Boeing Flys Plane on Hyrdogen, Fuel Cells

H

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Wow, we humans are a creative species.


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I wonder if, 100 years from now, people will look back at this plane just like we do towards the Wright Brothers' plane at Kitty Hawk. I mean, if you look at that plane and look at where planes are now you'd say "that plane at Kitty Hawk was pretty dang primitive." I just think that people may look at the plane shown here and say "wow, that first hyrdrogen fuel cell plane was pretty dang primitive."
 
The energy density of H2 versus the energy density of batteries will be an interesting competition. I think that in the end (i.e. before either is commercialized), batteries will prove easier to handle than H2.
 
i may be speaking out of school, but i dont think either will ever approach the density of fossil fuels. maybe on a net basis after the effeciency of the engine is put into the equation. on a gross basis i just dont see it happening.
 
Frat, that's what they used to say about the size of computers 50 years ago. The barriers to faster chips, smaller fixed memory, etc., etc.
 
My analogy is much more simple. It's about the perception of a physical barrier because the lack of a) technology to advance through that barrier or b) understanding the actual physics that allow us to master a new technology.
 
Mass is what matters if you're thinking of the energy required to move something around until something is so voluminous that it interferes with aerodynamics. However, that only gives you a 3:1 advantage for Hydrogen.H2 is converted to electricity at about 60-65% efficiency in an alkaline cell. A 100hp motor operates at a maximum 90% efficiency. So you wind up with:
143 MJ/kg*.6*.9= 77MJ/kg.

For gasoline it's about 30% efficiency, and we'll ignore the rest of the system. That gives:
47MJ/kg*.3=14MJ/kg.

You wind up with about 5.5x more energy per unit weight of fuel with H2. These are best efficiencies, and both will be worse when accelerating (though an H2/electric vehicle will do better there unless the gasoline vehicle also has regenerative braking).

Now, the problem that you mentioned about H2 being a ***** to contain is certainly valid, thus my original post. The new Li-ion nanowire batteries are supposed to get an energy density of around 6 MJ/kg, which is a 10x increase over where the tech is now. So, we come to the big question: Can we figure out a way to efficiently generate and compress H2 using water and electricity? Remember that the ****** MJ/L for H2 is with the H2 compressed to 10,000 PSI (i.e. a **** ton, remembering also that compressing a gas is a very energy intensive process).
 
Maduro, wouldn't volume come into play also? A larger tank would be necessary for storage. That tank would add to the weight, especially if we are talking about storing hydrogen.
 
hindenberg1.jpg
 
so if we agree that you can get to a workable automobile solution and are indifferent between Gasoline and H2 the question becomes, as you alluded to, what is the end to end energy cost of 'filling up the tank'.

crude is about 10:1 energy profit ratio and falling modestly. refining will have some effect but I am not sure the degree - Gasoline is probably the most energy dense of the distillates, but do you lose a lot when you crack it out? i dont know. what is the ultimate EPR of GASOLINE? 8:1? Transport is pretty efficient so there is probably not much loss there.

Hydrogen comes from i guess water and the separation of the molecule is probably pretty efficient so the question is one of

1) what energy source do you use to power the separation? wind is 50:1 but i dont think they take line loss into account for transporting the generation. that is a big number - can be over 50%

2) transport of the hydrogen - if its anything like nat gas probably a minimum effect - 2-3% loss. but the pressures you are talking about are much higher so the loss will be greater 10%? more?

3) pressurization - i have no idea here. somebody throw out a number. is your 50% loss number something we should go with or just a wild *** guess?

we are getting close to solving the energy crisis. lets not give up now!
 
Generating H2 from water and electricity is not efficient (nowhere near the 50% you generously gave it). This figure can be improved upon and it seems likely that we will be able to.

What can't be improved is the cost of compressing it, which I think will be more than the energy contained in the compressed gas. My point earlier was that at 10k PSI, you can make do with the increase in volume required to store a given amount of energy. At 1/10 of 1/100 of that pressure, you can't. So we have to expend the energy to compress the most "difficult" possible gas, and the technology for doing that won't become more efficient.

So, going back to your model, I'd say that you could get 80% of your energy back when you convert it to H2 (that's optimistic), but that you will then lower that to 10% efficiency once you get the H2 compressed. In a way, I'm with you on the usefulness of fossil fuels now- I think that for the next 20 years, we'll drive composite vehicles powered by small, two-stroke diesel-electric parallel hybrids with exhaust heat regeneration (BMW is working on this....I think they call it a Steam Assist Drive).

A car that really gets 70mpg and costs $20-25k is possible with the tech that's commercialized/will be presently. I think that we'll see Detroit adapt to that once the reality sets in with buyers about $3/gallon being "the good old days when gas was cheap".
 
Electrolysis take roughly 100 kcal/mol yielding H2 with about 70 kcal/mol, so that part is 70%.

Cryogenic liquification which is required for efficient transportation requires about 60% of the available energy from the H2. That knocks it down to ~30%.

Evaporative losses moving and transferring cryogenic liquids is high. The 50% figure may be optimistic, but if you go with it that is 15% if the initial energy making it to a vehicle where it is used.

If 10% of the initial energy that goes into making the hydrogen gas gets used then your process is real good.

Now go talk to Homeland Defense about what they think about the fuel air explosives being trucked all over the country lacking only a detonator, and then factor in the security, insurance, and cleanup costs.
 
thanks for the information you two. I havent bothered to multiply it all out, but it looks like H2 as a store is not really useful until the profit ratio on fossil fuels gets cut in half again. Its just too efficient of a system to fill the tank.

batteries have a long way to go to reach the density of either H2 or gasoline so they are not worth discussing until the 50x increase in density happens

seems like the best way to improve things is to get the most out of the gas in the tank, not replace the gas in the tank with something else.
 
One example, the EEStor capacitor takes up 1 cubic foot not counting control electronics and converters. 1 cubic foot = 7.5 gallons, so three cubic feet equates to an average gas tank. It would be pretty easy to make room for 5 or 10 cubic feet if necessary.
 
There are 3 threads on this ATM, but I think for one I figured out that the EEstor capacitor has an energy density of around 1.3 MJ/kg, the new Li-ion battery (which apparently needs another breakthrough to work_ is projected at just under 1, and gas stands at 47.

Frat, that energy density link rocks and it's a great quick reference.
 
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