Orkney Tidal Energy Cabling Project Final Phase
The final phase of a major project to investigate cost-effective methods of cable laying for tidal power arrays, with the aim of helping accelerate development of the marine energy industry, has been completed in Orkney.
Funded by Scottish Enterprise, the Â£2.4m Tidal Array Cabling Solution project was launched in December 2013 to develop and demonstrate efficient methods of locating, securing, protecting and retrieving cables for tidal energy arrays.
Stromness based energy and environmental consultancy Aquatera Ltd was one of a number of companies that took part in the initial concept development stage of the project in 2014, subsequently being awarded a contract to undertake two demonstration projects.
The first of these, completed last year, saw a team led by Aquatera successfully deploy a unique, 50 metre long, rigid 'U-tube' cabling protection structure - designed by Jee Ltd - at the European Marine Energy Centre's Shapinsay Sound tidal test site in Orkney. This is believed to be the longest fixed sub-sea structure in the world installed to date at a tidal site, with its deployment involving an innovative arrangement of vessels.
The second and final phase of the project was completed over the winter of 2015 at a specially licensed site in the fast moving tides of Hoy Sound, also in Orkney.
The programme of work successfully tested over 10 different technological and procedural innovations within a ground breaking set of cable laying trials. The key areas of innovation included the type of cable lay vessel, the decking arrangements, the mooring arrangement and materials, surveying techniques, the use of a novel cable locating and protection system and the proving of cost effective cable layout and cable deployment and recovery techniques.
Aquatera has led and managed the year long programme of design, fabrication, deployment, testing and reporting activities, with essential collaboration and support from Stromness based Green Marine, who also provided the specialised GM700L heavy lift barge. The barge was adapted for use as a cable-laying platform using a movable modular decking system installed between the barge hulls. Other key contractors in this second phase of the project included JGC (fabrication), LUPUS (structural design) TTI (mooring analysis) and Orcades Marine (procedures and onsite services) with Roving Eye, Sula and Triscom providing deployment support services.
Daniel Wise, Head of Offshore Technology with Aquatera, said: "Establishing a safe, cost-effective and accurate means of laying cables in demanding tidal environments has been identified as a major challenge for the tidal energy sector. Aquatera has been working on a range of solutions to this challenge over the last five years or so and was delighted to get the opportunity, through the support from Scottish Enterprise, to work alongside our delivery partners to prove that the solutions we had developed would work in reality. The results that we have achieved within just one year have been outstanding and give us real confidence that we can now further develop an approach to cabling design, cable laying and cable management that will transform the economics and reliability of tidal energy."
Neil Ferguson, Senior Executive, Energy and Clean Technologies, Scottish Enterprise, said: "We are delighted that the demonstration of Aquatera's tidal cabling solution went so well and offer our congratulations to Aquatera and their project partners for their highly professional approach to turning R&D into practical reality. This success is exactly what Scottish Enterprise had hoped would emerge from our Tidal Array Cabling Solution Project, developing effective solutions to key issues for the growing tidal energy industry and contributing to the drive to reduce costs."
ORKNEY VESSEL TRIALS PROJECT
This project, the Performance Review of Maritime Support Services for Orkney (PRoMSSO), was conceived to explore and characterise the performance of Orkney-located vessels and associated services in carrying out marine renewables operations.
The project was funded by the Scottish Government through EMEC and was undertaken by Aquatera Ltd, acting as Principal Contractor to EMEC, with Orcades Marine providing vessel management consultancy.
The project involved:
- 20 organisations
- Over 120 individuals
- More than 60 vessel operations
- And a total of 30 days at sea
The project comprised a set of 6 performance trials covering:
- Workboat positioning and dynamic loading
- Gantry Barge positioning and device deployment
- Clump weight friction
- ROV operations
- Responses to man overboard situations in tidal currents
- And dynamics of buoy submergence
Project summary results can be viewed by opening the below PDF. Full project results can be obtained by contacting Project Manager: Ian.Johnstone@aquatera.co.uk or call 01856 850 088.
A short video (see below) has also been compiled which showcases footage from trials, equipment and vessels used and highlights the main findings.
FINAL VESSEL TRIALS
Final vessel trials were completed on the 20th February 2014.
CLUMP WEIGHT FRICTION TRIAL
Sea conditions around Orkney have been challenging over the past few weeks, however all clump weight friction trials at sea have now been completed. The attached pictures detail the operations performed at sea.
CLUMP WEIGHT FRICTION TRIAL
The first part of the clump weight friction trial was completed last week. This involved pulling two clump weights of different types and at different angles to establish the frictional coefficient for the weights on dry land. This will then be replicated in the sea to compare and correlate the results.
FURTHER POSITION KEEPING TRIALS
Further position keeping trials were undertaken last week using a multicat work boat. These trials involved the vessels moving around a pre-defined 20m grid using different mooring combinations. Initial results look very promising, although detailed data analysis has still to be completed.
POSITION KEEPING TRIALS
These photos show the team of vessels working on Position Keeping Trials using the gantry barge (GM 700). These trials were undertaken in our test area near the Falls of Warness last week.
The Vessel Trial earlier this week involved the GM700 gantry barge, in conjunction with the Green Isle and Erlend, undergoing position keeping under tow in a tidal stream. The results were very encouraging and although not yet analysed, would indicate that this method of positioning is suitable for some operations.
Later in the week the GM700 gantry barge was moored in a tidal stream with measurements taken on the actual loads on the moorings. At a later date these will be compared with computer generated models.
ORCADIA MANOEUVRABILITY TRIAL
The multicat Orcadia pictured, completed a manoeuvrability trial on the 4th of October, in the tidal area known as the string between mainland Orkney and the island of Shapinsay.
ORKNEY MARITIME SUPPORT PROJECT
The Orkney Maritime Support Project is a Scottish Government funded scheme, which is being managed through the European Marine Energy Centre (EMEC). The main objective of the project is to co-ordinate a programme of experiments to validate the performance of safe and cost effective approaches to maritime support for marine energy projects.
Aquatera initially suggested this scope of work and are now coordinating and managing the project alongside Orcades Marine on EMEC’s behalf.
The outcomes of this project are expected to examine cost reduction in the deployment of maritime energy devices, as well as proving the versatility within high level safety parameters of the fleet.
Appropriate vessels were selected for the shipping trials, with monitoring equipment installed on each vessel and in some cases on the sea floor.
The first set of shipping trials commenced in mid-June and have continued throughout the summer months. All results and findings will be fully disseminated once they have been analysed.
A regular blog featuring vessel trials footage and stills, operations and findings will run throughout the remainder of this project.
Initial footage of boat based and sea bed based ADCP deployment is shown below: