What is Tidal Energy?

Tidal pool

Tidal energy is a pretty cool technology that takes the tide shifts within the ocean and transforms them into useable energy sources. It’s not as complicated a process as it seems and in almost all real world applications of the technology simple water turbines are turned by the flow of ocean water to generate electricity. It’s a useful way for countries to lower their dependence on fossil fuels, and a cool technology that makes use of one of our most massive natural resources.

The Benefits of Tidal Energy

Unlike many sources of energy used today like fossil fuels tidal energy is renewable. It relies on the change of the ocean’s tides and is something that happens regularly on a daily basis. By harnessing this source of power it would be easy to generate more energy for use without burning through fuel and creating harmful toxins.

Lower Carbon Footprint

While carbon dioxide is released during the development process of these tidal energy plants, once they are set in place no more carbon is given off from them. This makes tidal energy plants a highly effective way at reducing pollution out into the atmosphere. Replacing more harmful energy sources with tidal energy is a good step toward a more healthy energy infrastructure.


Not only is tidal energy good for the environment, it’s also highly affordable. The power just keeps on being produced each and every day without much input or maintenance from anyone. Eventually the turbines used will have to be replaced, but as long as they are designed from long-lasting materials they should hold up for several years in the harsh ocean water, more than long enough to be worth the initial investment.

The Downfalls of Tidal Energy

While there are a lot of benefits that come along with tidal energy, there are some downfalls as well. For one thing it has a major impact on the ecosystems of the ocean. Every turbine placed has the potential to harm creatures and dams can cause serious migration issues if not implemented carefully. This type of energy also isn’t as on-demand as fossil-fuel driven energy, and that’s one of the biggest hurdles that has to be overcome.

Energy Isn’t Always Available When It’s Needed

The tides come in and go out around twice a day in most locations, so you have two high tides and two low tides throughout the day and night. Since most tidal generators are only going to be able to create power when the tides are going from high to low tide, and likely only around half of that time will be usable by many of the systems, energy is generated between 3 and 6 hours a day from these systems. During those two energy generation windows each day a significant amount of power is generated, but that’s not the only time people want to make use of energy. There are some advanced turbines that can gather energy during both the flow and ebb of tide doubling the potential time to grab energy throughout the day. Excess energy could be stored in battery banks, but batteries are still very expensive and not all that effective for large amounts of energy. In general there are times when tidal energy just can’t be used that effectively because energy demands aren’t there, and there are other times when the demand is there and the tides aren’t working to create the energy leaving people to rely on other methods instead.

Damage to the Environment

Ecosystems in the ocean are highly complex. Fish are constantly migrating and blocking any of those migration paths can have a serious impact on the health of a species. That’s why tidal energy plants can cause significant damage and do in some instances. Dams potentially block delicate estuaries and can even lead to irregular salination levels that harm plants and organisms in the area. Since large-scale tidal generators aren’t in place in most areas of the world yet other than a few key locations, there isn’t a lot of evidence showing the extent of damage that these tools cause.


Tidal Barrage in France

Getting the Energy

There are several different ways that tidal energy is harnessed depending on the location and the conditions present there.

Tidal Turbines

If you’ve ever witnessed a windmill turning then you should be able to envision a tidal turbine running down in the ocean. It operates on the same general principle. The turbines are commonly placed in front of entrances to bays and rivers where water flows significantly faster than in the open ocean. These turbines spin rapidly as water passes over them and that spinning motion generates usable electricity. The main benefit to using tidal turbines rather than windmills to create electricity is that water is 832 times denser than air according to Marine Current Turbines. That means marine turbines generate significantly more energy than wind turbines do when sized the same. They are often added at the base of bridges and around straits and inlets as well where water speeds are higher.

The Barrage Method

In the barrage method of gathering tidal energy a large dam is built in the ocean to force water through a series of turbines. It’s a technique that’s used in the Rance Tidal Plant. The way that the dam works is pretty simple. A dam is installed that blocks most of the water from reaching shore or from making it back out to the sea after it’s already at shore. The dam leaves a bit of space underneath and has a series of sluice gates that open and close to allow water through toward shore when the tide rises.

The dam allows water to come in and create a section significantly higher than the surrounding sea level by letting water flow in and shutting it in. This forces water down underneath the dam through a series of turbines that generate electricity. That means each time the tide comes in, which is a few times a day, substantial levels of power are generated.

The Tidal Lagoon Method

A tidal lagoon relies on creating an artificial pathway for seawater to pass through. One key benefit of using this sort of method is that it won’t damage existing sea ecosystems quite so much because it’s an artificial ecosystem. The basic idea behind a lagoon is to open up a tunnel or similar passageway that’s connected to the sea. When high tide comes in this passageway would fill up with water rapidly and direct that water back out to sea. The water would move through the passageway at high speeds and could turn a large number of turbines on the way back to the ocean. It’s a simple concept that could generate impressive amounts of energy in many oceans around the world.

Tidal Energy Versus Solar

Both solar energy and tidal energy are popular renewable options that are being used in places around the world and considered for use in others. There are a couple of major differences between the two though. The first main difference is that tidal turbines are much more efficient than solar panels are. This means that significantly more energy is produced from these turbines than a similar sized solar setup. However, tidal energy can only be generated in a select number of places around the world, that’s not a limitation that solar panels face. While there are locations in the world that are better for solar panels because they receive more sunlight, solar energy can be collected just about anywhere on the face of the earth, opening up the area for energy collection much more. Either way both options are effective for generating the power we need, it’s just figuring out how to best use that power that is the real challenge.

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