Tidal power contributes a very small proportion of the electricity generation in the United Kingdom, but it could provide a meaningful amount of predictable renewable energy in future.
Several tidal stream turbines to harness currents flowing around the coastline have been developed and tested in the UK, and some of the world's first tidal stream arrays have been operating in Scotland since 2016. As of 2024 [update] , there is over 120 MW of tidal stream projected to be built by 2029.
Various proposals have also been developed in the UK for tidal range schemes, using barrages or lagoons, but none have been built.
There are two main forms of tidal resource:
There could be up to 20 GW of tidal range resource in the UK, able to generate 30 TWh/year or around 12% of the UK's electricity demand. [1]
A recent review of the tidal stream resource in the UK and British Channel Islands supported the latest national-scale practical resource estimate of 34 TWh/year. At around 11.5 GW of installed capacity, this is equivalent to 11% of the UK demand. [2]
The European Marine Energy Centre (EMEC) was set up in 2003, and has pre-consented sites for testing wave power devices and tidal stream turbines. The grid-connected tidal side is in the Fall of Warness, to the west of Eday in Orkney. The first turbine tested was a 250 kW OpenHydro turbine, installed in December 2006. [3] Since then, multiple devices from different developers have been tested.
Peter Fraenkel tested a 15 kW tidal turbine in Loch Linnhe in 1994. Fraenkel set up Marine Current Turbines (MCT), and demonstrated the 300 kW SeaFlow turbine off Lynmouth, England in 2003. MCT then built the twin-rotor 1.2 MW SeaGen turbine, which was installed in Strangford Lough, Northern Ireland, from 2008 until it was decommissioned between 2016 and 2019, having generated over 11.6 GWh of electricity. [4] [5]
Atlantis Resources developed and tested a series of turbines: the AK-1000 in 2010, [6] the 1 MW AR1000 was tested at EMEC in 2011, and the 1.5 MW AR1500 turbines in conjunction with Lockheed Martin in 2015. [7] Three AR1500 turbines were installed at MeyGen in 2017. [8] In 2021, an AR500 turbine was tested in Japan, which was subsequently upgraded to an AR1100 in 2022. [9] In October 2022, the Advanced Tidal Engineering and Services division of SIMEC Atlantis Energy became an independent company, Proteus Marine Renewables. [10] In 2024, Proteus unveiled their AR3000 turbines to be used in the Normandie Hydroliennes NH1 project. [9]
Edinburgh-based Nova Innovation deployed their first 30 kW turbine in the Bluemull Sound, Shetland in 2014. [11] Since 2016, they have operated an array of up to six of their 100 kW turbines in the Bluemull Sound. [12]
Scotrenewables Tidal Power (now Orbital Marine Power) tested their floating SR250 turbine at EMEC in 2012, which was the world's first grid connected floating tidal turbine. [13] They then tested a 2 MW version, the SR2000, in 2017/18, generating over 3 GWh in a year. [14] The Orbital O2 was launched from Dundee in April 2021, [15] and is undergoing long-term tests at EMEC since.
Several other British companies have developed tidal stream turbines, but were not commercially successful. This includes Pulse Tidal, Sustainable Marine Energy, Tidal Energy Ltd, and Tidal Generation Ltd.
The Renewables Obligation (RO), with associated schemes in Scotland and Northern Ireland, was intended to encourage generation of renewable electricity. Renewables obligation certificates (ROCs) are issued to generators free of charge. There is then a market to trade these, with electricity suppliers required to present a certain number every year to Ofgem. [16]
All technologies were initially awarded 1 ROC per MWh, but following a review in 2007, a four-level banding was introduced. Tidal was in the "emerging" band, and received increased support, at 2 ROCs/MWh. [17] A further banding review in 2012 increased support for tidal power to 5 ROCs/MWh, subject to a 30 MW limit per generating station. [18] The scheme closed to new generation in March 2017.
In 2024, there were nine accredited tidal stream generating stations listed in the Renewables and CHP Register. [19] These were: five berths at the EMEC Fall of Warness site near Eday, the MeyGen project (Ness of Quoys), the Nova Innovation Shetland tidal array, the Tidal Energy Ltd Ramsey Sound DeltaStream project, and the SeaGen turbine in Strangford Lough, Northern Ireland.
The Contracts for Difference (CfD) scheme is the main market support mechanism for low carbon generation in the UK. Capacity is awarded via a competitive auction process. Tidal stream was eligible to bid into the first three allocation rounds (AR) but no technology was successful.
A £20m ringfence was introduced for tidal stream technology in the fourth allocation round (AR4) in 2022. [20] This resulted in four projects, totalling over 40 MW being awarded contracts. [21] A further 53 MW was awarded CfD in AR5, despite the ringfence being reduced to £10m, capitalising on the fact no floating offshore wind projects were successful. [22] The tidal ringfence was increased to £15m by the incoming Labour government, which secured a further 28 MW of tidal stream CfD in 2024. This gives a pipeline of over 120 MW expected to be operational by 2029, [23] to be developed at EMEC, Meygen, and Morlais.
Developer | Site | Delivery year | Total | |||
---|---|---|---|---|---|---|
2025/26 | 2026/27 | 2027/28 | 2028/29 | |||
Hydrowing/Inyanga Marine | Morlais | 20.0 | 20.0 | |||
Magallanes Tidal Energy | EMEC | 1.5 | 3.0 | 4.5 | ||
Magallanes Tidal Energy | Morlais | 5.6 | 3.0 | 8.6 | ||
MeyGen | MeyGen | 28.0 | 21.9 | 9.0 | 58.9 | |
Mor Energy | Morlais | 4.5 | 4.5 | |||
Nova Innovation | EMEC | 6.0 | 6.0 | |||
Orbital Marine Power | EMEC | 7.2 | 7.2 | 14.4 | ||
Verdant Isles Ltd | Morlais | 4.9 | 4.9 | |||
Total | 5.6 | 39.7 | 58.5 | 18.0 | 121.9 |
As of 2024 [update] , there are three operational grid-connected tidal stream sites in the UK, all located in the north of Scotland. This includes the EMEC Fall of Warness test site.
The Nova Innovation project in the Bluemull Sound, Shetland, is claimed as the "world's first" tidal array, with two 100 kW turbines installed in 2016. [27] The array was expanded to six turbines in 2023, [28] however the three oldest turbines were decommissioned later that year. [29]
At 6 MW, the SAE Renewables (SAE) MeyGen project in the Pentland Firth is the world's largest tidal stream project in 2024 [update] . The first turbine was installed in November 2016. [30] Three further turbines were installed by February 2017, [8] and the first phase entered commercial operation in April 2018. [31] There are plans to expand the site to 400 MW in phases, with SAE securing CfD in 2022, 2023, and 2024 for a total of 59 MW to be constructed by 2029. [32]
In addition to the MeyGen project expansion, there are several other planned tidal stream projects in the UK.
The Morlais project has the potential for up to 240 MW of tidal stream generation off the coast of Holy Island, Anglesey, North Wales. As of September 2024 [update] , a total of four developers have secured CfD to develop a combined 38 MW of capacity at Morlais. The first turbines are expected to be installed in 2026. [33] [34]
There are also three developers planing arrays at EMEC, with a total of 25 MW awarded in CfD AR4–AR6. [24] [25] [26]
Tidal range schemes tend to involve large dams or barriers to impound the water, and as such could have significant environmental impacts.
Various schemes have been proposed for a Severn Barrage between England and Wales, potentially generating between 1 GW and 15 GW of renewable electricity. This would harness the significant tidal range of the Severn Estuary, the second largest tides globally. [35] In addition to tidal power, these may also have offered transport links, flood control or harbour creation. In 2010, the UK government announced there was no strategic case for investing in a scheme to build a barrage 10 miles (16 km) long, which could cost over £30bn. [36] However, in 2022 following the Russian invasion of Ukraine, the government launched an independent commission to revisit proposals. [35]
Slightly smaller scale impoundment was proposed for the Tidal Lagoon Swansea Bay project. A breakwater 9.5 kilometres (5.9 mi) long and up to 4 kilometres (2.5 mi) from shore was proposed to impound the tide. Bi-directional turbines meant the scheme was expected to generate power around 14 hours a day. [37] Despite backing from the Welsh Government, the UK government claimed the £1.3bn project was not good value for money. [38] In addition to Swansea Bay, the developer Tidal Lagoon Power was also considering lagoons at Cardiff; Newport; Bridgwater Bay in the Severn Estuary; Colwyn Bay in North Wales; and West Cumbria. [39]
A Mersey Barrage across the River Mersey estuary between Liverpool and the Wirral Peninsula has been proposed, with an initial public consultation on the scheme in October 2024. [40] The project development and planning stage is expected to take until 2028, with construction and commissioning taking a further 10 years. The scheme could potentially generate up to 1 GW, and may incorporate walking and cycling paths across the estuary. [41]
Tidal power or tidal energy is harnessed by converting energy from tides into useful forms of power, mainly electricity using various methods.
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.
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.
The European Marine Energy Centre (EMEC) Ltd. is a UKAS accredited test and research centre focused on wave and tidal power development, based in the Orkney Islands off the mainland of Scotland. The centre provides developers with the opportunity to test full-scale grid-connected prototype devices in wave and tidal conditions, at pre-consented test sites. EMEC also has sites for testing smaller-scale prototypes in more sheltered conditions.
Marine Current Turbines Ltd (MCT), was a United Kingdom-based company that developed tidal stream generators, most notably the 1.2 MW SeaGen turbine. The company was bought by the German automation company, Siemens in 2012, who later sold the company to Atlantis Resources in 2015.
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 the run of a 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.
A tidal barrage is a dam-like structure used to capture the energy from masses of water moving in and out of a bay or river due to tidal forces.
The Saltire Prize, named after the flag of Scotland, was a national award for advances in the commercial development of marine energy.
MeyGen is a tidal stream energy plant in the north of Scotland. The project is located in the Pentland Firth, specifically the Inner Sound between the Island of Stroma and the Scottish mainland.
SAE is a renewable energy company. It is incorporated in Singapore, but its operational headquarters are in Edinburgh, Scotland, United Kingdom. Initially, it was a developer of the tidal power turbines and projects, but after becoming a part of GFG Alliance it has expanded its business also to the waste-to-energy and hydropower.
Orbital Marine Power is a Scottish renewable energy company focused on the development and global deployment of floating tidal stream turbine technology. The company was founded in 2002, and as of 2024 has build and tested three different turbines.
In 2019, Wales generated 27% of its electricity consumption as renewable electricity, an increase from 19% in 2014. The Welsh Government set a target of 70% by 2030. In 2019, Wales was a net exporter of electricity. It produced 27.9 TWh of electricity while only consuming 14.7 TWh. The natural resource base for renewable energy is high by European standards, with the core sources being wind, wave, and tidal. Wales has a long history of renewable energy: in the 1880s, the first house in Wales with electric lighting powered from its own hydro-electric power station was in Plas Tan y Bwlch, Gwynedd. In 1963, the Ffestiniog Power Station was constructed, providing a large scale generation of hydroelectricity, and in November 1973, the Centre for Alternative Technology was opened in Machynlleth.
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.
OpenHydro Group Ltd was an Irish developer of tidal stream turbines, established in 2004. It was acquired by Naval Energies in 2013, however, Naval Energies decided in July 2018 to stop developing tidal turbines and focus on floating wind turbines. The company subsequently went into liquidation with debts of about €280m.
Contracts for Difference (CfD) are the main market support mechanism for low carbon electricity generation in the UK. The scheme replaced the Renewables Obligation which closed to new generation in March 2017. It is administered by the Low Carbon Contracts Company (LCCC), which is owned by the UK Government.
Magallanes Renovables, S.L. is a Spanish developer of floating tidal stream energy devices, set up in 2009. The company's head office is in Redondela, Galicia, with a UK subsidiary Magallanes Tidal Energy Ltd. based in Kirkwall.