Canada's Bay of Fundy, renowned for its formidable tides, has long been a testing ground for tidal energy technologies. The region's extreme currents have proven to be a formidable challenge for traditional seabed-mounted turbines, which have a history of blade damage, failure, and even disappearance. However, a recent development in tidal energy technology offers a glimmer of hope for harnessing this powerful resource. The Orbital O2, a floating, towable tidal turbine, has been approved for deployment in the Bay of Fundy, marking a significant advancement in the field.
The O2, developed by Orbital Marine Power, is a marvel of engineering. It is a 74-meter floating steel structure weighing approximately 680 tons, equipped with two retractable legs that lower 1-megawatt turbines into the tidal flow. This innovative design allows the turbine to be towed back to a harbor for maintenance, a stark contrast to the traditional approach of anchoring heavy structures to the seabed. The O2's floating platform is a concept China is also exploring with its skyscraper-sized floating offshore wind turbine.
Orbital's next-generation turbine, the O2-X, is set to be even more ambitious. With a power rating of 2.4 MW per unit, six O2-X turbines are planned for deployment in Orkney by 2028. The company has secured funding through two UK Contracts for Difference rounds, ensuring the project's financial viability. The O2-X's blades are a key feature, with plans to extend them from 10 meters to 13 meters, making them the longest tidal blades in the world. This increase in rotor swept area is a significant step towards reducing costs in tidal energy.
The Bay of Fundy, with its treacherous tides, presents a unique challenge. The Minas Passage, a narrow gap where the tides funnel in and out, carries more water than all the world's rivers combined, pushing it through at speeds of up to 5 meters per second. The region's extreme conditions have already claimed victims, with several seabed turbines failing or disappearing. However, the floating O2-X design offers a solution, as it can be towed away from dangerous conditions, potentially ensuring its survival.
The approval of three floating O2-X turbines for the Minas Passage is a significant milestone. Orbital has partnered with Eauclaire Tidal to deploy the turbines at the Fundy Ocean Research Centre for Energy (FORCE). This project marks the first deployment under Canada's revised, staged approach to tidal permitting, allowing for the addition of more turbines as environmental monitoring progresses. The province of Nova Scotia has approved a total of 16.5 MW, enough to support the planned six O2-X machines.
Despite the progress, tidal energy remains an expensive endeavor. In the UK's Contracts for Difference auction, tidal stream projects were contracted at £172 per megawatt-hour, roughly three times the price of fixed offshore wind. However, tidal energy has the advantage of predictability, producing electricity on calm nights and still afternoons when wind and solar farms are quiet. This makes tidal energy a valuable asset for grid operators, and the UK's push for tidal energy, including large Welsh schemes in the Menai Strait, reflects this understanding.
Orbital now faces the challenge of proving the O2-X's viability in the Bay of Fundy's extreme conditions. The floating design is a smart solution, but it must withstand the region's powerful tides. The company has a December 2030 deadline to deploy a turbine and secure a 15-year power contract with Nova Scotia Power. The success of the O2-X in the Bay of Fundy could be a turning point for tidal energy, offering a sustainable and predictable source of electricity in one of the world's most challenging environments.
