Sorry if this isn't the place to ask this question (if anyone knows of a more appropriate one, please let me know)

I'm interested in seeing if a large weight, (several tons, at least) when raised up to a certain height and hooked up to a portable generator, could supply a decent amount of electricity for a decent length of time.

Let's say I raised a 2 ton weight 20 feet above the ground and attached it (using some kind of pulley system w/gears) to a 3500-5000 watt portable generator. (sans motor)

Obviously (even to a neophyte like me) there would be a lot of variables to consider, but I'm just looking for some rough estimates to see if it's even worth considering.

I'd really appreciate it If someone could give me some idea (an educated guess) on the amount of time/watts/ per feet I could expect to get.