Offshore energy in the UK

Materials World magazine
1 Jun 2016

The stakes are high for British efforts to develop tidal power. Katherine Williams takes a look at developments across the country.

This summer will see the installation of the first phase of Edinburgh-based Atlantis Resources’ flagship MeyGen tidal array in the Inner Sound of the Pentland Firth. Financed with £51.3m of mostly public funds, the four-turbine, 6MW MeyGen Phase 1A is set to be the first tidal array worthy of the name when fully operational in the autumn. The project is carrying the torch for, in essence, the entire tidal industry and another high-profile failure such as that which befell bankrupted Scottish wave developers Pelamis and Aquamarine Power would result in a catastrophic loss of public confidence.

Tidal streams are currents in the sea that flow as the tide moves in and out. Tidal stream turbines are similar to wind turbines but use fast moving tidal streams to generate electricity instead of the wind. Sea currents are much more powerful than the wind and so tidal stream turbines tend to be smaller than wind turbines. 

Atlantis is using two types of turbine for MeyGen Phase 1A, both rated at 1.5MW – three HS1500 machines by German outfit Andritz Hammerfest Hydro HS1500 machines and a single AR1500 device. The AR1500 is Atlantis’ own turbine designed in collaboration with US behemoth Lockheed Martin. Each is a three-bladed horizontal axis turbine with an 18-metre diameter rotor that will be affixed to the seabed at a depth of around 10 metres.

Andritz Hammerfest Hydro is assembling the three HS1500 turbines at its Ravensberg factory in Germany. The AR1500 tidal turbine is undergoing fabrication and assembly at Atlantis’ facility at Nigg Energy Park in Easter Ross. Each turbine will be positioned on the seabed with a tripod gravity-base turbine support structure and a 4.4kV subsea cable. The cables will connect the turbines to the onshore power conversion centre at the Ness of Quoys. The cables run along the seabed until they reach horizontal directionally drilled bores and then run under the seabed through the bores to the Ness of Quoys site. From the power conversion centre, the project is connected to the grid via Scottish Hydro Electric Power Distribution’s 17km onshore cable.

Thurso’s JGC Engineering and Technical Services is building 24 ballast blocks, required for the project’s turbine support structure. Once completed, the 200-tonne foundation ballast blocks will be transported to Scrabster in preparation for deployment onto pre-installed turbine foundations. Global Energy Group’s Isleburn is fabricating the 255-tonne foundations at its Aberdeen yard with final load out at Nigg. Atlantis expects to install all four turbines by the autumn and commission the 6MW array by the end of the year. 

The impact of low-cost oil

The marine energy sector is often hit by delays and setbacks but progress on MeyGen is, so far, running smoothly. Atlantis chief executive Tim Cornelius said the falling price of vessels and crews because of the dip in oil prices is allowing the company to increase the workforce on MeyGen cost-effectively.

The sharp drop-off of drilling activity in the offshore oil and gas industry, particularly in places such as the UK's North Sea, has meant engineering and offshore services contractors are now seriously under-employed. ‘Nobody wants to see a downturn in any industry, but our industry sees direct benefits derived from low oil prices,’ he said. ‘There has been a significant reduction in day rates, and also a huge increase in the available fleet. So that is obviously very positive, in terms of the financials for our project. Secondly, there is a huge pool of talent now, obviously as we continue to expand our project delivery team we're seeing the pool of talent and the quality is incredible.’

While Phase 1A work proceeds, Atlantis is working to finalise funding for MeyGen Phase 1B. Cornelius said Atlantis will deploy the next generation of Marine Current Turbines’ (MCT) SeaGen tidal technology for Phase 1B. MCT was acquired by Atlantis last year after it was put up for sale by German engineering giant Siemens. The Bristol company was behind the landmark 1.2MW SeaGen S tidal turbine installed in Northern Ireland’s Strangford Lough in 2008.

Atlantis could install up to four fully-submerged SeaGen U turbines, an evolution of the surface-piercing SeaGen S, which was operated for seven years and is now being decommissioned. Atlantis could start construction of the 6MW Phase 1B at the turn of the year following commissioning of Phase 1A. Financial close for Phase 1B is expected by the end of the year.

After Phase 1B, Atlantis plans to build the 74MW MeyGen 1C project and the 10MW Sound of Islay site, which was acquired from utility Scottish Power last year. It also has an option to build a 100MW array at Ness of Duncansby close to the MeyGen site.

Record-breaking tidal power

While MeyGen and Atlantis Resources are crucial for the UK’s tidal sector, the eggs are not in one basket. At the time of going to press, Orkney outfit Scotrenewables was about to deploy the world’s most power tidal device, the 2MW SR2000, at the European Marine Energy Centre. Once installed, the 500-tonne floating tidal turbine will begin a two-year test programme at EMEC’s Fall of Warness grid-connected site. 

After fabrication snags necessitated lengthy remedial repairs, the SR2000 was launched at Harland and Wolff’s Belfast shipyard. The Scotrenewables device was due to be towed along the west and north coast of Scotland to its Kirkwall base, where it will undergo final checks. The SR2000 will be towed site via a low-cost vessel and be installed via pre-installed mooring lines and secured via its mooring turret arrangement and patented retractable legs that tuck in underneath the turbine.

While testing is ongoing, Scotrenewables will simultaneously work on its next device – the SR2000-M2, for which it secured €10m funding from the European Union’s Horizon 2020 programme. The SR2000-M2 prototype will be installed alongside the SR2000-M1 at EMEC’s tidal test site at the Fall of Warness in Orkney, forming a 4MW array to serve as a demonstration platform for commercially viable floating tidal. The device will be deployed around 2018/19. Scotrenewables Business Development Manager James Murray said the second device could feature an energy storage system located onshore to effectively boost its energy efficiency.

Developers of smaller tidal turbines such as Nova Innovation, Sustainable Marine Energy and Nautricity will also install units in Scottish waters this year. Development of tidal power in England is hampered by a lack of suitable conditions, but the Perpetuus Tidal Energy Centre has planning consent from Isle of Wight Council to start onshore works for an up-to-30MW demonstration zone off St Catherine’s Point. The project is awaiting a permit from the Maritime Management Organisation for offshore works.

Elsewhere in the UK

In Wales, Tidal Energy Limited (TEL) deployed its 400kW prototype Deltastream device in Pembrokeshire’s Ramsey Sound last December. Weighing 200 tonnes, with a 16-metres-long frame and height of 18 metres, the demonstration device has a gravity-based foundation sitting atop the seabed under its own weight, without the need to drill or pile the structure into the seabed. TEL is currently planning the recovery of DeltaStream to carry out post-installation analysis in addition to the removable nacelle configuration upgrade. DeltaStream is expected to be recovered from the seabed this year and the modification work will take place in Pembroke Port. Re-deployment of the turbine is expected early next year. TEL, along with financial backers Eco2 Ltd, is continuing development plans for a 10MW commercial array project at St Davids Head in Pembrokeshire.

Other tidal projects in UK waters include Isle of Man developer Manx Tidal Energy’s efforts to develop a site off Point of Ayre on the island’s northern tip. The company will start survey work this summer to assess the viability of tidal resources and, if the site is deemed suitable, will seek to submit a planning application to the Isle of Man Government next year.

In the Channel Islands, Alderney Renewable Energy is planning to deploy the first phase of a 300MW tidal project developed in conjunction with Ireland’s Open Hydro in 2021. The first turbines for the Alderney Race Tidal project would be installed immediately after the proposed 1.4GW FabLink interconnector linking the UK and France via the Channel Islands is commissioned in 2020.

Scottish hopes to lead the world in wave power have taken a grievous blow over the past 18 months and non-UK developers will dominate future deployment in its waters. The bankruptcy of ‘sea snake’ developer Pelamis Wave Power in 2014 and Aquamarine Power last year have meant that there are no Scottish companies currently working on utility-scale wave energy converters.

EMEC currently has no active wave development at its Billia Croo test site following the demise of Aquamarine Power and the translocation of Finnish developer Wello’s 1MW Penguin to Wave Hub in Cornwall. There is a similar story at EMEC’s Scapa Flow nursery site for prototypes, which currently has no activity. 

Scotland’s indigenous wave industry has largely gone back to the drawing board, backed by vital national funding from Wave Energy Scotland (WES) via Highland and Islands Enterprise. WES’ mission statement is to use public sector money to develop wave technology to a point where the private sector is ready to re-invest. WES is currently supporting 25 projects under its novel wave energy converter and power take-off technology calls. The organisation will assess each of the 25 R&D projects and, after evaluating data, will select a number for future funding. WES operates a four-stage gateway process, with Stage I essentially desk-based research and Stage IV culminating in a full-scale or scale prototype. While the results of various WES funding calls will take several years to come to fruition, England’s Wave Hub demonstration zone located 10 miles north of Hayle will host its first grid-connected project this summer.

Finland’s wave energy developer Wello Oy will install its 1MW Penguin device in July off Orkney, the first of three similarly-sized units to be deployed each of the next three summers. The 48MW Wave Hub has four berths and other developers expected to set up shop at the test site include Australia’s Carnegie Wave Energy, Ireland’s Simply Blue Energy and Cornwall’s own Seatricity.

Wales is gearing up to be a prime destination for marine energy with two main sites – South Pembrokeshire Wave Demonstration Zone and the West Anglesey Demonstration Zone for tidal stream projects. The sites are backed via an allocation of €100.4m of EU Structural Funds, prioritised by the Welsh Government for marine energy. Working with Marine Energy Pembrokeshire and Pembroke Port, the South Pembrokeshire Wave Demonstration Zone would offer a 50m water depth, 19kW/metre wave resource and a 400kV transmission line and substation located at the Pembroke power station. Llangefni-based Morlais, which is managing the West Anglesey Demonstration Zone on behalf of Anglesey development body Menter Mon, plans to select by the summer up to eight developers to lease berths at the proposed site. 

With £51.3m at risk, MeyGen Phase 1A carries a lot on its shoulders. The Atlantis project may be sink or swim for UK tidal energy.