Tidal power or tidal energy is harnessed by converting energy from tides into useful forms of power, mainly electricity using various methods.
The Pelamis Wave Energy Converter was a technology that used the motion of ocean surface waves to create electricity. The machine was made up of connected sections which flex and bend as waves pass; it is this motion which is used to generate electricity.
Marine currents can carry large amounts of water, largely driven by the tides, which are a consequence of the gravitational effects of the planetary motion of the Earth, the Moon and the Sun. Augmented flow velocities can be found where the underwater topography in straits between islands and the mainland or in shallows around headlands plays a major role in enhancing the flow velocities, resulting in appreciable kinetic energy. The Sun acts as the primary driving force, causing winds and temperature differences. Because there are only small fluctuations in current speed and stream location with minimal changes in direction, ocean currents may be suitable locations for deploying energy extraction devices such as turbines. Other effects such as regional differences in temperature and salinity and the Coriolis effect due to the rotation of the earth are also major influences. The kinetic energy of marine currents can be converted in much the same way that a wind turbine extracts energy from the wind, using various types of open-flow rotors.
The production of renewable energy in Scotland is a topic that came to the fore in technical, economic, and political terms during the opening years of the 21st century. The natural resource base for renewable energy is high by European, and even global standards, with the most important potential sources being wind, wave, and tide. Renewables generate almost all of Scotland's electricity, mostly from the country's wind power.
Wind power generation capacity in India has significantly increased in recent years. As of 31 December 2023, the total installed wind power capacity was 44.736 gigawatts (GW), the fourth largest installed wind power capacity in the world. Wind power capacity is mainly spread across the southern, western, and northwestern states.
Verdant Power, Inc is a maker and installer of tidal power and hydroelectric systems. Their primary device is an underwater turbine, similar to a three-bladed wind turbine, that is designed to capture energy from tidal currents and (precipitation-driven) river currents. The company uses the trade term "kinetic hydropower" to distinguish their systems from those based on dam construction. The company's first project, the Roosevelt Island Tidal Energy Project, is several turbines in New York City's East River.
Renewable energy in the United Kingdom contributes to production for electricity, heat, and transport.
CETO is a wave-energy technology that converts kinetic energy from ocean swell into electrical power and directly desalinates freshwater through reverse osmosis. The technology was developed and tested onshore and offshore in Fremantle, Western Australia. In early 2015 a CETO 5 production installation was commissioned and connected to the grid. As of January 2016 all the electricity generated is being purchased to contribute towards the power requirements of HMAS Stirling naval base at Garden Island, Western Australia. Some of the energy will also be used directly to desalinate water.
The European Marine Energy Centre (EMEC) Ltd is a UKAS accredited test and research center focused on wave and tidal power development, based in the Orkney Islands, UK. The centre provides developers with the opportunity to test full-scale grid-connected prototype devices in wave and tidal conditions.
SeaGen was the world's first large scale commercial tidal stream generator. It was four times more powerful than any other tidal stream generator in the world at the time of installation. It was decommissioned by SIMEC Atlantis Energy Limited in summer 2019, having exported 11.6GWh to the grid since 2008.
Pelamis Wave Power designed and manufactured the Pelamis Wave Energy Converter – a technology that uses the motion of ocean surface waves to create electricity. The company was established in 1998 and had offices and fabrication facilities in Leith Docks, Edinburgh, Scotland. It went into administration in November 2014.
The Oyster was a hydro-electric wave energy device that used the motion of ocean waves to generate electricity. It was made up of a Power Connector Frame (PCF), which is bolted to the seabed, and a Power Capture Unit (PCU). The PCU is a hinged buoyant flap that moves back and forth with movement of the waves. The movement of the flap drives two hydraulic pistons that feed high-pressured water to an onshore hydro-electric turbine, which drives a generator to make electricity. Oyster was stationed at the European Marine Energy Centre (EMEC) at its Billia Croo site in Orkney, Scotland until the company ceased trading in 2015.
GE Wind Energy is a branch of GE Renewable Energy, a subsidiary of General Electric. The company manufactures and sells wind turbines to the international market. In 2018, GE was the fourth largest wind turbine manufacturer in the world.
A tidal stream generator, often referred to as a tidal energy converter (TEC), is a machine that extracts energy from moving masses of water, in particular tides, although the term is often used in reference to machines designed to extract energy from run of river or tidal estuarine sites. Certain types of these machines function very much like underwater wind turbines, and are thus often referred to as tidal turbines. They were first conceived in the 1970s during the oil crisis.
The Paimpol–Bréhat tidal farm is a tidal stream turbine demonstration site, located northeast of Île-de-Bréhat near Paimpol, Brittany, France. It was initially developed by Électricité de France (EdF), initiated in 2004 and construction work began in 2008, but the project was subsequently cancelled by EdF in 2018. This project was to use OpenHydro turbines, with two briefly installed in 2016, but they were later removed.
Energy in the Faroe Islands is produced primarily from imported fossil fuels, with further contributions from hydro and wind power. Oil products are the main energy source, mainly consumed by fishing vessels and sea transport. Electricity is produced by oil, hydropower and wind farms, mainly by SEV, which is owned by all the municipalities of the Faroe Islands. The Faroe Islands are not connected by power lines with continental Europe, and thus the archipelago cannot import or export electricity.
Orbital Marine Power is a Scottish renewable energy company focused on the development and global deployment of its pioneering floating turbine technology. The O2 is Orbital's first commercial turbine and represents the culmination of more than 15 years of world leading product development in the UK. The 74 m long turbine is expected to operate in the waters off Orkney for the next 15–20 years with the capacity to meet the annual electricity demand of around 2,000 UK homes with clean, predictable power from the fast-flowing waters while offsetting approximately 2,200 tonnes of CO2 production per year. In a further ground-breaking element of the project, the O2 will provide power to the European Marine Energy Centre's onshore electrolyser to generate green hydrogen that will be used to demonstrate decarbonisation of wider energy requirements.
Morlais is a grid connected tidal stream energy project located in the Irish Sea just off the west coast of Holy Island, Anglesey, Wales. It is being developed by the social enterprise agency Menter Môn. The site has the potential for up to 240 MW of renewable energy to be harnessed from the tides, using a mixture of seabed mounted and floating tidal energy devices from different companies.
Nova Innovation Ltd is a Scottish developer of tidal stream turbines, based in Leith, Edinburgh. They deployed their first 30 kW turbine in 2014. Since then, they have developed and tested a 100 kW seabed mounded two-bladed horizontal-axis tidal stream turbine, and plan to scale this up in future. Up to six of these turbines have been deployed simultaneously in the Bluemull Sound, Shetland since 2016.
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 (TST), tidal energy converters (TEC), or marine hydro-kinetic (MHK) 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.
