Tidal Power In Korea  

Korean network KBS has a report on tidal power in Korea - News In Zoom: Tidal Power Generation.

Securing energy is a matter of global concern, due to high-flying oil prices, and tidal power generation has emerged as an alternative energy source. The on-going construction of the Sihwa-ho tidal power plant will be completed in November 2009, and the planned Garorimman tidal power plant is now enjoying the limelight for its feasibility. The west coast is now expected to become the world’s largest tidal power plant belt. ...

The West Sea, also called the “Yellow Sea,” refers to a mass of water lying west of the Korean peninsula. Covering the area of 4,000km2, the West Sea is about 1,000km north and south and 700km east and west. Its average depth is 44m, and the sea bed is relatively flat. The gap between the rise and fall of the tide is about 9 m off Incheon, and 6 m off Asan Bay. The bid difference isn’t conducive to the development of a port or harbor, but is advantageous to power generation.

The frontrunner in the nation’s tidal power generation is the Sihwa-ho tidal power plant. The Sihwa-ho lake was converted from a fresh water lake to a sea lake in 2004 as part of efforts to improve the quality of the lake water. Construction of a tidal power plant began and is expected to be dedicated by November 2009. The construction will likely cost 254,000 KW (ten 25,400 KW power generators). If completed, the lake will beat the La Rance plant to become the world’s largest tidal power plant. Its annual power production is 550 million KW, which will save 39 billion won in annual energy imports and reduce the annual CO2 generation by 152,000 tons.

Garorim Bay is located between Seosan and Taean, South Chungcheong Province. The jar-shaped bay is known for big differences between the rise and fall of the tide. Just a two kilometer-long embankment will make it possible to install tidal power generating facilities. Construction of a tidal power plant was approved back in 1980, when the Korean economy was hit by the second oil crisis. But as oil prices stabilized, the project lost ground. Recently, due to high oil pirces, the shelved project began attracting attention. KOREA WESTERNPOWER, together with POSCO, DAEWOO Engineering and Construction, and Lotte Engineering and Construction are participating in the effort. The project is to construct a tidal power plant, which can also serve as a four-lane bridge, with an estimated cost of 1,002.2 billion won, and develop a huge tourist complex in the vicinity. It will have a general capacity of 520,000 KW.

Technology Review has a look at Marine Current Turbine's Seagen tidal power project in Northern Ireland - Tidal Power Comes to Market.

The world's first commercial tidal-power system has been connected to the National Grid in Northern Ireland. Built by the British tidal-energy company Marine Current Technologies (MCT), the 1.2-megawatt system consists of two submerged turbines that are harvesting energy from Strangford Lough's tidal currents. The company expects that once the system, called SeaGen, is fully operational, it will be able to provide electricity to approximately one thousand homes. The system is currently being tested and has briefly generated 150 kilowatts of power into the grid. ...

The technology works like a wind turbine, but instead of wind, the turbines are driven by the flow of tidal currents. It offers a significant advantage over wind because currents are predictable, says James Taylor, the general manager of environmental planning and monitoring at Nova Scotia Power, a company that also has plans for a one-megawatt tidal-power project. "Wind is intermittent and, because of that, is much more difficult and expensive to integrate in a power system," he says.

Generating power from currents in the form of "watermills" was first demonstrated by MCT in 1994 with a 15-kilowatt system in Loch Linnhe, off the west coast of Scotland. In 2003, MCT installed a 300-kilowatt system off the coast of Lynmouth, England. At the same time, a Norway-based energy company, Hammerfest Strom, installed a like-sized system in the Kvalsund strait. In the spring of 2007, Verdant Power submerged six 35-kilowatt turbines in New York City's East River. SeaGen, however, is much larger than any of these systems and is not an experimental device, says Fraenkel.

SeaGen uses two rotors that are 16 meters in diameter and can each produce 600 kilowatts of power. Fraenkel says that using two rotors is a "cost-effective solution" because the depth of the seas limits the size of the rotors. "We have to grow sideways," he says.

The researchers also have complete control over the rotors. "They are pitched like the propeller on an old aircraft, so by changing the angle--which dictates how much force is produced--of the blades, it allows us to optimize the rotor," says Fraenkel. The researchers can start and stop the rotor, and make it go faster or slower. And to prevent any damage to the ecosystem, it is important that the researchers keep the rotors at about 14 revolutions per minute, a speed that is too slow for marine life to run into the blades or to alter tides.

Unfortunately the plant had a setback a few days after going live, with a computer error resulting in a damaged turbine blade. Full operation is expected to restart in the northern autumn.

A plan to produce electricity from a tidal turbine installed near the mouth of Strangford Lough has been delayed. Seagen, the world's first commercial scale tidal turbine, began supplying a small amount of electricity to the National Grid last Thursday. But a programming fault led to damage to one of the blades the next day.

Seagen is calling it a "minor hiccup" - but the date for supplying full power has now slipped into early autumn at best.