theorein

Not currently. Until we learn more about how gravity works we won't know for sure. It has a section on gravity in Wikipedia's perpetual motion machines. You can read that.

The main problem is that it takes force and energy to get an object up to use gravity. It would have to be done a different way than this.

I have a theory on Gravity, and how we can use it positively. But first I need assurance that it will never used for evil. Will you take my word seriously?