Korea’s renewable energy wonder: The Sihwa Tidal Power Plant – High energy capacity, low environmental impact

By Habib Toumi

ANSANCITY: The comon view across teh globe is that power plants are associated with degrading the environment and spoiling the aesthetics of their surroundings.

But, such a view does not stand in the Republic of Korea where the Sihwa Tidal Power Plant (TPP) has, to the contrary of the generally-held view, in fact improved its environment and enhanced its surroundings making it particularly attractive to the public and safer for millions of birds.

From the 75-meter-high observatory overlooking the Sihwa TBPP, we have an amazing view of the setting for the Sihwa Lake project and the world’s largest operating tidal power station: the 254 MW Sihwa Lake project.

From high in the air, the barrage that houses the 400-meter-long tidal power plant looks like a soft thread stretched across the vast sea.

However, the facts on the ground are a massive tribute to a marvel of Korean engineering made to reap energy from the highest tides in the West Sea.

In terms of figures, the Sihwa lake tidal power plant helps boost Korea’s energy self-sufficiency through the green energy development. It can supply electricity to a population of 500,000, cut down petroleum imports by 862,000 barrels per year, and reduce the generation of CO2 by 315,000 tons per year.

In simple terms, the Sihwa tidal power plant generates power by storing water during the flow, and releasing it during the ebb. It relies on the change in water level between ebb and flow to generate power.

The Sihwa Lake project changed a nightmare into a dream thanks to Korea’s western coast boasting winding rias, numerous inlets and tidal ranges of up to 9 meters, providing a perfect setting for tidal power generation and a rich repository of tidal energy resources.

According to the tour guide and experts’ reports, South Korea in 1994 created the 56.5-square-kilometer (km²) freshwater Lake Sihwa by constructing a 12.7-km dike between Oido Island in Siheung city and Daebudo Island in Ansan city to secure agricultural and irrigation water, and to reclaim 173 km2 of land near the local metropolitan areas of three cities surrounding the lake.

Kuban Andymen, from Kyrgyzstan, poiting to the movement of the water

However, after the seawall was closed and the natural tidal currents were cut off, water quality deteriorated. This was due to a combination of factors, including low natural freshwater inflows and the increase of wastewater from the industrial complexes.

The pollution severely contaminated the basin and made it unusable as a freshwater reservoir, as intended. By 1997, officials reformulated their plans, and the government transitioned Sihwa’s operating strategy from a freshwater to a seawater lake by periodically opening up the seawall’s sluice gates to flush the basin by circulating seawater in an effort to improve the water quality.

South Korean governmental water authority Korea Water Resources Corp. (then KOWACO, and recently renamed K-water) stepped in and proposed a tidal power barrage that uses a single-effect flood generation method and allows up to 60 billion tons of seawater to be circulated annually.

As tidal energy generation gained increasing attention as a strategy in the early 21st century to counter rising international oil prices and reduce greenhouse gas emissions, the government saw an opportunity as tidal power offers strong advantages in comparison with other renewable sources, such as its periodicity and long-term predictability of tidal patterns.

Petko Azmanov, from Bulgaria, obsering the area where clean energy is generated 

By December 2002, the project was approved, and in 2004, construction began. Seven years later, in December 2011, K-water’s Sihwa Lake tidal power plant was connected to the grid, equipped with 10 bulb-type generator units (each 25.4 MW) that produce about 552.7 GWh annually.

The plant is housed in the concrete seawall that bridges two “eco-park” areas. One half of the bridge is taken up by the 10 generating units, and the other half, by eight culvert-type sluice gates.

The tidal units essentially produce power by exploiting the gap in the water level between the sea and Lake Sihwa.

Turbine structure

As the tide rises, saltwater flows through the turbines from the Yellow Sea and into Lake Sihwa, creating electricity. But at low tide, the gates are raised and the turbines revert to sluicing mode, allowing the lake to be emptied and no electricity to be produced.

The Sihwa tidal power plant generates one-way power twice a day at high tide.

With ten water turbine generators each with an installed capacity of 25.4 MW, the power plant produces 552.7 GWh of electricity annually – enough to support the domestic needs of a city with a population of 500,000. It is also equivalent to 862,000 barrels of oil.

Gate structure

The site has become very popular for learning about lively ecosystems, with over 146 bird species including stork and mallard, and some 23 million birds living in and around the lake.

The Sihwa embankment, 12.7 km long, is also a popular spot for leisure activities and sports. The tidal power station and surrounding area today attract some 1.5 million people annually.

Based on the success of the Sihwa tidal power plant and the utilization of large tides by K-water, the Korean governmental water authority, other companies in South Korea have taken the impulse to plan new tidal power plants in the West Sea off the country’s western coast.