Tidal Energy

Tidal energy is a form of hydropower that converts the energy of the tides into electricity or other useful forms of power. The tide is created by the gravitational effect of the sun and the moon on the earth causing cyclical movement of the seas. Tidal energy is therefore an entirely predictable form of renewable energy, which can be harnessed in two forms:

Tidal Range

Tidal Range is the vertical difference in height between the high tide and the succeeding low tide.

Artificial tidal barrages or lagoons may be constructed to capture the tide. Turbines in the barrier or lagoon generate electricity as the tide floods into the reservoir; water thus retained can then be released through turbines, again generating electricity once the tide outside the barrier has receded.

Tidal Stream

Tidal Stream is the flow of water as the tide ebbs and floods, and manifests itself as tidal current. Tidal Stream devices seek to extract energy from this kinetic movement of water, much as wind turbines extract energy from the movement of air.

The sea currents created by movement of the tides are often magnified where water is forced to flow through narrow channels or around headlands. There are a number of locations around the coastline of the UK where the tidal stream resource is high, and it is in these areas where early technology developments are taking place to explore the prospect of harnessing tidal energy.

Tidal power is yet to attract significant renewable energy investment, even despite having good potential in many areas around the world. Throughout this article I will mention the most important advantages and disadvantages of tidal power.

Tidal power advantages:

Tidal power belongs to renewable energy sources meaning it cannot be depleted like fossil fuels can. Tidal forces have their origin in the gravitational interaction with the Moon and Sun, meaning that we could harness tidal power as long as Moon and Sun continue to exist.

The efficiency of tidal power. Tidal power belongs to the most efficient energy sources by having efficiency of approximately 80%, this is much better efficiency as compared to other more popular renewable energy sources such as solar and wind.

Tides are predictable, and this predictability is also one of the advantages that tidal power has over other energy sources because rise and fall of tides are much more cyclic than random weather patterns. This predictability gives us knowledge when the tides will be in and out.

Harnessing tidal power has positive impact on climate change because it produces no greenhouse gas emissions. 

Harnessing tidal power on larger scale could even lead to reduced import of foreign fuels and improve our energy security because we wouldn't have to rely so much on expensive foreign fuel import to satisfy our growing energy demand.

Barrages and small dams used to harness tidal power could protect coastal areas or ship ports from dangerous tides during a stormy weather

Tidal power disadvantages: 

Tidal power plants are connected with high upfront costs needed for construction, and therefore lack cost-competitiveness on global energy market.

Tidal power is intermittent source of energy that can only produce electricity during tidal surges which is in average around 10 hours each day. This means that in order for tidal power to be considered as a reliable source of energy needs to be accompanied with some effective energy storage solution.

Tidal power plants could lead to environmental damage in some cases as the frames of the turbines have potential to disrupt the movement of large marine animals. Also, the construction of tidal power plant can disrupt fish migration in the oceans.

Still more a theoretic source of energy, limited in real life to just a few prototype projects because technology has just started developing and needs big funds and plenty of scientific research before reaching the commercial character.