Well I guess it's sort of free.. If I can figure out how to harness it. We built our house about 4 years ago and I will try to explain this as good as I can, but we have power coming out of the ground. If you stand outside barefoot and touch something metal.. You get a tingle. For example, we were planting some trees and the root ball had the metal cage around it. The cage was in contact with the ground, and when I knelt down with a bare knee to the ground and touched the cage...zaaaaap ! My A/C guy was pressurizing the condenser last summer and was getting hit when his bare knee was on the ground and he touched the copper on the unit. In the basement, if you ground a meter, you can pick up voltage from the foundation ties ! After finding this last year I notified the electric utility and they came out and drove grounding rods tied to all our outside mechanicals, then I checked all the other houses on our road and they are all hot as well. I think I could stick some low voltage lighting into the ground and they may work. ..