Honestly, dumping any renewable surplus into water electrolysis admixing produced hydrogen to the natgas grid beats curtailing. You've already paid for the infrastructure, and as capacity increases failure to do so will only hurt more in future.
this post was submitted on 04 Jul 2023
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There are lots of less expensive, higher impact ways to use surplus electricity to decarbonize. Spending money on upgrading fossil gas infrastructure and electrolysers to run at 10% duty cycle is well below even building more power generation and curtailing more in terms of cost effectiveness.
Photovoltaics capacity factor is about 10% of nominal peak where I sit, so you will have to build out massively which will put you far in excess of those current 50% renewable electrivity peaks in Germany. There simply isn't a cheaper way to capture these peaks as there isn't even transport infrastructure for electricity. Alcaline water electrolysis is stupid cheap and the natgas grid is already there. Price isn't a good argument versus curtailing. And natgas availability in future is rather uncertain.
The fossil gas grid there can't move hydrogen beyond about 5% by energy.
Even if it were economically feasible to run your electrolysers at 5% capacity factor (it's very much not) there are countless better uses for the curtailed energy than hydrogen and countless better uses for hydrogen than reducing the emissions from fossil gas by 5%
This is wholly a greenwashing and distraction tactic.
The fossil gas grid there can’t move hydrogen beyond about 5% by energy.
I don't know where you're taking these numbers. City gas used to be 50% vol hydrogen, and I bet you dollars to donuts current gas network edge can deal with that fraction without refitting. You will need to adjust the furnace burners for high volumes of hydrogen, but not for 5% vol and perhaps not even 15% vol. We're not talking long-distance high-pressure pipelines and pump stations, because they're not relevant for decentral production, storage, and consumption. But you can build these, if you have to.
Natgas demand in Germany is about 1.5 PWh/year so 5% of that is 75 TWh/year. Only 58 TWh total of solar PV were generated in 2022. So once we 3-5x (hard to estimate future need curtailing versus capacity) the currently installed solar PV capacity we might be able cover some 5% of German natgas demand, which is a lot. Both in terms of the demand and the solar PV infrastructure involved.
5% capacity factor
I don't know what you refer to, efficiency of commercial water electrolysers is some 75% with some lab stuff that is 95% efficient. The amount of surplus depends on the number of spikes which you can't sell to the grid or neighbor countries even at negative prices, so it's becoming a problem at multiples of today's installed renewable (not counting biofuels, since these are already not renewable nor net energy sources). If you don't have that multiples of today's capacity installed very soon, there will be a lot of dead people. Which, admittely, use a lot less energy, so there's that silver lining.
there are countless better uses for the curtailed energy than hydrogen
Which would be what exactly? We can't even charge all the projected EVs given that local infrastructure is shit. There are no energy storage systems worth spit in homes, and currently 1 kWh battery storage will set you back 1 kEUR. The storage which isn't there, while the natgas grid is already there, and you can plonk down water electrolysis containers anywhere you want. And, no, these don't have to be PEM. Conversion efficiency is secondary if you're dealing with 100% loss, aka curtailing of paid-for infrastructure. Use it, or lose it.
and countless better uses for hydrogen than reducing the emissions from fossil gas by 5%
I'm not talking about reducing emissions. I'm talking about having seasonal load level storage, and having at all energy available. Fraction of tight gas on LNG market is growing, which is not good news, at all. Another interesting thing: net energy from total oil liquids is supposed to peak as soon as 2025. That is net energy volume total, not per capita. That already peaked a while ago.
This is wholly a greenwashing
What is particularly nongreen about renewable (solar and wind) electric power decentrally producing 100% renewable hydrogen? It doesn't get greener and more renewable than this. I'm honestly boggled by this statement.
distraction tactic
I don't think you're arguing in bad faith. I think you're not at all understanding what the actual problem is. May I recommend you have a thorough look at https://escholarship.org/uc/item/9js5291m ? Then perhaps people can start understanding what we're dealing with here.
You keep flipping between efficiency vs capacity factor, and PEM vs alkaline electrolysers. You're also paltering by talking about volume (hydrogen has much lower energy per volume). The usual proposals are15-20% by volume or 5-8% by energy.
If the electrolyser is your storage for 10% CF solar, then it is operating definitionally much less than 10% of the time (ie. The amount of time it's curtailing)
At 50c/W installed, then per watt of output energy your cheap platinum-free alkiline electrolyser and compressor system running at <35% efficiency 5% of the time costs $25/W of time averaged delivered heat or around $75/W of final energy (as electrification of most functions is at least 3x as efficient). This "free curtailed energy hydrogen" costs more than even the most corrupt and over-budget nuclear project.
This is completely ignoring storage as well.
The idea is ridiculous, and anyone claiming we should take it seriously is very obviously shilling fossil gas.
If "we haven't built it yet" is a valid objection to batteries or v2g, then it's also a sufficient reason to dismiss gas blending out of hand.
Your argument is definitely in bad faith. Please leave and never come back.