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Comment by iamthemonster | Hacker News Reader

"Hydrogen" is a fundamentally different thing to "solar". There is no "straw man argument" being made because it's comparing apples and pears.

The only purpose of hydrogen is to make energy in one point in space & time and then use it in another point of your choice without CO2 emissions. Solar is to convert sunlight to electrical energy, but you don't get to control when the sun is shining. The technology to generate hydrogen is also completely mature and has been since before I was born, whether we are talking steam methane reforming or electrolysis. It's just not very cheap.

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except hydrogen is a horrible option. It is hard to store safely, it is highly explosive, energy expensive to produce vs the energy you get back out, it damages its own holding vessels via hydrogen embitterment, outside of a few niche areas it in generally a bad option.

No idea about energy consumption, so I would assume using dirt cheap solar in remote places with defacto zero variable production costs (over simplified, but this is one reason wind and solar are pricing out other sources on the German spot market which ignores fix costs) might change that.

Long term storage of hydrogen is quite easy so. It can be stored in thermal oil, rendering it inert. In thay form it isn't even considered dangerous goods for transportation anymore.

Source: I consulted a green hydrogen project on logistics a while ago.

> highly explosive

It's only explosive when mixed with air in confined places, as is gasoline, LPG, CNG, steel, wood and flour. Unlike most others, confinement is a requirement, otherwise it escapes too quickly. See [1] for comparison.

> hard to store safely, damages its own holding vessels

For these reasons I suggest we should produce and store methane, though hydrogen issues aren't a showstopper and hydrogen fuel cells are more efficient.

[1] https://hydrogen.wsu.edu/2017/03/17/so-just-how-dangerous-is...

Hydrogen is highly explosive at almost all concentrations in air, extremely easy to ignite, and leaks through most widely-used materials. It's much worse in all these aspects than common fuels like gasoline, LPG, natural gas, etc.

While the claims are (likely) technically true, if you are trying to insinuate it is less safe, then that is a false conclusion.

As an example, many garages ban LPG cars, but don't care about CNG, AFAICT, because LPG can pool around on the bottom, but methane is light and easily escapes. Hydrogen is even lighter and harder to contain.

The link [1] has compelling arguments.

> hard to store safely

It's far easier to store it (underground, as compressed gas; this is a demonstrated technology) than it is to store energy in batteries. The cost/energy capacity can be extremely low, ~ $1/kWh equivalent.

at that point we are no longer looking at a fuel for mobile vehicles and other technologies become better without the lossful need for electrolysis. pumped storage is highly effective for example.

Sure, but the cost per unit of energy storage capacity is also higher for PHES. So PHES (and batteries on one side, and hydrogen on the other) have different storage use cases. In general combining several storage technologies like these can end up being better than using just one.

If you can acquire hydrogen economically, it can be converted to ammonia cheaply.

For many industrial processes, ammonia is a well-established common feedstock, having none of the issues of hydrogen you mention.

Here in Japan, some Combined Cycle Gas Turbine plants are already running with 10% ammonia blend.

I think you are right about pure hydrogen, but I can see green-hydrogen-into-ammonia as viable for many applications including heavy transportation (train, ship, truck).

We just need much more economic electrolysis, because hydrogen is almost always produced from fossil fuels today.

I learned about this only 10 years ago and then it was to late already, but had they started to convert to Flex-Fuel Vehicle in the 90s it would have meant much cheaper fuel in the 2000s (because natural gas to methanol is cheap and gas was cheap).

Plus you could easily replace it with solar produced methanol overtime.

EV however killed the need for that for the most part.

Today I don't really think synfuels have much of a application. Batteries and storing energy electrically will win. It will not be so long until you can basically do Iron-Silicon battery for a very cheap price. Or if we finally figure Sulfer we could have amazing batteries for super cheap.

> The technology to generate hydrogen is also completely mature

That depends on what metric you are looking at. Efficiency? Perhaps. Cost/kW of the electrolyzer? Not true at all.

Also, the use case for electrolyzers has changed: from converting relatively pricy baseload power to hydrogen to converting cheap intermittent power to hydrogen. For the latter you want to trade efficiency for lower capital cost.

Hydrogen has very low energy density compared to gasoline. Like how diesel has more energy than gasoline. It also has a terrible efficiency. I think you lose ~70% from electrolysis.

You also have the problem that most hydrogen today is made from petroleum!

That matters for hydrogen cars, which are a terrible idea. But for grid storage energy density doesn't matter too much.

Hydrogen, with all it's downsides, is awesome for long term storage because it scales sublinearly with capacity.

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