[epithermal]

I still have trouble seeing how heating water a few degrees more is storing energy like a battery does. Maybe I am not looking at it right, but say the water is now warmer, but there is still the same volume of water as you had before. So, unless my appliances can intelligently use less hot water when the water is hotter, I don’t see where the energy is stored.

What am I missing?

[JD_UTDallas]

Epi the quick and dirty physics of this in dreaded English units the rest of the world uses and understands metric.… one gallon of water weighs 8.345404lb there for to raise one gallon of water one degree F you need 8.35 BTU of energy so 50 gallons of water raised 20 degress F is 8350BTU at 100% energy efficiency…impossible but electric resistance coils approaches 95% so ok. There are 3413 btu in one kilowatt hour. So to raise 50 gallons 20 degree F takes 2.45 kilowatt hours per tank now multiply that over thousands of tanks you get the idea how you can store energy in water. This just the thermal energy in the water. What the power company is concerned with is not total stored energy but power rate draw form the mains. The resistance coils in an average high efficiency heater are not 1 or 2 kilowatt coils more like 240v and 30 amps something like 5.5kw each. This is what the power company sees thousands of 5.5 kilowatt devices that can be turned on and off at will. 10000 water heaters is 55 Megawatts of shedable load that is nothing to sneeze at. This what a small city or county with tens of thousands or hundreds of thousands of homes with heaters in it. That hundreds of megawatts of shedable load or the size of one of the peak plants. This is the whole goal avoid building and running a peak plant.