The number of basins employed for power generation is how tidal power facilities are commonly characterised. They are further classified into one-way and two-way systems based on the power generating cycle.
The operation of several tidal power plants
1. One-way cycle in a single basin
The most basic type of tidal power plant. During flood tides, a basin is permitted to fill, and during ebb tides, water flows from the basin to the sea, passing through the turbine and generating electricity. For a brief period during the ebb tide, power is accessible.
2. Two-way cycle in a single basin
This design generates electricity during both the flood and ebb tides. Power generation is likewise intermittent, although the duration of generation is longer than with a one-way cycle. The resulting peak, however, is lower than the one-way cycle. The basin’s layout and the power cycle are depicted in the diagram.
The fundamental disadvantage of this configuration is that the prime mover must be the same turbine since the ebb and tide flows travel through it in opposing directions. This design makes use of a variable pitch turbine and a dual rotation generator.
3. Two-way single-basin cycle with pump storage
Power is generated in this system at both flood and ebb tides. Complex machinery are utilised that can generate electricity and pump water in both directions. A portion of the energy generated is utilised to create a differential in water levels between the basin and the sea at any time of the tide by pushing water into the basin up or down. This technology produces power for a significantly longer amount of time than the other two systems mentioned previously.
4. Type with two basins
The turbine is positioned between the basins in this configuration, as illustrated in the diagram. The ebb tide fills one basin occasionally, while the flood tide drains the other. As a result, this system provides a modest capacity but constant electricity, as indicated in the diagram. The primary drawbacks of this system are that it wastes half of its potential energy by introducing differences in the water levels of the two basins.
5. Pumping in a double basin
Off-peak electricity from a base load plant in a linked transmission system is utilised to pump water up the high basin in this example. If the pumping head is less than the basin-to-basin turbine producing head, a net energy gain is feasible with this arrangement.