Development of tidal stream generators
Many tidal stream generators have been developed over the years to harness the power of tidal currents flowing around coastlines. These are also called tidal stream turbines, tidal energy converters, or marine hydro-kinetic generation. These turbines operate on a similar principle to wind turbines, but are designed to work in a fluid approximately 800 times more dense than air which is moving at a slower velocity. Note that tidal barrages or lagoons operate on a different principle, generating power by impounding the rising and falling tide.
Lots of different technology variants have been tested, and there has not been convergence on a predominant typology. Most have been horizontal-axis, like wind turbines, but with 2, 3, or more blades and either mounted on a seabed fixed foundation or on a floating platform. In addition, vertical-axis turbines and tidal kites are also being developed.
Historically, development has largely been focused around Europe, but devices have been built and tested in North America – including at the Fundy Ocean Research Centre for Energy, Japan, and elsewhere. The European Marine Energy Centre was set up in Orkney in 2003, and developed a tidal test site in the Fall of Warness, to the west of the island of Eday. The site opened in 2006, and EMEC was granted a license in 2016 to test up to 10 MW of tidal stream devices, and has since hosted the testing of many of these devices.
There have been various acquisitions of technology developers over the years. Many of the companies are no longer trading, or have ceased development of tidal-stream turbines. However, the first pre-commercial array demonstration projects have been operating since around 2016. Building on this, commercial arrays are expected to be operational by around 2027, at EMEC, Morlais and elsewhere.
Development timeline
Key historical milestones in the development of tidal-stream turbines are summarised below:- The 300 kW Marine Current Turbines SeaFlow turbine was installed in summer 2003 and tested off the coast of Lynmouth, Devon, England.
- In 2004, the world's first tidal-stream turbine was connected to an electricity grid, the 300 kW Hammerfest Strøm HS300, located in the waters of Kvalsundet, Finnmark, Norway.
- The first tidal stream turbine test site was constructed in 2005 and opened in 2006, in the Fall of Wanress to the west of Eday, Orkney, part of the European Marine Energy Centre.
- The significantly more powerful, 1.2 MW MCT SeaGen turbine was installed in Strangford Lough, Northern Ireland, in May 2008 and grid connected in July.
- Also in May 2008, OpenHydro was the first tidal turbine connected to the National Grid in Great Britain. The 250 kW device was tested in the Fall of Warness, Eday, Orkney.
- Verdant Power installed six 35 kW turbines in New York's East River, supplying power to two local businesses, claimed as the world's first tidal array.
- In August 2016, Nova Innovation installed a second 100 kW turbine in the Bluemull Sound, Shetland, connected to the GB Grid, also claimed as the world's first tidal array.
- A dedicated site for testing tidal stream turbines was pre-consented at the European Marine Energy Centre in 2016, to simplify the process for developers testing devices.
- Phase 1 of the MeyGen project was commissioned in 2017, with four turbines totaling 6 MW installed, making it the largest tidal array to date.
Key companies and turbines
Alstom
French manufacturer Alstom acquired Tidal Generation Ltd in 2012, but this part of the business was sold to General Electric in 2015.Andritz Hydro Hammerfest
Hammerfest Strøm AS was a Norwegian developer of tidal stream turbines, based in Hammerfest. In 2010, Austrian hydropower company Andritz AG bought one third of the shares. In 2012, Andritz became the majority stakeholder and rebranded the company Andritz Hydro Hammerfest.In November 2003, Hammerfest Strøm installed their HS300 turbine in Kvalsundet, Norway. This 300 kW prototype was a 20 m diameter three-bladed horizontal-axis turbine. It sat on a monopile foundation in 50 m deep water. In 2003, the project was reported to have cost US$11m. The HS300 turbine was connected to the grid in 2004, and operated for over 16,000 hours before it was decommissioned in 2011 and removed in 2012.
A more powerful 1MW device was then tested at EMEC from 2012. The HS1000 was a 21 m diameter three-bladed horizontal-axis turbine, installed at the Fall of Warness test site in December 2011.
Three Andritz Hydro Hammerfest Mk1 turbines were installed as part of phase 1 of the MeyGen project in 2016. These turbines are also three-bladed, but with an 18 m diameter rotor and each rated at 1.5 MW. These machines have generated in excess of 80GWh to date, and one machines has remained subsea and in operation for over 6 years to date.
BigMoon Power
BigMoon Power was a Canadian company founded in 2015 developing a floating tidal stream generator. The concept is designed to be simple, with an optimised waterwheel mounted between two hulls of a barge, moored by foundations built from old train cars filled with concrete. BigMoon plan to build and install 18 devices, each 0.5 MW, at in the Bay of Fundy at FORCE. As part of the contract to test at FORCE Berth D, BigMoon was expected to remove before the end of 2024 the OpenHydro turbine that was abandoned there in July 2018 when that company went into administration. In May 2024, Big Moon Power rebranded as Occurrent Power, however in September 2024 it filed for insolvency, having failed to deploy the turbine.Flumill
Flumill AS is a Norwegian developer of an unconventional tidal stream turbine. It consists of two counter-rotating helical screws made from fiberglass, each attached to a gear-less permanent magnet generator. The unit is mounted to the seabed and held up by a buoyant float/fin. In 2011 Flumill was the first turbine to be tested at the EMEC Shapinsay Sound non-grid-connected test site, after tow tests in Tromøysund, Arendal, Norway. This device was nominally rated at 1.2 kW in the 1.5 m/s currents of Shapinsay Sound, although it could potentially generate 600 kW in faster flows.A phase 2 Flumill tidal device is currently being developed, where the screws and generators are mounted from a catamaran barge.
General Electric
In 2015, GE acquired the energy assets from Alstom which included the business originally developed by Tidal Generation Ltd.In 2024, GE Vernova signed a MoU with Proteus Marine Renewables to supply electrical systems for their tidal turbines.
HydroQuest
HydroQuest is a French developer of vertical-axis turbines, generating electricity from river and tidal currents, based in Grenoble. They have installed several small river turbines in France and French Guiana, powering the 200 inhabitants of the Camopi village.A 1 MW OceanQuest tidal turbine was tested at Paimpol–Bréhat between April 2019 and December 2021.
In collaboration with Constructions Mécaniques de Normandie and renewable energy company Qair, Hydroquest are developing the FloWatt project. This will comprise seven Hydroquest turbine units, each rated at 2.5 MW, to be installed at Raz Blanchard, Brittany by 2027.