Unless your electric hot water heater generates heat with thermocouples it won't work. An electric hot water heater heats water by running a current through the heater's elements. The elements have resistance so when current is applied the resistance generates heat, which is transferred into the water. The only way this might work, is if you have a hot spring on your property. If you have to heat the water to extract electricity from it you might as well just save that energy and use it for other purposes.
This doesn't work - if it did, you would have air conditioners that cool your house, and generate free electricity for you too!. Unfortunately it goes against the laws of thermodynamics.
In order to CHANGE temperature (up or down), you have to put in energy. So you would need to put electrical energy in to make the water cool down (not to mention, you need to do something with the heat energy already there - which is why air conditioners blow hot air outside of the house - they actually take the heat from the house, and dump it outside).
__________________ Team GasMisers5 - #1 for first three rounds of the original GS Fuel Economy Challenge
Miles displaced by e-bike since 1 Jan 2008: 62.6 (0 kWh used)
The temperature differential can be used to operate a mechanical device connected to a generator, but don't expect any meaningful output. The difference in thermal energy is quite small so little pressure can be created. A low pressure "Sterling" engine can operate on this little difference.
Steam powered generators operate more on the pressure difference than on thermal difference so the economies are quite different.
Well you can use your hot water for hot water and you've "made" whatever KWh it previously took to heat your water.
I remember The RoadWarrior..To understand who he was, you have to go back to another time..the world was powered by the black fuel & the desert sprouted great cities..Gone now, swept away..two mighty warrior tribes went to war & touched off a blaze which engulfed them all. Without fuel, they were nothing..thundering machines sputtered & stopped..Only those mobile enough to scavenge, brutal enough to pillage would survive. The gangs took over the highways, ready to wage war for a tank of juice