Tidal power is a renewable energy source in which water runs through turbines to make a clean energy source. Although it has not been used widely yet, many believe tidal energy will be a source for future generations.
Long before we used tides to give us energy, we still harnessed water with tide mills. A tide mill works by getting a wheel pushed by the water to grind flour. The earliest tide mill was made in 619. It was found at Nendrum Monastery in Northern Ireland and was probably used to grind grain.
It did this when the tide was low and water left the mill pond, causing the tide mill wheel to turn and grind the grain.
Tidal mills became more common in the middle ages and by the 18th century London had 76 of them. As time progressed our use of tide mills became more sophisticated.
In 1966 the Rance estuary in France (image on the right) became home to the first tidal power generating station. Unlike early tide mills it generates power during high tide and low tide.
Today there are several different ways of using tidal energy. These are:
Tidal barrages- a tidal barrage is a type of tidal power generation in which a low dam wall is is built across a tidal inlet or basin. This wall has a number of tunnels cut into its width allowing water to flow through in a controllable way using sluice gates. Inside the tunnels are large water turbines that spin as water rushes past creating electricity.
Tidal Stream- A tidal stream shares almost the same principle as wind power generation except the tide’s current spins on the rotors which move the turbine to create electricity.
Benefits and Costs of Tidal Energy
There are a number of benefits to tidal energy. These include:
It is a renewable energy source because tides are free and clean because no fuel is needed and no bi-products are produced.
It has a potential to produce great amounts of free green energy
It is not expensive to operate compared to other renewable energies
They have little visual impact because they are part or fully submerged
It creates low amounts of noise pollution because the sound cannot travel through the water
Tides can be predicted years in advance unlike other renewable energy sources
Tidal barrages protect land against flooding
Tidal reservoirs can be used as recreational lakes in areas where the were none
Despite The benefits there a some disadvantages of tidal energy. These include:
It relies on the strength of the tides which are affected by the moon and sun
It requires a suitable site where tides are consistently strong
It must be able to withstand forces of nature so it costs a lot to construct
It only generates power 10 hours a day during the ebbs and flows of the tide
It changes the ecosystem because the tides are concentrated
Fish and other sea animals can swim into turbines
It can cause damage to ships passing over