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filosoful OP t1_iwpb8xw wrote

Hydrogen is touted as a wonder fuel for everything from transport to home heating — but greener and more efficient options are often available.

The problem is that hydrogen is not freely available. On Earth, it exists mostly in molecules bound to other elements, from which it must be extracted at huge energetic cost.

Policymakers should beware potential unintended negative consequences for both people and the planet from an overwrought dash for hydrogen.

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Donttouchmybiscuits t1_iwpcgmk wrote

There are however a few instances where there’s really not much of a better option (as far as I understand it, I’m very much not an expert!) such as steel production. We’re going to need it as a part of our arsenal to decarbonise, and while it’s not yet a mature green tech, that’s much like solar was 20 years ago (and to a great extent still isn’t. Recycling panels really isn’t a thing yet). This “either or” mentality about electric and hydrogen is counter productive, they both need to work, have functional infrastructure, and get properly developed and deployed in their most appropriate applications.

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Salahuddin315 t1_iwqhilk wrote

Except that it is an "either/or" proposition. For an energy system to be feasible, there needs to be a focus on something. Either everyone uses the same technology or nobody does. Europe has thankfully realized this, so they're making a decisive move against fussil fuels in favor of wind and solar. That will be costly, but it is either that or sitting on the fossil needle until we're all screwed.

The planet is almost done for. There is no time or resourses left to spread out.

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Donttouchmybiscuits t1_iwuvvb0 wrote

Reread my last comment, take the time to understand what I’m saying (emphatically NOT that fossil fuels have a part to play) and then explain to me how wind and solar can take the place of the current fossil fuel used in the furnaces to make steel - not as a fuel, but as an essential part of the process. Hydrogen is pretty much the only answer at this stage. It’s not an either/or, because neither does everything, that’s a ridiculous way to look at it.

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[deleted] t1_iwphd9w wrote

Hydrogen does get around one massive issue - infrastructure. A lot of Europe is heated by gas, and switching everyone over to heat pumps will cost tens of thousands per home. Mixing hydrogen with something inert to mimic the volumetric energy density of methane would allow you to switch over at the distribution end, with little effort/cost to the individual. Generating hydrogen via green sources then burning it again isn't the best way of heating a home, but it's a fantastic stopgap in the transition period that allows us to switch off the natural gas aspect of our fossil fuel usage sooner than we otherwise would.

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Popswizz t1_iwq2mkq wrote

Except it's not really, I was part of analysis on the subject and with current technology, even with free electricity (as this would be a mean to offset green energy uncontrolled output) there's no payback to pay for the machine before 10 years unless hydrogen is subsidized

And even then as you said you need a natural gas pipeline near that can accommodate high hydrogen % and natural gas heater in home that can as well which is a logistics nightmare

There's some very niche usage and the one you mention is one but it's far from a widespread technology we can use everywhere

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[deleted] t1_iwq95pj wrote

That's not really a niche usage, pretty much every home and cooker in Europe is powered by natural gas. It's not an economic suggestion by any means, it's a green one due to the speed it can be rolled out. It's far less of a logistical nightmare than replacing every boiler (of which a high percentage don't have the required hot water tanks, or the space to accommodate them) with heat pumps over the same time period. Do we even have enough heating engineers to change 200 million homes over in the few years it would take to replace methane with hydrogen at the distribution level?

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Popswizz t1_iwqq8at wrote

It's niche because not all pipeline are able to accommodate hydrogen in large quantity, because not all boiler can accommodate high percentage of hydrogen, because not all green energy powerplant is near enough a pipeline to link to it with their hydrogen production, so it's niche because logistical it's a nightmare not because it's not technically doable

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Tenrath t1_iwqdc4a wrote

I could be wrong, but I think there are also changes required at the consumption end to accommodate the change in gas. Same reasons why a propane boiler and natural gas boiler are not interchangeable without modification kits.

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[deleted] t1_iwqe6y7 wrote

There'd be small changes, yeah. I'm on the aircraft side of things, but assuming they're similar enough it'd be a component analogous to the flame holder that would be the main issue. There's a minimum hole size a flame can propagate through that depends on the gasses.

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danielv123 t1_iwq861g wrote

Hydrogen is one of the worst alternatives to heat pumps I could imagine, short of resistant heating powered by hydrogen driven turbines. Electrolysis is about 75% efficient. That means you need a lot of extra electricity. In addition you need facilities for electrolysis, which isn't cheap.

It might help a bit as a form of storage but is still worse than hydrogen + tubine + heatpump.

Cost to the individual shouldn't matter, the lowest overall cost should be picked. In a hydrogen conversion scenario the lowest cost often ends up being natural gas, which gets us nowhere.

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[deleted] t1_iwq8rfs wrote

It's a matter of inertia, not just cost. You will get people transitioning to heat pumps over time, absolutely, and they're the best option by far. But in the mean time, hydrogen gets those same people off natural gas incredibly quickly, without the gargantuan total-war-like effort required to replace every boiler and cooker in every home in Europe in the same time frame.

The overall cost isn't the only consideration. Stopping a large chunk of emissions quicker but expensively is better than too late and cheaply.

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OptimalConcept143 t1_iwpgktt wrote

Hydrogen is the only fuel source that can replace fossil fuels for basically every use. The only reason it isn't doing so right now is because it requires too much energy to produce. If something like nuclear fusion finally happens, this wouldn't be an issue and it would by far be the most efficient and green fuel source possible, and that's from a physics perspective.

https://en.wikipedia.org/wiki/Energy_density#In_chemical_reactions_(oxidation)

As you can see here, hydrogen has more energy density than any other common fuel source, including fossil fuels. It's not a matter of "if" hydrogen becomes our main fuel source, but "when".

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real_grown_ass_man t1_iwpkaup wrote

Energy density per weight, yes. Energy density per volume is about the same as a lithium ion battery. On top of that, hydrogen is difficult to store at length.

For this reason, hydrogen will remain an energy carrier in very specific niches, where large volumes are no problem and where the necessary safety precautions are acceptable.

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OptimalConcept143 t1_iwpo0v5 wrote

Not true. The energy density of liquid hydrogen ranges from 4.5 MJ/L for low pressure hydrogen gas to 10 MJ/L for high pressure liquid hydrogen. Lithium Ion comes in around 0.93-2.63 MJ/L. You can see that on the Wikipedia article linked in the previous comment.

For vehicles such as airliners there simply isn't another alternative fuel that can replace kerosene, it will be hydrogen.

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real_grown_ass_man t1_iwps4p1 wrote

The article you quote has 10 MJ/L as HHV for liquid hydrogen. This is at 20k and 1bar. You will need to account for the cooling device to give a realistic number for volumetric energy density.

4,5 MJ is at 690 bara, which i am confident to classify as very high pressure. Lower pressures are also used, and i’d say that this is in the same ballpark as batteries (in volume). This all follows from your article.

I’d say hydrogen fuelled aircraft are a one of the niches where the high volume and safety measures might prove practical, although hydrogen might also be used to form CH4 or longer C chains from CO2 and turned into a traditional but green fuel.

For home heating or transportation I don’t think hydrogen is very practical. But who knows. I hope i am proven wrong.

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OptimalConcept143 t1_iwptosi wrote

If we had the ability to create cheap hydrogen you'd probably have enough electricity to just heat homes that way. Especially when systems like heat pumps can get well over 100% efficiency.

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RSomnambulist t1_iwpw3vu wrote

This also isn't taking into account battery advances like solid state. Amptricity is preselling home batteries now.

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OptimalConcept143 t1_iwpxljn wrote

Batteries can't chemically be as energy dense as hydrogen or fossil fuels. They will improve, but not significantly.

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jeffreynya t1_iwpxo6h wrote

the cost!! holy Crap!

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RSomnambulist t1_iwpy3do wrote

Yeah. They look to be about 2x-3x as expensive as just an LI battery, but there are insurance savings to take into account and the fact that they are significantly safer and more efficient and should last about 10-20y longer. I think the cost is worth it, but they're also the first people on the scene. I expect competition to make them close to LI cost.

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sawlaw t1_iwq54tt wrote

I try not to get too hyped for things just because there are a few pre sales. Once production begins in Ernest and there are a few thousand happy customers I think I'd be ready to make the move, until then it's something for people with money to burn and gamble.

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RSomnambulist t1_iwq6lcf wrote

I'm not spending my money on it, but I'd say that based on preproduction and existing samples and manufacturing that is online already--solid state is further along than HCV mainly because there is so few HCV infrastructure.

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UniversalMomentum t1_iwppclc wrote

We can dream, but I'll have to see real world LCOE stats before I start accepting Fusion as a cheap option. Until then it has horrible LCOE because it's all investments and no power output.

Nuclear has such a long history of claiming much cheaper costs than it winds up producing and with such high complexity I have my doubts it willproduce wind/solar level cheap energy.

Same thing happened with fission. On paper it was much cheaper than averaged real life costs. Plus nuclear LCOE doesn't take real long term waste storage or inevitable accidents into account. They are cheating LCOE pretty hard on the nuclear side just like the fossil fuel side and all it's externalized long term costs.

Also the problem of just convincing a country that can't build nuclear reactors to switch a huge chunk of its power generation over to nuclear reactors and then be completely dependent on one or a handful of countries that can maintain those reactors. As well as venting the countries making Fusion reactions to export to developing nations.

On Paper those obstacles might not look huge, but I'm pretty sure they are.

Of fusion can produce a levelized cost of energy around $25 per megawatt hour then it will at least be a good option for the handful of countries that can build the reactors, but I doubt it will scale out globally.

Try to think about it like you're the developing country and America has highly proprietary power plant design that it wants you to invest in and will require you to basically stay in America's favor or not be able to fix your own power plants.

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