Annex IV 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 Tiday Array (Bluemull Sound)

Project Site Annex IV

Title: Nova Innovation - Shetland Tiday Array (Bluemull Sound)
Start Date:
March 01, 2016
Research End Date:
January 01, 2035
Technology Type:
Info Updated:
July 22, 2019
Project Status: 
Device in operation
Two bladed, seabed mounted tidal turbine, M100 device
Project Scale: 
Array - three devices (due to increase to six in 2020)
Installed Capacity: 
300 kW

The Scottish tidal energy developer installed the first two Nova Innovation 100kW (M100) turbines in Bluemull Sound, Shetland in 2016, creating the world’s first offshore tidal array. A third turbine was added in 2017. The M100 device comprises a cylindrical nacelle unit, rotor attached to a steel frame gravity base foundation (therefore requiring no seabed drilling or additional site works). The negatively-buoyant nacelle is securely connected to the base by means of a latching system. The turbine has a rotor diameter of 9 m and a hub height of 9 m, making the total height 13.5 m from the bottom of feet to the tip of the blades.  The turbines n the Shetland Tidal Array are installed in water depths  of between  30 and 40 m, so clearance is always at least 15 m below lowest astronomical tide. As a result the are no navigational restrictions around the array or requirements for surface markers on. The footprint of each device is 13.5 x 12.2 m, and the weight in water is 80 tonnes.


Each turbine has a separate 1.2 km export cable which also contain fibre-optic cables for data and communications. The three cables come ashore at Cullivoe Pier, where onshore infrastructure receives information on operation and performance of the turbines and a small sub-station converts and supplies the electricity into the Shetland grid. In 2018 Nova Innovation also installed a series of Tesla lithium ion batteries and associated infrastructure at Cullivoe, enabling energy storage. The Shetland Tidal Array is now supplying baseload tidal power to the Shetland grid.


The next phase of the Shetland Tidal Array involves the addition of three further 100 kW turbines in 2020. In addition, a subsea hub and inter-array cabling will be used in the expanded array to remove the need for a dedicated export cable for each turbine.


The small size of Nova’s devices enables local vessels to be used for deployment, operations and maintenance and facilitated the development of local supply chain. To date the project has been delivered with 20 % content from the Northern Isles, over 80% from Scotland and 100% from within the European Union.


Bluemull Sound, Shetland in water depth between 30 and 40 m.

Process Status: 

After successful deployment and operation of the Shetland Tidal Array, in May 2017, secured around £190,000 in capital support to build and operate an energy storage solution for the Shetland Tidal Array. Tesla lithium ion batteries and associated infrastructure were installed at Cullivoe Pier in 2018 and the array is now suppling baseload power to the Shetland grid and contributing to grid stability.


The key aim of the project was to demonstrate the economic and technical benefit of Nova Innovation’s Tidal Energy Storage System (TESS) to expand and overcome grid constraints.


Nova Innovation is the lead partner in a €20.2 million flagship Horizon 2020 project, Enabling Future Arrays in Tidal (EnFAIT). The EnFAIT project began in July 2017 and will run until June 2022.

The EnFAIT project will expand the Shetland Tidal Array to six turbines with a total rated capacity of 600kW, and demonstrate that high array reliability and availability can be achieved using best practice maintenance regimes. The layout of the turbines will be adjusted to enable array interactions and optimisation to be studied for the very first time at an operational tidal energy site.


In May 2019 it was announced that EnFAIT has reduced the cost of tidal energy by 15 % and grown its supply chain from 4 to 14 countries.  In May 2019 Nova Innovation was awarded €5 million funding for another Horizon 2020 project, ELEMENT, which will incorporate Artificial Intelligence technology to improve tidal turbine performance. The project will deliver an adaptive control system that improves turbine performance, decreasing the lifetime cost of energy by 17% and driving the tidal energy sector to commercialisation. The control technology will be demonstrated on the Nova M100 turbine in the Shetland Tidal Array.

Licensing Information: 

A Marine Licence was issued under the Marine (Scotland) Act 2010 by Marine Scotland for the extension to the Bluemull Sound site on 13 April 2018 (Licence no. 06642/18/0).


The marine licence document and other information can be found at the following link:

Key Environmental Issues: 

The key environmental issues identified were the potential for impacts on qualifying features of Yell Sound Coast Special Area of Conservation and Hermaness, Saxa Vord and Valla Field Special Protected Area (SPA). This included possible disturbance as well as collision risk. Marine Scotland carried out a revised Appropriate Assessment (AA), required under Regulation 48 of the Conservation (Natural Habitats, &c.) Regulations 1994, for the project in 2018 in support of their determination process for the Marine Licence. Nova Innovation also produced an Environmental Assessment Report (EAR) for the project, since a statutory Environmental Impact Assessment was not required. The EAR and AA included updated collision risk assessments for the proposed six-turbine array and included an assessment for the proposed Special Protected Area (pSPA). They also considered the proximity of the development site to the Yell Sound Coast SAC and the foraging range of harbour seals, as well as the risk of collision between diving birds and operational turbines. Species specifically considered to be potentially significantly impacted by the proposal and requiring more detailed assessment included:


Yell Sound Coast SAC

  • Harbour seal (Phoca vitulina).

Following this further assessment it was concluded that there would be no adverse effect on the harbour seal feature of the Yell Sound Coast SAC and therefore no adverse effects on site integrity.


Hermaness, Saxa Vord and Valla Field SPA

  • Gannet (Morus bassana);
  • Puffin (Fratercula arctica);
  • Red-throated diver (Gavia Stellata);
  • Guillemot (Uria aalge); and
  • Shag (Phalacrocorax aristotelis).

Following further assessment it was concluded that there would be no significant effects on the above qualifying species of the SPA and therefore no adverse effect on site integrity.


Bluemull and Colgrave Sound pSPA

  • Red-throated diver (Gavia stellata).

Following further assessment it was concluded that there would be no significant effects on the red throated diver feature of the pSPA and therefore no adverse effect on site integrity.


The conclusions of the EAR and AA were dependent on a program of monitoring to understand collision risk and collision risk factors for diving birds and marine mammals.

Nova Innovation - Shetland Tiday Array (Bluemull Sound) is located in United Kingdom.

Baseline Assessment: Nova Innovation - Shetland Tiday Array (Bluemull Sound)

General Description:

Due to the small scale of the project, an Environmental Impact Assessment (EIA) was not required to be carried out, however due to the project’s proximity to a Special area of Conservation and 4 Special Protection Areas an Appropriate Assessment was carried out to determine the potential for Likely Significant Effects of the project. A revised appropriate assessment, issued in 2018, includes an assessment of the Bluemull and Colgrave Sounds pSPA.

ReceptorStudy Description Design and Methods Results Status
  • Marine Mammals

Encounter Rate Modelling (ERM) to inform collision risk

Use of computer models to determine the potential for sensitive species to collide with turbine blades. A 98% avoidance rate was assumed.

The following calculations are based on the assumption that the devices are operating for 73% of the time as estimated by Nova.

All year predicted encounter rate – 3.96

Breeding season parameters based on seals-at-sea density figure – 4.00

  • Sea and Shorebirds

ERM to inform collision risk

Use of computer models to determine the potential for sensitive species to collide with turbine blades. A 98% avoidance rate was assumed.


Breeding season ERM

All year ERM

Atlantic puffin



Red-throated diver



Northern gannet



Common guillemot



European shag



Reports and Papers

Nova Bluemull Sound - Appropriate Assessment

The 2018 Encounter Rate Modelling for the proposed six-turbine array can be accessed here.

Post-Installation Monitoring: Nova Innovation - Shetland Tiday Array (Bluemull Sound)

General Description:

For the Shetland Tidal Array extension to 6 turbines, Nova Innovation will produce a Project Environmental Monitoring Programme (PEMP) detailing the activities that will be carried out to improve the evidence base on the environmental impacts of the array on the environment which in turn, will inform the ongoing management of the project.

ReceptorMonitoring Program Description Design and Methods Results Status
  • Fish
  • Marine Mammals
  • Sea and Shorebirds

Underwater video monitoring

Nova Innovation has carried out extensive video monitoring of the turbines currently deployed in the area to assess the potential impact on marine wildlife. Each turbine is fitted with cameras that are triggered by the presence of wildlife.

There have been no observations of any marine wildlife colliding with the blades. Fish, birds and seals have been observed on the cameras, however, both the fish and their predators were observed to leave the region of the turbines while tide was flowing (and blades were rotating), with fish moving to areas of lower flow on the seabed.

Reports and Papers N/A
Research N/A
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