Probably just the simple economics of cost of land vs cost of construction of a new building + ongoing maintenance.

I'm sure if they ever saw need to place this in a city they would construct a building. But for now, it's probably cheaper to just build out where land is cheap (and possibly closer to generation source) and then transport the energy to where it's being used.

How safe would it be to put large quantities of a potentially unstable alkali metal in close proximity to lots of humans?

I know your comment is meant as a potshot, but it actually points out an interesting side-point: safer than putting in a natural gas plant.

In California, the Puente gas plant made headlines last year because they found it was cheaper to create battery storage than an equivalently-sized gas peaker plant. A large part was permitting and land rights. People don't want an emissions-spewing gas plant in their backyard, but an array of batteries in what looks like every other industrial warehouse is much more palatable. (Time-to-go-live was another factor: battery arrays are modular and can be distributed across multiple sites to further minimize risk, a gas plant is a massive multi-year centralized organizational challenge with all the associated costs and all-or-nothing risks)

https://www.greentechmedia.com/articles/read/sce-picks-major...

Another side of the organizational improvements that batteries have: redeployable.

Underprovision? Pour some more concrete, truck a couple more batteries in.

Overprovision? Load em up again and resell them to someone who wants them. Can't quite do that with a gas plant.

Sure there will be some overhead lost, but it just make soooo much sense to go with battiers from a risk perspective.

Definitely, I saw that these units are sized to standard container dimensions as well so they could even load them onto a truck for temporary load balancing or supplying power.

They also look (but I'm a layman) easily maintainable, more like server racks than high tension electricity stations. I wonder if the batteries would be hot swappable.

I mean, we all sleep with phones under our pillow, so

I'll have you know that my phone is at least eight inches away from my head at night.

Haha noooooo way. Even if the EM doesn’t cause any health issues, battery combustion due to overheating right under my head might.

Quite a bit of alkali metal ions exist in your body, your kitchen, and your food.

Probably pretty safe with an appropriate fire suppression system in the building.

I dunno, Teslas going up in flames sometimes cause pretty dangerous fires - iirc in one instance they put a car wreck in a container full of water so the lithium could burn out overnight.

But, if something starts to go wrong it should have monitoring systems and an engineer can swap out the faulty module, and if it does go wrong I hope they have good containment.

But, not much you can do against a proper lithium battery / electrical fire I suspect.

Replace all air in the facility with Halon. That'll put out most fires.

If it's stacked up in a building maybe they can use the energy to lift-off and self destruct elsewhere ;)

Besides land being cheap outside of cities, it might also be a safety thing. Like, you might not want batteries close enough that if one catches fire it could catch the rest on fire too. You might also want easy access for fire crews.

Yes, it's more expensive. They're not normally situated where land is expensive.

You can ask the same question about car parks. Same answer. Building up or down is expensive.

Space isn’t an issue in the places you need to locate these things, with a few notable exceptions (eg Japan).

Building up is a lot more expensive, and there is no shortage of available land on Earth at the moment.

Well I would assume they weigh a ton and moving them and/or replacing them will be less troublesome if you can just bring a crane or something similar

Amusingly, heavy things carried up and down by cranes are a promising way to store electricity.

I can't really agree with 'promising'. A tower that can lift 100 tons 50 meters is not exactly cheap, and only stores 13.6 kilowatt hours.

Here’s a company pursuing that very idea.

https://qz.com/1355672/stacking-concrete-blocks-is-a-surpris...

Ah, if you actually build the structure out of the items you're lifting, then that certainly changes the math. Compared to just lifting with a crane you get a thousand times the capacity at the same infrastructure price.

Exactly. It’s really the same principle as pumping water uphill except using concrete blocks and a crane. Potential energy is potential energy.

I’d just love to see it in action.

consider off shore gravity batteries that can drop mass down 2 to 4km. Major fixed cost is Hvdc out 100miles, but it’s extremely scalable after that.

Lead-acid batteries are pretty damned heavy and would make a great kinetic battery as well as a chemical one.

I wonder how much more energy this setup would store if they added cranes. Also it could be possible to make a circular vacuum maglev train out of these and add energy to it by accelerating.

There was an episode of Nova about energy storage that included a company that made kinetic energy storage devices. IIRC they had 5000 pound flywheels that spin in a vacuum and can be installed in your home. Expensive to purchase and install but essentially unlimited lifespan and totally renewable.

I've heard about either a working system, or a calculation of something like that but with regular trains. Long story short, it can't actually store that much energy.

More efficient (and less mechanically complicated) would be pumping water up a hill into a lake.