Mersey tidal barrage could take decade to build

The construction of the potential tidal barrage across the River Mersey could take a decade, according to current estimates.

The Liverpool City Region Combined Authority is currently finalising options for a new tidal barrage or lagoon in the river which has the potential to power up to one million homes with renewable energy for 120 years, create jobs, and “secure the UK’s reputation as a global leader in green energy.”

According to the Liverpool City Region Combined Authority, no decision has been made about the multi-billion pound project, which is in the early stages of planning, but a Freedom of Information request revealed “the construction period is likely to be around 7-10 years with construction, machine assembly and commissioning activity.”

Timescales are dependent on final designs and contractors but multiple projects could even go ahead including options for both a barrage and a lagoon.

The Combined Authority said there was potential for seven to 10 projects on the west coast of UK, adding, “We want Liverpool City region to be at the centre of the tidal range industry.”

A report published in October included illustrations of what a barrage on the Mersey could look like, with references to street furniture, cyclists, and “rest points along the route.” It also said the project would be “a major new piece of infrastructure – linking the left and right bank (Wirral and Liverpool).”

The Combined Authority is waiting on government feedback about options for a barrage or a lagoon and how this would help move energy supply towards net zero emissions.

Current estimates have the project delivered by 2040 but an early stage application examining potential environmental implications is expected to be submitted to the Planning Inspectorate “in the near future.”

More details have now been revealed including potential locations. The identified area for a tidal barrage for the last 40 years has been between Dingle and Otterspool on one side of the river and Port Sunlight and Bromborough on the other.

However, the Liverpool City Region said some options may no longer be viable and it is now considering locations “closer to the mouth of the river that may align to regeneration aspects around Liverpool Waters and Wirral Waters,” and help provide a flood defence against rising sea levels. The October report referenced Wirral Waters and the new Everton stadium.

It has also been confirmed “a walking or cycling route is considered part of the wider Active Travel consideration for the tidal scheme and the wider LCR region. Any such route could potentially provide connectivity and link to active travel and public transport.”

A previous price tag put the cost at £3.5bn and while this is likely to change, it will still cost billions to build, with the project needing substantial government backing.

The Combined Authority said, “The current scheme development stage has minimal information which provides the basis for outline costs but without the detail necessary to enable accurate cost estimates to be generated. 

“Significantly more detail is required in terms of location selection and engineering and construction methods to allow a reliable cost of construction for a 120 year operating asset.

“Estimates of project cost are currently in the multiple of billions but are subject to change as we understand more of the challenges of construction, the economic landscape and inflation rates, which have seen other major projects such as HS2 and Hinckley Point C suffer significant cost change. 

“We are very mindful that project costs can only be stated accurately when full market testing and supply chain quotations are received. To date, this has not happened.”

A Liverpool City Region Combined Authority spokesperson said, “Mersey Tidal Power has the potential to provide enough clean, predictable and renewable energy for up to one million homes for 120 years and create thousands of local jobs, apprenticeships and training opportunities in construction, science, research and development.

“Harnessing the power of the River Mersey is a bold and ambitious mission, however, it is not a recent concept. Talks of building a tidal barrage have been ongoing for more than four decades and, as such, various locations have been suggested throughout the years.

“In that time, the landscape of some of these locations has changed dramatically and redevelopment has meant that they may no longer be viable, but we have to consider all options in the business case to government.

“A project of this scale takes time to plan and exploratory work is still ongoing. The Combined Authority is continuing to explore all possibilities for Mersey Tidal Power and no decisions on the operating model or location have yet been made.”

Image: A CGI mock up included in a report about the Mersey tidal power project. Credit: Liverpool City Region Combined Authority

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