Hydraulic energy accumulator

An energy storage system comprising:

• a fluid circuit comprising:
• a first fluid container situated so content of the first fluid container experiences a first pressure level;
• wherein the first fluid container is submerged in a liquid, the first fluid container having a fluid container first internal region in communication with the liquid and a fluid container second internal region in communication with a first working fluid;
• a tank configured so that content of the tank is at a second pressure level, the second pressure level being less than the first pressure level;
• a first hydraulic motor/pump unit connected to communicate a first working fluid between the tank and the first fluid container;
• a second fluid container, the first hydraulic motor/pump unit being fluidically connected between the tank and the second fluid container for communicating a second working fluid between the tank and the second fluid container;
• an electrical unit configured to operate as a motor in a first phase of operation and to operate as a generator in a second phase of operation;
• wherein the first hydraulic motor/pump unit is configured during the first phase of operation to operate as a pump to transmit the second working fluid from the second fluid container to the tank and thereby drive the first working fluid from the tank to the fluid container first internal region and during the second phase of operation to operate as a motor as the second working fluid is driven by the first working fluid from the tank to the second fluid container;
• wherein the electrical unit is configured during the first phase of operation to operate as the motor for the first hydraulic motor/pump unit and during the second phase of operation to operate as a generator driven by the first hydraulic motor/pump unit.

A method of operating an energy storage system, the method comprising:

• situating a first fluid container so content of the first fluid container experiences a first pressure level;
• situating a second fluid container situated so that content of the second fluid container is at a second container pressure level, the second container pressure level being less than the first pressure level;
• situating a tank so that content of the tank is at a second pressure level, the second pressure level being less than the first pressure level:
• providing an electrical unit configured to operate as a motor in a first phase of operation and to operate as a generator in a second phase of operation:
• providing a first hydraulic motor/pump unit, a second hydraulic motor/pump unit, and a third hydraulic motor/pump unit;
• the second hydraulic motor/pump unit being operatively connected to the electrical unit and fluidically connected between the second fluid container and the third hydraulic motor/pump unit, wherein the third hydraulic motor/pump unit is fluidically connected between the second hydraulic motor/pump unit and the first fluid container;
• . communicating a first working fluid between the tank and the first fluid container in a first direction during the first phase of operation and in a second direction during the second phase of operation,
• in the first phase of operation supplying electricity to the first hydraulic/motor unit whereby the first hydraulic/motor unit transmits the first working fluid from the tank into the first fluid container:
• in the second phase of operation transmitting pressurized first working :fluid in the first fluid container from the first fluid container through the first hydraulic/motor unit to the tank thereby causing the electrical unit to generate electricity;
• during the first phase of operation operating the second hydraulic motor/pump unit and the third hydraulic motor/pump unit as pumps to transmit fluid from the second fluid container to the first fluid container,
• during the second phase of operation operating the second hydraulic motor/pump unit and the third hydraulic motor/pump unit as motors as fluid from the first fluid container is transmitted to the second fluid container;
• during the first phase of operation operating the electrical unit as the motor for the second hydraulic motor/pump unit;
• and
• during the second phase of operation operating the electrical unit as a generator driven by the second hydraulic motor/pump unit.

A method of operating an energy storage system, the method comprising:

• situating a first fluid container so content of the first fluid container experiences a first pressure level;
• situating a tank so that content of the tank is at a second pressure level, the second pressure level being less than the first pressure level;
• providing an electrical unit configured to operate as a motor in a first phase of operation and to operate as a generator in a second phase of operation;
• providing a second fluid container with a first hydraulic motor/pump unit being fluidically connected between the tank and the second fluid container for communicating a second working fluid between the tank and the second fluid container;
• submerging the first fluid container in a liquid and providing in the first fluid container a fluid container first internal region in communication with the liquid and a fluid container second internal region in communication with the first working fluid;
• communicating the first working fluid between the tank and the first fluid container in a first direction during the first phase of operation and in a second direction during the second phase of operation,
• during the first phase of operation operating the first hydraulic motor/pump unit as a pump to transmit the second working fluid from the second fluid container to the tank and thereby drive the first working fluid from the tank to the fluid container first internal region;
• during the second phase of operation operating the hydraulic motor/pump unit as a motor as the second working fluid is driven by the first working fluid from the tank to the second fluid container;
• during the first phase of operation operating the electrical unit as the motor for the first hydraulic motor/pump unit;
• and
• during the second phase of operation operating the electrical unit as a generator driven by the first hydraulic motor/pump unit.

An energy storage system comprising:

• a fluid circuit comprising:
• a fluid container submerged in a liquid;
• a storage cell situated above a surface of the liquid;
• connecting means for fluidically connected the fluid container and the storage cell;
• a first hydraulic motor/pump unit connected to communicate a pressurized fluid between the storage cell and the fluid container through the connecting means;
• an electrical unit situated above the surface of the liquid and configured to operate as a motor in a first phase of operation and to operate as a generator in a second phase of operation, wherein in the first phase of operation the first hydraulic/motor unit transmits the pressurized fluid from the storage cell into the first fluid container, and wherein in the second phase of operation the pressurized fluid in the fluid container is transmitted from the fluid container to the storage cell thereby causing the electrical unit to generate electricity.

A method of operating an energy storage system, the method comprising:

• submerging a fluid container in a liquid;
• situating a storage cell above a surface of the liquid;
• providing, above the surface of the liquid, an electrical unit configured to operate as a motor in a first phase of operation and to operate as a generator in a second phase of operation;
• communicating a pressurized fluid between the storage cell and the fluid container in a first direction during the first phase of operation and in a second direction during the second phase of operation,
• in the first phase of operation supplying electricity to the first hydraulic/motor unit whereby the first hydraulic/motor unit causes the pressurized fluid to be transmitted from the storage cell into the fluid container;
• in the second phase of operation transmitting the pressurized fluid in the fluid container from the fluid container to the storage cell thereby causing the electrical unit to generate electricity.