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.

EMEC Billia Croo Grid-Connected Wave Test Site

Project Site OES-Environmental

Title: EMEC Billia Croo Grid-Connected Wave Test Site
Start Date:
October 01, 2003
Technology Type:
Info Updated:
July 01, 2019
This chart provides a graphical display of the wave test site at Billia Croo and the associated infrastructure. (http://www.emec.org.uk/download/Wave%20Site%20Awareness%20Chart.pdf)
Project Status: 
Test site operational
Project Scale: 
Test site with six berths
Installed Capacity: 
Each of the six berths has a cable with 2.2MW capacity. Total site capacity is 7MW. EMEC is seeking site-wide consent for a generating capacity of 20MW.

In 2003 the Highlands and Islands Enterprise proposed to construct the infrastructure which would allow wave energy devices to be tested under working conditions. The purpose of the project was to allow the generating capacity of wave devices to be verified, in order that further investment could be obtained for establishing the technology on other offshore sites.


After a site selection study, Billia Croo was identified as the most suitable location for the test site. This site is an area with one of the highest wave energy potentials in Europe with an average significant wave height of 2 – 3 metres, reaching extremes of up to 17m. The site has a total of six berths; five cabled test berths in up to 70m water depth (four at 50m, one deeper), located approximately 2km offshore and 0.5km apart and one nearshore berth situated closer to the substation for shallow water projects.


Two waverider buoys are located on site measuring the wave height, period and direction, and a purpose-built weather station provides real-time met data for the site. This data is fed into a sophisticated SCADA (Supervisory, Control and Data Acquisition) system, with live data feeds on the marine and met conditions available to view on the EMEC website.


The test site berths are monitored by CCTV situated at an observation point at the Black Craig - a former coastguard lookout station which has been converted to house powerful cameras for monitoring the activity out at sea. This is controlled remotely from the data centre and office facilities.

Export Cables:

Each of the six berths has an 11kv cable on the seabed to export electricity to the onshore substation.These cables are wet-type composite cables consisting of three EPR-insulated stranded copper power cores designed for alternating current, three 2.5mm2 copper signal/pilot trip cables and a 12-core single-mode fibre-optic bundle. The cable is then armoured with two layers of galvanised steel wire. Cables were provided by AEI (wave test site cables) & Pirelli (tidal test site cables). The conductors on these cables are 50mm², giving a nominal rating of 2.2MW.


The cables were laid as standard sub-sea cables on the sea bed. As the cables approached the shore, in 15m of water, ductile iron cable protectors were attached. At the low water spring tide mark, each cable passes into a trench dug 12m into the seabed and beach. On shore, the cables are fed into a manhole and then into the substation. At the offshore mooring positions, a seabed anchor, of reinforced concrete, is installed to anchor the end of the cable, before it rises to connect to the wave energy device. A fibre optic communications cable will be incorporated within each of the armoured cables.


Onshore Infrastructure:

The substation at Billia Croo is broadly similar to that at the tidal test site at the Fall of Warness. Each cable coming from the test site terminates in the substation at an 11kV circuit breaker, along with the tripping cable. This provides an isolation switch for the devices under test and operates as the interface between EMEC and the UK national grid. The electrical output performance of each of the devices is measured by equipment within the substation and transmitted to the data centre. The quality of the electricity can then be analysed by EMEC to demonstrate that the devices can provide a smooth and reliable supply of electricity to the grid. The metered data is also provided to the developer through the Supervisory Control and Data Acquisition (SCADA) system and the power data is logged in the data historian to be made available for historical trending. EMEC ensures the confidentiality of the data collected.


Vessel Spread:

Vessels used in the installation of the EMEC wave test site are:

Vessel type



Cable lay vessel

Installation of sub-sea export cables

CS Sovereign

Survey vessel

Benthic and bathymetric surveys

Exact vessel used unknown

Dive vessel

Used to deploy divers for benthic surveys

Exact vessel used unknown


EMEC’s wave test facility is ideally placed on the western edge of the Orkney mainland, Billia Croo, Stromness. Subjected to the powerful dynamic forces of the North Atlantic Ocean, it is an area with one of the highest wave energy potentials in Europe with uninterrupted Atlantic waves of up to 17m. Four of the test berths are at 50m depth, while the fifth is located at 70m depth, all situated 1-2 km from the shore and 0.5 km apart. Shallow water test facilities situated close to the substation are also available.

Project Timeline: 

The Centre was established with around £30 million of funding from the Scottish Government, Highlands and Islands Enterprise, the Carbon Trust, the UK Government, Scottish Enterprise, the European Union and Orkney Islands Council. Construction of the wave test facility was completed in October 2003 and operational activities commenced shortly after.

The following is a list of all EMEC wave clients:

Licensing Information: 

EMEC has been examined and accredited as a test laboratory for full-scale wave and tidal test facilities by the United Kingdom Accreditation Service (UKAS), since 2005. EMEC is accredited to test the performance of wave and tidal energy devices against IEC Technical Specifications. EMEC can provide you with independent verification in accordance with ISO 17020 to confirm that your technology satisfies conceptual reliability, survivability and performance targets.


EMEC has been granted the consents required to install an agreed ‘envelope’ of device types and activities at the site.

EMEC holds licences and consents relating to the following legislation:

  • Town and Country Planning (Scotland) Act 1997
  • Marine (Scotland) Act 2010
  • Crown Estate Act 1971
  • Food & Environment Protection Act 1985 Part II Deposits in the sea (FEPA)
  • Coast Protection Act 1949 (section 34) (CPA)
  • Electricity Act 1989 (section 36)
  • The Conservation (Natural Habitats, &c.) Regulations 1994
  • The Wildlife and Countryside Act 1981


Each developer is required to submit device-specific information in order to acquire a marine licence to allow the installation of their device. This information includes a project summary and details on how the specific device details align with the EMEC’s environmental appraisal and navigational risk assessment. All developers are expected to submit an environmental monitoring programme.

Key Environmental Issues: 

Several potential environmental issues were identified in the Environmental Impact Assessment, these were:

  • Disturbance/modification to benthic habitats/communities as a result of cable and anchor laying in inshore waters;
  • Disturbance to intertidal environment from cable laying activities;
  • Effects of energy removal on adjacent marine biotopes;
  • Device noise;
  • Hydro acoustic signals from subsea cables;
  • Physical presence of devices interacting with birds and mammals; and
  • Colonization of subsea infrastructure and antifouling effects


Environmental Webpage: http://www.emec.org.uk/facilities/wave-test-site/environmental-description-wave/ 


Mitigation Measures:  


Note: the following section describes environmental mitigation measures undertaken during construction of the Billia Croo site only, and not those undertaken for ongoing developer testing activities.


During installation, general good civil engineering practices were adhered to in an attempt to reduce and contain disturbance to the shore and seabed habitats within as small an area as possible. 


Due to the limited knowledge on certain potential impacts arising from the presence of test devices, further research was encouraged.  In particular in relation to:

  • Impacts on shoreline ecology from the removal of energy from the marine environment.  The presence of Fucus distichus subsp. anceps. provides a useful sentinel species on the shore, which can be simply and cheaply monitored.
  • Characterisation of background noise prior to device installation and an attempt to determine the zones over which device sound signatures may be detectable.


The presence of the CCTV cameras at the coastguard lookout enable any significant effects on general marine life and ecology to be observed, and more generally provide data of interest to SMRU, the Orkney Field Club, local recorders and the Orkney Whale and Dolphin Group.


At the time of decommissioning, a BPEO study (best practicable environmental option) should be undertaken to fully investigate the impacts associated with different decommissioning options.


EMEC Billia Croo Grid-Connected Wave Test Site is located in United Kingdom.

Baseline Assessment: EMEC Billia Croo Grid-Connected Wave Test Site

General Description:

The following field surveys were undertaken (or commissioned by) the developer to inform baseline characterisation.

ReceptorStudy Description Design and Methods Results Status
  • Physical Environment

Bathymetric survey

Multibeam bathymetry at 1m spacing for wave site test area and 4m spacing for inner wave site test area. Sidescan conducted for both test area and inner test area.

General bathymetry maps show bedrock substrata to be characteristic of the shoreline of this region and extend steeply into the infrattorial zone. The underlying bedrock continues to dominate the circalittoral zone, with the predominantly offshore sublittoral sediment reached at around 45-47m.

  • Benthos

Dive surveys

A dive transect survey, undertaken by ICIT, Heriot-Watt University, extending shoreward from 20 m (video and stills photography) and for seven stations within the wave site test area (video, still photography and fine sediment cores for future biological reference)

Surveys of the area have indicated that there appears to be a transition from bedrock to a broken boulder/stone seabed to a sediment dominated seabed with distance from shore.


Dense kelp forests thinning to kelp park exist between the low water mark and to a depth of approximately 20-25m. Fauna typical of hard substrata and exposure to water movement were common on the bedrock, boulder and stone seabed. Sites with broken boulder/stone substrata supported more diverse communities, with F. foliacea and brittlestar biotopes.


Analysis of core samples taken from the offshore sedimentary area indicate that the sediments are dominated primarily by polychaete worms followed by nematode worms, although in some samples polychaetes accounted for over 80% of sample species composition.

  • Intertidal Ecology

Intertidal survey

Littoral survey undertaken by ICIT in conjunction with Dr Martin Wilkinson of Heriot-Watt University (transects and species list)

Species characteristics of extreme wave exposure were found.  Sparse fucoid growth is evident in the very upper reaches of the littoral area.


The boulder beach consists of a steep upper-littoral zone, which levels out through the mid- and lower-littoral/sublittoral areas.  Although not immediately apparent, there was a fairly abundant presence of plants and animals in the mid to lower reaches of the littoral zone, especially in the spaces between boulders, suggesting their size may provide a degree of shelter for some species.

Reports and Papers


Titlesort descending Data Type Date Research End Date Organization
EMEC Billia Croo FLOWBEC Fluorometer Monitoring Data July 10, 2013 August 12, 2013 University of Aberdeen
EMEC Billia Croo FLOWBEC Platform Acoustic Doppler Velocimeter Data July 10, 2013 August 12, 2013 University of Aberdeen
EMEC Billia Croo FLOWBEC Platform Multi-Beam Sonar and Echosounder Data Active Acoustics, Multi Beam July 10, 2013 August 12, 2013 University of Aberdeen
EMEC Billia Croo High-Intensity Wildlife Observation Data Observation, Boat/Land Based Survey July 10, 2013 August 12, 2013 University of Aberdeen
EMEC Billia Croo Wildlife Observation Data Observation, Boat/Land Based Survey June 15, 2009 July 28, 2015 European Marine Energy Centre (EMEC)

Post-Installation Monitoring: EMEC Billia Croo Grid-Connected Wave Test Site

General Description:

The following mitigation and monitoring measures are proposed within the project ES. The project team, along with Marine Scotland and other key stakeholders are currently preparing a Preliminary Environmental Monitoring Plan (PEMP) which will outline the proposed monitoring strategy in more detail.

ReceptorMonitoring Program Description Design and Methods Results Status
  • Birds
  • Marine Mammals

Land based wildlife observations

The Billia Croo wildlife observation project commenced in March 2009 with the Scottish Government funding the current contract. During the period between the 1st of April 2013 to 31st of March 2014, a total of 886 hours of observations were completed.


Observations were completed in December 2015.

Seasonal peaks in grey and harbour seal abundances corresponding with pupping seasons, which is mirrored in the data collected to date at the site. During this reporting period the majority of cetacean sightings have been of White-beaked Dolphin, whereas typically the most sighted cetacean is Harbour Porpoise. A typically diverse range of marine birds has also been observed, although for several species, numbers in April and May 2013 fell below the mean. This could be due to the enduring winter of 2012/2013 and resultant late spring experienced in Orkney as was the case for the rest of the UK. See here for further detail on methods and results.

  • Birds
  • Marine Mammals

Land based wildlife observations

Land-based observations take place from a look-out shelter on Black Craig, Billia Croo (58˚58.746’N 03˚21.499’W), approximately 110m above sea level. The observations for birds and marine mammals commenced at Billia Croo on 11th March 2009, with a four-hour watch format, five days per week (i.e. approximately 80 hours of observation per month), which are timetabled to cover different tidal states and times of day. This analysis will use data collected over a period of two years

Almost all species showed spatial variation in their use of the Billia Croo site. There are slight differences in the locations of hotspots and the extent to which different species used the wave test site. However, for a number of species (e.g. shag, auks and eider), sightings were concentrated between the Black Craig observation Tower and/or off Breck Ness.


Many species also showed seasonal variation in their use of the site, which reflected the breeding and wintering habits that are typical for the species. Fulmar, gannet, Arctic tern, black guillemot and puffin, were found to vary in their usage of the site throughout the day.


Encounter rates for some species were found to vary with tidal state and also under different environmental conditions, including wind strength, direction and glare extent.


See http://www.snh.org.uk/pdfs/publications/commissioned_reports/592.pdf for further detail on methods and results.

Reports and Papers

EMEC has carried out or has been involved with a number of research projects. These include national, international and site specific projects. More information about these can be found at the following location: http://www.emec.org.uk/research/


Site specific projects:

  • Acoustic monitoring
  • ReDAPT
  • Inshore crustacean fisheries
  • Hydrodynamic modeling
  • Wave resource monitoring
  • Surface Interactions with Wave Devices: Remote Observations
  • Marine safety course


National projects

  • Underwater Acoustic Monitoring at Wave and Tidal Energy Sites: Guidance Notes for Regulators
  • The provision of guidance to inform the simplification of marine renewable energy development application
  • A review of the potential impacts of wave and tidal energy development on Scotland’s marine environment
  • Flow, Water Column and Benthic Ecology 4D (FLOWBEC)
  • Understanding how marine renewable device operations influence fine-scale habitat use and behaviour of marine vertebrates (RESPONSE)
  • Optimising array form for energy extraction and environmental benefit (EBAO)
  • PerAWaT
  • Pentland Firth and Orkney Waters (PFOW) strategic data study
  • The consolidation of wave and tidal EIA/HRA issues and research priorities


International projects

  • MaRINET and MaRINET 2: The EU MaRINET2 project is working towards its vision of unlocking the energy potential of our oceans by ensuring the integration and enhancement of leading European research infrastructures specialising in research, development and testing of Offshore Renewable Energy (ORE) systems. EMEC’s test sites, including Shapinsay Sound scale site, form part of the infrastructure network available to developers with offshore renewable energy projects heading towards commercialisation

  • Equimar


  • Strategic Environmental Assessment of Wave Energy technologies (SEA Wave)

  • Clean Energy From Ocean Waves (CEFOW)

  • FORESEA: Funding Ocean Renewable Energy through Strategic European Action

  • CLEMATIS & ORCHIDS: Cable Lifetime Enhancement via Monitoring using Advanced Thermal and electrical Infrastructure Sensing (CLEMATIS) seeks to prove of a number of concepts devised during a previous desk based feasibility study (ORCHIDS)

  • PERISCOPE: Aims at establishing a permanent innovation ecosystem in the North Sea Region to grow transnational innovation partnerships for sustainable business development in emerging blue markets.

  • MONITOR: Multi-model investigation of tidal energy converter reliability.

  • ProtoAtlantic: Strengthening the transfer of innovation results to facilitate the emergence of new products, services and processes.

  •  MET-Certified: Development of International Standards and Certification schemes for Marine Energy Technologies

  • Reliability in a Sea of Risk (RiaSOR & RiaSOR II): RiaSOR established a framework for reliability assessment within the ocean energy sector, which builds upon established practices from the automotive industry. RiaSOR II is aimed at taking the RiaSOR I theoretical reliability assessment framework and applying it to the field test programme for developers to validate the findings and establish a practical monitoring platform.

  • ResourceCode: Resource Characterisation to Reduce the Cost of Energy through Coordinated Data Enterprise

  • Marine Energy Alliance (MEA): De-risk early stage marine energy concepts through desk-based technical and commercial services from an industry expert consortium.

  • Ocean Energy Scale-up Alliance (OESA): Delivery of technical and commercial services to TRL4-5 companies to prepare them for ocean site testing and demonstration.

  • Integrating Tidal Energy into the European Grid (ITEG): evelopment of an all-in-one solution that includes clean predictable energy generation (tidal energy); safe export to the grid; and the storage and delivery of the excess capacity in hydrogen

  • BlueGIFT: BlueGIFT brings together partners across the Atlantic Area (southern France, Portugal, Spain and the Canaries) to focus on the development and demonstration of the next generation of Ocean Energy technologies (floating wind, wave and tidal). The project will deliver a coordinated transitional programme which will ensure that the partners and countries involved will see the long term roll out of these low carbon ocean energy technologies in their regions.

  • OceanDEMO: This project will help bring offshore renewable energy technologies to the market by providing free access to North-West Europe’s world leading network of test centres. 

  • ReFLEX: Develop and deliver a replicable community based Integrated Energy System demonstration project. Use novel localised power balancing mechanisms alongside digital control to provide robust and responsive energy systems across the electricity, transport and heat networks.​ Develop a Virtual Power Plant to manage energy flows in each of the three sectors.​

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