Generation of electrical power offshore

A set comprising a plurality of floating electric power-generation groups, each group comprising:

• a floating hub;
• at least two floating power producer units that are connected electrically to the hub;
• and
• at least one subsea energy storage unit that is electrically connected to at least one of the hubs, the energy storage unit comprising a storage volume in fluid communication with pumping machinery that is arranged to expel water from the storage volume and with generating machinery that is arranged to generate electricity from a flow of water entering the storage volume;
• wherein the floating hub is anchored to a plurality of subsea foundations that are located in plan view between the power producer units and the hub;
• wherein the power producer units are each moored by a plurality of mooring lines, at least one of those mooring lines extending inwardly toward and effecting mechanical connection to one of the subsea foundations located between the power producer unit and the hub, and at least one other of those mooring lines extending outwardly away from the hub toward a further subsea foundation located outboard of the power producer unit in plan view to effect mechanical connection to the further subsea foundation.

An offshore electric power-generation arrangement, comprising:

• a plurality of electric power-generation groups, each group comprising a hub that is connected electrically to a plurality of power producer units;
• at least one subsea energy storage unit that electrically connects the hub of one of the groups to the hub of another of the groups;
• and
• wherein the energy storage unit comprises a storage volume in fluid communication with pumping machinery that is arranged to expel water from the storage volume and with generating machinery that is arranged to generate electricity from a flow of water entering the storage volume.

A method of generating electrical power offshore, the method comprising:

• generating electrical power using a plurality of electric power-generation groups, each group comprising a hub that is connected electrically to a plurality of power producer units;
• and
• conveying the generated electrical power from the hub of one group to the hub of another group via at least one subsea energy storage unit;
• converting the generated electrical power to potential energy by pumping water from a storage volume of the at least one subsea energy storage unit;
• and
• converting the potential energy to recovered electrical power by admitting a flow of water into the storage volume.