Tidal power plant
A tidal power plant is a hydroelectric power plant that converts potential and kinetic energy from the tidal range of the sea into electricity .
Tidal power plants ultimately derive their energy from the earth's rotation with the help of the gravitational pull of the moon and the sun (see also tides ). They slow down the flow movement of the oceans minimally by tides. Braking occurs through the damming of the upstream and downstream currents and subsequently through the use of the potential energy contained in the dammed water by turbines, which then convert the rotational energy generated by them into useful electrical energy via electrical generators . In relation to the total deceleration caused by the natural tidal friction, this is of no consequence, the earth has a very high rotational energy due to its high mass .
Dam construction method
So far, tidal power plants have always been realized with a dam on sea bays or in estuaries .
functionality
Tidal power plants work according to the dam principle and are built in bays and in estuaries (river mouths) that have a particularly high tidal range (difference between high and low water levels). So that this can take effect, the corresponding bay is dammed with a dike . In the dyke there are water turbines which are operated by the incoming water at high tide and by the outgoing water at low tide, which is why the turbines work in both flow directions. This can be achieved by moving the rotor blades. So-called bulb turbines, the best-known representative of which is the Kaplan turbine , are used so that even a small water gradient can be used to generate electricity .
Such a tidal power plant can also use excess electricity from other power plants to pump seawater into the reservoir. This means that additional electrical power can be generated during the subsequent return flow. In this case, the tidal power plant also acts as a pumped storage power plant .
Economy and ecology
If a minimum tidal range of 5 m is required, there are about a hundred suitable bays on earth that could be used for a tidal power plant. Only half of these would allow economic use. Since ebb and flow occur every 12 hours and 24 minutes, the power cannot be delivered evenly. This problem of uneven energy generation is exacerbated by high spring and weak nipping tides . Operation with salt water causes severe corrosion of the turbines; this means considerable maintenance costs, which in turn reduces profitability.
In addition, tidal power plants are ecologically problematic as they affect the fauna and flora of coastal waters. Coastal ecosystems were created with the natural twelve-hour cycle, but behind such a tidal power plant the phases are shifted. The migration of aquatic animals from and into the bay and into rivers flowing into it is hindered.
In the future, such tidal power plants with a dam will only be able to provide a small proportion of the electricity demand due to the limited possible locations and the high ecological impact (see also web links).
Investments
Systems in operation
| power plant | Capacity ( MW ) | country | Geographical location | Installation | Individual evidence |
|---|---|---|---|---|---|
| Annapolis tidal power station | 20th |
 Canada
|
44 ° 45 ′ 7 ″ N , 65 ° 30 ′ 40 ″ W. | 1984 | |
| Jiangxia tidal power station | 3.2 |
 People's Republic of China
|
28 ° 20 ′ 34 " N , 121 ° 14 ′ 25" E | 1980 | |
| Kislaja Guba tidal power plant | 1.7 |
 Russia
|
69 ° 22 ′ 37 " N , 33 ° 4 ′ 33" E | 1968 | |
| Usine marémotrice de la Rance | 240 |
 France
|
48 ° 37 '5 " N , 2 ° 1' 24" W. | 1966 | |
| Sihwa-ho tidal power station | 254 |
 South Korea
|
37 ° 18 ′ 47 " N , 126 ° 36 ′ 46" E | 2011 | |
| Uldolmok tidal power station | 1.5 |
South Korea
|
34 ° 32 ′ 7 " N , 126 ° 14 ′ 6" E | 2009 |
The first and for a long time the largest tidal power plant, the Rance tidal power plant , was built from 1961 on the Atlantic coast in the Rance estuary in France and opened in 1966. The tidal range in the bay near St. Malo is normally 12, sometimes 16 meters. The concrete dam is 750 m long, creating a reservoir with a surface area of 22 km² and a net volume of 184 million m³. The dam has 24 passages, in each of which a turbine with a nominal output of 10 MW is installed. The entire system has an output of 240 MW and delivers around 600 GWh of electrical energy annually . This power plant also works as a pumped storage power plant .
In 2011, the Sihwa-ho tidal power plant in South Korea was completed 40 km southwest of Seoul with ten turbines of 25.4 MW each (total 254 MW). Sihwa replaced La Rance as the largest tidal power station in the world. The power plant is part of an approximately 13 km long dam that separates a natural bay from the Yellow Sea and was originally intended to store process water for the surrounding communities. Since the stored water began to rot, the plan was changed. The now installed low-pressure turbines from the Austrian company Andritz Hydro are installed 22 meters below the water level and use the regularly generated power from the seawater flowing off at low tide .
Another tidal power plant, the Annapolis tidal power plant , with only 20 MW, is located in Annapolis Royal on a side bay of the Bay of Fundy in Nova Scotia , Canada . It was put into operation in 1984 and was primarily used for research and development. It works in one-way operation and only uses the ebb current.
An even smaller test facility, the Kislaja Guba tidal power plant with only around 400 kW, has existed since 1968 on the Kislaja Guba fjord (Acid Bay) on the Russian Barents Sea .
There are other smaller tidal power plants in Russia near Murmansk with 0.4 MW and in China . The largest Chinese tidal power plant is located near Jiangxia in Zhejiang Province. It was completed in 1986 and has an output of 10 MW.
Plants in planning or under construction
A large tidal power plant with an output of 5,000 MW has been planned on the Bay of Fundy in Newfoundland , Canada for a long time, but has not yet been implemented due to the high level of investment . There are also concerns about the effects of such a project; In addition to ecological consequences (the Bay of Fundy is an important fishing area), there are also fears that the tidal range on the opposite side of the bay would be changed by a power plant dam and that cities like Boston could be flooded as a result.
In the meantime, a dam project in the Bay of Fundy has been refrained from and plans to use turbines on the ocean floor instead. According to the exhibition shown in the Annapolis power station (as of Sep. 2011), the data transmission of the 12-meter-diameter turbine installed for test purposes in 2009 failed after a few days of running time. An investigation with underwater cameras was unsuccessful; due to the current, only two of the turbine blades made of composite materials could be examined. These showed significant damage. As the data connection to the system could no longer be established, the decision was made in 2010 to recover the turbine. Analysis of the stored data showed that the current at the bottom of the bay was so strong that the turbine had lost all leaves within three weeks.
In Great Britain the construction of a particularly large tidal power station was planned for a long time under the name Severn Barrage . At the mouth of the Severn between Cardiff and Bristol , a 16 km barrier was to be built through the Bristol Channel . The 216 turbines planned there should achieve a total output of 8,500 MW and thus cover five percent of UK electricity consumption. The location is favorable for a tidal power plant because of the high tidal range of up to 15 meters. So far, the project has been estimated to cost £ 15 billion (€ 19 billion). This major project is the subject of controversy in Great Britain. Various environmental groups are turning against the construction of the Severn Barrage because of the expected environmental damage . The follow-up to the project was stopped by the UK government at the end of 2010 after a feasibility study calculated costs of up to £ 34 billion.
As a successor to the abandoned Severn Barrage project , planning began in 2010 for the Swansea Bay tidal power plant, which is much smaller with 320 MW, in Swansea Bay, a bay on the north coast of the Bristol Channel. The construction was approved by the Ministry of Energy in 2015. Construction is not expected to start until the end of 2018 at the earliest [out of date] ;
Other designs
Nowadays, tidal power plants are rarely built according to the above principle, because the ecological effects are too strong. So-called in-flow tidal power plants are used, in which electricity is generated by turbines attached to the water. These can u. a. be helical or pinwheel-like.
They are described in more detail in the article Ocean Current Power Plant; in journalism or in layman's reports, these power plants are sometimes also referred to as tidal power plants, as the currents used are usually associated with a tide.
history
The power of the tidal range was already being used on the Channel coast in England and France in the 17th century . Even today you can see tide mills from earlier centuries on some sections of the coast . In 1933, the American engineer Olus J. Stewart had already planned in detail a test facility on the Atlantic coast, which was supposed to generate electricity “almost free of charge with the help of captured surf waves”.
In July 2019, a study was published, according to which electrical current can be generated via the electrokinetic effect in a flow of salt water .
literature
- Niels A. Lange, John Armstrong: Economic use of tidal energy . In: Schiff & Hafen , Issue 3/2013, pp. 76-78, Seehafen-Verlag, Hamburg 2013, ISSN 0938-1643
Web links
| Renewable energy |
|---|
- French tidal power plant Blue Coal / Houille Bleue 1927 (PDF; 2.3 MB)
- Report on the La Rance tidal power station near St. Malo ( Memento from July 15, 2011 in the Internet Archive )
- Tidal Power Plants - The History, Present, and Future of Tidal Power
- Image of the Russian tidal power station Kislogubskaya
- Article about the floating tidal power station Morild II, which is currently located in the fjord Gimsøystraumen ( Memento from January 25, 2012 in the Internet Archive )
Individual evidence
- ↑ How the St. Malo tidal power plant works ( Memento from December 12, 2007 in the Internet Archive ) www.poweron.ch
- ^ Nova Scotia Power: Annapolis Tidal Station. Archived from the original on March 3, 2012 ; accessed on April 16, 2012 (English).
- ↑ Jinangxia Tidal Power Station. Archived from the original on July 7, 2011 ; accessed on March 21, 2010 (English).
- ↑ Jinangxia Tidal Power Station. Retrieved March 21, 2010 (194 English).
- ^ Tidal power in South Korea. (PDF) Archived from the original on July 6, 2011 ; accessed on July 17, 2010 (English).
- ^ Korea JoongAng Daily : Turning tides. Archived from the original on October 5, 2013 ; accessed on January 10, 2013 .
- ^ South Korea starts up, to expand 1-MW Jindo Uldolmok tidal project. Retrieved August 30, 2010 .
- ↑ Energy sources with a future: Sea power for the socket ( Memento from March 23, 2010 in the Internet Archive ), www.sueddeutsche.de, January 8, 2008
- ^ Electricity from the power of waves in: FAZ of July 26, 2011, page T6
- ↑ Green electricity from the mudflats: Great Britain is planning the largest tidal power plant in the world ( Memento from August 8, 2008 in the Internet Archive ) www.spiegel.de, August 4, 2008
- ↑ PDF at www.decc.gov.uk ( memento of the original from December 17, 2012) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Reclams Universum Issue 19, vol. 50, Feb. 8, 1934, p. 693, with illus.
- ↑ Researched, discovered, developed - news from science. In: Current Research . Deutschlandfunk , July 31, 2019, accessed on August 6, 2019 .
- ^ Franz M. Geiger, Thomas F. Miller, Catherine E. Walker, Paul E. Ohno, Jeongmin Kim: Energy conversion via metal nanolayers . In: Proceedings of the National Academy of Sciences . July 29, 2019, ISSN 0027-8424 , p. 201906601 , doi : 10.1073 / pnas.1906601116 , PMID 31358629 ( pnas.org [accessed August 6, 2019]).
