UK Tidal Power Project Set To Be World’s Largest

April 01, 2024 by Shannon Cuthrell

Liverpool is developing a riverside project that will harness abundant tidal flows to generate electricity for over a million people.

The Liverpool City Region Combined Authority has spent three years undergoing technical planning for the world’s largest tidal range project, which could install 28 turbines totaling 700 MW over the next decade. The first-in-the-U.K. concept is expected to generate 2 TWh of electricity annually for up to 1 million local homes—serving 30% of the region’s demand. 

Located on Liverpool’s River Mersey, the project would incorporate a cycling and pedestrian route connecting the city to Wirral via a barrage. This design also provides flood defenses as the river’s water levels rise. Planners initially considered a lagoon layout, but documents submitted to the Combined Authority stated the barrage option would be cheaper and avoid the large-scale material imports needed to build the lagoon structure.


A mockup image of the Mersey Tidal Power project.

A mockup image of the Mersey Tidal Power project. Image used courtesy of Liverpool City Region Combined Authority 


The Mersey Tidal Power project is expected to have a 120-year operating life, similar to hydropower plants. Details on the grid connection haven’t been disclosed yet, but authorities have said the system wouldn’t require new long-distance transmission lines because it’s close to urban infrastructure. 

The project now moves to the planning and consent phase. Planners are expected to submit a scoping opinion in the third quarter of this year outlining the proposed development and approach to gathering onshore and offshore data for the environmental assessment. That would mark the first step in preparing a Development Control Order, which typically takes up to three years. 


Concept images showing a bird’s eye view (top) and the underwater turbines (bottom).

Concept images showing a bird’s eye view (top) and the underwater turbines (bottom). Images used courtesy of Liverpool City Region Combined Authority 


Tidal Range Technology

Mersey Tidal Power would be the world’s largest tidal range scheme, applying the technology for the first time in the U.K. The range concept differs from tidal stream technology, in which smaller, submerged turbines are placed in tidal flow channels, usually in more remote areas. 

Tidal range systems pull energy from the difference in water height between tides (up to 32.8 feet), benefitting from a predictable generation pattern. The U.K.’s resources account for 5–15% of worldwide tidal range generation. 


The flow concept.

The flow concept. Images used courtesy of Liverpool City Region Combined Authority  


The tidal system operates with two-way generation. Before the tide flows in, the turbine house sits idle with the opening closed on one side. When the tide arrives, the gateway opens, generation starts from the turbines, and the sluicing (water flow) continues as water is pumped out. The process repeats during the ebb tide in the opposite direction. 

One-way generation is also possible when the system is adjusted to allow the tide to flood quickly and produce electricity only with the outgoing (ebb) tide. 

The project concept will draw inspiration from existing tidal barrages like South Korea’s Sihwa Lake Tidal Power Plant. The 254 MW installation has been operating since 2011 and features eight sluice gates and 10 turbines rated 25.4 MW each. It supplies electricity to about 500,000 people. In 2022, the Liverpool City Region mayor signed an agreement with South Korean water company K-water to share lessons from its experience owning and operating the plant, which stands as the world’s largest tidal range power installation. 

EDF’s La Rance Tidal Power Plant in France is another blueprint for the project. It was the world’s first tidal power facility, opened in the 1960s. According to data from the Pacific Northwest National Laboratory, the 2,460-foot-long barrage has a peak rating of 240 MW generated by 24 bulb turbines, with an annual output of about 600 GWh. 

The multi-billion-dollar project still needs government backing for the development stage, and specific cost estimates haven’t been released yet. However, the price tag topped 3.5 billion pounds (or $4.4 billion) when the concept was conceived over a decade ago. Developer Peel Energy pulled out in 2011 due to high construction costs and concerns over medium-term profitability. 


Renewable Projects Ramp Up in Britain

Natural tidal resources along the U.K.’s west coast could join the island nation’s rapidly growing wind power sector. According to RenewableUK, more than 2,700 offshore turbines operate across 44 projects, totaling 14.7 GW of capacity. Another 8,993 onshore turbines supply 15 GW across 2,631 projects. These sites produce 83.5 TWh annually, powering 25.8 million homes. 

An auction for clean power contracts is set to take place this summer. RenewableUK estimates 14 wind farms could be eligible to bid, totaling nearly 10.3 GW of new capacity. Another 14.9 GW of offshore wind projects could also qualify—roughly equal to the U.K.’s existing 14.7 GW of offshore wind capacity, accounting for around 14% of national electricity demand. 

The Liverpool City Region is home to the U.K.’s second-largest wind farm cluster, supported by port infrastructure. Other offshore wind projects span Liverpool Bay and the northwest coast.