This is an interesting concept - using aluminum for seasonal energy storage. Smelt it with surplus of energy, use it in various reactions in the winter.
I haven’t fully read the paper yet (that’s on my plans for this evening), but it’s a very interesting concept, at least!
It’s thinking out of the box for sure. Very interesting concept. I wonder if it’s useful for fairly small size applications, or if you really need very large amounts/size/automation to make it work economically.
I’m on a coffee break and didn’t have time to do much beyond read the abstract, so maybe they mention this. Are they doing something different than ‘standard’ aluminum smelting? ‘Spent Potlining’ as they call it is full of toxic elements. I wouldn’t think it’s a great idea to make more of the stuff as a fuel.
Maybe those waste products are more from creating structural alloys than what they’re doing here. Still, I’d want to know how much waste product per kWh in fuel is made during this process. I’m guessing it’s not negligible.
How would this compare with the standard “pump water uphill” energy storage methods?
My first thought is it’s only similar in that it’s storing energy for later. In this case though, it’s storing chemical energy for release later on, rather than kinetic energy. And you’re also dealing, at some point in the process, with extremely hot metal. Not sure if it’s liquid or not, didn’t really read the article, but even if it’s not you’re dealing with HOT HOT HOT stuff.
It doesn’t freeze, for one (well, or, not in a way that impacts operation - it works with solid aluminum).
The concept is that you have a centralized “reprocessing” plant that does the high temperature work on surplus PV exported to the grid, and gets you aluminum pellets that you can use locally for heat and power. Waste is shipped back to be reprocessed.
In the winter, you run the pellets through a reaction that gets you heat (for building heat), hydrogen (for a fuel cell for power), and the waste that’s then processed again.
I don’t know enough about aluminum metallurgy to really evaluate what they’re doing, but it sounds like once you’ve gotten to aluminum, the process is circular, especially if you’re not using carbon based electrodes for the smelting.
I’ve always wondered if you could somehow use the “freezing force” of water to somehow generate power.
I’m sure you can, though I’m not sure how you’d generate an awful lot of power with it.
Found this: Utilize freezing water to generate energy | Discover Applied Sciences
The developed model showed that there is a possibility to generate about 22 kJ by freezing 1 l of water. Although this concept can produce a small amount of energy, one can imagine other applications that could make use of such a system. However, this amount of energy depends very much on the design and initial conditions. In other words, better designed system can increase the generated energy.
Interesting. That’s more than I would have guessed but still well under the heat of fusion of 334kJ/kg.
https://www.britannica.com/science/latent-heat
The heat of fusion for water at 0 °C is approximately 334 joules (79.7 calories) per gram, and the heat of vaporization at 100 °C is about 2,230 joules (533 calories) per gram.
The math and chemistry seems reasonable for a circular aluminum energy system, but that’s going to be a lot of aluminum for every one of those smelting plants and that’s a big, hot building building that people may not want in their back yard. The round trip efficiency they report of ~58.7% isn’t too bad and would get a little better if fuel cells manage to get more efficient.
I like the force of ice idea, you get the power when it’s cold enough that other sources don’t work as well. Similar to the solar powered lawnmowers, if it’s not sunny, the grass doesn’t grow as fast. The only problem I see is in climates that stay frozen, it’d only provide power a couple times a winter.
What about using used/scrap aluminum that might not be sorted for quality/type for this. That way we can re-use stuff that otherwise might be more costly to re-use, but in here where most of the properties of aluminum don’t matter so much.
I’m not familiar enough with the various aluminum metallurgy cycles to know what would or wouldn’t work.
But as I haul my recycling, I do wonder about using random aluminum cans as winter heat…