Someone downmodded you because you messed up your units.
It's 4.184 joules per gram Kelvin. Meaning it stores that much energy for each dress of heat you add to it. If you take water from near freezing to boiling that's 100 degrees of storage - meaning 418.4 joules per gram - which is much more reasonable.
And there is no reason you have to stop at boiling. Storing something at 500 degrees is not impractical, so assuming starting at 20 degrees (room temperature) you can store over 2000 joules per gram. And there are plenty of materials that can handle even higher temperatures.
And that's a big part of my question... given that in the abstract water can store any amount of heat (between absolute 0 and the point at which we can no longer call it "water" due to being a plasma of some form), what exactly does it mean for this material to be able to store 4 times as much?
I'm sure there's an answer, because I'm sure the journalist got that number from somewhere, but I lack the connections to know where to begin finding this information.
It's 4.184 joules per gram Kelvin. Meaning it stores that much energy for each dress of heat you add to it. If you take water from near freezing to boiling that's 100 degrees of storage - meaning 418.4 joules per gram - which is much more reasonable.
And there is no reason you have to stop at boiling. Storing something at 500 degrees is not impractical, so assuming starting at 20 degrees (room temperature) you can store over 2000 joules per gram. And there are plenty of materials that can handle even higher temperatures.