I've got a 36 foot tall vertical tower with a chain drive going around it, which chain drive has large scoops attached to it, and the scoops are all spaced 6 feet apart from each other going all the way around the chain drive. On the descending side of the tower all the scoops are loaded with weight (rock) at the top, and they slowly descend down to another level at the bottom of the tower, where the scoops are dumped into trucks. The total descending weight is a constant 30 ton, which is held to a slow descent by geared resistance (no motor needed to run the tower chain drive). It is constantly moving, and dumping one load every six minutes while another scoop at the top is simultaneously being loaded. I'd like to use the constant gravitational moving force from the tower to generate free electricity by maybe gearing a drive shaft to the chain drive, and instead of using gears to give resistance to the gravity power produced, use a generator to cause the required resistance and thereby keep the unit running at its present speed. I don't know enough to figure out how much torque and/or horsepower could be harnessed by gearing up the 30 ton of force/torque/low rpm from the tower to a generator. I know it may sound impractical but, I need some basic information on roughly how much electrical power might be generated from the 30 ton of constant gravitational force of such a unit.

Here's a rough calculation - tell me whether the assumptions I've made are correct.

First, I am converting everything to metric units, because they are so much easier to work with.

You have 6 scoops descending simultaneously, and the total weight in all 6 scoops is 30 tons. That's about 27,000 Kg.

The distance any one scoop descends is 36 feet - call it 11 meters.

The speed that they descend at is 36 feet/36 min, or 0.005 meters/sec.

The power that this mechanism could conceivable generate is , which works out to 1,345 watts. Since no generator is 100% efficient, and there are probably some significant frictional losses in your mechanism, I would bet that the practical energy production would be no more than a couple of hundred watts.