Tidal Energy (Tidal Power) Pros and Cons

by Andy Goldman on January 27, 2013


Tidal Energy together with Wave Energy are the two forms of Ocean Energy and ocean energy together with hydroelectric energy form the Water energy renewable energy group.

Tidal Energy (Tidal Power) Pros

We will first start by listing and describing in short the Pros of Tidal Energy. We have identified 8 major advantages of tidal energy.

  1. Renewable Energy Source, RES. Tidal Energy is a renewable energy source which means that it does not depend on fossil fuel, does not pollute the environment with CO2 emissions and it is renewed continuously. Tides occur daily in various parts of the world and once their power is captured it can be converted to useful electricity which will then connected to the power grid.
  2. Green Energy: As a renewable energy source, Tidal energy is green since it does not pollute the environment.
  3. Predictable Energy Source: Tides are predictable and as a matter of fact very predictable. The high and low tides not only follow a certain well known cycle but their power is also well known. These two characteristics make it possible to build tidal power plants which are properly sized to take advantage of the tides at specific area.
  4. Consistent Power: Tidal power is consistent throughout the day. This makes its exploitation easier since better planning and electricity management can be done by electricity providers and regulators.
  5. Effective at Low Speeds: Due to the fact that water is much denser than air, about 1000 times more, this enables tidal plants to produce electricity at lower tide speeds than wind plants would do so.
  6. Efficient: Tidal power plants are more efficient than many fossil operated plants. For example a tidal plant converts into useful energy, electricity, about 80% of the kinetic energy while a coal plant achieves only 30% efficiency.
  7. Low Operating Costs: Tidal Power plants have a high construction cost but they have low operating expenses, OPEX, and labor costs since they can virtually operate unattended.
  8. Long Life of Tidal Power Plants: Tidal power plants have a long expected life span, about 75-100 years. This however has yet to be proven since the oldest tidal power plant is the La Rance in France was built in 1966 and still produces electricity as efficiently as in 1966.

Tidal Energy (Tidal Power) Pros and Cons

Tidal Energy (Tidal Power) Cons

As we stated earlier every form of energy has its pros but also has its cons. The disadvantages of Tidal Energy are:

  1. Location Specific: Building a tidal power plant has to meet certain specifications and despite of the fact that tides are predictable the sites suitable are limited and so far only about 40 sites worldwide have been identified to meet all criteria.
  2. Distance from the Grid: Grid connectivity is essential so that the electricity produced can be consumed. Most often tidal plants are built at places distant from the grid and this makes their connectivity to the grid difficult and expensive.
  3. Useful Period: Tidal power plants can produce energy only 10 hours out of the 24 hours of the day. This means that despite of the fact that the tides a predictable the useful period is only about 40% of the year.
  4. High Initial Cost: Tidal Plants are expensive to be built and this is an important factor which has to be taken into account when formulating the business case for building such a plant.
  5. Environmental Impact: Building a tidal plant affects the marine life of the surroundings. It has an impact on fish, other marine life and sea birds. An environmental study should always accompany a feasibility and business case associated with a tidal power plant.
  6. Disruptions: Tidal plants with barrages disrupt the access to open water and the power plant itself disrupts tidal cycles. Also it was found that tidal power plants affect the salinity of water in the tidal basins.
  7. Device Breakdown: Due to the fact that the tidal converters are in the sea water and are exposed to tides, waves and sea weather they have increased breakdown and this increases the operational cost of the plant.
  8. Few implementations: Due to the fact that only a few tidal plants have been implemented so far there are no comparable figures for proper evaluation of their success and no economies of scale have been achieved for the equipment production
  9. Aesthetics: Building a tidal power plant affects the aesthetics of the area, which in its turn affects other economic activities in the area such as tourism. Aesthetics is one of the factors that local authorities consider before issuing a permit for tidal power plant.

Tidal Energy is the oldest renewable energy source and it should be exploited at locations where the business case justifies it and when it would be used to complement the production of electricity from other sources such as waves, wind or the sun.

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Andy Goldman


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