Tidal Power: Renewable Energy Created by the Moon [Digging Energy]

[Specialist Report]
Higher Tides During Full and New Moons
More Power Generated at Peak Tidal Range
Lunar Calendar Indicator in the Control Room
Tidal Power Plant Project Planned for Saemangeum
Korea Rural Community Corporation to Invest 680 Billion Won

Perspective view of Sihwa Tidal Power Plant. Korea Water Resources Corporation

The Sihwa Lake Tidal Power Plant, located in Danwon District, Ansan City, Gyeonggi Province, is home to the 25-story "Sihwa Iruna Tower (Moon Observatory)." From the top of this tower, visitors can enjoy a panoramic view of Sihwa Lake, where the tidal power plant is situated, as well as the surrounding sea. On clear days, it is even possible to see as far as Silmido Island. The Iruna Tower, which is open to the public free of charge, has become a popular tourist attraction on the west coast, drawing 2.2 million visitors annually.

The word "Luna" (meaning "moon") is included in the name of the Sihwa Tidal Power Plant observatory because tidal power generation relies on the power of the moon. Tidal power harnesses the difference in sea level between high tide and low tide (tidal range) to generate energy.

In all seas, the gravitational pull of the moon and the sun causes the regular rise and fall of tides, known as tidal phenomena. Tidal power generation produces electricity by using the difference in sea level created by these tides to turn tidal turbines. Like solar and wind power, tidal power is a form of clean energy provided by nature.

Internal structure of a tidal power plant. Korea Water Resources Corporation

In the control room of the Sihwa Tidal Power Plant, there is a display board showing sea level, electricity production, and frequency, as well as a unique indicator for the lunar calendar. This is because the height of the water changes depending on the position of the moon. When there is a full moon or a new moon, the gravitational forces of the moon and the sun combine, exerting the strongest pull on the seawater. At these times, the difference in sea level is greatest, resulting in relatively higher tidal power generation.

Tidal power generation is classified into one-way (ebb or flood) and two-way (ebb and flood) generation. The one-way type is further divided into flood generation, which produces electricity during high tide, and ebb generation, which operates during low tide. The Sihwa Tidal Power Plant uses a one-way flood generation method, producing electricity during high tide and discharging water through sluice gates during low tide.

The reason two-way generation was not adopted is that there are major industrial complexes inside Sihwa Lake, making it necessary to maintain the water level at a certain height.

At tidal power plants, hydro turbines generate electricity. The turbine transmits the power of seawater to the generator, converting potential energy into rotational energy. The Sihwa Tidal Power Plant is equipped with large turbines measuring 7.5 meters in diameter, each with three blades.

In Korea, following Sihwa Lake, the construction of the Saemangeum Tidal Power Plant is also being pursued. The Korea Rural Community Corporation plans to invest 680 billion won to develop a 140 MW tidal power project in Saemangeum.

In September, Kim Seonghwan, Minister of Climate, Energy and Environment, met with Kim Eui-gyeom, Administrator of the Saemangeum Development and Investment Agency, to discuss projects such as expanding drainage gates and tidal power generation to improve water quality in Saemangeum Lake. However, some point out that the tidal range in Saemangeum is only 6 to 7 meters at its maximum, which is smaller than that of Sihwa Lake, raising concerns about its economic viability.