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Comment by rini17 | Hacker News Reader

There is still a hard limit to hydrogen energy density that is likely to never be crossed. And safe consumer-friendly handling of pure hydrogen is much more expensive than electricity, that also stems from physical limitations. These limitations are being hit now. On the other side, batteries and chargers did not hit their hard physical limitations yet. Supercapacitors exchanging many megawatts of energy over superconductive wires are feasible.

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Hydrogen energy density is around 39,000 Wh/kg. That's rarely going to the limiting factor. The physical limitations are nearly the same as natural gas, which is to say they are easily solvable. Superconducting wires will have their own major issues that are a long ways away from being solved.

In reality, we're nearly at the point where hydrogen is a solved problem, but batteries will be a very long ways away from being a car for everyone. In particular, you've ignored the limits on battery energy density which will likely limit battery powered cars to either expensive luxury cars or short-ranged urban cars.

You conveniently omitted the storage vessel factor from the energy density. And it's definitely not comparable to natural gas in other respects too, such as hydrogen is corrosive and needs special alloys or nonmetal materials.

Superconducing wires are already and increasingly used in practice. Even without superconductors we can just keep raising the voltage and use copper, there are new silicon carbide power transistors that make it possible. We aren't near physical limit yet.

Other assertions of yours are likewise unfounded, too.

I can totally see hydrogen airplanes but for cars it's too little too late.

From a theoretical standpoint, you don't need to worry about that. You can conceive of metal hydrides or other forms of dense hydrogen storage. Even as LH₂, you're still looking at around 2700 Wh/L of energy. That's well beyond any known rechargeable battery.

And the "special alloys" really just mean certain types of steel alloy, and "nonmetal materials" really mean certain types of plastics. This is not a big challenge.

You still need very low temperatures and exotic materials for superconducting cables. Not to mention the power generation needed to sustain that level of power draw. This is a long-term problem that we're nowhere near solving.

As I said before, this is not a race and there is no finish line. There's nothing stopping fuel cell cars from displacing EVs at an arbitrary point in the future.

From theoretical standpoint why not jump ahead to antimatter? :)

Electricity is a solved problem, most obstacles to additional power generation and transport are bureaucratic in nature.

As soon as everyone agrees to build more nuclear power... We're not anywhere near ready to use anti-matter, but the next best thing faces extreme opposition for some reason.

Hydrogen is pretty much a solved problem too. Most of the critics are just stuck in 2010 or earlier.

I did not have primarily nuclear in mind, but obstacles to extending long-distance electric grid to support renewables. But hydrogen pipelines are going to have even worse problem with this. And you did not really debunk any of my "stuck in 2010" criticism.

Hydrogen pipelines are a solved problem. We have been doing it for decades[1]. I could have said "stuck in 1930" but that might be overdoing it.

[1] https://en.wikipedia.org/wiki/Hydrogen_pipeline_transport

> Hydrogen energy density is around 39,000 Wh/kg

Lithium's energy density is 11,600 Wh/kg.

> In reality, we're nearly at the point where hydrogen is a solved problem, but batteries will be a very long ways away from being a car for everyone

I can buy a battery powered vehicle today. Seriously it's 5pm on a Sunday. However the dealer is open till 7pm and they have a couple of dozen Chevy Bolts on the lot.

That's much lower than hydrogen. So what was the argument here?

You can buy a fuel cell car today too. I've notice that many of you guys are stuck in 2010 or so. Fuel cells cars are far beyond your outdated viewpoints.

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