The search for alternative energy sources in the age of climate change has overlooked tidal energy: a vast and unexploited worldwide resource.
For three decades now, tidal lagoon schemes have been recommended as an economically and environmentally attractive alternative to tidal barrages. More recently, two proposals for tidal lagoons in Swansea Bay, Wales, have emerged and there have been several reports documenting how such a project there could have the potential to harness significant energy resources.
Tidal energy involves constructing a barrage, a dam, or some other sort of barrier to harvest power from the height difference between high and low tides.
The power is generated by running the water through turbines, found within the barrier. The technology used is very similar to that found in hydropower schemes, however unlike rivers tidal currents run in two directions.
Where a tidal barrage blocks off an entire estuary, a tidal lagoon instead impounds an artificially created area of the sea or estuary. A lagoon doesn’t necessarily have to be connected to the shore—it could even sit out in the ocean.
As the tide goes out the lagoon remains closed, and full. It then opens the flood gates to let the water out until water levels on each side of the lagoon wall are even. When the tide comes in the process is reversed.
