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Energy

297: Tidal stream power generator

Problem:

How to harness the prodigioius electrical energy from outgoing and incoming tides?

Solution:

Immense supplies of electric energy are being harvest from tidal streams. Electricité de France (EDF) was a precursor with this technology when, in 1966, it built the tidal power plant on the mouth of the La Rance River in Brittany, France.


It is one of just two such plants in the world along with Sihwa in South Korea. The La Rance plant has an installed capacity of 240 MW distributed between 24 bulb-type turbine generators, each with a capacity of 10 MW. For almost 50 years, it has been producing around 500 GWh/year, equivalent to the consumption of a city the size of Rennes, France.

In 2007, Drew Blaxland, Director of Turbines and Engineering Services, having graduated from the University of Technology, Sydney, joined Atlantis to work with the Lockheed Martin Corporation, one of the world’s largest and most sophisticated global systems integrators in the development of a central axis underwater power generator.

In October 2008, Atlantis chose a site near the Castle of Mey for a computer data centre that would be powered by a tidal scheme in The Pentland Firth, off the north coast of Scotland is well known for the strength of its tides, which are among the fastest in the world, a speed of 19 mph (30 kph) being reported close west of Pentland Skerries.

Two years later, MeyGen, a consortium of ARC, Morgan Stanley and International Power, received operational lease from the Crown Estate to a 400 MW project for 25 years. By September 2013 they had been granted consent to install four turbines to generate 9 MW, three from Andritz Hydro Hammerfest (AHH) and one from Atlantis developed by Blaxland’s team.

Each turbine was installed on the seabed with a gravity-base turbine support structure and a 4.4kV turbine subsea cable. The onshore construction works of the project began in January 2015 and the first turbine was officially unveiled in September 2016.

In 2017, two MayGen turbines set a world record for monthly production from a tidal stream power station when, connected to a 15MW local distribution grid network managed by Scottish Hydro Electric Power Distribution (SHEPD), they generated 700 MWh of electricity, enough power for 2,200 homes. In April 2018, MeyGen Phase 1A formally entered its 25-year operations phase.

By June 2019, 17GWh had been exported to grid, a new record for the amount of electricity exported by a tidal stream project. Three months later, MayGen exported more than 21-gigawatt hours (GWh) of electricity to the national grid and the array had operated at above 90% availability during 2019. That year performance represented the longest period of uninterrupted generation from a multi-MW tidal turbine array ever achieved. Full-scale production from 400 turbines is expected to start by 2020. (simecatlantis.com)

In France, the Paimpol–Bréhat project is an 8 MW tidal turbine demonstration farm off Île-de-Bréhat near Paimpol, France. The project was initiated by Électricité de France (EdF) in 2004 and work began in 2008. By 2017, a hydrokinetic demonstrator designed and built by Thomas Jaquier at Hydroquest with a power output of 1 MW was installed on the EDF test site In 2019 it generated its first MWs. The tidal farm will consist of seven turbines, 2 MW each. (hydroquest.net)

In 2018 Normandy Region, SIMAC Atlantis Energy formed Normandie Hydrolienne to build a tidal stream plant in Raz Blanchard that could eventually deliver around 2 GW of capacity to the Normandy region. The first phase will be completed in 2021 following by an expansion of the project to 200 MW by 2023, enough to power 250,000 homes. Some of these are on the isle of Alderney. The total theoretical tidal energy capacity in the English Channel region is nearly 4 GW, enough to power up to 3 million homes. (energiesdelamer.eu)

In the Netherlands Tocardo installed its first tidal turbine in 2005. Three years later Tocardo began to install tidal turbines into a primary sea defense, the Eastern Scheldt storm surge barrier. The Eastern Scheldt storm surge barrier is the largest of the famous Delta Works, a series of dams and barriers, designed to protect the Netherlands from flooding.

In September 2012, the complete 164 ft (50 m.) long support structure, including turbines, was transported over water by famous heavy lift specialist Mammoet. Using a special barge and Mammoet’s Self-Propelled Modular Transporter, the structure was put into place between two of the barriers’ pillars. (tocardo.com)

The Afluitdijk, constructed between 1927 and 1932, is a major dam and causeway in the Netherlands. It runs from Den Oever in North Holland province to the village of Zurich in Friesland province, over a length of 20 mi. (32 km.) and a width of 300 ft. (90 m.) at an initial height of 23.8 ft. (7.25 m.) above sea level.

The Afsluitdijk is a fundamental part of the larger Zuiderzee Works, damming off the Zuiderzee, a salt water inlet of the North Sea, and turning it into the fresh water lake of the IJsselmeer.

In 2015 Tocardo installed three T1 turbines in the Afsluitdijk tidal barrage. The turbine array is an extension of the Tidal Testing Centre test facility and the tidal turbine that has already been producing electricity for more than seven years. The array has a capacity of more than 300 kW, producing electricity for about 100 local households. After fine-tuning and evaluation of the array, the project partners plan to deploy additional tidal installations in the Afsluitdijk with the capacity of up to 2 MW.

Tocardo has also installed its tidal technology at the Bay of Fundy Ocean Research Centre for Energy (FORCE) in Nova Scotia, Canada. Working with Minas Tidal, four of its 250kW-rated T2 bi-directional turbines, which are attached to the company’s semi-submersible Universal Floating Platform Structure to form a 1MW system held in place by catenary mooring systems.

In September 2019, Minas Tidal announced a partnership with Sustainable Marine Energy-Schottel Hydro to develop a 1.26 MW array in Canada that would ultimately sell energy to Nova Scotia Power. The first phase of the project is being financed by Reconcept Group of Hamburg, Germany.

Other firms such as Magallanes Renovables in Galicia, Spain have launched a148 ft (45,m) artefact (a steel-built trimaran), which incorporates a submerged part where the hydrogenerators are fitted, facilitating access for servicing and repairs.

In March 2019 Magallanes Renovables ATIR tidal energy converter (TEC) was installed at EMEC’s Fall of Warness tidal energy test site in Orkney, Scotland, by Orkney-based Leask Marine, as part of the Ocean_2G project. It was successfully connected to the grid via EMEC’s sub-sea cables and onshore substation and generated its first power a short time after.

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