[Kayou]

In that case what prevents us from building energy storage facilities that produce hydrogen at night and release the electricity back into the grid during the day? Wouldn't it be more efficient than transporting the hydrogen by truck and transporting the hydrogen battery on every train?

[rightbyte]

Yes. That would be a better idea.

[morphle]

but it would still be very much more expensive than just solar

[dragontamer]

Solar isn't even competing against Hydrogen.

Hydrogen is a storage technology, not really an energy source. Hydrogen competes with Li-ion batteries.

How many Li-ion batteries do you need to equal one 200-ton liquid H2 storage tank? At 120MJ per kg, 200-tons == 200,000 kg == 6GW-hrs of electricity. There's no Li-ion battery in the world that's anywhere close to that kind of storage capacity... and various researchers are aiming at 3000ton H2 storage tanks.

Erase 50% or even 80% of the energy due to inefficiency / costs of cryogenics, and you still have a bigger energy storage tank from H2 than anything possible with Li-ion. And the future of H2 is looking like 10x capacities are reasonable over the next 10 years.

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Whatever solar solution you were thinking, just do the same except instead of using big, expensive, heavy Li-ion batteries, replace the storage mechanism with H2 fuel cells.

[nine_k]

Higher energy density = higher danger of releasing it unintentionally.

I totally understand why hydrogen is a great rocket fuel. You need this high energy content and the extreme lightness for high Isp.

On land, I suppose, the energy density of 100 tons of hydrogen in one place is unnecessarily high. The fact that hydrogen has no odor, and its flame is entirely infrared, invisible, does not help.

By the same token, I think that lithium batteries have excessive energy density for large-scale land applications, like buffer storage for solar / wind power. Even a lead-acid battery, with all its environmental downsides, weight, etc is at least not a major fire hazard. I suppose that large-scale electricity storage will take off when cheaper and safer, while less dense, alternatives to lithium batteries are commercialized.

As a power source for a car, a lithium battery at least is not cryogenic. OTOH on the scale of a train this may already be not a big problem. Same possibly for an oceangoing ship, but it would be terrible to start losing fuel and power if a bad storm damages the cryogenic system.

An ideal (fantastic) system could use methane and turn it into carbon, only oxidizing the hydrogen. Sadly, similar reactions only work so far with much more complex molecules.

[_hypx]

Lithium batteries are extremely flammable. Worse, fires are extreme hard to extinguish. For trains this would be a truly huge fire.

Converting methane into hydrogen is known as steam reformation. We can easily due this, but we don't want to because it is a fossil fuel.

[ben_w]

> The fact that hydrogen has no odor, and its flame is entirely infrared, invisible, does not help.

I thought it was UV? (Which, if anything, is even worse).

[dragontamer]

> In that case what prevents us from building energy storage facilities that produce hydrogen at night and release the electricity back into the grid during the day?

That's literally the plan?

https://www.nrel.gov/news/program/2020/answer-to-energy-stor...

Hydrogen is a newer technology than Li-ion. But yeah, its more than capable of these things. We just gotta build out pipelines and facilities to handle it.

But no. To deliver MWs of electricity to trains requires using a ton of copper on all rail-lines, as well as advanced transistors to switch that electricity around. Hydrogen storage of electricity is a good idea and is being developed, but there are innate benefits to the fuel-methodology for applications like trains.

In particular, a pipeline will likely transmit more "energy" at cheaper costs than a bundle of copper wires. Steel and concrete pipelines are just cheaper. So instead of building expensive copper wires + expensive transistors to switch electricity all around the place, why not build pipelines?

> Wouldn't it be more efficient than transporting the hydrogen by truck and transporting the hydrogen battery on every train?

Well, first off, the most efficient form of transporting Hydrogen would be a pipeline. But lets say we're dealing with a remote area so a truck is necessary.

1kg of Hydrogen has 120MJ of power, or 0.033 MW-hrs of electricity. A singular kilogram.

https://www.energy.gov/eere/fuelcells/hydrogen-tube-trailers

These trailers can store 900kg of Hydrogen. Or in other words, 30 Megawatt-hours of Hydrogen based electricity. Larger vehicles, like trains, can likely afford to carry larger containers, possibly even cryogenic liquid-hydrogen that is even more compact.

https://demaco-cryogenics.com/blog/liquid-hydrogen-storage/

Current storage tanks from NASA can hold 270 tons of liquid Hydrogen, with plans to scale to 3000 tons of liquid hydrogen storage. That's 3000000 kg, or 100 Gigawatt-hours of energy storage per tank.

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So yeah, the amount of H2 energy storage available far exceeds what is possible with Li-ion technology.

Pipelines will be more efficient at moving Gigajoules / dozens of MW-hours at cheap costs. Trucks and trains can carry the fuel wherever they need to go. Energy storage / Hydrogen batteries will scale to far higher capacities than Li-ion could ever dream of.

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Hydrogen is an incredibly light fuel. Its difficulty in transportation is __volume__ rather than its weight. Storage technologies, such as higher pressure (700-bar or higher), and liquid cryogenics are needed for H2 storage to be effective. These technologies are just becoming possible today.

So only now can we dream of what liquid-hydrogen storage tanks can offer us. Literally 100GW-hrs of energy per liquid-hydrogen tank is feasible (while *current* prototypes from NASA are holding 9GW-hrs of energy storage).

[adrian_b]

Even if diesel fuel has only about 3/8 of the energy per mass of hydrogen, it has much higher energy per volume than hydrogen.

For a locomotive of a train, the volume of storage is a much more important limitation than the mass.

Moreover, after adding the mass of the fuel containers, it is likely that diesel fuel has also a greater energy per mass than hydrogen.

Hydrocarbon fuel can also be transported by pipelines.

So none of these arguments show any advantage of hydrogen versus the traditional diesel fuel.

[dragontamer]

The idea is to create a green fuel of the future, powered by Solar Panels and Nuclear energy, and wind and hydro.

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I do think that green-hydrocarbons have a potential future. Green diesel would be a biofuel. But Hydrogen can turn into a hydrocarbon through Syngas synthesis (eventually turning into Kerosene and other "green hydrocarbon" fuels).

If the chemistry works out, maybe that's the future. But experimentation with pure H2 looks promising right now.

[adrian_b]

I believe that as you say, converting the hydrogen obtained by electrolysis or photolysis into hydrocarbons via syngas is the most likely future solution for all energy storage problems where batteries are inappropriate.

Even if the energy efficiency of a storage cycle is lower than when using directly the hydrogen, the savings due to easier handling and storage are huge.

Moreover, that path will allow the reuse of all the existing infrastructure for hydrocarbons, whose replacement would require a very long time and very high costs.

[dragontamer]

H2 can be transported over natural gas pipelines. At least as high as 15% hydrogen / 85% Nat Gas.

Maybe that's not enough for the long term, but that mix/ratio should be sufficient to bootstrap the fledgling H2 industry.

If Syngas / synthetic diesel becomes more efficient in the future, we switch to that. I'm not against experimentation or tests.

[Kayou]

Thanks for the article on energy storage with hydrogen to resolve peaks on the grid. Seems like a nice solution on paper, although ineficient according to this article citing someone from the MIT, round-trip efficiency of 18%-46%.

https://www.spglobal.com/marketintelligence/en/news-insights...

[dragontamer]

Considering that night-time energy from nuclear plants, as well as peak 12pm noon energy from Solar Power plants, are going wasted right now, 18% round-trip efficiency is better than the 0%-efficient fully wasted energy that we're doing right now.

[ngcc_hk]

But is the liquid hydrogen that leaks and have fire hazard that delay the nasa launch now?