And, this was my comment on that website:
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I have a BSc in Applied Chemistry and an MSc in Environmental Management, so have some qualification to comment on this issue:
Hydrogen is a poor fuel for motor vehicles. Why?
The energy density is low. Note the very poor range regarding the post office vans.
The gas is made largely from hydrocarbons. Therefore the source is oil-based in the main.
The creation process and storage is very energy intensive as the gas must be kept super-cooled and compressed at a high pressure. Same in the "petrol" station place.
Due to the small atomic size (the smallest atom) the leakage rate is high, as very little can effectively contain it. Therefore when one of these vehicles is left parked, the gas will effectively evaporate.
The transportation cost and carbon footprint is far higher than normal hydrocarbon fuels as it will need specialist truck and as the energy density is low, you will need more of them for the same calorific value.
Storage on the user vehicle must be safe, the gas is highly explosive in air, (see the Hindenberg) so there are additional dangers in an impact, or in a fire, or with aged systems. Compare that to diesel cars where benign (atmospheric pressure) and standard containers and piping can be used.
Hydrogen is odourless and colourless, escapes will not be noticed until an explosion occurs, so mercaptans (as in domestic gas) will need to be added to ensure releases are noticed.
Hydrogen burns with an invisible flame, so even if a leak ignites it may not be noticed until it becomes catastrophic.
A hydrogen fire will be incredibly hard to extinguish.
There is no refuelling infrastructure, as noted.
Refuelling would have to be incredibly stringently overseen - we are not talking about hard to ignite hydrocarbons like diesel (and less so petrol).
There are probably many more drawbacks compared to traditional fuels.
The carbon footprint is actually far higher than either petrol or diesel (the same applies to grid-recharged EVs).
...and thinking about it, a further danger is that a Hydrogen leak into the car will asphyxiate you if concentrated (but will probably explode first as it will almost always spontaneously combust in contact with air), so really need to make that gas very smelly which alone will put many people off. There will always be a lingering smell, as those mercaptans are the smelliest substances known to man... and if an H2 leak gets on to your skin in liquid form (in any significant quantity), say bye bye to that part of your body, it will super freeze and snap off. MIND YOUR FINGERS, TECHNICIANS. May need full hazchem suits to work on these systems when charged. Imagine if a pipe is disconnected by accident... or in a few years by a home mechanic!
Hydrogen is also very likely to dissolve INTO many metals, making them very brittle over time, which leads to a nasty bang at some stage.
Loverly juberley stuff, who wants THAT H2 in your car? Even the safety stats I tried to look up are jumbled, as Hydrogen seems to change its form and effects over time - phenomena occur randomly - very jumbled data. H&SE will have a field day. How the fire brigade should react to a car fire or damage is unknown, but I think cars may have to carry warning HazChem signs with the suffix "E" which means "Evacuate". Hope the Post Office is well insured. Postmen are well known to keep their vans in tip-top shape after all...
Hydrogen fans, either you stupid or you are dreaming. Dream on.
Hydrogen will not become a good fuel for road vehicles, as many of the issues above are currently beyond the ability of cost-effectiveness to address.
This is simply a PR adventure for the Post Office.
I would recommend that the firm spending money on this technology does a full assessment of the future use of Hydrogen. It seems to me to be a fast-track to bankruptcy.
Hope this makes sense. Discuss!
- Ling
Last edited by: LINGsCARS on Mon 22 Feb 10 at 16:43
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Hydrogen fuelled vans (and cars) new
Hydrogen fuelled vans (and cars) new
