Two-Basin System:
Working Principle:
- Structure:
- Two basins: Upper Basin (A) and Lower Basin (B).
- Turbines are placed between the two basins.
- Sluice gates are provided at the mouths of the estuaries (in the dam).
- Flood Tide Operation:
- At the start of the flood tide:
- Turbines are shut down.
- Upper basin gates (A) are opened → A starts filling.
- Lower basin gates (B) are closed → B remains empty.
- As water level in A rises and a sufficient head develops between A and B, turbines are started.
- Water flows from A to B through turbines, generating power.
- Power generation continues while A is still filling.
- At the start of the flood tide:
- End of Flood Tide:
- A becomes full, its sluice gates are closed.
- As ebb tide begins and water level outside drops below B, B’s gates are opened.
- Water level in B falls, maintaining head with A for power generation to continue.
- Ebb Tide Ends → Next Cycle Begins:
- Once operating head is lost, turbines are stopped.
- With the next flood tide, the cycle repeats.
- An enhancement over the single-basin system, this configuration maintains a continuous output by adjusting turbine valves according to the operational head.
- Advantages: Provides a more consistent power output, though it still cannot fully manage variations between spring and neap tides.
- The challenges can be mitigated by integrating a pumped storage plant.
- Integration with Pumped Storage: Surplus (left over) energy can be stored and utilized when tidal energy output is low, making it technically feasible but expensive.
- Operation: The two basins operate alternately, with one generating power during rising tides (filling) and the other during falling tides (emptying). This arrangement can either have a shared powerhouse or separate ones for each basin, allowing for continuous power generation.
Co-operating Two-Basin Systems:
- Comprises two basins at different elevations, interconnected through turbines. The high-level basin fills during high tides and releases water through turbines to the low-level basin.
- Operation: As seawater rises, it fills the high-level basin; sluices are closed to retain water. When the sea level drops, the water flows through turbines to generate power. The cycle repeats with each tide.
- Continuous Generation: Allows for ongoing power generation but incurs high construction costs due to additional infrastructure.
Co-operating Two-Basin Systems:
