Circular dam and methods for generating, accumulating, storing, and releasing electrical energy

A circular dam for accumulating, storing, and releasing electrical energy, the circular dam comprising:

• a continuous wall defining a water reservoir within thereof, the wall is built in an abundant body of water and extending from a bottom thereof to or above a water level of the abundant body of water, wherein a bottom of the water reservoir remains open, the water reservoir has a diameter or width at or above 2 km, the wall is configured to contain water within the water reservoir at a water level below the water level of the abundant body of water, and wherein the water reservoir is located where the bottom of the abundant body of water contains a layer of sandy sediment with sand grains not exceeding 2 mm in size,
• a plurality of reversible water turbines operably associated with electrical motors/generators, the water turbines are configured to direct water between the water reservoir and the abundant body of water outside thereof, the water turbines are further configured to operate in an energy generating mode or a water pumping mode, wherein
• the energy generating mode is aimed to produce electrical energy by electrical motors/generators when the water turbines are driven to rotate by water draining therethrough from the abundant body of water into the water reservoir, and
• the water pumping mode is aimed to pump water from the water reservoir to the abundant body of water when the water turbines are driven by electrical motors/generators powered by excess electrical energy supplied thereto, and
• a computerized controller connected to electrical motors/generators and to an electrical power grid and configured to cause:
• accumulating energy by emptying the water reservoir using excess electrical energy from the electrical power grid to operate electrical motors/generators of the water turbines, or
• releasing energy by draining the water from the abundant body of water into the water reservoir to cause electrical motors/generators to generate electrical energy when rotated by water turbines and supply thereof to the electrical power grid,
• thereby reducing fluctuations in peak electrical energy supply and peak electrical energy demand of the electrical power grid.