A multi-mode subterranean energy system and a related multi-mode subterranean energy production method are disclosed. The system comprises subterranean tunnels (2, 3, 8, 9, 14) connecting an upper reservoir of water (1), an underground cavity (10) and a subterranean recipient (15), a turbine/pump unit (4), and water flow control means (5, 6, 7). The system optionally can be operated in four modes.

A multi-mode subterranean energy system and a related multi-mode subterranean energy production method are disclosed. The system comprises subterranean tunnels (2, 3, 8, 9, 14) connecting an upper reservoir of water (1), an underground cavity (10) and a subterranean recipient (15), a turbine/pump unit (4), and water flow control means (5, 6, 7). The system optionally can be operated in four modes.

An energy generating system includes a dam in an estuary defining a water containment area. The dam includes a plurality of dam elements, each including a plurality of dam panels hingedly connected in series, which are urgeable from an inoperative folded state in a chamber to an operative state by a corresponding pair of main or secondary buoyancy tanks as the tide rises and falls. Each pair of main buoyancy tanks with the corresponding dam element defines a water race within which a water wheel is located. The water wheels are mounted on corresponding drive shafts which are connected in series and which are rotatably carried on support frameworks which are supported on the main buoyancy tanks. Electricity generators are supported on carrier frameworks which are supported on the secondary buoyancy tanks at respective ends of the dam, and are driven by the adjacent one of the drive shafts.

An energy generating system includes a dam in an estuary defining a water containment area. The dam includes a plurality of dam elements, each including a plurality of dam panels hingedly connected in series, which are urgeable from an inoperative folded state in a chamber to an operative state by a corresponding pair of main or secondary buoyancy tanks as the tide rises and falls. Each pair of main buoyancy tanks with the corresponding dam element defines a water race within which a water wheel is located. The water wheels are mounted on corresponding drive shafts which are connected in series and which are rotatably carried on support frameworks which are supported on the main buoyancy tanks. Electricity generators are supported on carrier frameworks which are supported on the secondary buoyancy tanks at respective ends of the dam, and are driven by the adjacent one of the drive shafts.

A circular dam for generating, accumulating, storing, and releasing electrical energy comprises a wall defining a water reservoir built in an abundant body of water such as a sea or an ocean. Water inside the water reservoir is kept at a water level below the water level outside the wall so as to create a water level difference sufficient to operate one or more water turbines positioned across the wall of the water reservoir. Excess electrical energy from other renewable sources of electricity such as wind, solar power, or supplied by a local power grid is used to operate water turbines as water pumps to lower the water level inside the reservoir during times of peak supply of electricity. Water is drained from outside the wall back into the water reservoir to generate electrical energy by flowing over a plurality of water turbines. Generated electricity supplements electrical power for the local power grid during times of high demand.

A circular dam for generating, accumulating, storing, and releasing electrical energy comprises a wall defining a water reservoir built in an abundant body of water such as a sea or an ocean. Water inside the water reservoir is kept at a water level below the water level outside the wall so as to create a water level difference sufficient to operate one or more water turbines positioned across the wall of the water reservoir. Excess electrical energy from other renewable sources of electricity such as wind, solar power, or supplied by a local power grid is used to operate water turbines as water pumps to lower the water level inside the reservoir during times of peak supply of electricity. Water is drained from outside the wall back into the water reservoir to generate electrical energy by flowing over a plurality of water turbines. Generated electricity supplements electrical power for the local power grid during times of high demand.

In a penstock internal maintenance system, the penstock includes an inclined portion between upper and lower ends, the upper end arranged in an edifice including a water collecting chamber and a gate bearing structure allowing a gate to close the penstock, the gate bearing structure adjacent the water collecting chamber forming a vertical pit. The system includes a set of units assembled in an assembled configuration and separated in a dismounted configuration, the units including an anchor unit, a launching unit and a penstock inspection platform unit, the units in the dismounted configuration being enter the penstock through the gate bearing structure adjacent the water collecting chamber, the units are assembled when located in the penstock, the anchor unit slidingly received and retained in the gate bearing structure, the anchor unit having two lateral edges being guided and retained in two vertical lateral grooves of the gate bearing structure.

A gate valve for use in controlling the level of a dam has a first plate with an aperture on an upstream face of the dam and a movable plate on the upstream side of the fixed plate, with apertures sixed and dimensioned to operate as a scissors when the movable plate is urged in a linear motion parallel to fixed plate. One or more edges of the apertures in the plates are provided with a sharp edge or a serrate edge oriented to sever obstructing object present in the apertures when the valve is transitioning from an open position to a closed position.

A hydrodynamic installation includes an upper water tank, a lower water tank, a water way system which has a plurality of partial water ways and which connects the upper water tank to the lower water tank. A hydraulic machine is arranged in the water way system, a water protection is arranged in a partial water way, and an electric drive provided for actuating the water protection. The electric drive is constructed in such a manner that it also ensures safe closing of the water protection in the event of a power failure without an emergency power supply being provided to this end.

A portable hydropower module is provided for the generation of economical hydroelectric power at low-head sites, such as dams and weirs. More particularly, the portable hydropower modules are able to streamline the construction of power generation facilities and improve the economics of hydropower development for low-head sites. The portable hydropower modules may be produced off-site and then transported, such as by floating, to the designated low-head site. The portable hydropower modules may be specifically designed to efficiently facilitate the energy capabilities at the chosen low-head sites.