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. Consequently, we should consider the advantages & disadvantages of tidal energy and the growing role of converting the movement of the tides into clean energy8.
While the planet provides us with fossil fuels, it also provides us with other forms of renewable energy that we can harness. This can include the likes of wind and solar power 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 more significant role in producing our future energy needs5.
While many of us might be aware of tides, how many understand how they are created? Tides are the rise and fall of sea levels in their simplest form, caused by the gravitational pull between the earth and the moon.
The size of the tides is determined by the new Moon and the full Moon and accordingly alters 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 in the Bay of Fundy, Canada, where the tidal range is 16.3 meters. The Bristol Channel in the UK has the second-highest tidal range globally at 15 meters.
Tides are a phenomenon that is guaranteed every day. It is possible to predict the tides many years in advance, so we can predictably forecast the potential for tidal energy creation.
The ocean covers much of the earth, and it moves around the world via tidal patterns. This moving of the tides and the waves that accompany them all generate energy. As the currents flow, they produce kinetic 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 us6. Researchers have found that tidal energy could produce as much as 10–25% of our worldwide energy needs. Estimates suggest that the tides could provide us with 700TWh each year.
However, renewable tidal energy is still relatively new, and turning tides into energy is still in development. Meanwhile, early tidal energy deployments show how to leverage tidal energy as a replacement for fossil fuels1. With the focus on renewable energy becoming more apparent7, clean energy is something we have to make use of.
However, as with many things, Tidal energy has advantages and disadvantages.
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 endlessly use this renewable energy source to generate the energy we need.
Because the tides rely on the gravitational forces from the sun and the moon, these forces will not disappear any time soon. Because they persist, it makes tidal energy a renewable source, unlike fossil fuels, which will run out in the not-so-distant future.
Once the technology is in place, tidal energy is an environmentally friendly energy source. There is a reduction in greenhouse gases which makes it cleaner than other forms of energy.
Further tidal energy does not require as much land as large solar installations. For example, the Sihwas Lake Tidal Power Station on the west coast of South Korea generates 254 MW of tidal energy production. The required space is only around 12km of the seawall.
However, the overall effects of a tidal power system on the environment are still relatively unknown in the long term.
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 because the tides are always there, unlike the wind, which can be sporadic. While the technology works differently, too, and so, one of the clear tidal energy pros is that tidal energy plants have the potential to generate electricity in significant amounts.
As water has a higher density than air, even when the tide is moving at a slower speed, it can still generate energy. So, this makes it highly effective 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.
In contrast to solar or wind farms, a tidal power plant 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 spread across river estuaries. These structures 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 favorably to wind turbines and solar panels, which 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.
A tidal barrage or other systems can harm marine and sea life. Tidal barrages rely on the flow of water in and out of estuaries to produce energy. However, once put in place, the barrages alter water flow. The water is forced through the tidal turbines, which can disrupt the way marine life thrives and navigates low and high tides4.
The blades also pose a risk to any marine life that attempts to swim through them. They also pose a threat to aquatic plants due to a change in silt deposits changing the structure of the estuary.
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, tidal energy generation has to be able to withstand 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 challenging to work on.
The strongest currents are close to land. As a result, 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 because many fast 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.
Tidal energy is still relatively new. Despite the use of other renewable energy systems in certain areas worldwide, 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.
We are all aware of the power of water. From flowing rivers to the ocean's tides, the amount of energy that it generates is staggering. This is a plentiful source of energy and one that could help us 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 an energy source that we should look to harness. As technology advances and our need to go green becomes even more critical, 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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