Severn estuary: Reef better than barrage?

According to a recently published report, a new tidal power scheme involving the creation of an artificial reef, could safeguard wildlife and generate more clean energy from the Severn Estuary than a 10-mile barrage.

A tidal reef built further downstream would not only be less costly than the proposed Cardiff to Weston barrage but it would also minimise the threat to most of the Severn estuary’s salt marshes and mudflats. The latter providing home for up to seventy thousand birds in the winter months.

Furthermore, it is claimed, the manmade reef would operate for longer and have more underwater turbines than a conventional barrage – hence affording the possibility of greater power generation.

A spokesman for engineering consultants, Atkins (the largest consulting engineering firm in Europe), who authored the report, is quoted as saying: “We believe this scheme could be more powerful but less costly than other plans being put forward, particularly the Cardiff to Weston barrage.”

As previously reported on by Land & People, current thinking revolves around utilising the 45-foot tidal range of the Severn – the difference between low and high tides – to generate electricity.

Government ministers are to shortlist some of the 10 proposals for the Severn estuary in December and the tidal reef and Cardiff-Weston barrage are among those being considered.

The Atkins study, makes four major conclusions:

(1) That the technology behind a conventional barrage could be used to build a tidal reef.
(2) That a tidal reef could generate more energy than the conventional barrage.
(3) That a tidal reef would cost £2 billion less than the Cardiff-Weston barrage.
(4) That a tidal reef could be designed within the government’s target date.

The Atkins proposal suggests an artificial reef stretching 12 miles from Minehead in Somerset to Aberthaw, in the Vale of Glamorgan. Its design would allow for locks at set points to allow large container ships to pass and allow for construction in sections – enabling the much earlier generation of power.

An engineering expert added: “The potential of a tidal reef is enormous. As well as electricity, it could produce hydrogen for use in non-polluting cars or the gas network. Its construction would mean far less road traffic because of rail connections, and would require less material and cost significantly less than other tidal options or nuclear power. It would cut Britain’s carbon emissions by around 12 million tons annually, create more than 30,000 jobs during construction and give a global lead for local manufacturing companies, particularly in the marine engineering sector. Other schemes either defy the laws of Europe and would result in years of litigation, and some even defy the laws of physics and simply wouldn’t work.”

On paper, at least, the reef proposal would appear to have four advantages over the Severn barrage proposal. Firstly, it is significantly cheaper. Secondly, it can generate more power. Thirdly, it can deliver power to the national grid much earlier and lastly, it is potentially less destructive to the wildlife habitats of the estuary.

Land & People will be monitoring progress on this interesting proposal.