Your questions answered: tidal lagoons

In recent years, much of the development of tidal energy has focused on turbines that sit directly in the tidal flow in regions where the tides are strong and fast. But this was not the first way in which tides were used for energy in Britain. On the coast of East Anglia, in Orkney and in the Hebrides are the remains of tidal mills, where lagoons were created to trap the tidal water as it came in and then used the outflow to grind grain; some of these date back to the Vikings and even before. Now, this technique is under investigation again, as part of an ambitious project to generate tidal energy in Swansea, Somerset and Cumbria. We asked readers of The Engineer for their questions about these schemes, and Ton Fijen (TF), technical director of Swansea Tidal Energy, the company developing these concepts, answered them.