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Comment by bcatanzaro | Hacker News Reader

The article states that storing 10kWh of electricity with this will take 45m3 of concrete, weighing 110 megagrams.

One Tesla Powerwall takes 0.127m3, weighs 0.114 megagrams, and stores 13.5 kWh.

Now of course the attraction of this energy storage device is that the materials are cheap, but I have to wonder if storing energy in concrete is cheaper and easier by moving it up and down a gravity field rather than trying to use it as a capacitor.

For example, take a look at this 100MWh gravity storage facility being built in China: https://www.energyvault.com/project-cn-rudong

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Isn’t the idea that with this cement mixture your house’s foundation acts as energy storage “for free”?

I think the application is for cases where you’re already using cement as a building material, so you might as well mix in some carbon and also get energy storage out of it.

Is it free? They don't mention home energy storage as a potential application. I would have no trouble believing that the extra electrical work and additions to the foundation beyond what's involved in a traditional cement foundation cost a whole lot less than a lithium battery.

I'd also be concerned about problems with the foundation. Foundations crack and suffer water damage. My mom just had her foundation repaired. What risk is there that the electricity can discharge?

Like if it's as simple as running some inexpensive cables through the cement mix and plugging in a little box, awesome. But I suspect this is hardly the case, and I suspect the sheer volume of cement needed to be practical/useful is quite high for residential use.

When I glanced at the paper in a previous posting, it mentioned cycle life on the order of 100,000 charge-discharge cycles IIRC. Saying that being a capacitor it doesn't have the limited lifetime of a battery.

Weight is simply not a significant factor for stationary large-scale energy storage. It's arguably weird to be using the same cells you'd put in a car as a "powerwall".

WRT gravity storage that's going to have moving parts and require regular maintenance like a hydroelectric dam.

I'm not sure what counts as a charge-discharge cycle, but if it happens once a day that's about 277 years. Significantly longer than any battery I've heard of, most of which are warranted in the single-digit years.

On the other hand, the cement manufacturing process has high carbon emissions.

It appears that the benefit of this is that the concrete can be used structurally as well as storing electricity

Batteries get noticeably hot when charging and discharging. I wonder how significant this effect will be for the concrete and if it will have a meaningful impact on its effective lifespan.

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