could this float generate enough electricity to be practical
Up and down only twice a day isn't very much motion. To make the ocean work for us, I would prefer to see submerged turbines in the paths of the major ocean currents, like the Gulf Steam that flows continuously from the Florida strait to Newfoundland.
as slow as the tide is it would float the ball up and attaced rod's teeth would turn a transmission attached to a generator. if this can't get the rpms then possibly float the ball up in an enclosed tube locking drain at bottom then in 6 hours releasing ball to fall at arranged speed possible i hope
You are only using a mass of water equivalent to the volume of the sphere - you system is exactly the same as somebody filling an empty sphere with water every tide and using the downward motion.
A tidal barrage system uses the mass of ALL the water contained in each tide flow.
A system like yours can be used with waves, where it will generate energy on each wave - see Salter's ducks
I am against using tidal waves for electricity generation. I don't want days to become longer and longer.
But the nights get longer as well so you get a lie-in every morning!
Have a look at the wiki for tidal power: http://en.wikipedia.org/wiki/Tidal_power
A single float just doesn't displace enough mass of water to generate much power. The typical ways tidal power is generated are able to harness the entire mass of water moved in a large area such as a bay. And even then, the economics aren't great.
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