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Comment by pjc50 | Hacker News Reader

Where does the hydrogen come from, or is this just natural gas with extra steps?

What's the state of the art on producing hydrogen from electricity without incredibly expensive catalysts again?

State of the art is about 93% efficiency for electrolysis of water "in the lab". It was about 80% efficient at industrial scale back in 2017 (see https://www.carboncommentary.com/blog/2017/7/5/hydrogen-made...), so we can expect that to be a few percentage points higher today.

Apart from the aforementioned hydrogen agreement with Canada, construction is underway for a wind-powered multi-GW electrolyzer plant in the Netherlands, which is pretty much next door to the German trains from TFA.

In the lab is a very very very very very different thing than at scale.

Hydrogen is not feasible anytime soon. Maybe when we get Fusion but then it's most likely going to be used for materials not energy.

4% of current industrial hydrogen production is from electrolysis. This is 8 GW electrical for a production of about 3.5e6 tons/year, i.e. 72 MJ/kg, compared to the energy density of hydrogen of 120 MJ/kg is an efficiency of 60% in the actually deployed systems. While we know how to do better even at industrial scale, PV (in the right place) is so cheap that even 60% makes sense economically.

Technologically, hydrogen electrolysis predates batteries by nearly 50 years, and practically speaking it is so trivial today that I first did it when I was single-digit-years-old.

Not sure what you're thinking of when you suggest fusion might be used for materials instead of energy. Transmutation?

Fusion is the sun. In the future we will be able to do what the sub does which is to create the raw materials we all do.

Keep in mind fusion is not just another way to power our lightbulbs, it's a different type of energy among others with the ability to get us to 10% of the speed of light.

Electrolyses uses mostly fossil fuel and will continue to do so. It's a simple question of physics.

The sun only fuses up to carbon; bigger stars go up to iron; supernova and colliding neutron stars produce the heavier stuff we currently use.

Trying to use this process artificially for various elements in current annual demand by our economy involves more than enough energy to boil the ocean in fairly short periods — I'd have to redo the calculations to see if that period was hours or years, but it's a simple question of physics.

We might skip fusion rockets for antimatter (making that is painfully expensive, but it would get us up to 0.4c) or laser propulsion (needs massive infrastructure, but can arbitrarily approach c).

> Electrolyses uses mostly fossil fuel and will continue to do so. It's a simple question of physics.

Physics doesn't require that electrolysis uses fossil fuels, it requires only electricity. Electrolysis will use whatever electricity is cheapest. Right now, for new installations, that's PV. Ten years ago it was not. It's a simple question of economics.

You are agreeing with me.

How? Are you counting PV as fusion? In which case I think you used the wrong tense earlier. I still claim you're wrong about fossil fuels being necessary for hydrogen, BTW.

You can claim that all you want. Let me know when we are creating hydrogen without fossil fuels and at scale.

This is still important, even if right now the hydrogen comes from natural gas. Otherwise, it's a chicken and egg problem: if there's no demand for hydrogen, people won't build plants to make green hydrogen, and if green hydrogen is not available, people won't build the trains and other vehicles to use that.

There is in fact already significant industrial use of hydrogen https://en.wikipedia.org/wiki/Hydrogen_production#Use_of_hyd... -- independently from the use case of replacing fossil fuels. So there is already significant demand for hydrogen that could be green, but the vast majority of hydrogen produced today is from fossil fuels.

That is true. But the vast majority of the hydrogen produced today is used for things hydrogen was used for decades (fertilizers and oil refining). As such it already has its infrastructure in place, so it's quite a change to migrate to a new way of producing this hydrogen. New uses can demand green hydrogen however.

Germany in particular has a number of green hydrogen producing projects. [1] is a very good source.

[1] https://www.iea.org/reports/hydrogen

The German chancellor recently signed a deal from Canada which will provide us with green hydrogen produced by wind farms in Newfoundland.

There is no deal. They just signed a "joint declaration of intent". They still have neither the wind turbines nor hydrogen production facilities.

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