Marine mineral resources are either present in the waters or in reserves under the seabed. In the shallow waters of depths of only tens of meters, most of useful minerals are found. The sand and gravel from the sedimentary layers in beaches or shallow waters are used as basis materials for building apartments, houses, and road. Other resources such as titanium, which is used in high intensity alloys, as coal, iron, manganese, and diamonds can all be found in the seabed.
In case of fuel, about 20% of annual production comes from the seabed.
Marine life resources can be divided into plankton, nekton, and benthos depending on the living environment and movement characteristics. Planktons that live in seas, lakes and rivers are small organisms that float around in waves or currents. Nektons are animals that can swim regardless of the current, such as cod, pollack, squid, and whales. Benthos are organisms that crawl on the floor of seas or lakes, such as conch, sea cucumber, crab, seaweed, laver, and agar-agar weed are such a kind.
Marine space resource refers to the construction of residential facilities, cities, airports and ports on seas to fully utilize the marine space. Marine structures are structures that are installed underwater or above water. Power plants, factories, hotels, cities, and other tourism facilities can be developed as off shore structures, while underwater parks, cruises, observatory, tunnels, pipelines, aquariums, and sea farms can be developed underwater. As for sea bed facilities, seabed tunnels and storage facilities are other examples.
Regarding water resources, the lack of sources for fresh drinking water can be addressed through desalination processes that remove salinity from sea water and development of deep sea water.
Energy sources can be secured by generating electricity through wave force, tidal currents, and differential thermal generation. Marine energy resources are a type of renewable energy with virtually unlimited potential considering the scale of the ocean. Other sources of renewable energy include tidal power generation, wave force generation, tidal current generation, and marine thermal differential generation.
Tidal power generation produces electricity via a rotating water wheel using the difference in the sea level between ebb tide and high tide. Although Korea is surrounded by water on three sides, the difference between the two tides is greater on the western coast than the eastern coast; consequently, it is more advantageous to use tidal power generation on the western coast. In the global landscape of tidal power stations, there is Rance (400KW) in France, Kislaya (800KW) in Russia, Annapolis (20,000KW) in Canada, and Jiangxia (3000KW) in China.
Wave force generation produces electricity by using the up-and-down movement of waves. With incoming and outgoing flow of waves, the air within chambers is repeatedly expanded and contracted, which operates a cam or air turbine.
The marine thermal differential power generation uses the difference in sea water temperature to produce electricity. The steam from turning the turbine is cooled with sea water to return to a fluid state.
Tidal current generation uses the natural current that flows quickly to turn the turbine of a generator. Because tidal current generation can produce electricity without a need to construct a dam, it is an eco-friendly energy facility that has no adverse impact on the marine ecosystem. In addition, because it can be operated sustainably regardless of the weather, it is an attractive option. Uldolmok on the southern coast of Korea is regarded as the ideal location for tidal current power generation.
There is a wide variety of natural resources in the ocean that can be considered treasures. Because resources that can be obtained on land are continuously decreasing, marine natural resources are growing in importance. The following are some of the resources of such importance.
It is also called the deep sea gold mine, black gold of the deep sea, or the black pearl. Manganese nodules are composed of metals such as manganese, copper, nickel, and cobalt. Manganese nodules grow 2 to 6 mm every million years and are located in deep sea basins that are thousands of meters below the water surface. The metals in manganese nodules can be used in the construction of automobiles, electronic communication, airplanes, engines, and medical equipment. It is estimated that some 500 billion tons of manganese nodules are stored under the sea. In the Clarion-Clipperton Fracture Zone, southeast of Hawaii in the Pacific Ocean, Korea possesses marine territory of 77,000㎢ in size. Research has shown that underwater minerals such as manganese nodules can be found in large quantities in this area.
Methane hydrate is a substance created by solidified methane gas from extremely low temperature and high pressure. With 1㎡ of methane hydrate, 172㎡ of methane gas can be created. The current amount of methane hydrate buried under the sea equals to what can be used by the entire world for over 5,000 years. Since reserves of an estimated 600 million tons of methane hydrates are near Ulleungdo and Dokdo, the importance of Dokdo Island has risen significantly.
Deep sea water refers to water from more than 200m below the surface, where sun light cannot reach. It is not only nutritious but also clean due to its long period of purification. Deep sea water is a useful marine resource and a vast clean resource.
Thorium is used in incandescent gas and atomic fuels. Because it is resistant to heat, light weight and high in intensity, it is an important material used in the building of satellites and airplanes.
The most commonly used energy source in the world, about 30% of all petroleum reserves on Earth are located under the sea.
Most oil, coal, and natural gas are located on continental shelves. The sea from the beach to the point where the depth is less than 200m is called the continental shelf. These areas account for 7.5% of the entire ocean. Because sedimentary layers have built up in this area, many natural resources like oil fields are located on continental shelves. In particular, continental shelves in Korea are 3.5 times larger than the entire Korean peninsula and they are mostly spread on the northern coast and the Yellow Sea coastline. Some valuable mineral resources can be found in the shape of pillars that are built up around underwater vents sprout hot water from the bedrock. These hydrothermal deposits contain mineral resources such as gold, silver, copper, and zinc. However, they are difficult to find and effective utilization of this resource requires more advanced technological development.
※ The texts were written based on the outcome of "Development of Ocean Education Textbook" and "Development of Contents for Ocean Education Textbook" projects conducted by the Korea Maritime Foundation in 2010 and 2011.
