OES-Environmental distributes metadata forms (questionnaires) to solicit information from developers involved in environmental monitoring around marine renewable energy project sites around the world. This page provides project descriptions, baseline assessment, post-installation monitoring, and links to available data and reports. Content is updated on an annual basis.

Nova Innovation - Shetland Tidal Array

Description

The first three Nova M100 devices (installed capacity 300 kW) were deployed in 2016 and 2017. This was the world’s first offshore tidal array to supply electricity to the grid with greater than 17,000 generating hours reached in 2019. 

In 2018 licences were granted to extend the array to six turbines (increase capacity to 600 kW). In 2018, Nova Innovation worked with Tesla to add energy storage to their tidal technology. This created the world’s first grid connected tidal power station with the ability to deliver baseload (constant, steady state) power and deliver energy on demand to meet consumer needs.

In August 2020 a fourth 100 kW turbine was added to the array. This was the M100-D, next generation of Nova's M100 turbine, with no gearbox (direct drive). A further two 100 kW M100-D turbines were installed in January 2023, taking the total number of turbines to six. An offshore hub was also installed, enabling a single export cable to take the power from the fifth and sixth turbines to shore.

In 2023 licences were granted to partially decommission the array by removing the three original M100 turbines and associated offshore infrastructure. This was carried out as part of the EnFAIT project to gather information on the full end-to-end lifetime of an operational tidal array. Decommissioning the three M100 devices was completed in October 2023. The three M100-D turbines continue to generate and export electricity to the grid.

A comprehensive environmental monitoring programme has gathered data from the operational array since the installation of the first turbine in Bluemull Sound and is ongoing. The primary objective of the monitoring programme is to gather data on nearfield interactions between marine wildlife and the operational turbines, with a focus on marine mammals and diving seabirds. Over time the environmental monitoring programme has evolved, in line with the principles of adaptive management, to ensure it remains fit for purpose. All previous monitoring reports, along with other licensing information and documentation, are available online via the Marine Scotland Information website.

The environmental monitoring programme is now based on the use of turbine-mounted high-definition cameras to gather data on nearfield interactions between marine wildlife and the operational turbines. Other methods, including land-based bird and mammal surveys were previously employed, but have since been retired, having demonstrated that the risk of adverse effects to birds and mammals is very low.

Location

The Shetland Tidal Array is located in the Bluemull Sound, Shetland off the far north-east coast of mainland UK, between the islands of Yell and Unst.

Licensing Information

  • Marine Licence required from Marine Directorate Licensing Operations Team for construction and operation of the project.
  • Marine Licence required from Marine Directorate Licensing Operations Team for decommissioning the three original turbines.
  • Offshore Works Licence required from Shetland Islands Council.
  • Onshore Works licence required from Shetland Islands Council.
  • Licence to disturb European Protected Species (EPS) required from Marine Directorate Licensing Operations Team.

Project Progress

First three geared M100 turbines installed 2016-17. Fourth direct drive M100-D turbine installed 2020. Two more direct drive M100-D turbines and an offshore hub installed 2023. Three original geared turbines decommissioned in 2023.

Key Environmental Issues

Collision risk and disturbance to EPS. See https://marine.gov.scot/ml/marine-licence-shetland-tidal-array-extended-bluemull-sound-shetland-0664200009110 and https://marine.gov.scot/node/23874 

   

Papers, Reports, Research Studies

Licence application document:

Monitoring reports:

Environmental Monitoring: Nova Innovation - Shetland Tidal Array

Phase Stressor & Receptor Design and Methods Results
Baseline Collision

Marine Mammals 		Land-based surveys.
3120 20-minute scans for mammals. 		Completed
Marine animals (mammals and basking shark) were recorded in the surveys relatively infrequently and in low numbers. Some species such as humpback whale (Megaptera novaeangliae), minke whale (Balaenoptera acutorostrata), Risso‘s dolphin (Grampus griseus), killer whale (Orca orcinus) and basking shark (Cetorhinus maximus) were only recorded in one or two scans over the entire nine-year survey period.
Baseline Collision

Birds 		Land-based surveys.
5208 10-minute snapshot scans for birds. 		Completed
Two diving bird species, black guillemot (Cepphus grylle) and European shag (Phalacrocorax
aristotelis) accounted for over 90% of all birds recorded in surveys. Black guillemot, the most frequent and abundant bird species, was recorded in the array area
(Zone 1) in 11% of all scans (561 scans of 5208), with birds observed diving in the array area in
fewer than 3% of scans (143 scans). The second most frequent and abundant species, European
shag, was only recorded in the array area (Zone 1) in <3% of all scans (150 scans), with birds
observed diving in the array area in 1% of scans (54 scans).
Post-Installation Monitoring Collision Species presence, identification, and behavioural observations.
Land-based surveys and subsea video. 		and-based surveys completed in 2023. Subsea video ongoing.
Land-based survey: The absence of black guillemot, European shag or other bird or marine mammal species in footage in this subset aligns with the findings of Nova’s land-based surveys, in which black guillemot was observed diving in the array area in fewer than 3% of all scans and European shag in 1% of all scans, indicating that diving bird numbers are low in the array area.

Subsea video: Analysis of the vantage point data for these two species indicated an elevated probability of birds diving in proximity to the turbines around low water slack and on increasing flood tides and lowest probability on maximum ebb tides, suggesting they may not be expected to be seen in subsea video when turbines are operating. These birds were observed infrequently in the footage, with ten occurrences of European shag (Phalacrocorax aristotelis), six of black guillemot (Cepphus grylle) which were only observed in footage when turbines were not operating, such that blades were stationary.
Post-Installation Monitoring , Decommissioning Noise

Marine Mammals 		Turbine noise measurements carried out in 2023.
Environmental assessment with auditory recordings. 		Completed
Recovery of the turbines and export cables will not involve any noisy activities such as drilling. The temporary and short duration of the activities, the lack of noisy marine works and the use of a small Multicat vessel mean the potential for disturbance by noise or vibration generated during decommissioning is negligible. No drilling or piling to be carried out during decommissioning, avoiding significant underwater noise or vibrations.
Post-Installation Monitoring Collision

Marine Mammals 		Species presence and identification.
Land-based surveys and subsea video. 		Land-based surveys completed in 2023. Subsea video ongoing.
Land-based survey: Harbour seal was observed in the array area in just 0.3% of all surface scans and hCarbour porpoise in 0.7% of all scans, indicating that marine mammal presence in the array area is generally very low.

Subsea video: Harbour seals (Phoca vitulina) were infrequently observed thirteen times and only when the turbines were stationary.
Post-Installation Monitoring Collision

Fish 		Species presence, identification, and behavioural observations.
Subsea video and still photography. 		Ongoing
No physical contact between fish and the turbine blades was observed in any of the video footage or stills in this subset. Saithe (Pollachius virens) was the most frequently observed and abundant species, with groups observed aggregating around the turbines, moving vertically up and down in the water column according to tidal flow.