Cornwall based wave energy developer Seatricity Ltd’s Oceanus 2 Wave Energy Convertor was relaunched from A&P shipyard in Falmouth on 3rd May under the gaze of a visiting group of Marine Renewable Energy Master’s students from Plymouth and Exeter Universities. Thanks to the pro-active support of Harbourmaster Capt Mark Killingback, initial in-water recommissioning took place in the ideal, picture-perfect still water surroundings of the upper reaches of the River Fal. The device left the Port of Truro under tow by Keynvor MorLift’s specialist support vessel ‘Severn Sea’ on the evening of the 9th of May and arrived safely to a temporary anchorage near St Ives on the morning of the 10th.
It was then a slow process meticulously to survey the pre-existing moorings at Wave Hub’s test site north of Hayle to map and understand any damage that had occurred whilst the Oceanus 2 has not been on station through the winter. In normal circumstances the Oceanus 2 holds the moorings up from the seabed and safely in tension. When the device is not there to provide support, the extra slack moorings creates the potential to twist, tangle and suffer abrasion and chafe. If something can go wrong, at sea it will; and with the extreme conditions of recent Storm Imogen adding another twist, the initial findings of the survey revealed much heavy lifting work to do. The moorings themselves are not easy to handle.
Whilst it may not look much on the surface, the picture below represented a minor triumph! Four carefully positioned marks (only three visible in this shot) in a perfect square indicating the ends of four newly refurbished positional moorings. It also marked the end of three complete day’s hard graft.
But this was only the start of the process. The biggest and most important task was now to recover the main pump’s main reactive tether; a massive bespoke fibre rope and connection assembly weighing over 200kg and now tangled on the seabed in a middle of loose lines and other hazards to divers and remote approach by ROV.
Without the outstanding support and perseverance of Falmouth based marine contractors KML on Severn Sea under the expert command of Captain Sasha Hall and the divers of Seawide Services Ltd under the expert supervision of Dive Supervisor Brendan Rowe this stage of the operation would have faltered. Both teams were, however, as determined and committed as Seatricity Ltd to bring the Oceanus 2 home to Wave Hub; all recognise the potential of Wave Energy and devices such as the Oceanus 2 to bring about a revolution in green, clean power generation and the opportunity for local economic regeneration as a result. We were in good hands.
Taking one small step at a time, ROV pilots Eric and Tom’s uncanny capacity to manoeuvre the ROV in 3D and exploit its manipulator dexterity allowed the picture became clearer, hazards to be cleared one by one, a safe working area to be established and a mapped survey plan was pieced together to clear a route for the ROV to establish a lift line on the main tether just below its unwieldy pump connection fitting.
Working late into the night the team worked on with common purpose. Using the lift line, the tether could then be gingerly raised to a depth at which the divers could work safely to re-attach its end fitting to the Oceanus 2’s 170KW pump.
Working with a 110kg attachment fitting hanging from a line and trying to align it with a eye requiring a precision measured in millimetres and then to connect it to a pump end which is also pitching and heaving at 24m is no mean feat. It was not until the final dive of the final day that Seawide Service Ltd’s divers’ extraordinary determination paid off. Local Cornish diver Kieran hammered home the final pin but the credit belongs to them all.
SME Seatricity Ltd has, to date, been wholly funded privately by its Directors. Now, in the wake of the demise of competitors pursuing entirely different technologies, we hope the UK might be sufficiently convinced to join us for the journey.
Click here to view a short film about Seatricity.