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 18m. 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.
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 18m. 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.
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 developers 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, holding 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
All projects at EMEC require a Marine Licence under the Marine (Scotland) Act 2010. For clients wishing to install at EMEC’s test sites the consenting process requires the client to produce the following documentation to accompany their Marine Licence applications, alongside the relevant site-wide environmental report and navigational risk assessment: Project Information Summary, Project-specific Environmental Monitoring Programme (PEMP), Project-specific Navigational Risk Assessment (NRA), Third-party Verification/Certificate (TPV/TPC), and Decommissioning Programme (DP). The project-specific assessments should make reference to the findings from the site-wide assessments and be direct in their findings and recommendations. EMEC is continually working with regulators to make sure that the most efficient and effective licensing processes are put in place at the sites.
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:
- Pelamis Wave Power P1 Demonstration, Pelamis Wave Power - Installed August 2004 to 2007
- Wave Roller, AW Energy - Installed 2005 to 2005
- Oyster 1, Aquamarine Power - Installed November 2009 to March 2011
- Pelamis Wave Power P2 Demonstration, E.ON & Scottish Power Renewables - Installed October 2010 & May 2012
- Penguin, Wello Oy - Installed July 2012, reinstalled March 2017
- Oyster 800, Aquamarine Power - Installed June 2012
- Oceanus 1, Seatricity - Installed 2013 to 2014
In 2019 EMEC submitted an application to Marine Scotland for site-wide consent under Section 36 of the Electricity Act 1989, for a maximum installed generating capacity of up to 20 MW at the Billia Croo test site. Following a formal consultation exercise carried out by Marine Scotland, in 2021 EMEC conducted further consultations and contracted supplementary work to address additional information requests.
Consent was awarded in 2023, and has additionally allowed for the site to be expanded by an area of 2.6 km2 to the north-west enabling access to deeper water. Technologies over 1 MW can now demonstrate at the Billia Croo test site without having to apply for individual section 36 consents.
To support the section 36 application, seascape, landscape and visual impact assessments were conducted alongside an environmental appraisal. These assessments focused on an agreed ‘envelope’ of device types and activities that could be deployed within the test site boundaries and considered the potential impacts that may occur during the installation, operation and decommissioning phases of device and infrastructure testing. The site-wide consent lasts until 2040, future-proofing the consenting process for clients accessing EMEC’s facilities.
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/services/consents/ and https://www.emec.org.uk/services/environmental-services/
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.
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.
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.
Vessels used in the installation of the EMEC wave test site are:
Cable lay vessel
Installation of sub-sea export cables
Benthic and bathymetric surveys
Exact vessel used unknown
Used to deploy divers for benthic surveys
Exact vessel used unknown
Papers, Reports, Research Studies
- Billia Croo Environmental Appraisal 2019
- Billia Croo Environmental Statement 2019
- Billia Croo Navigational Risk Assessment 2019
- Billia Croo Environmental Description 2005
- Billia Croo Environmental Statement 2002
During the development of the facilities, Environmental Impact Assessments (EIAs) were performed for the grid-connected wave and tidal test sites, detailing considerations of the potential issues relating to the build of the test facility and use of the site in principal. Environmental characteristics of each site (including the two scale test sites) have been detailed in the Environmental Descriptions. Environmental Appraisals were produced to support developers’ applications for Marine Licences and a site-wide Section 36 consent for deployment of an ‘envelope’ of device types and operations at the grid-connected sites.
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 locations: http://www.emec.org.uk/research/ and http://www.emec.org.uk/projects/ocean-energy-projects/. Selected projects relevant to environmental impacts, assessment and monitoring are listed below:
- Acoustic Monitoring Programme (2011-2012): aimed to develop a methodology and procure equipment for characterising the acoustic output of devices, and establish an acoustic baseline. Outputs:
- Acoustic noise measurement methodology for the Billia Croo wave energy test site 2012
- Acoustic noise measurement methodology for the Billia Croo wave energy test site Annex A: Summary of operational underwater noise from a wave energy converter system at the EMEC wave energy test site May 2011: comparison of Pelamis system operational and baseline noise 2012
- Wildlife Observations Programme and Wildlife Analysis Project (2009 – 2015): aimed to collect data which can inform on whether or not displacement, or other alteration to behaviour and distribution, occurs in the resident wildlife due to the presence and/or operation of marine energy devices. Outputs:
- Billia Croo data available through Marine Scotland
- Long, C. (2018). No evidence of long-term displacement of key wildlife species from wave and tidal energy testing. Paper presented at 4th Asian Wave and Tidal Energy Conference (AWTEC), Taipei, Taiwan
- Analysis of the Possible Displacement of Bird and Marine Mammal Species Related to the Installation and Operation of Marine Energy Conversion Systems 2017
- EMEC Billia Croo Wave Test Site: Wildlife Observations Project Annual Report 2014
- Analysis of Bird and Marine Mammal Data for Billia Croo Wave Test Site, Orkney 2012
- Billia Croo Fisheries Project (2010 – 2012): aimed to determine likely influence of a small-scale refuge area on local lobster population abundance and availability to the fishery, and to explore the potential for using such areas to augment local lobster stocks by using them as nursery grounds for the release of hatchery-reared juveniles. Report available here.
- Underwater Acoustic Monitoring at Wave and Tidal Energy Sites: Guidance Notes for Regulators (2014)
- A review of the potential impacts of wave and tidal energy development on Scotland’s marine environment (2014)
- FLOWBEC (Flow, Water Column and Benthic Ecology 4D) 2012 – 2016: aimed to improve the understanding of how the physical behaviour of the water such as currents, waves and turbulence at tide and wave energy sites influences the behaviour of marine wildlife, and how tide and wave energy devices might alter the behaviour of such wildlife. Development of an autonomous seabed platform with integrated monitoring technologies.
- Understanding how marine renewable device operations influence fine-scale habitat use and behavior of marine vertebrates (RESPONSE) 2011 – 2015
- Offshore Renewable Joint Industry Programme (ORJIP): as part of EMEC’s remit, a short summary of the opportunities, issues and challenges associated with sharing environmental monitoring data was published in 2020, which is available here.
- WEDUSEA (Wave Energy Demonstration at Utility Scale to Enable Arrays): The project aims to decrease the levelised cost of energy (LCOE) and create a technology deployment pathway for a 20 MW pilot farm. The project will also explore a techno-economic and life cycle analysis, looking at the circular economy and opportunities for reuse and recycling of components at the end of the operations life of the device.
- FORWARD2030 (Fast-tracking Offshore Renewable energy With Advanced Research to Deploy 2030MW of tidal energy before 2030) 2021 - 2025: part of the project will see the development of environmental monitoring to support the consenting of future large-scale floating tidal arrays.
- SEA Wave (Strategic Environmental Assessment of Wave energy technologies): involved environmental research at Billia Croo, undertaking a gap analysis to address the lack of knowledge regarding the potential environmental impacts associated with deploying wave and tidal energy converters in the marine environment and provide strategic recommendations for consenting. Project deliverables are available here.
- CEFOW (Clean Energy From Ocean Waves): device-specific research was conducted to investigate responses of species receptor groups to the deployment of single and multiple wave energy converters at EMEC.
- MaRINET and MaRINET2 (Marine Renewables Infrastructure Network): provided marine energy development companies, entrepreneurs, start-ups and researchers with funded access to marine energy experts and the world’s leading wave, tidal and offshore-wind test facilities. A short course on “Methods and environmental data collection in Marine Renewable Energy sites” was delivered in 2021 and is available here.
- FloTEC (Floating Tidal Energy Commercialisation) 2016 – 2021: EMEC carried out resource and environmental assessments around Orbital Marine Power’s floating tidal technology, with a final webinar on lessons learnt presented in September 2021.
- EquiMar: Equitable Testing and Evaluation of Marine Energy Extraction Devices in terms of Performance, Cost and Environmental Impact
- RESOURCECODE (Resource Characterisation to Reduce the Cost of Energy through Coordinated Data Enterprise): aimed to support investment and growth in the wave and tidal energy sector through the creation of an integrated marine data toolbox. The open source toolbox (available here) was launched in March 2022, using 27 years of model data to create the highest resolution wave model in North West Europe.
Baseline Assessment: EMEC Billia Croo Grid-Connected Wave Test Site
|Design and Methods
|Dive transect survey of invertebrates.
|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.
|Physical Environment, Sediment Transport
|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.
|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.
Post-Installation Monitoring: EMEC Billia Croo Grid-Connected Wave Test Site
|Design and Methods
|Birds, Marine Mammals
|EMEC procured a high magnification camera, which was mounted on the Black Craig observations point with the potential to inform wave energy device operators, as well as the regulatory and other decision makers, about the frequency and nature of any specific interactions between surface-piercing parts of devices and wildlife.
|Data has been made available as Microsoft Access databases via Marine Scotland Information website. The data analysis phase of the project was guided by advice from the Centre for Research into Ecological and Environmental Modelling (CREEM). EMEC produced a Wildlife Observations Project Annual Report as well as a final report (EMEC, 2014). A report detailing the analysis of bird and marine mammal data for Billia Croo was produced by SNH in 2012 (Robbins, 2012). A detailed analysis of the potential for displacement of marine mammal and bird species was completed in 2015 and commissioned by Scottish Government, Marine Scotland and SNH (Long, 2017).
|An operational noise assessment was conducted on the Pelamis P2 system at the Billia Croo EMEC wave site in May 2011.
|Underwater sound data was collected using (i) autonomous recording units and (ii) cabled hydrophones deployed from a vessel. Longer-term data collection was made using acoustic recorders on seabed mounted frames.
|Comparison of device and baseline noise in different sea states shown in figure 3-18 and 3-19 show a significant variation in both baseline and operational noise trials. Comparison of baseline energy in the 100 Hz band shows an increase of around 35 dB with increasing sea states.
|Land-based observations to understand the spatial and temporal distribution of wildlife at the test site, and specifically enable identification of where and when particular species are more likely to encounter test devices or related deployment activity.
|Land-based observations taken from a look-out shelter on Black Craig, Billia Croo approximately 110m above sea level. The observations for
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), timetabled to cover different tidal states and times of day. This analysis uses data collected over a period of two years.
|Seals and harbour porpoises were found to show a significant seasonal pattern. Seal sightings were found to vary significantly with wind direction (p=1.68E-07). In particular, greater numbers of seals were encountered with onshore winds (i.e. Easterly), which may be a consequence of reduced swell in the test site.
|Land-based observations to understand the spatial and temporal distribution of birds and wildlife at the test site, and specifically enable identification of where and when particular species are more likely to encounter test devices or related deployment activity.
|Land-based observations taken from a look-out shelter on Black Craig, Billia Croo approximately 110m above sea level. The observations for birds 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), timetabled to cover different tidal states and times of day. This analysis uses data collected over a period of two years.
|Many species 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.
|Human Dimensions, Fisheries
|To determine the likely influence of a small-scale refuge area on local lobster population abundance and availability to the fishery, explore the potential for using such areas to augment local lobster stocks by using them as nursery grounds for the release of hatchery-reared juveniles, and to characterise experimental creel catches of all crustacean species in the area in the context of catches experienced by the commercial fishery operating in adjacent areas that are completely open to fishing.
|The project released juvenile lobster into the Billia Croo test site and performed a tagging release study. A fishery scientific monitoring zone (SMZ) was established in the vicinity of the Billia Croo test site for the project duration.
|The study concludes that the area within the EMEC wave test site at Billia Croo provides suitable feeding and refuge habitat for lobster, and has the potential to act as a nursery area to both the local fishery and to the Orkney Islands as a whole.
|A project was developed to assess available techniques and development of a methodology appropriate to EMEC’s Billia Croo wave test site to enable acoustic data collection and analysis, and subsequent use of the methodology to collect data from which an acoustic baseline description of the test site can be formed. Led by Loughborough University in partnership with the National Physical Laboratory, Teddington, and Chickerell BioAcoustics of Chickerell, Dorset and the Sea Mammal Research Unit (SMRU).
|Two acoustic underwater noise measurement methodologies were proposed for a variety of wave energy converter devices that may be present at the EMEC Billia Croo site: the first is a bottom mounted high-bandwidth recorder with a suitable duty cycle for long-term surveys, and the second describes the use of wide bandwidth ‘drifting snap-shot techniques’ conducted at the surface off a study vessel.
|Comparison of device and baseline noise in different sea states indicate a significant variation in both baseline and operational noise trials. Comparison of baseline energy in the 100 Hz band shows an increase of around 35 dB with increasing sea states. This variation is higher than traditionally observed for deep ambient water noise curves for a sea state changing over a similar range. However shallow water ‘ambient’ noise is relatively poorly understood and potential for higher absolute levels and higher variation under different sea state conditions exist.
|Crustacean monitoring project.
|The project was undertaken between 2011 –2012 with the aim of monitoring the abundance of lobster at the Billia Croo. Lobsters hatchlings were tagged with microchips to monitor their distribution and movement within the site.
|The results were presented in a report to the Scottish Government in 2012.