Tidal giants - the world’s five biggest tidal power plants
The Swansea Bay tidal lagoon project in the UK and the MeyGen tidal array project in Scotland stand out among the few large-scale tidal power projects currently under development. Power-technology.com lists five of the world’s biggest tidal power plants, including those both operational and under construction.
Sihwa Lake Tidal Power Station, South Korea - 254MW
With an output capacity of 254MW, the Sihwa Lake tidal power station located on Lake Sihwa, approximately 4km from the city of Siheung in Gyeonggi Province of South Korea, is the world's biggest tidal power plant.
The project, owned by Korea Water Resources Corporation, was opened in August 2011 and utilises a 12.5km long seawall constructed in 1994 for flood mitigation and agricultural purposes. Power is generated on tidal inflows into the 30km2 basin with the help of ten 25.4MW submerged bulb turbines. Eight culvert type sluice gates are used for the water outflow from the barrage.
The $355.1m tidal power project was built between 2003 and 2010. Daewoo Engineering & Construction was the engineering, procurement and construction (EPC) contractor for the project. The annual generation capacity of the facility is 552.7GWh.
La Rance Tidal Power Plant, France - 240MW
The 240MW La Rance tidal power plant on the estuary of the Rance River in Brittany, France, has been operational since 1966 making it the world's oldest and second biggest tidal power station. The renewable power plant, currently operated by Électricité de France (EDF), has an annual generation capacity of 540GWh.
The La Rance tidal power facility, built between 1961 and 1966, involved the construction of a 145.1m long barrage with six fixed wheel gates and a 163.6m-long dyke. The basin area covered by the plant is 22km2. Power is produced through 24 reversible bulb turbines with a rated capacity of 10MW each.
The plant site features an average tidal range of 8.2m, the highest in France. Electricity is fed into the 225kV national transmission network serving the needs of approximately 130,000 households every year.
Swansea Bay Tidal Lagoon, United Kingdom - 240MW
The 240MW Swansea Bay Tidal Lagoon project, to be built at Swansea Bay in the UK, is the world's biggest tidal power project and will become the world's third biggest tidal power project upon completion. The planning application for the £850m ($1.4bn) project was approved in March 2013.
The plant will be located at a site with average tidal range of 8.5m and will involve the construction of a 9.5km-long sea wall or breakwater facility to create a lagoon cordoning off 11.5km2 of sea. The plant will use reversible bulb turbines to generate power as water passes in and out of the lagoon with the rise and fall of tides.
The ground breaking for the tidal power project is scheduled for 2015 while full commissioning is expected in 2018. The tidal lagoon, with an estimated annual power generation capacity 400GWh, will power over 120,000 homes for 120 years.
MeyGen Tidal Energy Project, Scotland - 86MW
MeyGen Tidal Energy Project located in the Inner Sound of the Pentland Firth off the north coast of Caithness, Scotland, is currently the world's biggest underwater tidal turbine power project under development.
The tidal array project received offshore planning consent for its 86MW first phase development from the Scottish Government towards the end of 2013. The second phase development of the project is expected to raise the total installed capacity to 398MW by 2020.
The MyGen project was initiated in 2006 by the Scottish company MeyGen, a joint venture between the tidal technology company Atlantis Resources and Morgan Stanley. Atlantis Resources acquired full ownership of the tidal array project in December 2013. Construction is expected to start for a demonstration array involving up to six AR1000 single-rotor tidal turbines in 2014 with final commissioning expected in 2015. The first 1MW prototype of the 22.5m tall AR1000 tidal turbine with 18m rotor diameter was deployed at the European Marine Energy Centre in 2011.
Annapolis Royal Generating Station, Canada - 20MW
The Annapolis tidal power generating station located in the Annapolis Basin, a sub-basin of the Bay of Fundy in Canada, has an installed capacity of 20MW making it the world's third biggest operating tidal power plant. It generates 50GWh of electricity annually to power over 4,000 homes.
The plant, operated by Nova Scotia Power, came online in 1984 after four years of construction. The plant utilises a causeway built in the early 1960s, which was originally designed to serve as a transportation link as well as a water control structure to prevent flooding.
The power plant comprises of a single four blade turbine and sluice gates. The gates are closed as the incoming tides create a head pond in the lower reaches of the Annapolis River upstream of the causeway. The gates are opened and the water rushing into the sea drives the turbine to generate power when a head of 1.6m or more is created between the head pond and sea side with the falling of the tide.