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Harnessing the Moon's Power for Clean Energy
Tidal Power
The moon moves at a very slow pace, yet tirelessly circles the Earth. The ocean tides rise and fall in rhythm with the moon's gravitational pull. Harnessing the power of the moon's gravitational tug on the ocean tides to generate clean energy is known as "tidal power.” Delve into the world of tidal power, an energy source deeply intertwined with the natural world.
Written by the Editorial Team, Data provided by the Climate Change & Carbon Neutral Business Dept. and Sihwa Tidal Power Plant Office in K-water
Energy generated from the flow of nature
Sometimes, even when we are looking at the same scene from the same spot, it can seem like a completely different picture. This is the case with the ebb tide—which exposes the muddy expanse of the tidal flat—and the flood tide, which covers everything up with deep water, obscuring the depths of the ocean. Ebb and flood tides are caused by the gravitational pull of the Earth and Moon. The difference in sea level between high tide and low tide is called "tidal range.” This tidal range is harnessed to generate electricity through a process called tidal power.
Tidal power harnesses the energy of rising and falling tides by building dams across bays or estuaries with significant tidal ranges. Tidal power generation works by opening sluice gates to let seawater flood into a reservoir inside the seawall during high tide. During low tide, the gates are opened again to release the seawater, generating electricity as the turbines in the generators rotate.
The biggest advantage of tidal power lies in its reliance on a natural energy source. Utilizing the tides in their natural state makes it an environment-friendly option. Furthermore, tidal energy offers an impressive production capacity. The amount of energy that can be harnessed by hydroelectric power plants is constrained by their reliance on storing rainwater during the wet season. In contrast, tidal power is a renewable energy source that will never be depleted as long as there are tides. In other words, as long as the moon exists and orbits Earth, generating electricity will continue to be possible. The amount of electricity generated can also be predicted. Tidal power, which is generated by the gravitational pull of the moon, experiences fluctuations in production levels that coincide with the lunar cycle. During full and new moons, the combined gravitational forces of the moon and the sun exert the strongest influence, resulting in more significant tidal variations. Therefore, this is the time of year when tidal power generation is at its highest.
Tidal power plants around the world in diverse forms
For these reasons, tidal power has been acknowledged for its potential to mitigate the climate crisis and facilitate sustainable power generation, drawing global attention as a promising energy source. Anticipating future energy challenges, France established the world's first operational tidal power station on the estuary of Rance River in Brittany, Northwestern France in 1966. The power plant commenced full-scale energy production in 1968 following a successful trial period. It now generates around 500 million kWh of electricity annually. Two years later, Russia's tidal power plant commenced operation. As a small-scale facility featuring a single 400 kW tidal generator, the Kislaya Guba Tidal Power Station is situated in the Kola Peninsula near Murmansk in Northwestern Russia. It is currently operational for research and testing purposes.
The global tidal power movement gained momentum in the 1980s, marking a pivotal era for harnessing the power of the tides. Canada constructed the Annapolis Tidal Power Plant in 1984, utilizing an existing seawall at a river estuary by retrofitting it for tidal power generation. Due to aging facilities, however, the 20 MW tidal generator is currently inactive. A distinguishing feature of this plant is its employment of Straflo-type water turbines. These propeller-shaped turbines serve as the generator's rotors, resulting in a compact design for both turbines and power plant itself.
The Jiangxia Tidal Power Station in China employs a "single-basin and double-effect generation" method to generate electricity by collecting and releasing seawater in a single reservoir. This system uses both "ebb generation" method—where sluice gates are opened during high tide to fill the reservoir and then closed to release water during low tide—and "flood generation" method where water is drained from the reservoir during low tide and seawater is allowed to fill the reservoir during high tide. While this method comes with the drawbacks of complex structure and high construction costs, it offers the advantages of high power generation capacity and extended operation times. Leveraging the expertise and experience gained from operating the Jiangxia Tidal Power Station, China is poised to apply its knowledge actively to the development of tidal energy along its eastern coastline.
Capacities of Major Tidal Power Plants Around the World
K-Tidal Power: Expanding its Reach Globally
Aside from the tidal power plants mentioned earlier, South Korea presents its own remarkable achievement: the Sihwa Lake Tidal Power Plant, which has been operational since 2011. The Sihwa Lake Tidal Power Plant reigns supreme as South Korea's only tidal power plant, while simultaneously holding the title of the world's largest facility of such kind. The power generated here is enough to supply half a million people for an entire year. Tidal power generation can be categorized into two main types: single-effect and double-effect. Harnessing the energy of tides, the Sihwa Lake Tidal Power Plant utilizes the single-effect method for electricity production.
Before the tidal power plant was built, Sihwa Lake was known as the "Lake of Death.” It was heavily polluted due to the influx of various effluents, and the oxygen levels were so low that it was nearly impossible for any life to survive. By opening up the blocked waterway, however, the Sihwa Lake Tidal Power Plant has enhanced water quality and drawn marine organisms. Thus, the Sihwa Lake Tidal Power Plant holds significance beyond being a mere power plant. Fronting Sihwa Lake, Daesong Wetland serves as a critical habitat for endangered oystercatchers and a stopover for migrating Black-faced Spoonbills. The observation deck, Sihwa Narae Tidal Power Culture Pavilion, and Sihwa Narae Tidal Power Park have become beloved recreational spots among locals and popular tourist destinations. With a vision of establishing itself as a hub for renewable energy, the Sihwa Lake Tidal Power Plant has embarked on a series of initiatives including the installation of building-integrated photovoltaic (BIPV) systems, implementation of a seawater heat pump (SHP) heating and cooling demonstration system, and advancement of a parking lot photovoltaic power generation project.
The Plant also stands as a beacon of K-tidal power technology, embodying the culmination of advancements in this field. At the forefront of these advancements is K-TOP digital twin technology. This sophisticated system accurately calculates the power output of real-world generators, predicts water level fluctuations, and optimizes plant operations. Recently, the introduction of AI-powered K-TOP 4.0 has further refined the system, minimizing prediction errors and maximizing efficiency. The tidal power generation expertise of K-water has attracted the attention of Britain, leading to potential collaboration. As part of its ambitious plan to transform the industrial city of Liverpool into a carbon-neutral hub, the city has signed a Memorandum of Understanding (MOU) with K-water. This collaboration will foster technological exchange and pave the way for joint initiatives in water, energy, and urban development, propelling Liverpool toward a sustainable future.
Annual trend of the Sihwa-lake tidal power plant
