Tidal hydro

I have come up with an idea for generating electricity from the rise and fall of the tidal river on my property rather than the flow (not much flow)
I have on average a 3.5m or 12feet of rise and fall.
By using a float with a specific buoyancy attached via a pulley, fixed to the bottom of the river, with a cable to a counter weight on the bank of equal weight as the buoyancy of the float could I turn a generator?
Obviously it would have to be geared up as the river rises and falls by only 1cm/half an inch per minute.
Also the generator would have to be able to work in both directions, rise and fall, so I’m guessing an AC system?
I can increase the buoyancy and counter weight to accommodate the power needed but I have no idea how to do the calculations.
I would like ideally to run a 30KVA generator.
Is there anyone that could help or at least tell me why it wouldn’t work before I start wasting my hard earned cash?

Hi John,
no clue if your idea works but 30kVA sounds like a lot, pretty sure you won't get there.

All the tidal generators I know (masters in renewable energy) basically trap the water on high tide and then let the water "fall" to low tide height and turn a regular water turbine with that. All of them rely on masses of water and a pretty big tidal difference.

Maybe someone else has an idea...

Welcome to Permies!

My understanding of tidal hydro is a dam and turbine system. There is still a lot of challenges being worked out with tidal systems due to the infrastructure needs of current systems. They primarily rely on steady, predictable, flow to operate a turbine.

I believe you might have a novel idea, I just worry that it might turn expensive as you tinker with it as time goes by.

Hi I read an article on a similar invention within the last decade.  I think the idea was to use a large gearing ratio to convert a small distance change to many rotations.