Power Supply for UUV/AUV Recharge Station

Autonomous Underwater Vehicles are electric vehicles travelling autonomously subsea. With a finite battery capacity, they must return to shore for recharge, which defines their potential operating range.

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Presentation material can be downloaded here

Offshore UUV/AUV Recharge Stations

Serious effort are undertaken by several defence supply companies and navy military engineering institutions to develop a recharge station that could be located along the AUV preferred path to enable them to charge during their patrol. This would remove the currenlt use of vessels and personnel in UUV operation and as such dramatically reduce cost and increase capability and efficiency of UUV operation.

Such charging stations need energy generated on site in the multi kW regime. We believe our wave energy technology provides an ideal power supply solution for such charging stations, as they are deemed to be located far offshore, in deep waters, often with requirement for low or no visiblity and where energy supply is unavailable.

Wave generated power is advantagous over solar, wind and other renewable sources because they are

  • Compact and small
  • Located close at surface with low visibility or below surface with no visibility
  • Low heat signature
  • Robust and can handle rough conditions
  • Low maintenance requirement
  • Reliability and uptime

The components involved in a deep water configuration of a power supply solution would be a power producing unit at the top:

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A reactive body of encased seawater that the winch can work against:

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And the seabed assembly with charger and moorings:

UUV recharge power supply - Surface config 36

The complete assembly could be stored in a compact state and towed or transported onboard a vessel, for self installation.

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For shallow water configuration (<200m), the power unit can be towed with it's moorings winched up, lowering it by itself once on site. This makes for a very cost effective installation and recovery.

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Sumberged Configuration

The Fred. Olsen Power Take-Off Unit requires a force to be inflicted on it for it's winch line tension algorithm to function. This force could be in the form of a floating structure. However, this force may as well be provided by a submerged enclosed air volume like illustrated below.

UUV recharge power supply - Subsurface config 37UUV recharge power supply - Subsurface config 37

Fred. Olsen has done extensive simulation work on buoancy control for vertical positioning, and power absorbation. Based on this, we believe an adaptation of our current surface based PTO to a submerged version for completely underwater power production and export, is possible. 10m to 20m would be a suitable range in terms of available pressure difference for power production, buoancy control, stealthiness, communication and accessibility.

Below is an exceprt from a simulation model developed in house. This scenario produced an average power output of 0.3kW.

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A system like this could be sized to fit within the boundaries of a torpedo tube and as such be forward deployed by a submarine.

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