Low cost heaters

[Realview]

http://www.fuellesspower.com/8_Heater2.htm

has plans for a heater that requires very little energy. It is basically a can within a can with a liquid between the cans and the inner can rotating at 1,000 rpm +.

I have not built one yet but I suspect it does work and scales to heat an entire house.

Another is this - http://www.youtube.com/watch?v=yh_-DUKQ4Uw

A design I thought of that I believe would also work is to pancake a series of disks together on a motor shaft separating the disks by small washers. The stack of disks would be inside a containing cylinder and rotate at high speed. I believe this would produce a greater amount of heat than would be needed to power the motor and would also scale well. It could be build with a series of can food lids for example. So the cost is to construct is minimal as with the can in a can approach.

Again, I have not personally built any of these at this time but I believe they could be used for survival or home heating purposes.