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Comment by yodelshady | Hacker News Reader

Yeah, hydrogen's the only storage medium that makes sense at that scale.

I'd expect some - actually probably quite a lot - of excess CAPEX on wind+solar, and some deficit (less CAPEX, but buying some electricity at retail) so you don't have electrolysers and thermal plants just lying around.

You're still stuck with the investment issue: either you pay (Hinckley-scale!) fees to providers to just lie around, or the public sector runs it itself, and the "private more efficient" bollocks is exactly that, because the private sector isn't providing the value. The people providing SLAs are.

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The point of hydrogen is not mainly energy storage but hydrogen is the only viable way to clean up two of the most carbon intensive industrial processes: steel smelting and ammonia (fertilizer) synthesis. Smelting steel requires coal to reduce the oxygen from raw iron to carbon dioxide. The coal can be replaced by hydrogen, which will then react to water vapor. Synthesizing ammonia needs elemental hydrogen which is as of now extracted from methane (natural gas) using steam reformation. This leads to CO2 as waste product whereas electrolysis crates hydrogen and oxygen directly/cleanly from water.

You need huge amounts of "base load" hydrogen generation capacities for these industries alone. Flexible generation, i.e. produce more to soak up excess renewable energy which you can then export or turn back into electricity (at a huge loss) later, is just the cherry on top.

The initial funding will absolutely come from the steel and chemical industry (and also government subsidies to get the transformation started).

You can purify iron by electrolysis too. You don't need hydrogen for that.

But you still must get a way to put carbon in it. This is usually done by mixing the steel with CO, and the easiest way to get from renewables to CO is by reacting CO2 and H2.

The Salzgitter AG certainly thinks hydrogen is the way to go.

Well, hydrogen is a way to go.

I don't think anybody has enough information to know what is the way to go. But well, I'm an outsider with very little information.

Hydrogen is not at all required for steel melting. Look at Boston Metal. In fact I would argue its the worst solution of the two by a big margin.

For ammonia this will eventually be required.

Smelting isn't just melting, it chemically reduces Iron oxide and needs a reducing agent (hydrogen, CO etc.)

Aluminum is reduced through electrolysis. I think he means that method can be used for iron which means you don't have to use electrolysis on hydrogen.

As always the much better solution would be to build dedicated nuclear plants that operate at really high thermal energy and use that to make they hydrogen.

Nuclear neat is totally green, you actually get 100% utility out of the plant rather then having constant highly inefficient 'start-stop' operations.

And its actually a better less complex process then electrolysis.

But I guess its much better to absurdly gigantically over-provision renewables so one in a while we can run electrolysers and then by inefficent fossil fuels to drive inefficent electrolysers the rest of the time.

And its not at all clear that hydrogen as storage is actually a good idea, and its also not at all clear its the only thing that scales. It very much unproven at the kind of production scale AND storage scale you suggest. And even in the best case its incredibly inefficient and incredibly expensive make/store/produce.

Something like Iron based batteries will likely turn out to be a better solution.

Japan is going down this path.

> hydrogen's the only storage medium that makes sense at that scale.

There's more hydrogen in a liter of gasoline than in a liter of liquid hydrogen.

Electricity to gasoline produces a safe product that is easily storable for years and easily transportable requiring only minor safety precautions. Not something that can be said for hydrogen.

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