Tidal Energy Achieves Global Record with Six Years of Uninterrupted Power

A significant milestone in renewable energy has been reached, as systems at the MeyGen tidal energy project in Scotland's Pentland Firth have set a new global record for continuous power generation. This breakthrough marks a pivotal moment for tidal stream technology, demonstrating its long-term reliability and commercial viability.

The MeyGen Project: A Beacon of Tidal Power

The MeyGen project, recognised as the world's largest tidal stream array, is situated in Scotland's Pentland Firth, a strait known for its powerful tidal currents. Operated by SAE Renewables, the project has been at the forefront of developing utility-scale tidal stream arrays for over a decade. The recent achievement involves cutting-edge technology delivered by SKF in collaboration with Proteus Marine Renewables, highlighting the importance of partnerships in advancing renewable energy solutions.

The Physics of Pentland Firth Tidal Power

The Pentland Firth is widely considered the "Saudi Arabia of marine energy" due to its exceptional hydrodynamic properties. Positioned between the Scottish mainland and the Orkney Islands, this narrow channel connects the North Atlantic Ocean with the North Sea. Because of the differing times of high tide on either side of this strait, water is forced through the channel at immense speeds.

The kinetic energy available in these currents can be calculated using the kinetic power density formula:

Where:

• $P$ is the power generated in watts.
• $\rho$ is the density of seawater (approximately $1025{\text{ kg/m}}^3$).
• $A$ is the sweep area of the turbine rotor in square metres.
• v is the velocity of the tidal flow in metres per second.

Because the power output is proportional to the cube of the velocity ($v^3$), even small increases in current speeds yield massive gains in electricity generation. With tidal flows in the Inner Sound of the Pentland Firth reaching speeds of up to 5 metres per second (approx. 10 knots), the location provides some of the highest concentration of kinetic marine energy in the world, making Pentland Firth tidal power exceptionally efficient.

Setting a New Global Benchmark for Reliability

The core of this breakthrough lies in the remarkable operational endurance of the tidal turbines. SKF announced that their systems have run continuously for over six years at 1.5 megawatts (MW) without requiring any unplanned or disruptive maintenance. This sustained performance, with turbines in continuous operation since 2018, establishes a new standard for reliability and performance in the demanding subsea environment. The ability to operate for such extended periods without intervention is crucial for validating the commercial viability of tidal energy on a global scale.

To withstand these harsh operational conditions, the turbines use custom-engineered seals and specialised spherical roller bearings designed by SKF. This ensures that the internal drive trains can absorb the immense bending moments and thrust forces exerted by the relentless Pentland Firth currents.

Overcoming the Challenges of the Ocean Environment

A persistent challenge for the tidal stream energy sector has been designing turbines capable of operating reliably underwater for prolonged durations. The harsh marine conditions, including saltwater corrosion, biofouling, and powerful currents, can significantly compromise components. This record-setting operation at MeyGen directly addresses this hurdle, proving that a condition-based maintenance strategy can enable equipment to run for over six years between overhauls.

By utilising subsea sensors that monitor temperature, vibration, and acoustic emissions in real-time, the monitoring platform forecasts potential wear patterns, enabling operators to act before components fail. This achievement is a testament to the robust engineering and innovative solutions employed by SKF and Proteus Marine Renewables, who believe their approach has been validated by the MeyGen pathfinder array, which was commissioned in 2017 as a blueprint for utility-scale tidal stream projects.

The Inner Sound deployment site features water depths ranging from 30 to 40 metres, where the seabed is composed of swept bedrock. This environment minimises sediment movement that could wear down moving parts, yet presents immense challenges for underwater installations, requiring heavy gravity-base foundations (weighing up to 350 tonnes each) to keep the turbines secured against the force of the tides.

The Predictable Power of Tides and its Economic Promise

Tidal energy stands out among renewable resources due to its inherent predictability. Unlike solar or wind power, which are subject to weather variability, tidal flows are governed by the gravitational forces of the moon and sun, making them highly consistent and foreseeable. This predictability allows tidal energy to serve as a reliable source of baseload power, complementing other intermittent renewables.

The long-term operation record at MeyGen is expected to significantly boost confidence in the economic potential of tidal energy. The global tidal energy market, valued at approximately €1.1 billion in 2023, is projected to expand to around €6.9 billion over the next seven years. Furthermore, with declining costs, tidal stream energy is anticipated to become cost-competitive with nuclear energy by 2035. This growing sector is also poised to contribute significantly to economies, with projections indicating it could generate up to £17 billion and 15,000 jobs in the UK alone by 2050.

Future Expansion and Broader Impact

Building on this success, there are ambitious plans for the MeyGen project and the broader tidal energy sector. SKF is set to contribute to a minimum 59 MW addition to the existing 6 MW pilot array, with intentions for further substantial scaling through 2025 and beyond. Proteus Marine Renewables aims to install at least 30 larger 3-megawatt turbines in Scotland, France, and Japan over the five years starting from 2026, each capable of powering approximately 3,000 homes.

This breakthrough strengthens the global commitment to tidal stream technologies, with targets such as deploying 1 gigawatt (GW) of tidal stream energy in the UK by 2035, sufficient to power around 829,000 homes. Harnessing the full potential of Pentland Firth tidal power is a cornerstone of this strategy, as the strait contains approximately half of the UK's total tidal resource.

A History of Milestones in Tidal Energy

The MeyGen project has consistently pushed the boundaries of tidal energy. In February 2023, it became the first tidal stream array worldwide to generate 50 gigawatt-hours (GWh) of clean electricity over its lifespan, an amount exceeding the total global generation from all other tidal devices and sites combined at that time. Earlier, in 2019, the MeyGen array also achieved the longest uninterrupted generation period from a multi-megawatt tidal turbine installation, exporting energy equivalent to the annual consumption of about 3,800 UK homes. These cumulative achievements underscore MeyGen's role as a vital global prototype, providing invaluable performance data to inform future projects and accelerate the industry's growth.

The achievement of six years of uninterrupted power generation at MeyGen signifies a critical turning point for tidal energy, moving it from a promising technology to a proven, reliable, and economically viable component of the global renewable energy mix.