Optimising Subsea Power Connection Systems for Tidal Energy Devices

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New solutions are desperately needed to combat grid connection challenges related to laying long distance subsea cables.

These (will) include direct tie-backs where each individual system has its own link to shore or situations where many devices are manifolded into a single cable. These configurations balance different features of redundancy and availability to the grid

Subsea cabling features in all marine energy installations and forms a significant cost component in such projects. The role of cable installation and maintenance is fundamental to the success of any interconnector project.

Subsea connection methods are currently feasible to water depths close to 3,000m using Remotely Operated Vehicles and Diverless Connection Technologies.

"With the advent of subsea processing, high power voltage cables have also become more prevalent as multiple MW of power are required to power subsea compression and pumping systems," according to VerdErg's corporate development officer Ron Tucker.

VerdErg, who are scheduled to share information about techniques and developments in subsea cabling methodologies at the forthcoming 3rd International Tidal Energy Summit 2009 in London this year (November 17-18), has been engaged in the subsea connection of multiple control umbilicals, which have included electric power/signal, hydraulic control and fibre optics.

It is believed that advancements made in the subsea processing area will directly benefit power connection systems for renewable energy devices.

"New installation vessels are entering the market to lay longer and larger cables faster, which is lowering their costs. This will allow renewable energy devices to step further into water depths where more energy can be captured. To date, we have seen most systems in shallow water with surface tie-ins of the cables. In deep water, currents such as the Gulf Stream could be tapped in water depths of close to 1,000 m," Tucker said.

Challenges

The industry has faced challenges pertaining to laying long distance subsea cables from renewable energy projects to areas of large population.

For instance, in the past, TNEI, in its study for island authorities together with Highlands and Islands Enterprise (HIE) and the Scottish Executive to investigate the best options for transmitting power generated by island renewable energy projects to the mainland, has described the laying of subsea cables as a Catch-22 scenario.

Prospective renewable energy developers require confidence that they will be able to connect to the grid, but conversely, investment in grid infrastructure is reliant on securing a guaranteed level of supply. It has been highlighted that the length of time it takes to co-ordinate supply and demand between projects and transmission capacity could be minimised by planning consents and wayleave agreements being secured ahead of full investment approval for infrastructure.

Connecting devices

Tucker believes there will be emergence of many configurations similar to subsea systems.

"These (will) include direct tie-backs where each individual system has its own link to shore or situations where many devices are manifolded into a single cable. These configurations balance different features of redundancy and availability to the grid," said Tucker.

As far as setting up of electricity transmission network is concerned, the industry is also witnessing the usage of high voltage direct current (HVDC) transmission technology.

VerdErg will join a host of other speakers will discuss issues related to cable installation, grid connection and tidal energy development in detail during the 3rd International Tidal Energy Summit 2009.

Other speakers include:

  •          Martin Wright, Managing Director, Marine Current Turbines
  •          Trey Taylor, President, Verdant Power
  •          Billy Langley, Developer - Marine, RWE npower

For more information, click here:
http://www.tidaltoday.com/ITES/4/

or Contact: Abbie Badcock - abbie@tidaltoday.com or 44 (0)207 375 7581

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Abbie Badcock
Tidal Today
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