Can a submerged styrofoam block with lift force of 228kg generate 23kw of electricity.. ?

Question

a styrofoam block with lift force of 228kg is submerged at 20m(60ft) underwater. the block is attached to a chain wrapped around a gear whose radius is 1 meter. this generates 2280Nm of force on the shaft. at a lift speed of 5,3m/s this will be 100rpm. 2280Nm x 100 rpm = 23.88kw. if this process was to continue for 1 hour i would be making 23,88 kw/h - if i attached a generator with 95% efficiency it would be producing 95% of these 23,88kw/h of electricity?

10x

Answer 1

I haven't checked the calculations but at 5.3m/s the block reaches the surface in less than 4 seconds.  The process stops. An equal (and more due to inefficiency losses) energy input is required to rewind the block.  The process is not continuous and time is wasted during the rewind. The output assuming rewinding at the same speed will be less than half of any calculated.

Also, as the process is discontinuous, the speeds, generator efficiency etc will all vary during that short ride to the surface.