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Researchers from the University of Plymouth found that installing tidal stream systems, in addition to solar and offshore wind farms, is about 25% more effective at balancing supply with demand than just relying on solar and wind technologies.
Using tidal technologies as part of a renewable energy mix can also reduce the space required for power-generating facilities by about 33%, both on land and at sea, significantly reducing their visual impact since much of their operation is below the sea’s surface.
The power source can also help reduce the levelised cost of whole-system energy relative to solar and wind systems, the researchers found, because it reduces the requirement to access expensive reserve supplies.
The Plymouth study focused on the Isle of Wight, which plans to generate as much renewable energy as it consumes, and achieve net-zero emissions, by 2040. To achieve this, the island will need to generate an average of 136MW clean energy to meet its projected annual demand.
The island’s primary source of power is currently a gas-fired power station. While solar power generates 80MW, plans for a nearby offshore wind farm were refused in 2015 on the grounds of its perceived visual impact. The island’s tidal stream potential, meanwhile, has not been fully explored.
To understand some of the challenges of achieving the island’s goals, researchers developed a model that considers the need for supply-demand balancing, the whole-system cost of energy, and the spatial coverage of the renewable energy projects.
They found that installing 150MW of solar power, 150MW of offshore wind and 120MW of tidal stream capacity maximises both supply-demand balancing, and the magnitude of maximum power surplus, by an extra 25% relative to the best-performing solar and wind systems.
Tidal stream adoption also minimises the magnitude of maximum power shortages and surpluses across the year by 11% and 24% respectively, the team found.
“Tidal stream energy provides a predictable, reliable source of renewable power that, if harnessed, can complement the variability of wind and solar,” said study leader Dr Danny Coles, research fellow at the University of Plymouth on the Interreg V A France (Channel) Tiger Project, working with the European Marine Energy Centre, Hydrowing Ltd, Perpetuus Tidal Energy Centre, and the University of Edinburgh.
“Unlike wind and sun, the tides are present every day of the year. Our results show that adopting a combination of all three can reduce reliance on imported power and volatile prices. This is particularly relevant to the current energy landscape, when cold weather is increasing heating demand and millions will be paid to use less electricity to avoid blackouts.
“As the transition to net zero energy continues, there is a need to better understand how to build system resilience to overcome periods of high demand and low wind resource. While it is well understood that tidal stream power is predictable and reliable, this research quantifies the system benefits that predictable and reliable tidal supply can provide.”
The research is already being used by the Isle of Wight Council and Scottish & Southern Electricity Networks to assess the scope of work needed for grid upgrades.
The results are also being used by Scotia Gas Networks (SGN) in a whole-system study that builds on the research and focuses on the island’s entire electricity system.
The work was published in the journal Applied Energy.
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