Fuel for Thought
Is the UK poised to become a world leader in tidal power?
Nov 09 2023
Tidal power, a form of hydropower, capitalizes on the kinetic and potential energy of tidal streams and the gravitational pull of the moon and sun to generate electricity. As the global community gravitates towards sustainable energy sources, tidal energy stands out due to its predictability and minimal environmental impact, especially when compared to other renewable resources like wind and solar. This article delineates the mechanisms of tidal power generation and explores its advantages in the broader context of renewable energy technologies.
Tidal energy generation harnesses the movement of water caused by tidal forces exerted by celestial bodies, primarily the moon, and to a lesser extent, the sun. The predictability of celestial mechanics imparts tidal power with a significant advantage over other renewables: its predictability. Tidal power plants can forecast power output with high accuracy, which is invaluable for grid stability and energy management.
The process of tidal power generation can be classified into three primary methods: Tidal Stream Generators (TSGs), Barrage Generation, and Tidal Lagoon Power Plants:
TSGs operate akin to underwater wind turbines, capturing kinetic energy from tidal currents. These generators are typically installed on the seabed at locations with high tidal current velocities. As water passes through the turbines, it spins the blades, which are connected to generators that produce electricity. TSGs are less intrusive and have a smaller environmental footprint compared to barrages.
Barrage systems involve the construction of barriers across tidal rivers or estuaries. These barrages capture potential energy from the difference in height (or head) between high and low tides. Sluice gates on the barrage are opened to allow the tide to fill up the estuary. Once the tide is at its peak, the gates close, and water is then released through turbines at a controlled rate to generate electricity.
Similar to barrages but on a smaller scale and usually without blocking entire estuaries, tidal lagoons are artificial pools created by constructing a perimeter breakwater. These lagoons harness energy from incoming and outgoing tides.
The advantages of tidal power over wind and solar energy are significant. Firstly, the tidal cycles are predictable and reliable, unlike the intermittency issues associated with solar and wind power, which depend on weather conditions. This predictability allows for better grid management and a consistent power supply.
Secondly, tidal power is highly efficient. Water is over 800 times denser than air, providing a much greater energy density. As a result, even slow-moving tidal currents can generate substantial amounts of energy.
Thirdly, tidal power installations have a longer lifespan and are less visually intrusive. While wind turbines and solar panels are subject to significant wear and tear from the elements and typically require replacement after 20-25 years, tidal installations are robust and can last for several decades.
Lastly, the environmental impact of tidal power is relatively low. After the initial construction phase, tidal power plants have a minimal carbon footprint. The technology can be engineered to have a lower impact on marine ecosystems, especially in the case of TSGs.
Tidal power presents a compelling case for investment and development within the portfolio of renewable energy. Its predictability, efficiency, durability, and low environmental impact offer substantial benefits over wind and solar power. As technology advances and costs decrease, tidal energy could play a pivotal role in achieving a sustainable and reliable energy future – and the United Kingdom might just be the country to lead the charge.
The announcement of four tidal stream projects amassing a capacity of 40.82 megawatts (MW), successfully securing contracts in the Contracts for Difference (CfD) scheme’s fourth allocation round, heralds a new era for the UK's energy sector. This milestone highlights the nation’s escalating ambitions to dominate the tidal power arena.
The significance of this development is profound when considered within the wider context of 93 renewable energy projects, summing to an impressive 11 gigawatts (GW), also reaping the benefits of the CfD scheme. SIMEC Atlantis Energy's MeyGen project in Scotland, earmarked for a substantial 28 MW boost, embodies the optimism permeating through the industry. With a proposed operational launch in 2027, and financial closure expected by 2024, the path is set for the MeyGen project to ultimately deliver a staggering 400 MW of tidal energy.
The UK’s tide of innovation does not stop there. Orbital Marine Power Ltd has emerged victorious in securing CfDs for two ventures totaling 7.2 MW in Orkney, promising to supply clean electricity to approximately 7,200 homes. Simultaneously, the Spanish trailblazer Magallanes Renovables has been granted support for a 5.62 MW initiative in Wales, set to materialize between 2025 and 2026.
Tidal energy’s competitive edge was further solidified by the CfD auction, locking in a strike price of GBP 178.54 per megawatt-hour (MWh) for tidal stream technology. This rate underscores the economic viability and the scaling potential of tidal power.
Amidst the jubilation, industry experts like Simon Cheeseman, wave and tidal energy sector lead at the Offshore Renewable Energy (ORE) Catapult, call for sustained and strategic support to escalate the UK's tidal capacity to 1 GW by 2035, thereby cementing its contribution to the Net Zero targets. He advocates for continuous CfD allocation to foster investor confidence, critical for the sector's evolution.
Enthusiasm was equally palpable from Ocean Energy Europe, which lauded the UK for joining nations like Canada and France in incentivizing tidal energy progress. The sector's potential cost-competitiveness with nuclear power at the 1 GW threshold, as predicted by UK Marine Energy Council Chair Sue Barr, spotlights the broader economic implications, promising job creation and bolstering energy security with a consistent and forecastable energy source.
The historical context is essential to appreciate the recent advancements. Despite the UK's rich tidal resources, the formidable challenges associated with tapping into this power deterred investors and policymakers alike. However, the landscape began to shift as the industry overcame operational hurdles, propelling tidal power to a promising threshold of economic and practical feasibility. The dramatic reduction in cost — a 40% decrease since 2018 — coupled with the Offshore Renewable Energy Catapult's projections that tidal energy could undercut nuclear power costs by 2035, has sparked renewed interest and ambition within the sector.
This new phase of development is not merely speculative. Companies like Orbital Marine are setting ambitious targets, with plans to install additional floating turbines capable of energizing thousands of homes and generating significant employment. Simec Atlantis Energy's aspirations to expand their MeyGen project to 34 MW further illustrate the sector's maturation and the world's increasing reliance on the UK’s tidal prowess.
The transformational shift in perception among investors, underscored by recent government funding commitments, has been remarkable. Yet, challenges persist, such as lengthy approval processes and the absence of an official marine energy target, which could impede the tidal industry's trajectory. Developers like Nova Innovation underscore the contrast between international projects and the prolonged timelines characteristic of UK ventures, a gap that needs closing to maintain momentum.
Tidal stream turbines' integration into the marine environment, their minimally invasive profiles, and their predictable energy output present a robust case for the tidal sector’s expansion. Despite representing a smaller fraction of the UK's renewable energy portfolio, tidal power's role in decarbonizing the nation's energy system is pivotal.
The commitment of the UK government, reflected in the allocated £20 million for tidal energy under the CfD scheme, has reinvigorated the industry. However, the permanence of such support remains uncertain. As the industry stands at the cusp of commercial viability and international market expansion, the necessity for unwavering governmental commitment is unequivocal. The coming years are poised to be decisive, with the UK's leadership in tidal energy innovation having the potential to forge a sustainable and secure energy future, not just for the nation but also as a blueprint for global energy strategies.
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