an open and a closed system versions of a float tank actuated hydroelectric generator system is provided for generating work or electrical power . the closed system includes a fluid chamber , a float tank , a drain tank and plug , and a convertor for converting mechanical energy into work or electricity . additionally , a piston , shaft , and recycling pool may be used . in its closed system form , in one version consistent with the invention , the float tank becomes negatively buoyant by allowing its inner chamber to flood or to become positively buoyant by draining its water ballast . the descent of the float tank pushes the piston into the shaft which force water through a hydroelectric generator . water discharging from the generator is captured in a recycling pool which refills the shaft when the float tank ascends . the float tank is drained into a drain tank which in turn allows the float tank to ascend . the drain tank is recycled by first allowing it to descend over a plug , thus expelling its fluid back into the fluid chamber . the slidable plug then descends through the drain tank , drawing air back into the tank , whereby the drain tank and plug are enabled to ascend together . a plurality of valves control the flow of air and water in the system .