Orbital Marine Power is a Scottish engineering company focused on the development of tidal energy turbine technology with the potential to produce a step-change reduction in the cost of energy from tidal stream. The company is based in Orkney and Edinburgh.
Orbital Marine Power’s tidal technology is a floating tidal stream energy generator. The Orbital O2 2 MW turbine comprises a 74 m long cylindrical floating steel superstructure, which houses power conversion and auxiliary systems and provides reference and attachment for two leg structures with nacelles mounted at their ends. A key innovation building on the company’s previous SR2000 iteration was the introduction of full wing leg configuration, enabling the 20 m diameter rotors to be brought up above the water line for onsite access and maintenance. A modular gravity-based anchoring system recycled ballast from the SR2000. Each of the mooring lines used to anchor the O2 is strong enough to pick up 50 double decker buses.
The Orbital O2 is fundamentally designed for ease of access and inexpensive maintenance. As a floating device, scheduled and unscheduled maintenance operations on electrical, control and hydraulic systems can be carried out onboard the device simply by transferring personnel from a small vessel such as a RIB onto the hull of the Orbital O2. From here personnel can enter the hull and access the majority of equipment.
The O2 is installed at the European Marine Energy Centre (EMEC) Fall of Warness grid-connected tidal test site, berth 5. EMEC’s grid-connected tidal test site is situated in a narrow channel between the Westray Firth and Stronsay Firth, where there is a very strong tidal current with a typical spring flow of up to 4 m/s (8 knots).
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, which is granted by the Marine Scotland Licensing Operations Team (MS-LOT) on behalf of Scottish ministers. Orbital Marine Power was granted a Marine Licence effective July 2019 - December 2039 for installation, operation, maintenance and decommissioning of the O2 tidal energy device.
Three iterations of Orbital marine Power’s technology have been tested at EMEC so far: the SR250; the SR2000; and the O2. The O2 is Orbital Marine Power’s first commercial demonstrator and represents the culmination of more than 15 years of product development and testing in Orkney.
The O2 was constructed by TEXO Group in Dundee, Scotland and was towed from the city to Orkney in April 2021. Following a period of commissioning at it was announced in July 2021 that the O2 had commenced grid-connected power generation at EMEC. Since the O2 began operating, Orbital has reported peak power of 2.5 MW. The next iteration of the O2 is being developed as part of the EU funded FORWARD-2030 project which aims to develop a multi-vector energy system combining tidal energy, wind generation, grid export, battery storage and green hydrogen production.
In July 2022 it was announced that Orbital Marine Power was awarded two contracts for difference (CfDs) in the UK Allocation Round 4 (AR4) process, totalling 7.2 MW tidal energy deployments at EMEC’s Fall of Warness site. The CfD scheme is the government’s main mechanism for supporting low-carbon electricity generation helping to boost British energy security and independence with cleaner, more affordable and diverse energy created in the UK.
Key Environmental Issues
The Fall of Warness supports a number of marine mammal and bird species with are either afforded national and international protection or are connected with local designated sites. A number of fish and shellfish species are likely to be present within the site, some of which are of commercial importance or are important prey species. EMEC has developed a site environmental appraisal which assesses the potential environmental impacts of installation, operation and maintenance of devices within a defined project envelope. Testing of the Orbital O2 falls within the assessed project envelope, therefore the following potential impact pathways were identified for the project:
- Acoustic disturbance due to increase vessel presence onsite, installation and maintenance work and the direct acoustic output from the turbine during operation;
- Risk of entanglement of marine megafauna with the mooring system and dynamic cable;
- Displacement and disturbance to species in the immediate vicinity;
- Seabed clearance including impact to benthos;
- Biofouling and introduction of non-native species during towing operations; and
- Collision risk of marine megafauna with the moving parts of the device.
The following mitigation measures were proposed in the Environmental Monitoring Programme submitted in support of the Marine Licence application to MS-LOT:
- Adherence to the Scottish Marine Wildlife Watching Code (SMWWC).
- Vessel speeds will be reduced to 6 knots when a cetacean is sighted in close proximity to the immediate vessel transit route.
- A steady speed and vessel course will be maintained if a cetacean approaches a vessel involved in marine operations.
- Utmost care will be taken in ensuring groups and mothers and young are not split up by vessels.
- Sudden changes in speed and direction will be avoided to reduce the likelihood of any further disturbance to cetaceans in the vicinity.
- During all vessel activity a minimum approach distance will be complied with when passing designated seal haul-outs.
- Rafts of birds will not be intentionally flushed.
- During seabird breeding season (April to August inclusive), vessel transit corridors will be at least 50m from shore in the vicinity of cliff-nesting seabirds to avoid disturbance.
- Compliance with good practice measures detailed in the ‘Alien invasive species and the oil and gas industry – Guidance for prevention and management’ produced by the IPIECA in 2010, ‘Guidance for minimizing the transfer of invasive aquatic species as biofouling (hull fouling) for recreational craft’ produced by the IMO in 2012 and the ‘Code of Practice on Non-Native Species’ made by Scottish Ministers under section 14C of the Wildlife and Countryside Act 1981.
- Local vessels will be used throughout all installation, maintenance and decommissioning operations as far as possible.
- Antifouling paints will be used which comply with the IMO International Convention on the Control of Harmful Anti-fouling Systems on Ships and national legislation.
- Opportunistic inspections of biofouling will be implemented which will have a dedicated procedure for removing biofouling species from the device. A full device biofouling inspection may be conducted as the device is decommissioned.
Orbital Marine Power deployed the O2 device in the same Fall of Warness tidal berth location as the company’s previous iteration, the SR2000. A baseline assessment was conducted for the SR2000 and further informed by the detailed assessment captured within the EMEC Fall of Warness Test Site Environmental Appraisal.
Papers, Reports, Research Studies
Papers and Reports:
- Orbital O2 Environmental Monitoring Programme: prepared to support the marine licence application for the deployment, operation and decommissioning of the Orbital O2 2MW Tidal Turbine. The Environmental Monitoring Programme documents the proposed mitigation and monitoring measures relating to the installation, operation and decommissioning of the Orbital O2.
- Proving a robust approach to assess bio-physical interactions with floating tidal turbines: a two-stage feasibility study around Orbital’s O2 floating tidal energy structure set in Orkney to inform on industry-relevant flow measures (stage 1) and environmental interactions (stage 2) to prove a low-cost, robust and reproducible monitoring approach. This work was supported by the Supergen ECR fund and led by a consortium of partners including the Bryden Centre/Queen’s University Belfast, University of Plymouth, Bangor University, UHI Shetland, Orbital Marine Power and EMEC.
- 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.
- 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.
Post-Installation Monitoring: Orbital Marine Power O2 at EMEC
|Design and Methods
|Drifting Acoustic Recorder and Tracker (DART) survey – supported by the FloTEC project.
|A full acoustic survey campaign has been completed during July and August 2021, using the DART system. A reference site was also surveyed to be used as baseline data.
|Results showed that under low wind conditions and drifting speed ranging from 2.6 to 3.5 m/s, the operational O2 turbine, generating at 25% of rated capacity, was clearly detectable at frequencies between 10 and 1000 Hz, with a difference in median sound pressure level (SPL) of 40 dB above ambient noise recorded at Westray South and 10-15 dB compared to when the device was not generating (i.e. 0% of rated capacity).
|Changes in Flow
|Testing a reproducible monitoring approach for biophysical interactions.
|Field work was conducted in April 2022 over spring tides. Parallel-line survey transects used a vessel-mounted Acoustic Doppler Current Profiler (ADCP) and Simrad EK8- echosounder to characterise the flow fields and acoustic scattering (fish and turbulence quantification). Drone transects and hovers were performed to map the near-surface velocity fields up- and downstream of the O2. Dedicated seabird observations were performed during all transects.
|Hourly O2 transects consisted of one upstream and several (4-9) downstream lines and will be used to quantify both the inflow conditions and the scale and intensity of the wake signature of the O2. Underway velocity and EK80 data will be analysed in combination with the aerial drone data to quantify near-surface velocities and turbulence features in relation to water column measurements