Riding a tidal wave

The MeyGen tidal turbine project and a significant expansion have ensured a busy 2016 for AC Marine and Composites to date. Adrian Wilson reports.

The first of four 1.5MW turbines weighing almost 200 tons each was delivered to the Nigg Energy Park on the Cromarty Firth in north-east Scotland on September 11th this year, in a ceremony attended by the country’s First Minister Nicola Sturgeon.

It will be employed in the demonstration phase of the ambitious MeyGen project which is destined to become the largest tidal turbine plant in the world and is now expected to begin generating power before the end of this year.

“MeyGen is set to invigorate the marine renewables industry in Scotland and provide vital jobs for a skilled workforce, retaining valuable offshore expertise here in Scotland that would otherwise be lost overseas,” said Sturgeon at the event.

Tim Cornelius, CEO of Atlantis Resources, the Edinburgh-headquartered tidal energy specialist which owns 85% of MeyGen added: “It gives me enormous pride to have reached this juncture after ten years of tireless work, preparation and planning by everyone associated with this project. This is the day the tidal power industry announced itself as the most exciting new asset class of renewable, sustainable generation in the UK’s future energy mix.”

It is estimated that there is a technical resource of 29 terawatt hours (TWh) of energy per year available in tidal currents in the UK, of which 11TWh is found in the tidal flows in the Pentland Firth.

The lease area, which was awarded to a consortium led by Atlantis in 2010 by The Crown Estate for MeyGen lies in the channel between the island of Stroma and the north easterly tip of the Scottish mainland. The site encompasses almost 3.5 square kilometres of fast flowing water.

Kinetic power

Tidal current or stream turbines use the kinetic power of the sea’s currents in the same way that wind turbines use the movement of air, but this type of generation has lower capital cost and minimal environmental and visual impact. The greatest advantage over other alternative energy sources is that it is almost entirely independent of the weather – although it can be variable, it is also predictable.

 The first 1.5MW turbine was delivered to the Nigg Energy Park on September 11th in a ceremony attended by First Minister, Nicola Sturgeon
The first 1.5MW turbine was delivered to the Nigg Energy Park on September 11th in a ceremony attended by First Minister, Nicola Sturgeon

Since sea water is also 832 times denser than air, ocean currents have an extremely high energy density, which means that tidal turbines require a smaller rotor size than an offshore wind turbine of equivalent power rating. Nevertheless, the four 15m high turbines that are currently being built for MeyGen will have blades that are each 18m in diameter.

Three of the turbines, including the first, are being built by Andritz Hammerfest with conventional marine steel rotors, while the fourth will be an AR1500 unit designed and built by Atlantis itself and exploiting the many benefits of composites for its blades.

Composites will certainly bring a number of inherent advantages to this application, including corrosion resistance, excellent fatigue performance and reduced density compared with traditional steel fabrications. The geometry requirements to best exploit hydrodynamic efficiency are structurally demanding for these parts and savings in the rotating mass can have very significant positive knock-on effects in the design and operation of the entire unit.

A whirlwind year

Against competition from 19 other companies across Europe, Gosport-based AC Marine & Composites (ACM&C) succeeded in its tender for the contract to manufacture the tidal turbine blades for the Atlantis AR1500 unit – ensuring it’s been something of a whirlwind of a year for the small UK company. ACM&C was founded in 2010 by Alex Newton, who over the years has established a dedicated team with a background in high end composite components and sailing campaigns.

“Marine and renewable energy were always going to be core sectors for ACM&C, given the versatility of composite materials,” he says. “In essence they can be applied to anything – whether a composite bridge or lightweight Olympic hardware.”

Even prior to the formation of ACM&C, Newton built Olympic Gold medal-winning keelboats and was heavily involved in Americas Cup, Volvo Ocean Race and other high performance racing yacht projects.

A growing reputation in this field led to the formation of the company, which until early this year operated from a converted barn in the New Forest.

“The move was intended to be short term,” says Newton. “We ended up spending close to four years there, building up the company organically.”

ACM&C moved into its new Gosport facility in February, and while working on the MeyGen project, has also been busy setting up its new facilities involving a ramp up from 1,500ft2 of space to a dedicated 22,000ft2.

Alex Newton, director and founder of AC Marine & Composites
Alex Newton, director and founder of AC Marine & Composites

It is equipped with all of the latest technology required for the production of high quality medium-sized resin and prepreg parts, including an Assyst Bullmer ply cutter, Siemens-controlled ovens and a Cijet 2 epoxy resin injection machine. Four independent vacuum systems are now in place, with a 9m x 3m carbon vacuum table, in addition to a toughened glass vacuum table. The company is now planning to purchase a robotic arm, which it hopes will be fully operational by next February.

Heading in the right direction

Newton reckons that the new set-up the company has in Gosport gives the company the space and flexibility it needs to continue to grow the company.

“The technology we have invested in, has automated certain processes, which in turn enables us to deliver greater quality assurance statistics to our customers,” Newton concludes. “This is invaluable when working on projects of this scale. Despite the changes, we continue to have an open door policy and our customers are habitually on site for the major milestones - non-destructive testing being one of them. Our customers often have the results before the reports have even been issued. It’s been a very exciting period for the company and we are now at the stage of delivering the first set of blades to Atlantis.”

Composites UK is arranging a site visit to the new A C Marine and Composites facility in Gosport on Thursday, February 9, 2017. For details see: https://compositesuk.co.uk/events/site-visit-c-marine-and-composites

www.acmarineandcomposites.com

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