Using gravity to generate power

Question

I believe that a 17.18 lb weight pushed off a 32ft ledge is one horsepower being that 550 foot pounds/ second is equal to 1hp and G is 32ft/s squared. Thus dropping 17.18 lbs for 32 feet equals 746 watts (one hp). Then if I was to use a pendulum escapement mechanism to control the duration of the fall to last 6 hours (this duration is only important in maintaining low temperature/ high efficiency and endurance of materials) to generate 2200 watts output for 6 hours, I would need to drop 310lbs from 32 ft. Or more realistically, 775lbs from 16feet. Since gravity is acceleration at T squared, I think that if I cut the distance in half the weight must increase by 2 plus half. Anticipating 10% loss in efficiency, I could run 2 gravity driven generators based on this configuration and produce 4Kw for 6 hours of use. Am I right on this? Should I put this in practice?

Answer 1

I believe that a 17.18 lb weight pushed off a 32ft ledge is one horsepower

Force multiplied by distance is a unit of energy, not power. You get power based on how quickly the energy is released. If that energy were released in a single second, it would be equivalent to 1 HP during that time.

Then if I was to use a pendulum escapement mechanism to control the duration of the fall to last 6 hours

Then you would release the same amount of energy (745 J), but at a much lower power. Instead of 1 second, it would take 21,600 seconds. This would then be (1/21600) of a horsepower or about 35 mW. Enough power to run a couple of LEDs.

Answer 2

The way to use gravity as a source of energy would first need to know how much weight do you need and what gear ratio would you use to have the weight drop at, say, a speed of a $\text{ft/h}$, and create enough torque to turn a pulley at $10\,\text{hp}$ to turn a $7\,\text{kW}$ generator at $3500\,\text{rpm}$, etc. The generator could charge batteries to use a winch to reset the weight at $24\,\text{ft}$ of course. Even at $2\,\text{ft/h}$, you would only have to reset it twice.