Storing renewable energy for a cloudy day,

or even just for use that same night, has been the holy grail of the renewables industry for years. Generating power from the sun when it is shining is a doddle, storing that energy in a usable form for later has been the nightmare side of things.

Yet this, from The New York Times, suggests that the technologies for storing the energy from solar systems are moving on apace. Molten salt in an insulated tank seems to be one method that shows high promise.

"a coffee thermos and a laptop computer’s battery store about the same amount of energy"
"The thermos costs about $5 and the laptop battery $150".

So its a really big thermos flask full of molten salt. Hmmmm, I wonder if they need to add vinegar?