Capturing untapped tidal potential 

It’s time to pay more attention to tidal and wave energy capacity

As the climate crisis accelerates and the world intensifies its search for reliable renewable energy, there’s growing interest in the energy potential of the oceans. Covering more than 70% of our planet, the waves and tides contain huge amounts of untapped power with the reliability to balance out the seasonal variations and unpredictability of wind and solar. To date, however, progress to capture this vast energy resource has been slow, hampered by technological challenges and high costs, with only a few wave and tidal projects edging out of pilot testing and into commercial production.

Optimising design

This may be about to change as this fledgling industry begins to gain traction and starts to bend the cost curve. This month the world's first rapid testing facility for tidal turbine blades opened in Fife, Scotland in a bid to help bring down costs and accelerate marine energy technology development. FastBlade, a £4.6 million facility developed by the University of Edinburgh and engineering group Babcock International, will stress test blades made from composite materials.

The facility's 75-tonne reaction frame is capable of exerting powerful forces on turbine blades more than 50 feet long to fatigue test the structures that, once in operation, will have to withstand harsh ocean conditions for 20 years. FastBlade uses a system of powerful hydraulic cylinders to replicate the complex forces to which tidal turbines are exposed to at sea, with the facility able to simulate two decades of stress in less than three months. By providing developers with better data on how tidal turbine blades deteriorate over time, the research team hopes to help optimise the design of more durable, efficient structures.

This dedicated facility matters because tidal blades face a different category of stress to offshore wind turbines, limiting transference of knowledge to accelerate development. Neil Young, engineering director for Babcock, said the facility would be able to carry out “large-scale accelerated testing of structural composites in a more sustainable way”. 

Minesto’s tidal-powered kite is fuelling the Faroe Islands’ electricity grid (Credit: Minesto)

Upswell in testing

This isn’t the first marine energy testing facility in the UK. The European Marine Energy Centre (EMEC) in Orkney, Scotland already provides a scale test site at Shapinsay Sound, and just this month scooped its first US client. California-based tidal energy developer, Aquantis, has booked a six-month test programme in 2023 to put its second generation floating tidal energy converter, the Tidal Power Tug, through its paces.

“The scale test sites are designed to provide developers with their first real-sea experiences, in gentler conditions to our grid-connected sites, so that they can get to grips with installation processes, test survivability in the gritty, salty sea environment and collect data to verify models developed during tank testing,” explained Richy Ainsworth, US project engineer at EMEC.  

Around the world, islands and archipelagos are proving prime testing grounds for pioneering wave and tidal projects. These include Orbital Marine Power’s commercial O2 project in Orkney, Eco Wave Power’s recently announced plans for a 2MW wave energy project at Port Adriano on the Mediterranean island of Mallorca, and Simec Atlantis’ pilot turbine project in the Goto Island chain in Japan.

Contributing to the grid

In the Faroe Islands, Minesto recently announced detailed plans for a large-scale build-out of tidal energy arrays that could supply 40% of the nation’s growing electricity consumption as it strives to hit its goal of 100% renewable energy by 2030. In addition to Minesto’s existing grid-connected site in Vestmannasund, the company has identified Hestfjord, Leirviksfjord, Skopunarfjord and Svinoyarfjord as ideal sites for future arrays that could together generate 120 MW of tidal energy.

“Islands clearly have a huge, but under-utilised resource in ocean energy,” said James Ellsmoor, renewable energy specialist and founder of Island Innovation. “However, implementation is overall lagging behind compared to wind and solar. There are high initial costs for the technology and a lack of existing case studies, that cast doubt on its economic competitiveness.” 

Ellsmoor praised the “great strides” being made at EMEC, which is helping develop the technology to a point where it can be viable on a larger scale. As yet, however, commercial progress remains sedate, with trade body Ocean Energy Europe expecting sustained growth in 2022, building on last year’s rebound in activity levels. In Europe, up to 2.8 MW of wave energy capacity is lined up for deployment in 2022 while international installations could add another 1.1 MW to the global total. Tidal stream projects are expected to “continue at steady pace” this year, with another 1.4 MW of capacity set to be added in Europe. These installations are, however, a very small contribution to the global energy mix and the IEA warns the technologies are not on track to help the world reach carbon neutrality by 2050, calling for additional policy support to help harness the power of our beautiful blue planet. 

Amy McLellan is a journalist and author. She was previously editor of Energy Day. Twitter  @AmyMcLellan2