-- Reverse water heaters to create electricity?!? --
 

I know its a random question,

but I was just wondering if instead of;
- Putting electricity in a water heater (which makes the water hot, duh... :D )

You
- Put hot water in and create electricity through the other end...

Would this work?

So, instead of cold water coming in and hot water coming out. Hot water goes in, and cold water gets cooled off and generates electricity...

???

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.

-Jay

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).

Yes and no. He never specified a source for the hot water. Obviously steam generation of any sort can be used in precisely this way through a turbine.

So the question is where will the heat energy come from? And would it come in the form of steam?

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.

Again, the only way I think this could be economically viable is if you had a geothermal source for hot water.

Well you can use your hot water for hot water and you've "made" whatever KWh it previously took to heat your water.

Yeah, except for the laws of thermodynamics. 100% efficiency is not possible, at least as we understand it.

Heh, I know you didn't mean it to be funny. But it reminds me of trying to push my car to fill the gas tank. That'd be awesome if it worked.

Well if it were electric or able to hydrolize water . . ;)