TIDAL RANGE & OFF SHORE
Offshore Hydro power
As the opportunities for large scale traditional hydropower applications in the UK are now very rare it seems sensible to look towards the sea to provide further opportunities. There is estimated to be around 6.5GW of marine energy capacity in the seas around Wales alone.
Tidal energy can be divided into 3 main categories:
· Tidal Range
· Tidal Stream
Relies on the difference in head created by the tides, the high tide is stored behind a bund or lagoon wall and then released through turbines as the tide falls and electrical energy is produced. When the tide turns, water runs in the opposite direction powering the turbines once again. The cycle repeats day in day out. Cycles can be enhanced by pumping and the operation of sluices. Such schemes can offer improved coastal protection if coastally attached and can provide reliable and predictable large scale electrical energy for hundreds of years. The UK has particularly good tidal range 7-10m not being uncommon.
Utilises the flow of the tide. Devices sit within the tidal flow and generate predictable electrical energy using rotors driven by the tidal flow. Often looking like undersea wind-turbines but shorter and stronger to withstand the greater forces within the sea. Devices typically require 3-6m flow speed although there are devices designed to run efficiently in less than 2m flow.
Less predicable than tidal range or tidal stream energy, as wave energy is a function of wind strength. These devices turn wave energy into electrical energy by harnessing the vertical component of the wave’s energy and converting to electrical energy either directly or by hydraulic means. Large scale deployment of wave devices may co-locate with floating wind plant many miles offshore.