Are hydrogen tanks superior to batteries?

Discussion in 'General' started by Martin Williams, Apr 3, 2018.

  1. Martin Williams

    Martin Williams Active Member

    The UK is currently constructing a large nuclear power plant. Well, in fact its a French company that's doing the building, and the money is Chinese! The company constructing it has had severe problems in constructing this type of reactor - in fact they haven't actually built a working one yet - and the UK consumer is committed to buying the electricity at an inflated price (About twice that of offshore wind) for 35 years, if it works at all.

    By the time this idiotic project is finished - if it ever is - it is unlikely to be needed. More and more companies and households are turning to wind or solar or both for their power, and as a result, the demand on the UK grid is steadily falling year on year, and more and more seems to be coming from wind anyway. So it seems to me its output could well be used for hydrogen production. It will be expensive of course as the power produced is grossly overpriced so the Chinese investors can make a profit on their investment, but perhaps it might be able to make hydrogen economically?
     
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  2. Martin Williams

    Martin Williams Active Member

    I don't believe the battery is entirely necessary unless the fuel cell is incapable of supplying peak demand. This is a sensible design solution in a car, as one doesn't want to have to supply a bigger fuel cell than is needed, however, it seems to me that supercapacitors are far better adapted to storing energy for shortish periods and delivering it at very high power when demanded than batteries, particularly if the new hydrophilic dielectric ones fulfill their promise.

    Even if they don't, the existing ones are adequate. You just need more.
     
  3. bwilson4web

    bwilson4web Active Member

    A suggestion, www.greencarcongress.com, has a good collection of summaries of these technologies. The last one I read involved a column of melted metals that break down methane into hydrogen and carbon that can be skimmed off.

    Bob Wilson
     
  4. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    That is certainly physically possible -- in a sharp contrast to most of your other comments promoting the "hydrogen economy" hoax and bashing BEVs, comments which fearlessly defy the laws of physics and economics. But one wonders: if this really is (as you claim) less expensive and simpler than the usual setup, then why isn't every H2 generation facility and every H2 dispensing station using that tech?
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  5. bwilson4web

    bwilson4web Active Member

    Near as I can tell, it is a research lab technology. Scaling up a new technology takes time and effort and much harder if there is no clear market. Steam and methane generation remains a primary industrial H{2} source which means mechanical compressors.

    Bob Wilson
     
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  6. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Unlike every other "magical" tech I've ever seen touted by fool cell fanboys, this looks to me like it might actually hold some promise. Sure, the market for commercial-scale H2 from electrolysis is limited; perhaps it's accurate to call it a niche market. But the market is there. For example, I've seen it claimed that the U.S. Navy has H2 generators on board some of their ships, which I suppose are used to generate fuel for the fuel cells which power the Navy's unmanned underwater drones. Unless the electrolysis device is unreasonably expensive to manufacture in small quantities, it should certainly allow an improvement in the energy efficiency of "renewable" H2. Admittedly only a small improvement, since there are so many energy-wasting steps. But if the device really is as simple and effective as Martin wants us to believe, then it should represent a significant savings in the cost (and possibly size) of a generation/ compression/ storage system for compressed H2 fuel.

    Pumps which can compress H2 to 10,000 PSI are expensive! If we can eliminate (or at least significantly reduce) the need for those at the generating station, then that would be a significant lowering of costs. (That still won't eliminate the need for expensive high-pressure pumps at the dispensing station, because the H2 has to be recompressed as it's dispensed, to maintain sufficient pressure to fill the vehicle's fuel tank.)
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  7. Martin Williams

    Martin Williams Active Member

    I imagine that those organisation already producing hydrogen by other means are not using electricity to produce the stuff anyway, so it's no advantage to them. I don't see the need for an electrolyser or a compressor at a hydrogen station at all. The gas is simply stored at a higher pressure than that required by the car. You just need a pressure reducing valve and metering equipment, and that's about it.

    Bob, I think its a bit more than a lab. model. Honda have actually built a demonstration hydrogen dispensing station that is used to supply a car from solar panels. Its probably moved from the lab to the pilot plant stage. I guess it would be most attractive to new-build renewable generators who wish to utilise energy generated at periods of low demand.
     
  8. Martin Williams

    Martin Williams Active Member

    Not so.

    All that is required is a significantly bigger tank at the filling station - normally the case or it can't serve many cars - containing hydrogen at significantly more than 70 MPa - let's say 100 MPa. Each filled tank will diminish the pressure from 100MPa a small amount, and the service station is effectively 'empty' when this sinks to 70 MPa. (Although it can continue to dispense at 35 MPa ) Yes, the service station will always retain a lot of hydrogen, but that is a much more cost-effective and simpler solution than providing compressors. You might need to warm the hydrogen as it leaves the pressure reducing valve as the lowered pressure will cause a drop in temperature. Alternatively, you allow the temperature to drop and fill the tank at a slightly lower pressure than 70MPa in the knowledge that as it warms up the pressure will rise to 70MPa

    I am not sure how hydrogen will be delivered to the service station. If a large road tanker is to be used to replenish the stations fixed tanks, then you might need a compressor, but the sensible place to locate this would be on the tanker where it will be put to use at every delivery rather than at the service station where it will be sitting idle between fills. The alternative is to deliver the hydrogen in cylinders on a pallet, removing the old ones. This won't need compressors anywhere or the need for a purpose-built truck. Any truck capable of delivering pallets will do. Overall this involves less expensive infrastructure and will probably be the preferred way.

    Perhaps you'd like to explain your belief in the need for compressors at the dispensers if I've missed something.
     
  9. NeilBlanchard

    NeilBlanchard Active Member

    There are several grid storage battery projects that have not been mentioned yet, that are are cheaper than lithium, and much closer to reality than any hydrogen storage system.

    http://news.mit.edu/2016/battery-molten-metals-0112

    http://www.ambri.com/

    http://www.wbur.org/bostonomix/2017/03/27/ambri-molten-battery

    https://spectrum.ieee.org/energywis...ould-provide-affordable-longterm-grid-storage

    https://www.technologyreview.com/s/...cheaper-than-natural-gas-plants-in-minnesota/

    Also, pumped hydro and trains on mountain sides, and hoist weights are other very simple, high efficiency storage methods.
     
  10. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    I think you meant lower pressure, but still, just how do you think you're going to pressurize the H2 from reforming natural gas without using a compressor of some sort? The generating plant may be able to get away with using low-pressure storage -- altho that would require such large tanks that, if my understanding is correct, they generally try to use an existing underground cavern instead -- but it's still going to take a pump, and electricity to run that pump.

    Furthermore, H2 produced by the usual method -- reforming natural gas -- has to be moved to the dispensing station by special tanker trucks which use cryogenics to lower the temperature of the H2 to the point that it can be pressurized enough to be liquid. What is the energy cost for all that, hmmm? And cryogenic equipment is expensive, too! Moving H2 that way must be much, much more expensive than moving gasoline or diesel by tanker truck.

    It's true that an electrolyzer capable of producing H2 under high pressure won't reduce any of those costs. Since 95% of commercially produced H2 is generated by reforming natural gas, that won't impact the cost of 95% of it. But advocates of the "hydrogen economy" hoax always talk about using renewable H2, and the cost of that would be impacted by a high-pressure electrolyzer which doesn't need a special, expensive, high-pressure pump attached to it.
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  11. Martin Williams

    Martin Williams Active Member

    One I've always liked is Pumped Heat Energy Storage (PHES), A company called Isentropics Ltd was awarded a £14 million contract to construct a grid level system. They completed the plant but went bankrupt shortly after. The pilot plant seems to work however and is currently being run by Newcastle University.

    It uses large tanks of gravel to store energy. One is heated to several hundred degrees whilst the other is simultaneously cooled to several hundred degrees below zero using a heat engine running on argon as the heat transfer fluid (cheap, inert and decent enthalpy) during the charging cycle. The heat engine is driven by a motor powered from the mains for this, but on the discharge cycle, the heat engine goes into reverse driving the motor as a generator.

    Round trip efficiency is between 75% to 80% but the real attraction is the relatively low capital cost, the scaleability, and the fact that it doesn't need a mountain to work like pumped storage. You can put it anywhere.

    Newcastle University has published some initial findings an finds the cost-effectiveness is highly dependent on how often it is used. If used a lot it beats most other systems. Those interested can find more detail by looking at isentropic.co.uk which will take you to Newcastle University's Sir Joseph Swan Centre for Energy Research. where explanatory videos can be viewed.

    I like the fact that it's closed cycle, doesn't use any exotic or rare elements, and apart from inevitable wear on the mechanical parts, seems set to last a very long time indeed. I also like the thermodynamic elegance of it.

    Whatever method of storage is used, I think the fact that the energy comes from wind or solar means that its primary cost is zero. Any cost in the energy supplied is therefore almost 100% dominated by the cost of the equipment required to collect and store it. Wind and solar have both fallen dramatically and look set to fall even further, meaning that whatever is used to store the energy has to be as inexpensive as possible, if necessary sacrificing efficiency for lower capital cost.

    Some people - used to thinking about BEVs where efficiency is vitally important - find it hard to accept that it is not the most important consideration in applications like this, but this doesn't damage its validity.
     
  12. Martin Williams

    Martin Williams Active Member

    No. I meant exactly what I said. A higher pressure.

    Go away and read my post more carefully. You seem to have understood almost nothing of it.
     
  13. bwilson4web

    bwilson4web Active Member

    In the following time interval, I've driven over 1,000 battery miles:
    • March 16, 2018 - Hope for battery cars? thread started
    • April 16, 2018 - this post
    This reminds me of a favorite song:


    Or Voltaire:
    • Dans ses √©crits, un sage Italien
      Dit que le mieux est l'ennemi du bien.
    An English version, "Never let perfect be the enemy of good enough."

    The discussion has been useful if nothing else to review what is available, its cost, and progress:
    [​IMG]

    Bob Wilson
     
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  14. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Ridiculous. That means even more expensive, higher pressure storage tanks, even greater need for special expensive seals, even more degradation from H2 embrittling metals, and even greater loss from leakage.

    I certainly cannot see things from the perspective of someone who prefers wishful thinking to reality; prefers it so strongly that he deliberately ignores clear evidence even when it's repeatedly presented to him.

    I have no interest in going far enough down the rabbit hole to understand your perspective, Martin.
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  15. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    May the Great Flying Spaghetti Monster save us from armchair engineers who prefer wishful thinking to the Laws of Physics or practical concerns!

    Martin, it's bad enough that H2 dispensing stations waste energy by pressurizing H2 to 10,000 PSI. Pumping up the pressure even higher would waste even more energy! But hey, you go ahead and send your idea to everybody running an H2 dispensing station, and let them know they're doing it wrong! I'm sure they'll get a good laugh out of your idea.

    My understanding is that most if not all H2 dispensing stations use a separate tank for buffer storage to maintain the H2 at ~10,000 PSI, so it can be dispensed into a fool cell car's tank at that pressure. The bulk of the gas is maintained at a lower pressure, which is not only safer, the storage is also cheaper that way, and loses less over time from leakage. Most people, Martin, would not need to have it pointed out to them that maintaining a gas pressure in the dispensing station's storage which is significantly higher than what the fool cell car's gas tank, seals, and pipes can tolerate, would be extremely dangerous! What you propose is a recipe for disaster, and a pretty predictable one.

    [​IMG]
     
    Last edited: Apr 16, 2018
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  16. bwilson4web

    bwilson4web Active Member

    Waiting for Proton
    By Samuel Beckett (edited by Bob Wilson)​

    WILLIAMS "Let's go!"
    PULLYU "We can't."
    WILLIAMS "Why not?"
    PULLYU "We're waiting for Proton."
    WILLIAMS "(despairingly) Ah!"
    . . .
    PULLYU "Why are we here, that is the question? And we are blessed in this, that we happen to know the answer. Yes, in this immense confusion one thing alone is clear. We are waiting for Proton to come. ...We are not saints, but we have kept our appointment."
     
  17. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Hmmm, well I appreciate you making an attempt at somewhat sophisticated humor. However, I don't see much of an analogy there. If Martin wants to buy a Mirai or other FCEV, nobody is stopping him from doing so. And if anyone is saying "We can't!", it's Martin... who keeps arguing -- contrary to all evidence -- that battery tech has suddenly hit a wall and won't continue the trend of improvements we've seen over the past 35-40 years.

    Sure, there is a vague analogy with "Waiting for Godot", in that we're engaged in endless discussion of minutae while waiting for that "Everyman" electric car to appear on the market; the EV analog to the Ford Model T in the motorcar revolution. The car which will convince Joe Average that EVs are better than gasmobiles, and going to make them obsolete. That hasn't happened yet, and may not for several more years.

    But I'm not -- nobody is -- telling Martin that he can't run out and buy a fool cell car just because most of us are waiting for that Everyman BEV to appear on the market. Obviously Martin isn't waiting for any Everyman BEV, because he doesn't believe there will ever be one!
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  18. bwilson4web

    bwilson4web Active Member

    Going back to the old dial-up, bulletin boards and USENET, discussion groups have always had members who remain remarkable detached from an empirical universe. After making several attempts to achieve a consensus, we are reduced to: insult; ignore; flee, or; humor.
    • Insult - doesn't really work but rapidly degrades to a few, Anglo-Saxon words like the ones used in Marine bootcamp (I have some experience.)
    • Ignore - this can work but it leaves behind those still trying to talk sense. One-sided threads that often have unexpected humor.
    • Flee - USENET is pretty much unusable.
    • Humor - at least now we can grin and move on.
    I've never really understood how some folks can hold to a point of view even when it means denying the advantages to themselves. Just it is how it is.

    Bob Wilson
     
  19. Martin Williams

    Martin Williams Active Member

    My point is that energy is cheap, and getting cheaper by the day. Compressors and the associated coolers are expensive. So it makes perfect sense to trade the one off for the other. Nor do I accept that it is any more dangerous. Hydrogen storage is carried out above ground. Any leakage will be tiny anyway and will rapidly dispense. Pressure reducing to 70MPa at the outlet from the transfer tanks to what the car needs (or a bit lower for the reason I gave earlier) mean that all pressure in the station after that point will be at 70MPa or lower and poses no greater danger than now. The elimination of the compressor alone will reduce leakage. It is pretty unlikely that a compressor would not involve numerous seals and gaskets, all of which are likely sources of leaks, particularly after hours of vibration.

    That the diagram you display is how it is done now is certainly one way of doing it, but it is not the only way, nor the cheapest in terms of capital cost. I believe the logic of the situation will eventually force my way of doing it.

    That it costs more energy is debatable anyway. I suspect a large industrial compressor (or a high differential electrolyser) pumping transfer tanks to 100MPa is likely to be more efficient than transferring it at low pressure and then compressing it expensively at every filling stations simply because large compressors can be made a lot more efficient than small ones.

    Probably the fact that it is currently done in the expensive way you exhibit has more to do with what is industrially available at the moment than any analysis of the wider advantages and disadvantages.

    I am a great believer in KISS - Keep It Simple, Stupid. Generally the less complex the solution, the better it works.
     
  20. NeilBlanchard

    NeilBlanchard Active Member

    Whatever the cost of energy is - the cost of running battery electric cars will be about 1/6th the cost of fuel cell electric cars.

    Infrastructure for hydrogen is even worse - by an order of magnitude, at least.
     

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