Tidal lagoon power

The UK has some of the highest tidal ranges in the world, in areas of shallow water around a number of its coastal areas.

West coast:

• Solway Firth
• Morecombe Bay
• Blackpool
• Mersey
• Colwyn Bay
• Severn Estuary
• Welsh Grounds
• Swansea Bay
• Bridgewater Bay

East coast:

• East Lincs Coast
• The Wash
• Thames Estuary
• Sheerness

South coast.

• Sussex Coast

These places present an opportunity to create artificial lagoons by constructing perimeter breakwater walls to enclose a tidal area. The bunded area is then dredged. Two way hydro turbines are installed in a single section at the base of the perimeter wall through which estuarine water flows in one direction or the other four times daily. For fifteen out of twenty four hours enough tidal flow is generated to operate the turbines and generate electrical power.

One company was formed to design and construct such a scheme in Swansea Bay where the tidal range can reach up to 12m, second highest in the world. See Swansea Bay tidal lagoon for more information.

In March 2015, the same company submitted an Environmental Impact Assessment scoping report for a much larger tidal lagoon between Cardiff and Newport. See Cardiff tidal lagoon for more information.

As tides are more reliable than wind, its energy might be considered a better bet than the rush to erect wind turbines across Britain’s countryside. The Swansea Bay scheme is calculated to save 216,000 tonnes of CO2 annually which is equivalent to taking 81,000 cars off the road. Turbine blades are of a size and speed that allow large fish to freely enter and exit the lagoon without harm. Additionally the perimeter walls provide leisure access for pedestrians and cyclists and the lagoon will attract dinghy sailing and other activities.

However, there remain issues to overcome, including the potential environmental damage (to both plants and animals) and the high strike price needed to make the project viable.

In January 2016, Prime Minister David Cameron cast doubt over tidal power whilst giving evidence to the Parliament’s Liason Committee, when he said, “The problem with tidal power, simply put, is that at the moment we have not seen any ideas come forward that can hit a strike price in terms of pounds per megawatt-hour that is very attractive. That is the challenge for tidal. Maybe they can come up with something. They are very long-term schemes with big investments up front, and they can last for many, many years, but right now my enthusiasm is reduced slightly by the fact that the cost would be quite high.”

[edit] Related articles on Designing Buildings

• Barrage.
• Cardiff tidal lagoon.
• Dam construction.
• Development Consent Order.
• Dove Stone Hydropower.
• Hydroelectricity.
• Hydropower.
• Lagoon.
• Marine energy.
• Renewable energy.
• Thames barrier.
• Tidal estuary.
• Water engineering.
• Water transfers and interconnections.

[edit] External reference

• Construction Manager Magazine, special report 26 August 2015.
• Daedalus Partners LLP (Daedalus) prospectus.
• Technology4Change, Oyster building centrepiece for new £850m tidal project. 14/2/2014.