A submersible reverse osmosis desalination apparatus uses low temperature concentrate or brine from the desalination apparatus to provide a high volume cold liquid stream to an Ocean Thermal Energy Conversion (OTEC) heat engine. The OTEC engine also employs a warm liquid stream and uses the cold and warm liquid streams to obtain electrical power from a closed-cycle or open-cycle heat exchange and generator system. Use of the concentrate or brine stream provides a much greater liquid volume and much greater cold thermal energy content than would be obtained by using cold desalinated product water from the desalination apparatus in the OTEC heat engine.

A submersible water desalination apparatus includes an array of hot-swappable water separation membrane modules arrayed in an approximately polygonal configuration around a product water collection conduit that represents or is proximate to and generally aligned with a central axis of the array; a plurality of hot-swap product water valves connected to the conduit and detachably connected to generally radially-extending product water collection manifolds in fluid communication with a plurality of water separation membrane cartridges within the modules; the modules having in cross-section generally tapered module sides that converge towards the conduit and assist in underwater docking and attachment of a replacement module to a hot-swap product water valve.

A submersible water desalination apparatus includes a plurality of water separation membrane elements that when supplied with salinated water under pressure at a first depth will produce at least partially desalinated product water and concentrate or brine; a product water collector that receives product water from the membrane elements; and a permeate conduit that transports product water from the collector downwardly to a motorized submersible pump remotely located from the membrane elements and collector at a second depth greater than the first depth. The second depth is sufficiently greater than the first depth so that the height of a standing column of product water in the product water collector and permeate conduit between the membrane elements and the suction side of the pump maintains a net positive suction head that prevents inlet side cavitation during pump startup and operation.

Power generated by a wind turbine is applied to drive reverse osmosis (RO) desalination. Rather than discharging the brine back into the ocean, it is concentrated and modified through industrial-scale processes to produce sodium hydroxide (NaOH). Direct air capture of CO.sub.2 occurs when liquid NaOH, created from the RO desalination brine, is conveyed to the rotor hub and emitted from the wind turbine blades to react with CO.sub.2 in the atmosphere. The power of an offshore wind turbine is used for the onboard production of fresh water to supply shoreside water needs, or water may be electrolyzed to produce hydrogen while adding the vital process of CO.sub.2 sequestration to the ocean.

A submersible water desalination apparatus includes an array of generally parallel water separation membrane cartridges each having a water separation membrane, an impermeable cartridge wall surrounding the membrane, and a product water collection tube that collects from inside the cartridges at least partially desalinated product water passing through the membrane, and through which the at least partially desalinated water exits the cartridges and enters a product water collection manifold. The cartridges are mounted in a perforated divider plate. In embodiments, a) the manifold is adhesively bonded to a plurality of the collection tubes, orb) the divider plate is adhesively bonded to a plurality of the cartridge walls or ends, or both a) and b). The adhesive reduces the likelihood of leakage at the manifold or divider plate.

A submersible water desalination apparatus includes a plurality of water separation membrane elements, a product water collector that receives product water from the membrane elements, and a variable output motorized submersible pump having a suction side that receives product water from the product water collector and a discharge side that pumps product water away from the apparatus through a product water conduit for surface or subsurface use. An automatic control or coupling is employed to reduce the pump output upon the occurrence or onset of suction side cavitation, and discourage or prevent cavitation over a range of product water flow rates from the membrane elements.

A submersible water desalination apparatus includes a plurality of water separation membrane elements, a product water collector that receives product water from the membrane elements, and a variable output motorized submersible pump having a suction side that receives product water from the product water collector and a discharge side that pumps product water away from the apparatus through a product water conduit for surface or subsurface use. At least a portion of the product water is used to lubricate and optionally also cool at least a portion of the pump, motor or both the pump and motor.

An emitter apparatus is mounted on a marine structure powered by wind or marine hydrokinetic energy to disperse a carbon dioxide sorbent such as sodium hydroxide. The sorbent can be generated by reverse osmosis of seawater with electrolysis of the brine, or delivered from an external supply. Suitable marine structures include offshore wind turbines, marine hydrokinetic generators, offshore oil platforms, merchant vessels, and other fixed and mobile structures. Effective capture is made by dispersing a fine mist or fog of aqueous sorbent from nozzles with a particle size from a nozzle of less than 100 microns. The sorbent reacts with atmospheric carbon dioxide forming carbonates and bicarbonates, which drift and fall to the ocean surface, reducing surface acidity and capturing additional atmospheric carbon dioxide via absorption at the local ocean surface. The resulting carbonates sink to the ocean floor and are there sequestered.

A cap removal device is adapted to remove end caps from water pump devices. The cap removal device has a cap remover that is adapted to be secured to the end caps of pressure vessels. The cap removal device further has a honed tube that is adapted to stabilize the cap removal device and the end cap during removal of the end cap thereby preventing cross-threading. The cap removal device also has a puller handle that is adapted to make removal of the end cap more efficient.

A subsea desalination template includes subsea desalination module zones and module fluid couplings. A desalinated water outlet is in fluid connection with the module fluid coupling in the subsea desalination module zone. Subsea desalination modules with reverse osmosis cartridges are in fluid connection with a subsea template fluid coupling, a seawater inlet section, and a concentrated seawater outlet section. A transport pump assembly for desalinated water in a pump module is in fluid connection with the subsea desalination template and the desalination modules. A seawater circulation pump is in fluid connection with a seawater side of the at least one reverse osmosis cartridge. A desalinated water pipeline conveys fluid from the desalinated water transport pump assembly to a location above sea level.