Tidal Energy

Benefits

Tidal energy has an essential characteristic that no other renewable energy system has, total predictability. Wind and solar energy, two widely utilized renewable energy sources, are not as predictable as tidal energy as they are greatly influenced by varying weather conditions that can be unpredictable, particularly during a time of climate change. However, tidal energy is unhindered by extreme weather and purely controlled by the consistent cyclical patterns of the earth, moon, and sun.

As the earth rotates, the gravitational pull of the moon onto the earth acts upon our oceans. The area of the earth that is farthest and closest to the moon often experience high tide due to the stretch-like effect the moon has on the earth as it rotates. The high and low tides caused by the moon and earth's orbits are 100% reliable as these movements are guaranteed to occur every single day. Unlike other renewable sources, tidal patterns can be predicted with pinpoint accuracy years, even decades, in advance. This unparalleled predictability allows for precise energy generation forecasts, making tidal power an exceptionally reliable and manageable renewable energy source.

Tidal energy is also the most efficient of all renewable energy systems. As water is approximately 832 times denser than air, each rotation in a tidal turbine provides significantly more energy than if it were being rotated by wind due to the fact that higher density means higher stored energy. Additionally, the conversion rate of mechanical energy into useable electrical energy in tidal systems is approximately 90%, higher than every single renewable energy source besides hydroelectricity. If fully utilized, tidal energy could generate 150-800TWh per year, enough to fully power up to 56 million homes.

Tidal energy also takes up far less space than solar or wind energy. The largest tidal energy plant in the world is a 12.5km long wall, while the largest solar farm in the world is 43km² and the the biggest wind farm in the united states is 12.9km². As they take up significantly less space, the environmental impact due to habitat disruption is greatly limited compared to other energy systems.

The area utilized by tidal farms also offers a unique opportunity for multipurpose development, extending far beyond mere energy production. Due to the nature of tidal power systems being situated near or below water, the surface area above and around these installations can be ingeniously repurposed for various beneficial uses. This dual-functionality approach significantly enhances the overall value and efficiency of the land use.

A prime examplpe of this innovative land utilization is the Sihwa Lake Tidal Power Station in South Korea. This facility has brilliantly transformed what could have been single-purpose industrial space into a vibrant, multifaceted destination. The station has become a notable tourist attraction, drawing visitors with an array of leisurely and recreational activities. The excess space provided by the tidal plant has been thoughtfully developed to include scenic walkways, cycling paths, and observation decks, offering breathtaking views of the surrounding seascape and the impressive tidal infrastructure.

Moreover, the area has been equipped with educational facilities, allowing visitors to learn about tidal energy and marine ecosystems. Cafes, rest areas, and even small parks have been integrated into the design, creating a harmonious blend of sustainable energy production and public recreational space. This approach not only maximizes the use of the area but also fosters public engagement and understanding of renewable energy technologies.

Concerns

Despite the numerous advantages and potential benefits of tidal energy, it's important to recognize that its application is not universally feasible across all global locations. Tidal energy production is primarily confined to specific coastal areas that meet certain geographical and hydrological criteria. The most crucial factor determining the viability of a tidal energy installation is the tidal range - the difference in water height between high and low tides.

For optimal energy production and economic feasibility, tidal energy plants typically require locations with a tidal range of around 10 meters or more. This significant difference in water levels is necessary to generate sufficient power and make the installation economically viable. Such pronounced tidal ranges are not common worldwide and tend to occur in relatively few coastal regions, often where unique topographical features amplify tidal effects.

Areas with smaller tidal ranges, while still experiencing tides, may not produce enough energy to justify the substantial infrastructure investment required for tidal power systems. This is an additional issue with tidal energy systems- high initial investment costs. Although the longevity and reliability of tidal power plants ensure that these initial expenses are eventually offset by decades of stable energy production and minimal fuel costs, the sheer magnitude of the initial investment often deters potential investors and policymakers. Additionally, as the few tidal power plants that exist differ in shape and size, the supply chain for creating more plants is practically non-existent, raising expenses of tidal energy production.

Additionally, tidal energy systems can be detrimental to local environments and ecosystems as well. The turbines and gates themselves can cause issues in possibly catching fish and other aquatic animals in their blades. The artificial water levels and adjusted salinity created by barrages and lagoons could harm plant and animal life, displacing populations and disrupting coastal ecosystems.

However, when barrages were utilized in the La Rance Tidal Power Plant in France, environmental impacts were seen as minimal. After opening in 1966, sand-eels and plaice were seen disappearing from the ecosystem and cuttlefish and seabass entering. Although population displacement did occur, major additional ecological impacts were not identified and was classified as richly diversified by 1976, ten years after its opening, proving that large tidal energy plants could function without devastating the local environment.

In fact, the environment could possibly hurt tidal energy plants instead. As global warming has irreversibly damaged our planet, it has melted major glaciers and ice sheets as well, contributing to the already rising seas levels due to the thermal expansion of the ocean due to the rising heat. If sea levels continue to rise, the already scarce locations suitable for tidal energy generation will diminish even further by altering amphidromic points and resonance. Amphidromic points are areas with little to no tidal range that can adjust how the tide hits the coastline. When these amphidromic points are adjusted, the tidal range in a specific area can change significantly, potentially rendering it unsuitable for tidal energy production. This alteration in tidal dynamics can affect the efficiency and feasibility of harnessing tidal energy in that region. Resonance is the oscillation frequency of the waves unique to each coastal region that is created by the depth, width, and shape of the coast. With rising sea levels, the resonant frequency of the area can increase or decrease, brining it closer or farther away from the moon's tidal cycle of 12.42 hours. The relation of the coast's frequency to the moon's tidal cycle is essential as the closer the frequency is to the moon's cycle, the higher the tidal range would be. Potential alterations in resonant frequency due to increased depth could additionally decrease the optimal locations available for tidal energy production.