BIG BATTERY BLAZE.

Agree, site these batteries were they can do minimal harm in the event of accident. They are probably no more dangerous than petrol, LNG, hydrogen, or LPG tanks with a similar energy content.

The energy storage per cubic metre for Li ion batteries is much more than any of these compressed / liquid gasses. This needs to be very firmly understood, and is why the "hydrogen economy" is very much a non-starter. A litre of liquid hydrogen ony contains about 1/12 th of the energy of a litre of diesel! It appears to me that the danger from large scale Li storage is not yet realised. A facility that stored say 10GWhr of power would have more energy than a large nuke, and I wouldn't want to be within miles if it really went up.

The energy storage per cubic metre for Li ion batteries is much more than any of these compressed / liquid gasses. This needs to be very firmly understood, and is why the "hydrogen economy" is very much a non-starter. A litre of liquid hydrogen ony contains about 1/12 th of the energy of a litre of diesel! It appears to me that the danger from large scale Li storage is not yet realised. A facility that stored say 10GWhr of power would have more energy than a large nuke, and I wouldn't want to be within miles if it really went up.

The energy in the batteries is more than that associated with the pressure in e.g. a propane tank, but less than that associated with the fuel content, for a given volume. Batteries tend to catch fire and burn, exploding only weakly from e.g. pressurisation of the casings. Still, if you want to look at it in terms of energy:

10 GWh = 3.6e+13 Joules
Lets say a "large nuke" is 250 kilotons, that's 1e+15 Joules
Let's call a "small nuke" 10 kilotons, 4e+13 Joules, more comparable.

And for reference:
A road tanker full of diesel: 35,000 litres * 38 MJ/L = 1e+12 Joules

The big pile of coal formerly outside Drax, 8e+15 Joules

Buncefield oil terminal, 2.7e+8 litres of various oil products, around 1e+16 Joules

Typical LNG carrier, 1.3e+19 Joules.

It's not about how much energy, it's about how quickly you release it. I'd worry about being downwind of a big battery fire from a pollution perspective, but no more than I'd worry about Fawley refinery which I am currently downwind of.