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A viable pathway for hydrogen as fuel

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Re: A viable pathway for hydrogen as fuel

#31

Post by mojomark »

_ph_ wrote: post #3

The article names it, but then does not dive deeper into it: the hydrogen chain has huge energy losses. First, electrolysis unfortunately has not a high efficiency - I have read numbers around 70%, but then the compression of the produced hydrogen takes a lot of energy, as compressing gases heats them up. Then the hydrogen has to be transported and stored, requiring further energy. Finally, you have to use the hydrog…

Did you read the full article? It's in there - he developed a new Titanium electrode to improve the efficiency ond reduce the footprint of the electrolysis hardware and he also developed a new hydride (with a weak H2 bond to support release of H2 using waste heat) for greatly improved energy density. The specific values are in the article; maybe someone nicer than me will do more work to pull that for you.

Re: A viable pathway for hydrogen as fuel

#32

Post by dpark »

nine_k wrote: post #27
phkahler wrote: post #16

Earlier quoted context omitted.

HyTech doesn't solve the main problem with hydrogen - that there isn't any available as fuel, and it takes more energy to extract the hydrogen than you get back from burning it or even using it in a fuel cell. The idea of injecting small amounts of hydrogen into a combustion engine to improve fuel economy is not new, but congrats if they can bring that concept to market. That would be a win, but is not the same as hy…

It takes more energy to charge a battery than can be had back discharging it. Does it make the battery in your mobile phone useless?

No one cares about the efficiency of the tiny battery in your phone. But if charging and discharging a Tesla used twice as much energy as burning gasoline directly then people would probably care.

At some level of inefficiency, an energy solution can indeed become useless at scale.

Re: A viable pathway for hydrogen as fuel

#33

Post by dpark »

MechEStudent wrote: post #30

Hydrogen has hard risks, and high costs. Density. Corrosion. Tunneling/leaking. A new trillion-dollar distribution infrastructure to replace the fluid-version we use for petrol. What about methanol? We can convert hydrogen to hydrocarbon. Liquid is dense, much less dangerous, less acidic, less leaky, and our current trillion-dollar infrastructure already uses it as a substantial additive.

Methanol isn’t a common additive is it? Most (all?) gasoline in the US has ethanol added.

Re: A viable pathway for hydrogen as fuel

#34

Post by Animats »

Something is wrong with his numbers.

"Johnson boasts that his electrolyzer can produce hydrogen at about three or four times the rate of electrolyzers with similar footprints, using about a third the electrical current. That represents a stepwise drop in costs."

Three or four times? Current efficiencies are 65-70% for larger plants.[1] There's a theoretical maximum here; it takes a known amount of energy to break down water into oxygen and hydrogen. This isn't magic or perpetual motion. Electrolysis is energetically uphill. You can get most of the energy back recombining oxygen and hydrogen in a fuel cell or by combustion.

The "with similar footprints" is very suspicious. His demo unit is small. Little electrolyzers are known to be inefficient. Industrial units are bigger and more efficient.

As an emissions control measure, it might work out.

[1] https://en.wikipedia.org/wiki/Electrolysis_of_water#Industri...

Re: A viable pathway for hydrogen as fuel

#35

Post by DesertVarnish »

dpark wrote: post #33
MechEStudent wrote: post #30

Hydrogen has hard risks, and high costs. Density. Corrosion. Tunneling/leaking. A new trillion-dollar distribution infrastructure to replace the fluid-version we use for petrol. What about methanol? We can convert hydrogen to hydrocarbon. Liquid is dense, much less dangerous, less acidic, less leaky, and our current trillion-dollar infrastructure already uses it as a substantial additive.

Methanol isn’t a common additive is it? Most (all?) gasoline in the US has ethanol added.

Methanol is commonly sold as "octane booster". It's definitely around.

Re: A viable pathway for hydrogen as fuel

#36

Post by noir_lord »

dpark wrote: post #32
nine_k wrote: post #27

Earlier quoted context omitted.

It takes more energy to charge a battery than can be had back discharging it. Does it make the battery in your mobile phone useless?

No one cares about the efficiency of the tiny battery in your phone. But if charging and discharging a Tesla used twice as much energy as burning gasoline directly then people would probably care. At some level of inefficiency, an energy solution can indeed become useless at scale.

That depends though on a bunch of factors including base price of electricity, renewable potential and how easily hydrogen can be shipped.

There are a few developed countries I can think of that have vast renewable capacity but the distances between the optimum location for renewables make it impractical at present.

Also modern nuclear plants are an option if you want to produce vast amounts of electricity with a smaller carbon footprint than coal/gas.

Re: A viable pathway for hydrogen as fuel

#37

Post by [deleted] »

nine_k wrote: post #26
semi-extrinsic wrote: post #25

Earlier quoted context omitted.

> the best engineering solution to the remainder of the task list of transport, store, and burn the resulting carbon-free hydrogen, is to modify the hydrogen by synthesize up some carbon containing hydrocarbons If that's the case, it's equally true for H2 from renewables, no? And I don't think it's true. LPG vehicles today are common enough, and they've solved very similar transport and distribution problems.

Not really. Hydrocarbons are much easier to store and handle. Cars may not need it so much, but as a jet fuel, kerosene is much easier than hydrogen.

[deleted]

Re: A viable pathway for hydrogen as fuel

#38

Post by yongjik »

asgeirn wrote: post #19

Most counterarguments related to Hydrogen refer to the poor efficiency of converting (electric) energy to Hydrogen and back. True, directly using that electric energy from wind or solar is definitely the best option. However, that is not always possible, since there is no place to consume, transport or store that electric energy. Furthermore, scrapping all ICE vehicles for BEVs is most likely the end goal. But replac…

If you have excess electric capacity, I think there are more convenient things to produce, such as aluminum. It lasts forever, it's easy to transport, producing it is very energy-intensive, and there's a constant demand. E.g., aluminum is a big industry in Iceland thanks to its cheap geothermal/hydro energy.

Re: A viable pathway for hydrogen as fuel

#39

Post by ekun »

sebazzz wrote: post #17
_ph_ wrote: post #3

The article names it, but then does not dive deeper into it: the hydrogen chain has huge energy losses. First, electrolysis unfortunately has not a high efficiency - I have read numbers around 70%, but then the compression of the produced hydrogen takes a lot of energy, as compressing gases heats them up. Then the hydrogen has to be transported and stored, requiring further energy. Finally, you have to use the hydrog…

How does that compare to using batteries? Batteries are re-usable of course, but also degrade over time and need to be replaced.

It mentions this in the article Li-ion go have a life cycle of roughly 1,000 recharges whereas these have 10,000.

Re: A viable pathway for hydrogen as fuel

#40

Post by [deleted] »

Animats wrote: post #34

Something is wrong with his numbers. "Johnson boasts that his electrolyzer can produce hydrogen at about three or four times the rate of electrolyzers with similar footprints, using about a third the electrical current. That represents a stepwise drop in costs. " Three or four times? Current efficiencies are 65-70% for larger plants.[1] There's a theoretical maximum here; it takes a known amount of energy to break do…

[deleted]
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