperature would accelerate hydrogen diffusion into iron but my inference is that the hydrogen past the injection would be a weak mixture. Town gas was a mixture of hydrogen, carbon monoxide and 10% nitrogen, did this cause problems? It was definitely used in stationary engines.

[Countrypaul]

Does hydrogen actually need injecting? Given it is already gaseous (and probaby under some pressure) can it not be simply mixed with air before entering the cylinders?

[openspaceman]

I have no idea but as it is stored at 350bar I expect it would be direct injection into the combustion chamber after the intake stroke in order for there to be a stratified richer mix around the spark plug.