Marine Renewable Energy Technology

There has been a lot of information available recently on developments in the marine renewable energy field, but it should be borne in mind that most of these wave and tidal technologies are still at an early stage of development. It is not anticipated that the Island will be able to receive any energy from tidal power for a few years (the exact date is difficult to accurately estimate), but it is important that RET and the Guernsey in general are ready to utilise these new technologies, when the time is right.

Trial/small commercial projects are soon to be set up in a number of locations, including in the Raz Blanchard (Alderney Race) a strait that runs between Alderney and Cap de la Hague which experiences strong tidal flows.  In addition there are projects being developed for an area of sea off Paimpol on the Brittany coast, Scotland and in the South-West of England at Have Hub. In the Pentland Firth in Scotland there is the European Marine Energy Centre (EMEC) where a number of wave and tidal devices have already been deployed. There have also been sea trials of devices in America and Canada, as well as planned deployments in Asia and Australasia.

Technologies currently being used are not yet in commercial production and so the companies that are involved in these projects invest in research and development. This, coupled with the difficulties of the marine environment, means that energy from marine renewable sources will initially cost much more to produce than electricity produced by conventional fossil fuel based generation plants. In addition to the purchase cost, there is also the necessary cabling and beachhead connections to join the generators to the power grid.

The Guernsey Renewable Energy Team is investigating whether the Island would be able to benefit from any UK or EU subsidies, but it is inevitable that some of the costs of using renewable energy will have to be paid for locally. It is hoped that the Islands will be able to benefit from the renewable energy generated by our tides and possibly receive an income through the supply of surplus electrical power via the subsea electrical cable that links the Island with Jersey and France.

There are a number of renewable energy options that may be applicable to Guernsey.

Tidal current devices - these extract energy from the flow of water, and often take the form of propellers or oscillating vanes fixed to a structure that is mounted on the seabed.

Wave energy devices - these take energy from waves. There are a number of types of device, one commonly known is the offshore snake-like Pelamis device. However, there are also buoy-type point absorber devices, and near-shore or shallow water devices.

Offshore Wind - Guernsey has a significant wind energy resource and although areas of suitably shallow water off the west coast are limited there is sufficient area for small scale development. RET is currently looking at the mature technology of monopole turbine as floating turbines are still being investigated. Should floating turbines become more common in the future RET will investigate the possibility of deploying these turbines off the west coast.

The above options are considered to be most suitable for Guernsey due to the geography of the region, and formed the focus of the Regional Environmental Assessment of Marine Energy. However, we will keep track of developments regarding other technology options for possible future use.

Of the marine renewable technologies there is one that RET have currently discounted for use in Guernsey’s territorial waters:

Tidal Barrages or Lagoons - There are a number of bays, inlets and areas of shallow water around the coast of Guernsey. However, tidal barrage / lagoon technologies are not being investigated further at this time because:

  • None of the areas of the bays are sufficiently large to provide commercial amounts of electricity

  • The offshore engineering works necessary to create a barrage or lagoon would be expensive in relation to the value of the energy produced

  • The visual impact of a large concrete structure

  • The impact on sediment movements and bathymetry

  • Secondary ecological impacts as a result of habitat change