There is an interesting paper by Fran de Aquino available at http://vixra.org/abs/1205.0119, which suggests that it is possible to convert gravitational energy directly into electrical energy. The abstract of his paper is as follows: "We show that it is possible to produce strong gravitational accelerations on the free electrons of a conductor in order to obtain electrical current. This allows the conversion of gravitational energy directly into electrical energy. Here, we propose a system that can produce several tens of kilowatts of electrical energy converted from the gravitational energy."
Considering that there is formal analogy between gravitational theory and electromagnetic theory, then it seems that such a proposition is possible, at least theoretically. But I am not sure yet if his "theory" can be turned into a practical technology. And if it is indeed possible to convert gravitational energy into electrical energy, will it imply potential destruction of natural gravitational field? My curiosity is on possible damage caused by the use of Earth gravitational energy.
What is your opinion? Comments and suggestions are welcome.
I have included de Aquino's paper below.