Tidal Range EnergyTidal range is the vertical difference between high and low tide.
While the tide is rising, the reservoir behind the dam is filled with water through open sluices. The gate to the turbine is closed. When high tide is reached, the sluices are shut. Once sea level has receded to sufficiently low levels, the turbine gate is opened and the water from the reservoir channeled onto the turbine.
Due to low head (<10m), the turbine type is similar to a Kaplan turbine
While the tide is rising, water flows through the turbine into the reservoir, generating electricity during flood.
Less efficient than ebb generation.
In combination with ebb generation, use surplus grid energy to pump additional water into the reservoir, similar to hydro pump storage.
- La Rance estuary, France (240MW)
- Bay of Fundy, Canada (8MW)
- Silting: Similar to hydro power dams
- Loss of intertidal habitat, as it alters the flow of salt water in and out of estuaries.
- Potentially more flooding in the vicinity.
- High capital costs > €/kWh 2,000, but long lifetime. La Rance is in operation since 1966.
- Long payback time
Only feasible in few sites, though with huge potential. Construction of tidal barrages are underway in South Korea and China. There are advanced plans for a plant in Kamtchatka (87GW). Plans for the Severn Barrage (near Bristol, UK) for 8.6GW have been scrapped in October 2010 due to cost pressure, as the expected capital outlay would have been £30bn (~£/kWh3,500).