Image: Doug McLean – Shutterstock.

The seas and oceans have long provided us with a great deal of food. Now, a new type of untapped resource has been born: tidal energy.

Our seas store abundant energy in the form of moving water. If we could find a way to efficiently harness all this energy, we could easily meet the energy needs of the entire world population.

The use of tidal energy is nothing new. Humans have used tidal energy for centuries. It has been used to help with such laborious tasks as grinding grain.

But with the help of modern technology, we can harness the limitless power of the tides. We can use it to generate clean, renewable electric power.

Fundamentals of tidal energy.

In summary, the energy of the tides is found in the gravitational and kinetic energy of the large bodies of water on our planet. The attraction of the Moon, the Sun and the rotation of the Earth creates the ebb and flow of water.

Every day, these astronomical forces move a bewildering number of liters of water. And where the water moves, there is kinetic energy that we could take advantage of.

A turbine that converts kinetic energy into electrical energy can take advantage of the energy generated by all moving water. This form of power generation is similar to hydropower, except that does not require a waterfall.

Tidal power differs from many other forms of renewable energy in that it’s very predictable, unlike wind or solar power. Often it depends on the climate for efficient production of renewable energy.

However, the tides are constant and unfold on a well-established schedule across the world, which is an invaluable asset for any potential energy producer.

Simple definitions:

  1. Kinetic energy: The energy that an object or a mass (such as a body of water) has due to its movement. For example, dropping a ball from the top of a building would create kinetic energy.
  2. Gravitational energy: The potential energy created between a smaller object and a larger object due to gravity. For example, there is a lot of gravitational potential energy before a bullet is released from the top of a building because gravity will pull it towards the ground.

How is tidal energy harnessed?

Before you can harness tidal energy, you must first convert kinetic energy into electrical energy.

The best way to do this is to use a turbine that turns from the physical thrust of the tides and converts the movement of water into electricity. There are currently three different types of tidal turbine systems:

  • Hydraulic barrier: Tidal dams are the most efficient way to harness tidal energy. They require the construction of a dam-like structure that forces water at high speed through the neck of a bottle where a turbine is located. Higher water velocities mean more kinetic energy, which in turn means more power. In many ways, it looks like a hydroelectric dam system.
  • Tidal turbines: This system works similar to that of a wind turbine. A simple turbine is placed in the water. There, water passing over it can drive the rotors. This type is probably the simplest of all systems and has a cheaper installation cost, although it produces less energy than the others.
  • Floating tide turbines. Turbines can spin in the current flowing near the surface of the water. This design eliminates the need for any type of construction on the seabed, making it easier, cheaper and less damaging to the environment than any other system currently in use.
  • Buoy system. A system of submerged row buoys that rise and fall in turns, which allows the energy capture to not stop despite the oscillation of the waves.

Advantages and disadvantages of tidal power

Like any type of innovative technology, tidal power has its own advantages and disadvantages.

Advantage.

  • Clean and renewable: Tidal power is as clean and renewable as any sustainable resource available today. It does not generate pollution and does not occupy as much physical space as other renewable energy systems.
  • Predictable and reliable: Most countries in the world experience two high tides and two low tides per day. This cycle is easily predictable and is not subject to unexpected changes, unlike many other renewable resources. Some systems also generate power from tidal currents regardless of the direction in which they flow, allowing electricity production to be completely uninterrupted.
  • Long duration: Tidal systems are inherently resistant to aging and have a long lifespan. The estimated average for most tidal systems is 75 to 100 years of operation. In comparison, a solar panel typically degrades after an average of 25 to 30 years. It invests time, energy and money and is generally less expensive when implemented on a large scale.
  • Effective at low speed: Tidal systems can generate energy even when the water passing through or passing through them moves relatively slowly. Water is 1000 times denser than air, which means it can drive a turbine even when it is moving at the speed of a snail.

Disadvantages.

  • Environmental impactWhile placing tide generators underwater can be great for humans, the same cannot be said for all sea creatures. Since the systems require turbulent water to feed them, a large foundation must be built. This type of underwater construction can lead to habitat destruction. The biggest offender is the tidal dam which uses dikes that can hamper the movement of marine life and potentially wreak havoc on aquatic ecosystems.
  • High construction costs: Building structures strong enough to withstand the turbulent and corrosive nature of seawater is not a cheap endeavor. Other renewable solutions have cheaper upfront costs. While tidal systems have a long lifespan and are more cost effective, governments are more concerned with their five-year budget rather than a 60-year projection. The initial investment for these systems is often your biggest problem.
  • Shortage of suitable locations: Not all seascapes close to shore are suitable for a tidal installation. They require a very specific set of factors to function effectively and efficiently. For example, the height of the sea at low and high tide. The lack of available places to install tidal systems is one of the main reasons why they are not more popular.

Tidal farms.

Although tidal power is still far from becoming something as common as solar power, we can already find several tidal power farms spread around the world.

Why haven’t we seen more tidal farms?

As we have discussed, there are many drawbacks that tidal power generation has yet to resolve.

  • Construction difficulties: Rough seas are a difficult place to do any type of construction and finding companies with experience to build and install these structures is not an easy task. There is a lack of knowledge and investment in the sector and more research is needed to refine the methodology when it comes to harnessing tidal energy efficiently.
  • Environmental factors: The specific environmental requirements of tidal farms make them inaccessible to most coastal towns. The positive side is that as technology advances and these energy farms become more efficient and therefore more accessible.

The future of tidal power.

The industry is still in its infancy, but with more investment and experience it will become cheaper and more accessible to install worldwide. With each tidal farm put into operation, we learn more about the challenges and how to overcome them.

Market growth.

As interest in tidal power grows around the world, people are doing more and more research and development. You can see a simple indicator of the growth of this industry in its market value. Experts valued the tidal power market at $ 487 million in 2014, but experts expect it to be worth $ 11.3 billion by 2024.