Design innovation for 20MW Wales tidal energy project a ‘step forward’ in commercialisation of tidal stream

Hydrowing parent company Inyanga Marine Energy Group has unveiled a design that “dramatically reduces capex and installation costs” for the 20MW Hydrowing technology deployed at Morlais, Wales.

The venture, which is managed by the social enterprise Menter Môn, is Europe’s largest consented tidal energy scheme. Menter Môn manages an area of 35 km2 of the seabed near Holy Island, Anglesey for the scheme, which has the potential to generate up to 240MW of low carbon clean electricity.

This week Inyanga Marine Energy Group confirmed that the tidal energy array will incorporate the Tocardo T3 turbine for the first time, with each of its 20 Hydrowing units to be powered by two T3 turbines. The T3 turbine is an updated and optimised version of the previous T2 design and boasts double the power of its previous iteration.

According to the group, a key improvement is the turbine’s passive pitch, through a design innovation allowing the force of the tide to twist the blade relative to incoming flow. This eliminates the need for complex active pitch systems. Pitching reduces the forces induced allowing for the blade swept area and power to be doubled without increasing loads.

The innovation is one of a number developed by Hydrowing to drive down tidal power’s levelised cost of energy – the average total cost of building and operating the asset per unit of total electricity generated – the group said. It said high costs have to date prevented the tidal power sector from becoming competitive and thriving within the renewable energy market.

Two key issues are turbine complexity and high-cost offshore maintenance, with the “engineering drive to optimise energy extraction” having resulted in the development of complex systems to increase output. This has resulted in issues with device reliability, leading to increased down time and loss of revenue.

The Hydrowing tidal device is designed to tackle system complexity and lack of reliability with a modular, multi-rotor design comprising two main components. These are a permanent gravity based support structure and one to three retrievable wings, each comprising two to five turbines

Inyanga Marine Energy Group CEO Richard Parkinson said the design represents a “step change in tidal energy design”, increasing energy yield and reducing costs. He noted: “The ‘all in one’ Hydrowing system is based on a modular approach, which dramatically reduces capex and installation costs.

“Firstly, the modular substructure comes in road haulable sections, which can be rapidly assembled quayside for installation. The T3 turbines can also be easily transported and installed. Previously, turbines have been large and expensive, if not impossible to deliver to some of the remote locations in which we operate, whereas the compact T3 turbines can be delivered ‘in a box’. In fact, all the Hydrowing components will fit in containers for easy, low cost transport.

“Additionally, the well proven wet mate connection system from the transformer hub to the export cable allows for instantaneous ‘plug and play’ connection. The two micro-pile fixings on each foot of the substructure are lightweight and low cost and can be installed by small workboats.

“We estimate that there is an up to 60% saving in fixation costs, increasing rapidly with scale. What’s more, the patented Hydrowing Quad Barge [unveiled in January] also has a modular design, enabling operations and maintenance costs to be minimised too.

The Hydrowing system also includes features to increase energy yield.

“For example, the patented T3 turbine blades (each 600KW with 14m rotor diameter) benefit from passive pitch and a gearbox, delivering optimal yield, whilst the 19m nacelle height places the turbine in optimal flow conditions for maximum yield as well,” Parkinson said. “The winning combination means that energy yield is increased dramatically, up to 60%.”

Menter Mon Morlais CEO Andy Billcliff said: “This is a groundbreaking design that we expect to be a gamechanger for tidal energy. It offers the magic combination of reduced costs and increased energy yield. This represents a big step forward towards the commercialisation of tidal stream energy, paving the way for global applications.”

Inyanga Marine Energy Group has secured 20MW of capacity for its tidal energy project at Morlais through the UK Government’s Contracts for Difference scheme Allocation Rounds 5 and 6 (AR5 and AR6). The Hydrowing allocation in AR6 is the largest tidal energy award in the UK and saw the group awarded 10MW for the project in September, doubling its previous 10MW capacity to its current 20MW capacity. A demonstration project will be implemented at Morlais in 2025.

Inyanga Marine Energy Group has also signed a Memorandum of Understanding with Verdant Morlais to deliver a further 4.9MW tidal stream energy project at Morlais.

Morlais provides the required infrastructure in the zone, including a connection to the national grid and substations on the shore. It rents berths to various turbine development companies so they can use tidal energy to generate electricity.

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