Iron as an inexpensive storage medium for hydrogen
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Re: Iron as an inexpensive storage medium for hydrogen
#2At scale, what I don’t get is this requires a lot of energy to kickstart the reaction (heating the iron ore to 400 degrees). Where is that energy coming from when energy production is constrained in winter.
Or would the plan be to slowly heat over fall?
Re: Iron as an inexpensive storage medium for hydrogen
#3At scale, what I don’t get is this requires a lot of energy to kickstart the reaction (heating the iron ore to 400 degrees). Where is that energy coming from when energy production is constrained in winter. Or would the plan be to slowly heat over fall?
They mention using waste heat from the reaction to minimize the energy cost of discharge. As long as they still get some power out of it, it could be a win even if it’s quite inefficient. When the input hydrogen is “free” in the summer (due to excess production), inefficiency can be tolerable.
I do wonder if “free” will actually pan out, or whether someone will find a way to demand-shift from winter to summer and use it all up.
Re: Iron as an inexpensive storage medium for hydrogen
#4At scale, what I don’t get is this requires a lot of energy to kickstart the reaction (heating the iron ore to 400 degrees). Where is that energy coming from when energy production is constrained in winter. Or would the plan be to slowly heat over fall?
Energy production from solar is lower in winter, but it's not zero. And other forms (notably wind) are not reduced.
It's a non-problem, really. Especially at scale.
Re: Iron as an inexpensive storage medium for hydrogen
#5At scale, what I don’t get is this requires a lot of energy to kickstart the reaction (heating the iron ore to 400 degrees). Where is that energy coming from when energy production is constrained in winter. Or would the plan be to slowly heat over fall?
The article says they're currently powered from a grid connection but hope to be fully solar powered soon.
What I'm not getting is how this process produces more energy than the solar input to power the process.
Unless they're getting solar collectors to try to generate 400 degree temperatures rather than PV solar to electricity, but that seems like a sketchy proposition at best in winter.
Re: Iron as an inexpensive storage medium for hydrogen
#6Actual publication linked is very readable: https://pubs.rsc.org/en/content/articlelanding/2024/se/d3se0...
Re: Iron as an inexpensive storage medium for hydrogen
#7Looks like a variant of iron-air battery project to me.
Re: Iron as an inexpensive storage medium for hydrogen
#8At scale, what I don’t get is this requires a lot of energy to kickstart the reaction (heating the iron ore to 400 degrees). Where is that energy coming from when energy production is constrained in winter. Or would the plan be to slowly heat over fall?
Even most internal-combustion engines require energy stored in a battery to kickstart them, so this is not different.
Obviously the energy efficiency of this process based on iron is modest. It is likely that the energy efficiency is even lower than for the process of storing energy by making synthetic hydrocarbons (e.g. synthetic gasoline), which are much easier to use once energy is stored in them.
The only advantage is the very low cost even for very large storage capacities.
Re: Iron as an inexpensive storage medium for hydrogen
#9At scale, what I don’t get is this requires a lot of energy to kickstart the reaction (heating the iron ore to 400 degrees). Where is that energy coming from when energy production is constrained in winter. Or would the plan be to slowly heat over fall?
They mention using waste heat from the reaction to minimize the energy cost of discharge. As long as they still get some power out of it, it could be a win even if it’s quite inefficient. When the input hydrogen is “free” in the summer (due to excess production), inefficiency can be tolerable. I do wonder if “free” will actually pan out, or whether someone will find a way to demand-shift from winter to summer and use…
They're storing the hydrogen as water, though. The only reason to produce it in the summer from excess production via electrolysis is to be able to reduce iron oxide to pure iron rather than just buying the pure iron to start with.
Re: Iron as an inexpensive storage medium for hydrogen
#10Actual publication linked is very readable: https://pubs.rsc.org/en/content/articlelanding/2024/se/d3se0...
I'd like to point out row 3 of the excellent Fig. 6 where the authors evaluate the risk of fine iron powder being exposed to air, which heats up to about 600°C due to oxidation. https://pubs.rsc.org/image/article/2024/se/d3se01228j/d3se01...
