Much of the energy we use today comes from non-renewable sources. Ultimately, this means that in time, these sources will run out. Along with this, much of this energy plays a significant role in polluting the planet by emitting greenhouse gases. Therefore, we need alternative sources of energy. Therefore, we should consider the advantages & disadvantages of tidal energy and the growing role of converting the movement of the tides into clean energy7.
While the planet provides us with fossil fuels, it also provides us with other forms of energy that we can harness. This can include the likes of wind, solar and, of course, tidal energy. The environmental effects of traditional energy are devastating. As a result, we need long term solutions that we can rely on, and tidal looks set to play a larger role in producing our future energy needs6.
Tides – What Are They?
While many of us might be aware of tides, how many of us understand how they are created? In its simplest form, tides are the rise and fall of sea levels, caused by the gravitational pull between the Earth and the Moon.
The size of the tides are determined by the new moon and the full moon and accordingly alter through the course of a month. When the earth, the sun and the moon align, the gravitational pull will be at its strongest which results in the largest tidal movements in any month3. During the day, we will see two high tides and two low tides.
The biggest tidal range is seen in the Bay of Fundy, Canada where the tidal range is 16.3 metres. The Bristol Channel in the UK has the second-highest tidal range in the world of 15 metres.
What is Tidal Energy?
Tides are a phenomenon that is guaranteed every day. It is possible to predict the tides many years in advance and so, we can predictably forecast the potential for tidal energy creation.
This moving of the tides and the waves that accompany them all generate energy. The ocean covers much of the earth and it moves around the world via tidal patterns. As the currents flow, we can take this energy and turn it into energy that we can use.
Due to the ubiquity of tides and their regularity tidal energy could prove one of the more important renewable energy sources available to us8. Researchers have found that tidal energy could produce as much 10–25% of our worldwide energy needs. Estimates suggest that the tides could provide us with 700TWh each year.
However, tidal energy is still relatively new and turning tides into energy is still in development. Meanwhile, early tidal energy deployments show the way towards leveraging tidal energy as a replacement for fossil fuels1. With the focus on renewable energy becoming more apparent9, clean energy is something we have to make use of.
However, as with many things, Tidal energy has its advantages and disadvantages
The Advantages of Tidal Energy
1. It’s a Renewable Source of Energy
The tides will always flow and move, which means that it is a source of energy that we can use time and time again. Whether we are using stream generators, tidal barrages or even dynamic tidal power, we can, potentially, endlessly use this source of renewable energy to generate the energy that we need.
Because the tides rely on the gravitational forces from the sun and the moon, these forces are not going to disappear any time soon. Because they persist, it makes tidal energy a renewable source. Unlike fossil fuels, which are going to run out in the not so distant future5.
2. It is Environmentally Friendly
Once the technology is in place, tidal energy is an environmentally friendly source of energy. There is a reduction in greenhouse gases which makes it cleaner than other forms of energy.
However, the overall effects of a tidal power system on the environment are still relatively unknown in the long-term.
3. Tides Are Predictable
Just like the sun shining in the sky, we will always have tides. The currents are predictable and as such, we can create systems that work efficiently with them. For example, placing tidal energy systems where we will see the highest energy yields.
The system works in a similar way to wind turbines. However, the size of the system and the installed capacity are very different. This is down to the fact that the tides are always there, unlike the wind, which can be sporadic. While the technology works differently too and so, tidal energy plants have the potential to generate large amounts of energy.
4. It Generates Energy at Low Speeds
As water has a higher density than air, it means that even when the tide is moving at a slower speed, it can still generate energy. So, this makes it highly effective when compared to the likes of wind energy. What’s more, on a day where there is no wind, there is a possibility that a wind turbine won’t generate any energy at all.
5. Durable Equipment
In contrast to solar or wind farms, tidal power plants can last a lot longer. In fact, they can last around four times longer in comparison. If we consider tidal barrages, these are concrete structures that are spread across river estuaries. The structures are considered to have a lifespan of as much as 100 years. A prime example of this is La Rance in France. It first went into operation in 1966 and still, to this day, it continues to create clean energy.
This compares favourably to wind turbines and solar panels that have an average lifespan of around 20-25 years. Along with this, the equipment can diminish and become obsolete based on efficiency. So, from a cost-effective perspective, tidal power is a better option in the long-term.
The Disadvantages of Tidal Energy
1. They Have an Impact on Marine Life
If we consider tidal barrages or even other systems, they can have a negative impact on marine life. Tidal barrages rely on the flow of water in and out of estuaries. However, once put in place, the barrages alter the flow of water. The water is forced through the turbines and that can disrupt the way in which marine life thrives4.
Along with this, the blades also pose a risk to any marine life that attempts to swim through them. They also pose a threat to marine plants due to a change in silt deposits and the changing of the structure of the estuary.
2. Maintenance and Corrosion are an Issue
The constant movement of water and the saltwater itself can corrode machinery. As a result, the machinery needs to be regularly maintained. What’s more, the systems can prove costly because they have to be designed using corrosion-resistant materials2. From the turbines to the cabling, it all has to be able to withstand the constant exposure to water.
As tidal energy systems are costly and difficult to maintain, the aim is to make them as reliable and maintenance-free as possible. Despite this, maintenance remains a requirement and when anything is submerged underwater, it becomes more difficult to work on.
3. They Have to Be Within Close Proximity to Land
The strongest currents are close to land. As a result, it means that tidal energy systems have to be located close to land.
As it stands, it’s difficult and more costly to transport energy longer distances. This is due to the fact that many of the fastest tidal flows are in areas that are shipping lanes and in some cases, too far from the grid. This is another factor that holds back this form of energy. However, there is hope that technology will evolve so that tidal energy systems can be located out at sea.
4. It is a Costly Technology
Tidal energy is still relatively new. Despite systems being used in certain areas around the world, growth has not been on the same level as other sources of energy such as wind or solar.
As such, the technology is still comparatively expensive. Despite this, estimates suggest that tidal energy could be commercially profitable in 2020. This is in instances where systems are installed on a large scale using the latest technology.
However, the plants that harness the energy are also susceptible to high costs. As a result, this could prevent the progress of tidal energy.
Surely Tidal Energy Has a Future?
We are all aware of the power of water. From flowing rivers to the tides of the ocean, the amount of energy that it generates is staggering. This is a source of energy that is plentiful and one that could help us to change our ways.
The planet consists of up to 71% water, of which 96.5% of that water is in the oceans. As a result, it is undoubtedly a source of energy that we should look to harness. As technology advances and our need to go green becomes even more important, tidal energy will prove less of an untapped resource. So, it has to be a case of when, not if, when it comes to tidal energy.
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|Shahzad, Umair. (2015). The Need For Renewable Energy Sources.|