>>14048801There's a few factors that go into it:
>High specific heatWater can hold a LOT of heat in a small volume. It can hold 4.18 J for every degree kelvin you heat it per gram (4.18J/k-g). For reference, steel is 0.466 J/k-g. Water's specific heat is one of the highest of naturally occuring materials.
>There's a fuckton of water and it is therefore cheap. Even for the ultra-pure stuff.>Water is (generally) chemically non-reactive>The power cycle (Rankine cycle) is able to use water's evaporation/boiling temperature easily transport a LOT of thermal massThe downside of water is that it has a low boiling point and gaseous water expands to about 1600x the volume of liquid water so you have pressure limits to watch out for. you also can't bottom-out the temperature because you don't want to have water droplets in your turbine. This limits your thermal efficiency (N=1-TL/TH...TL -> temperature of cold reservoir, TH -> temperature of the heated steam)
That said, there are alternatives, but in general the downsides don't make it worth it.
