Abstract
Since 2003, the European Marine Energy Centre Ltd (EMEC) has provided purpose-built, accredited open-sea testing facilities for wave and tidal energy convertors across four test sites in the Orkney Islands. The Shapinsay Sound test site is situated east of Kirkwall and was established in 2011. It is a small-scale (0.9km x 0.4km) non-grid connected tidal energy test site situated in relatively benign velocity marine currents with a peak of 1.5m/s.
EMEC has identified a requirement for a Navigational Risk Assessment compliant to the Maritime and Coastguard Agency MGN 543 in order to update the previous Navigation Risk Assessment including impact on navigational safety, identifying any revised recommendations as required.
The Shapinsay Sound test site is within a Statutory Harbour Authority Area. Orkney Islands Council Marine Services is the Statutory Harbour Authority and provides Vessel Traffic Services with full radar coverage of the Shapinsay Sound test site and actively monitors and directs traffic within the harbour limits.
This Navigation Risk Assessment is device neutral, not assessing any particular device or type of device, but instead assumes a range of possible devices located within the test site. Vessel traffic analysis was undertaken using data from the Automatic Identification System, visual observations from a shore-based survey conducted over a number of years and a variety of secondary sources.
The greatest density of traffic is to the north of the test site and is chiefly associated with commercial vessel transits to and from Kirkwall. The density of traffic close inshore is not significant. The principal traffic close to the site is from service/ support vessels and vessels servicing the aquaculture site immediately to the west of the test site.
As part of this assessment, consultation was undertaken with local stakeholders and statutory regulators to better understand the baseline conditions and possible impacts to their activities. No consultees raised any significant concerns regarding the test site. A review of incident data from the Marine Accident Investigation Branch identified one incident close to the test site: a mechanical failure of an unknown vessel in June 2013.
Impacts to navigation were identified and individually assessed. The assessment considered the following baseline assumptions:
- There are no underwater cables associated with the Shapinsay Sound test site;
- No impact on Search and Rescue capability was anticipated;
- There are no other renewable developments currently in close proximity to Shapinsay Sound. Future exploitation of existing and planned lease areas is unlikely to result in cumulative and in-combination effects; and
- No impact on communications, radar or positioning systems is anticipated.
A navigational risk assessment was conducted that identified 11 hazards relevant to this site. The likelihood and consequence of each were scored based on the results of this assessment and all hazards were deemed to be low risk. From the assessment the following conclusions were drawn:
- The impact on vessel traffic routeing is low, with no existing routes through the Shapinsay Sound test site;
- Devices positioned in the site posed a low risk of contact from passing vessels;
- The impact on collision risk and visual navigation is assessed to be low given the small physical size of the devices anticipated to be deployed;
- The impact of device breakout was assessed and deemed to be low given the traffic density close to the site and unlikelihood of its occurrence;
- The impact on vessel grounding is assessed to be low; and
- No significant impacts on recreational or fishing activity were identified due to the low density of these vessel types within the site.
A number of embedded site wide risk controls were identified. In addition to this, a list of possible additional risk controls which could be considered for future devices were identified.
Guidance is provided for developers conducting device-specific NRA addendums and the considerations which should be made in each case. This assessment has provided a device neutral baseline. Any deviations resulting from the specific characteristics of a device should be considered within device specific assessments.
The NRA has not identified any significant hazards that relate to the current Shapinsay Sound test site. This document should be reviewed and updated at regular intervals to provide developers with an up-to-date and relevant site-wide assessment of the risks associated with the continued operation of the Shapinsay Sound test site.