Discussion in 'Steam Traction' started by aron33, Aug 15, 2017.
Perfectly reasonable hexadecimal numbers...
Which got me to thinking of Bulleid building an 0-8-0...
Brilliant idea, but where does the the iron come from in the first place ? ... Iron ore which is generally an oxygen bearing compound, so you use energy to drive off the compound and then gain some energy getting it back.
True - but I think the idea is that the Iron powder is seen as a more efficient energy storage system. It can be reprocessed and reused. The energy for that could come from renewable sources which are difficult/impossible to store.
Several thoughts came to mind. One is, as @class8mikado says, where does the iron come from? The article says iron ore, which is reduced using hydrogen. OK, fine, where does the hydrogen come from? Presumably you need a source of hydrogen from renewables, which as yet is not cost effective. (Main industrial source of hydrogen is from methane, which is not carbon neutral by any means. Electrolysis - which could use renewable electricity - is possible, but currently more expensive).
At which point - suppose you have a source of carbon-neutral hydrogen? What is gained by a complex redox cycle involving burning iron and then reducing the iron ore back to iron, that couldn't just be done more easily by burning the hydrogen in the first place? That's the main thing I can't get my head around.
The other issue is that the byproduct is iron ore. I can imagine a hot jet of rust particles being pretty abrasive in your furnace on whatever they impinge on. You also presumably need to take a fluidised mass of iron filings and blow them into the furnace, which is also potentially abrasive.
So I'm struggling with this to work out where the advantage lies. By time you have cheap, carbon-neutral hydrogen (needed to make this viable), what do you gain by having this complex secondary iron redox process?
OTOH: Someone more knowledgeable than me is researching this, and to have got as far as they have, their research grant application must have survived multiple rounds of peer review rather more probing than what I can think of in 30 seconds. So I'm guessing there is some use case. But hard to see what it is. I'm guessing the possible advantage is maybe to avoid transporting hydrogen, which is low density, i.e. having a combined hydrogen production and iron ore reduction plant on one site (near renewable energy and a source of water); and then have transport flows of iron powder out (with high energy density) and iron ore powder back. Shipping, maybe.
I think it is because the Iron oxide powder is more easily stored than Hydrogen (- which needs low temp or high pressure). But I agree it is a complex solution.
Absolutely true .... to date. There's been an announcement, in the past few days, that the Chinese have cracked this problem. Along with everyone else, I've not yet had a chance to dig in to the details, but if this new process stands close scrutiny, it's a game changer.
A second "D" class...
Would a developed Leader on eight wheel bogies be a D0D0? Or may be an 0DD-ity?
Chop it up and shove it on the fire...
It would be like 2 tenders wheels. Under an engine. I don’t think there was a name for this! Haha
I think, if all axles were separately powered, it would be a DoDo.
The only application that I can recall is the Union Pacific's rather short-lived DD40AX units. These were more or less 2 GP40's on one chassis, with 2 v16 EMD motor generator sets, total power output was 6,600Hp, which was a lot in 1970. They were expensive to maintain, and presented little benefit compared with having a pair of GP40's or SD 40's.
Bulleid would probably have approved!
Unless it were an 0-2-2-2-2-0+0-2-2-2-2-0
Not clear there's a single reason; it could be a combination of several; and one would have to do all the math on everything (e.g. on shipping costs, and the per-vehicle systems to store the hydrogen at pressure) to see. The thing that would give me pause on hydrogen is safety - but given that we manage with gasoline (which is almost as bad), maybe that's not insurmountable.
Where hydrogen's concerned, it's energy density that gives me pause - a 4 car EMU at UK loading gauge loses a carriage worth of capacity if converted to hydrogen power.
There seems to be some confusion, in recent postings on this thread, between the use of iron as an alternative fuel for steam locomotives, which seems possible in principle if beset by all manner of difficulties in practice, and its use as a less bulky alternative to hydrogen for modern trains. You can use the hydrogen in an internal combustion engine or a bank of fuel cells, but how would you fit an iron-fired boiler and a steam turbine into a modern multiple unit?
I think the perceived danger of hydrogen is mischaracterised - a few airship disasters in the 1930s have a lot to answer for! We produce, pipe into homes and safely burn billions of cubic feet of methane every year with a very high degree of safety; how is hydrogen worse? Interestingly, the density of hydrogen in the gas phase is so low that in the event of a ruptured fuel line, it will harmlessly disperse very quickly. The same can't be said for petrol (gasoline) which, if spilled, presents both a clean up problem and a real fire hazard until such time as it is cleaned away.
There are problems with hydrogen as a fuel - but safety, at least relative to any other energy rich gaseous or liquid fuel, is not really one of those problems.
I don't think that was the use case being outlined. The high volumetric energy density seemed to point to use cases where fuel storage space, but not weight, might be an issue - shipping being an example. If there is eventually a commercial use, it feels to me it will be for a specific niche, not as a mainstream fuel. (Though to be fair, the post-carbon economy is likely to be powered by a very diverse technology mix of energy production, storage and saving solutions: there isn't likely to be a single magic "do everything" bullet in the way that oil has, for a hundred years, been simultaneously cheap to produce, easy to store and transport and readily useable in everything from heating to turning an engine).
Hydrogen is very dangerous. Just look at a hydrogen leak on Challenger . I would rather deal with a diesel spill than any gaseous fuel.
One important rule in safety. What you do not have cannot hurt you. - Remove the inflammable fuel from the train/car etc.
What do you see as the problems? Just density (even in liquid form, which is a bear to work with, it's not very dense), or are there others as well? (The Saturn V first stage used kerosene because the low density meant that it would have required larger tankage, which would increase vehicle mass and drag; the upper stages used LH2 because of its higher Specific Impulse.)
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