You can convert energy from pretty much anywhere into (say) electricity. A small solar cell placed on the ground for example.
It's not really free though, since there is a cost involved to make the item (e.g. solar panel). I believe, (I could be wrong) energy harvesting is not really concerned with reducing cost to 'free', but more to do with getting energy where it is impractical or unfeasible to connect to mains or a battery that needs replacement/maintenance. The mains power consumption of a low power device could cost less than a dollar for the entire lifetime of the product, whereas a small solar cell may cost more. It's the practicality of it that drives energy harvesting.
okay but I thought there is such devices like transformers that can convert micro voltages to pickup electricity from earth then step-up the voltages pickup in ground or any devices available to siphon earths ground electricity to serviceable electricity I supposed to expect.
Anyway sir shabaz, ahm do you know some devices like microelectricity converter here in element14? maybe this will be helpful for my planned project like nikola tesla did on his project.
Voltages can be converted using circuits and transformers but there is always a loss of energy as heat (2nd law of thermodynamics) and the voltage doesn't define the amount of energy that you have. The amount of energy is the voltage multiplied by the current in Amps. This means that any conversion from one voltage to a higher voltage results in a proportional drop in current so that the final energy plus the energy lost in the conversion is equal to the original energy. Nature is the ultimate book keeper and makes certain that we don't get any energy for free.
Voltages can be converted using circuits and transformers but there is always a loss of energy as heat (2nd law of thermodynamics) and the voltage doesn't define the amount of energy that you have. The amount of energy is the voltage multiplied by the current in Amps. This means that any conversion from one voltage to a higher voltage results in a proportional drop in current so that the final energy plus the energy lost in the conversion is equal to the original energy. Nature is the ultimate book keeper and makes certain that we don't get any energy for free.
