Gravity energy generator?

No. You're simply compressing and then decompressing a fluid. What's floating in it doesn't add or subtract from the energy you put in.

Maybe you could use it in a refrigerator, though.

Yeah. Or an object raiser-upper and lower-downer.
Seriously though, this could be used as energy storage.

Yeah, or a pressure accumulator to even out pump surges. Like a water tower, except they tell me water doesn't really compress.

No. Because you haven't altered the mass of the stuff you are moving up and down.

All of human technology involves manipulation of Electromagnetic forces. We have no ability to manipulate any of the other fundamental forces (Strong Force, Weak Force or Gravity). In a pinch you might argue that we have some technology involving the Strong and Weak forces because we can make atomic weapons. But all we're really doing there is smashing things together really hard until they break, not a very elegant or versatile technology. But our ability to interact with or manipulate gravity is even worse. In that case, we don't even have theories which apply, much less actual mechanisms.

A Tidal Force generator is essentially what we are talking about. These have been known for years and were one of the options for a huge tidal energy project during the Roosevelt Years . They were going to make huge dam at the end of the Bay of Fundy and install these huge generators that would use the pressure and head of the tides at that area.(Tides along the Fundy are 25 to 32 feet.

The Canadians have been building tidal power generators in the Bay of Fundy since the 1980s. Ocean Renewable Power Corporation was the first company to deliver tidal power to the US grid in September, 2012 when its pilot TidGen system was successfully deployed in Cobscook Bay, near Eastport, also in the Bay of Fundy. A number of large scale projects are being built around the world, including a 400 MW scheme in Scotland.

I am pretty sure this is another scheme for a perpetual motion machine.

You all are being too kind.

what you are talking about is the tidal research stuff thats been going on, I think through Batelle Memorial Institute, near LUBEC , not Eastport. They have a tube with tidal props that, installed in the deeper bay waters, harness the tidal head. The research generator is only capable of about 200 kW and has only been there since 2012.
Ive been out there many times and its a big dispute going on , (not technological) but environmental(The area is an alewife spawning site an these are major baitfish for the lobstermen and deep liners. The two Indian tribes have had the sites in court on a Constitutional and Indian Treaty dispute ( denial of susbistance fishing is breaking an 1867 agreement tween the US and the Tribes)
The BIG project was on the books back in the 1930;s and they were talking GIGA watts

I guess you mean Dexter P Cooper's Quoddy Dam project. Construction of workers’ barracks and a dike began in 1935, but Congress pulled the plug a year later. There was opposition from Central Maine Power Co., Bangor Hydro-Electric and other power generating firms in Maine that feared the federally funded project would generate electricity at a lower cost than they could, thereby hurting their businesses. Republican Governor Ralph Owen Brewster agreed to support the project if he was guaranteed some Democratic support and credit, something Roosevelt-loyal Democrats did not want to do. In Congress, Southern opposition defeated funding for the project. Over the years the plan has been put forward again. Nothing wrong with the engineering (there wasn't in 1935), but as in FDR's time, other factors came into play. As you say, gigawatts. A total energy collection of 14 GW was estimated.

the engineering was based upon 1930's thinking where environmental and public health issues meant absolutely nothing. There were never any NEPA requirements or even an EIS required. Today the entire area is b ound by some of the richest seafood grounds in Passamaquoddy and Fundy,
The use of the submerged drums with the spinning armatures that generate small amounts of electricity during both rising and ebbing tide cycles is what The Batelle reearch design was based on. I wasnt aware that Canada was even invloved. Was it a purchase?

The effects of dams would have breached certain treaty obligations, I think.

Cobscook is now just an artificial offshoot of Passamaquoddy and doesnt connect the St Croix River which is the only Cross border river that exits t the lower Bay of Fundy. We have property on 190 off Carlow's Island and Our land overlooks the other end of old tidal berms which have been taken over by aPassamaquoddy tribal smoke ceremonial site. That entire stretch of what was once a planned tidal dam, has been infilled and the Road from Rt 1 to Eastport was built. Its a neat re-entrant that allows a boat to be beached and "scraped off" or anchored further out. It blocks off the ST Croix and Cobscook can now only be approached by going all the way around through the Lubec Narrows and down to the flats

Think of gravity as an energy storage mechanism. Lifting something 'up' imparts exactly the amount of energy necessary to do so, and pushing something 'down' releases that same energy.

In Britain there was a project, the Severn Barrage, where a dyke was going to be built across an estuary with England on one side and Wales on the other. Getting local politicians on both sides to agree was one problem. What really held it back were environmental concerns and cost versus benefit calculations.

buoyancy is based on gravity .if fluid has low density then low gravity force for buoyancy. if the system has high density fluid then high gravitational force for buoyancy. my understanding .

Unfortunately you can't alter the density of your liquid. AngleWyrm is right. It's like compressing a spring. You won't get more energy back when the spring is released.

By Jove, you are so close to inventing hydro-electricity.

what if :
there was a balloon and it had a gas that would compress and still keep it's gas form. now the same balloon with an object that at such a pressure the object would compress 1 million times less than the gas did at the same pressure. what would happen if :

1st test -balloon not compressed, gas not compressed, object not compressed , object moving up ,then everything the same except object coming down.( balanced energy so I think)nothing changed but the object.

2nd test - balloon is being compressed, gas compressed , object barely compressed, object moving up ,then everything the same except object coming down.( balanced energy so I think)

3rd test- balloon is being compressed, gas compressed, object barely compressed, object moving up, then decompress balloon, not compressed gas or object. object moves down.
what u think (not taking in consideration friction)

what I think
to lift the object would take less energy when balloon is compressed than when the balloon is not.