The Gulf of Khambhat, the Gulf of Kutch and the Sundarbans offer ideal conditions for harnessing which form of energy?

Tidal energy is produced by using the rise and fall of sea levels caused by tides. It needs a large tidal range (the difference in height between high tide and low tide) and a suitable bay, gulf or estuary where water can be held behind a barrage or dam.

Why these places are suitable:

The Gulf of Khambhat (Cambay) in Gujarat has the highest tidal range in India, up to about 11 metres. Its funnel shape increases the height of the tides.

The Gulf of Kutch in Gujarat has a tidal range of about 5 to 8 metres.

The Sundarbans and the Hooghly estuary in West Bengal have a tidal range of about 3 to 5 metres, with many creeks.

How tidal energy works:

Tidal barrage: a dam is built across a bay or estuary. As the tide rises and falls, water flows through turbines in the barrage, generating electricity.

Advantages:

• Tides are predictable and regular, unlike wind and sunshine.
• It is a renewable and clean source of energy.

Disadvantages:

• High construction costs.
• Possible harm to marine life, fish migration and mudflat ecosystems.
• Electricity is produced only at certain times of the tidal cycle.

Projects in India:

A tidal power project was planned at Durgaduani Creek in the Sundarbans, but it was cancelled because of high costs.

World examples:

• La Rance tidal power station in France, opened in 1966, was the world's first large tidal power station.
• The Sihwa Lake tidal power station in South Korea is the world's largest by capacity.

Why not the other options?

• ✗Geothermal energy uses heat from inside the Earth; in India, the Puga valley in Ladakh is a potential site.
• ✗Solar energy depends on sunshine, not tides.
• ✗Wind energy depends on steady winds, usually on coasts or open plains.