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Comment by pbronez | Hacker News Reader

Energy storage is hard. We'll need to iterate firefighting techniques to handle large batteries, just like we need to work on third-party repair for BEV and battery recycling programs. Fortunately these are all relatively straightforward engineering problems... small steps towards the sustainable future we must invent to survive as a species.

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Intrinsically safe energy storage is an oxymoron. The objective is storing large amounts of energy to be released slowly over time - if there exists any possibility whatsoever of imperfect containment, there is (by definition) some probability that it will fail and release that energy all at once.

Can they be made to fail safely? Sure.

Can they be made to never fail? Not for what anyone's willing to pay for them.

Lithium batteries store about 0.5 MJ/kg. Compared to the specific energy of burning lithium metal (40 MJ/kg) the energy from the electricity producing redox reaction is pretty low.

In the case of lithium batteries. Our problem isn't the stored electric energy, it's the medium being a highly flammable alkaline metal. If we could somehow store that 0.5 MJ/kg in a non-flammable medium with similar energy density it would have 5% the specific energy of a similarly massing piece of hardwood.

Oh damn, TIL. You'd still have the issue of the stored energy in a non-flammable medium, but that 80x energy multiplier makes the problem distinct from any other energy storage I can think of. That's like keeping your diesel in a tank made entirely out of dynamite.

A candle stick has 100x the energy of a stick of TNT. I know which one I would rather be driving a truck full of.

Energy density is not the main danger factor.

> We'll need to iterate firefighting techniques to handle large batteries

Are there any firefighting techniques in use for handling car-size batteries?

Absolutely!

The state of the art is to have a container, fill it with water, and put the car in. You then wait a week or two.

For installations like this one which just burned down the answer is mostly: Don't let it catch fire! And if it does catch fire, make sure that you built it with large enough gaps between each unit that the fire can't spread, because you're not putting it out.

Also, maybe "dont use tricky NMC batteries for stationary storage, when LFT can be cheaper and safer".

Still, hypothetically, can you use a (large) hose to fill a burning MegaPack container with water to cool it down? Maybe possible shorts in the other pods will make things worse?

LFP*?

> The state of the art is to have a container, fill it with water, and put the car in. You then wait a week or two.

As a firefighter I can confirm this.

What worries me though is, that this might work well for cars, but what about batteries in homes, like Tesla powerwall and alike?

We do not yet have any plans for those, you can't "easily" attach them to a crane and lift them into a container. They are built in basements, garages and more. This will become challenging in the future...

These are also all negative externalities at this point.

Even straightforward engineering problems need funding to get engineers assigned to them.

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