Tidal power

Tidal power

Tidal energy involves building a dam across the opening to a tidal basin, called an estuary. The dam, called a barrage, is composed of turbines, located within tunnels in the dam that rotate when a tide comes in, generating electricity.

Pros:
Tidal power is free once the dam is built. This is because tidal power harnesses the natural power of tides and does not consume fuel. In addition, the maintenance costs associated with running a tidal station are relatively low.

Tides are very reliable because it is easy to predict when high and low tides will occur. The tide goes in and out twice a day usually at the predicted times. This makes tidal energy easy to maintain, and positive and negative spikes in energy can be managed.



Cons:
Tidal energy is not strictly "renewable": because all energy produced from tidal generation results in an equal loss of the earth's rotational energy it consumes the earth's rotational inertia, very slightly slowing it down.[citation needed] Tidal power relies on the gravitational pull of the Moon and the earth's rotation, which pull the sea backwards and forwards, generating tides.
It provides power only for around 10 hours each day, when the tide is moving in or out of the basin.
The barrage construction can affect the transportation system in water. Boats may not be able to cross the barrage outside of a lock system.
The erection of a barrage may affect the aquatic ecosystems surrounding it. The environment affected by the dam is very wide, altering areas numerous miles upstream and downstream. For example, many birds rely on low tides to unearth mud flats, which are used as feeding areas.
Maximum energy production is limited to 2.5 terawatts. This is the total amount of tidal dissipation or the friction measured by the slowing of the lunar orbit.

From wikipedia