An underwater energy storage system comprising a container where energy is stored by transporting water between the container and a body of water, is disclosed. 5 The container comprises a water- and gas-tight membrane surrounding a container volume, where the container is rendered mainly incompressible by a fill material comprising densely packed, incompressible objects arranged in the container volume, the fill material forming a mainly incompressible aggregate.

The gas turbine power generation system of the present invention repeats either the supply or absorption of power, in addition to generating power. The gas turbine power generation system is provided with a first rotation shaft, a compressor, a combustor, a first turbine upon which combustion gasses impinge, thereby causing the first turbine to rotate, and driving the first rotation shaft, a rotating electrical machine connected to the first rotation shaft, a speed adjustment mechanism for controlling the speed of the compressor by adjusting an air volume, a frequency converter for converting a frequency of power, the frequency converter being connected between the rotating electrical machine and a power system via a power line, and a controller for obtaining a request for an output from the gas turbine power generation system and controlling the combustor on the basis of the request. With respect to the frequency converter, the controller performs frequency converter control for changing the rotational speed of the rotating electrical machine on the basis of the request. The rotating electrical machine supplies or absorbs power in accordance with the change in the rotational speed. With respect to the speed adjustment mechanism, the controller performs speed adjustment mechanism control for setting the rotational speed to a reference value.

The method according to the invention relates to the storage of energy in the form of a compressed fluid which is pumped into a container (2) arranged below a water surface (4) to store the energy, wherein the fluid entering the container displaces an existing content, comprising water, from the container and into the surrounding water, and compressed fluid is removed from the container (2) to remove energy, wherein surrounding water flows back into the container according to the volume of the removed, compressed fluid, characterized in that the container (2) is provided with flexible walls at least in some parts and is arranged on a seabed (6) or lake bed (6) and there is covered by ballast (15) such that it is pressed against the substrate even when completely filled with compressed fluid.

The invention relates to a system for storing and recovering energy, comprising at least two liquid containers for storing a liquid, the two liquid containers being preferably located at substantially the same level and/or preferably having a substantially identical volume, and a turbine unit for power generation, which connects the two liquid containers to one another and is designed in such a way that the liquid can flow from the one liquid container through the turbine and into the other liquid container and thereby drives the turbine, and a working gas provision unit for providing a working gas, in particular air, having a substantially constant working gas pressure, the working gas provision unit being connected to the two liquid containers and designed in such a way that the working gas having said constant working pressure conveys the liquid from the one liquid container, via the turbine unit and into the other liquid container.

An energy storage system includes at least one heterogeneous pressure media and interactive actuation module (“module”), a liquid source, a pump, a converter, a first pipeline, and a second pipeline. The module includes a first container storing an initial gas and a second container storing an initial liquid. The liquid source stores a working liquid. The pump regulates the working liquid from the liquid source into the module. The initial liquid is driven by the working liquid to continuously compress the initial gas so that the first container stores a first pressure energy, and the initial gas is continuously expanded to drive the initial liquid to convert the first pressure energy into a second pressure energy. The second pressure energy through the first pipe drives the converter to generate an electrical energy, and the working liquid after driving the converter is returned to the liquid source through the second pipeline.

This disclosure describes novel hybrid energy storage systems for providing short-term and long-term storage and delivery of electricity generated by any energy source including renewable energy sources such as solar energy and wind energy. The hybrid energy storage systems described herein have a higher overall real-world efficiency than energy storage systems currently available.

An energy storage system includes at least one heterogeneous pressure media and interactive actuation module (“module”), a liquid source, a pump, a converter, a first pipeline, and a second pipeline. The module includes a first container storing an initial gas and a second container storing an initial liquid. The liquid source stores a working liquid. The pump regulates the working liquid from the liquid source into the module. The initial liquid is driven by the working liquid to continuously compress the initial gas so that the first container stores a first pressure energy, and the initial gas is continuously expanded to drive the initial liquid to convert the first pressure energy into a second pressure energy. The second pressure energy through the first pipe drives the converter to generate an electrical energy, and the working liquid after driving the converter is returned to the liquid source through the second pipeline.

A hybrid compressed air energy storage system is provided. A heat exchanger 114 extracts thermal energy from a compressed air to generate a cooled compressed air stored in an air storage reservoir 120, e.g., a cavern. A heat exchanger 124 transfers thermal energy generated by a carbon-neutral thermal energy source 130 to cooled compressed air conveyed from reservoir 120 to generate a heated compressed air. An expander 140 is solely responsive to the heated compressed air by heat exchanger 124 to produce power and generate an expanded air. Expander 140 is effective to reduce a temperature of the expanded air by expander 140, and thus a transfer of thermal energy from an expanded exhaust gas received by a recuperator 146 (used to heat the expanded air by the first expander) is effective for reducing waste of thermal energy in exhaust gas cooled by recuperator 146.

Method is for operating fluid-processing plant configured to generate and store pressurized fluid, and spaced apart from body of water. Method includes: (A) positioning variable-buoyancy assembly in body of water in such way that buoyancy force urges variable-buoyancy assembly to move toward surface of body of water; (B) positionally anchoring, at least in part, non-collapsible fluid-line assembly underground in such way that non-collapsible fluid-line assembly extends, at least in part, into body of water; (C) fluidly connecting, via non-collapsible fluid-line assembly, fluid-processing plant and variable-buoyancy assembly together in such way that non-collapsible fluid-line assembly conveys pressurized fluid between fluid-processing plant and variable-buoyancy assembly; and (D) transmitting an anchoring force, via non-collapsible fluid-line assembly, from ground to variable-buoyancy assembly in such way that anchoring force substantially counteracts buoyancy force acting on non-collapsible fluid-line assembly, and anchoring force substantially urges variable-buoyancy assembly to remain below surface of body of water.

An underwater energy storage system includes a tank for storing a compressed gas that is adapted to be stored underwater. The tank includes at least one water opening through which water from surrounding environment can flow into and out of the tank, and at least one gas opening through which the compressed gas is received. The underwater energy storage system further includes at least one duct communicating between the at least one opening for gas flow and a source of compressed gas and a compartment constructed over a roof of the tank, wherein said compartment is adapted for receiving weights at a sinking site of the tank.