Page 28 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report

Alderney Regional Environmental Assessment of Renewable Energy:
Environmental Report
1.2.2 Marine Renewable Energy
The Draft Plan includes the consideration of future tidal development by any developer across
all of Alderney’s territorial waters. Studies that have been commissioned by ARE have
determined that the extractable energy contained within Alderney’s territorial waters exceeds 4
GW. Other studies indicate lower tidal resource estimates (e.g. Wilson, 2005; Black & Veatch,
2005; Caldwell, 2011). ARE currently has an exclusive licence for tidal energy generation with
access to 48 of the 96 available square miles of Alderney's territorial waters (Figure 1). These
48 blocks are considered to have the greatest tidal energy resource and have therefore been
the focus of survey studies to date. The Commission, however, has also been approached by
potential developers with an interest in exploiting the remaining tidal resource of Alderney’s
waters.
The 48 blocks that are currently licensed to ARE can be sub-divided into the following
individual projects that fall within the three main tidal streams around Alderney:
ƒ Project 1: The Race;
ƒ Project 2: The Casquets; and
ƒ Project 3: The Ortac Channel.
ARE is proposing to take forward the development, consenting and deployment of devices
within the Race in 5 phases. It is envisaged that an EIA will be undertaken for each of the 5
phases and will be reported within separate Environmental Statements (ES). The Casquets
and Ortac Channel Projects will be submitted as 2 individual consenting applications and are
not currently divided into individual phases. Based on ARE’s high level tidal development
programme plan, and subject to obtaining the necessary consents, it is anticipated that tidal
farm construction will take place between 2015 and 2022. Details of the operational and
decommissioning phases of the programme have not yet been fully defined.
As outlined in ARE’s Business Development Plan (ARE, 2011), it has been assumed that the
individual projects will comprise offshore tidal stream turbine deployments of the OpenHydro
16m diameter Open-Centre Turbine. The arrays will consist of Open-Centre Turbines which
will be deployed on separate gravity based subsea foundations. The structure’s own weight will
be used to penetrate the sub-sea floor with rock spikes i.e. no drilling, piling or pining would be
required. The dimensions of the entire structure (turbine and base) are 30m (l) x 26m (w) x
18m (h).
It is planned that the turbines will be installed using OpenHydro’s especially designed
Deployment Vehicle. This deployment process is claimed to take less than an hour (excluding
cable connections) and comprises the following steps:
ƒ The Deployment Vehicle is towed to site using a standard tug;
ƒ Whilst being held in position by the tug, the turbine and Subsea Base are lowered by
the Deployment Vehicle;
ƒ Once on the seabed, the lifting lines are released and the Deployment Vehicle is towed
back to harbour; and
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