Tidal Energy's Impact: Noise Pollution Or Quiet Revolution?

Tidal energy is a promising renewable energy source that harnesses the power of ocean tides to generate electricity. With the world seeking clean and sustainable alternatives to combat climate change, researchers are exploring the potential of tidal energy as a significant and consistent energy source. However, one of the key concerns surrounding tidal energy projects is their potential impact on the environment, specifically the possible noise pollution they may cause. As tidal energy technology is relatively new, there is limited research on its acoustic effects, and scientists are only beginning to understand how the noise generated by these structures may affect marine life. This introduction will delve into the potential advantages and disadvantages of tidal energy, with a focus on its acoustic impacts, and discuss the ongoing research and challenges in this emerging field.

Impact on marine life

Noise pollution in the ocean has increased dramatically over the last few decades. As most marine species depend heavily on sound for survival, this type of pollution is extremely harmful to marine wildlife. It not only disrupts their key life functions but can even lead to death in some cases. Marine mammals, such as whales, dolphins, and porpoises, are particularly vulnerable as they rely on sound for communication, locating mates and prey, avoiding predators, navigation, and territorial defense.

Underwater noise can cause various negative effects on marine mammals, including temporary or permanent hearing loss, behavioral and physiological changes, masking of sounds, injury, and death. Very loud noises can induce panic, causing them to ascend too rapidly and leading to decompression sickness and potential tissue damage from gas bubble lesions. Additionally, loud anthropogenic noises have been linked to mass stranding and breaching events worldwide.

The construction and operation of tidal energy infrastructure can contribute to noise pollution, which can have significant impacts on marine life. During the construction phase, activities such as pile driving, seismic work, and increased vessel traffic can generate considerable noise that affects different species in diverse ways. For example, the noise from pile driving can lead to hearing loss and behavioral changes in marine mammals.

To mitigate the impact of tidal energy projects on marine life, several measures can be implemented:

• Biodiversity-friendly elements: Structures can incorporate features such as intertidal areas or lagoons that provide feeding grounds during high water periods.
• Dual-cycle generation regime: Using a dual-cycle generation approach can help minimize habitat loss or change effects.
• Fish-passes: Similar to hydropower installations, fish-passes can be utilized to facilitate fish migration and reduce disruption.
• Tidal fences: In some cases, substituting a barrage with a tidal fence can reduce the environmental impact while still harnessing tidal energy.

By adopting these strategies, it is possible to balance the need for low-carbon energy sources with the preservation of marine ecosystems and the protection of sensitive marine life from the detrimental effects of noise pollution.

Noise pollution and sea creatures

Noise pollution in the ocean has increased dramatically over the past few decades, threatening the natural soundscape of the marine environment. This type of pollution is often overlooked, but its impacts are now being documented across all types of marine ecosystems. Marine life depends on sound for communication and survival, and in the ocean, light doesn't penetrate very far, so sound is especially important.

Noise pollution can interfere with the detection of acoustic signals, masking the sounds produced by marine wildlife. This can lead to changes in individual and social behaviour, such as increased anti-predatory behaviour, altered metabolisms, and hampered population recruitment, which in turn can affect the health and service functions of marine ecosystems. For example, sonar has been recorded to alter the feeding behaviour of endangered blue whales, causing them to stop feeding, increase their swimming speed, and move away from the sound source. Noise pollution can also cause hearing loss in marine animals, and it can decrease the communication range of marine mammals, causing them to change their vocal behaviour. For instance, increased ship noise has caused bottlenose dolphins to simplify their vocal calls, which may reduce the information content of their calls and decrease effective communication.

The potential impact of tidal energy on noise pollution is a concern for researchers studying coastal power. Any machine with moving parts makes noise, and the whirring and pounding of wave and tidal turbines could interfere with marine animals' communication and navigation. As the technology is relatively new, there is not much research on the noise created by wave and tidal power, but marine biologist Jakob Tougaard has studied the intensity of noise created by a prototype wave power generator, finding that the noise produced was "very weak" and too quiet to disrupt the communications of local sea creatures. However, another marine biologist, Matt Pine, is studying the potential impact of noise pollution on sea life in Kaipara Harbour, New Zealand, where tidal power generators are being considered for installation. Pine and his team are particularly concerned about the impact on crustaceans, which need to hear cues from the shoreline to reach the shore and complete the transition to adulthood.

To reduce noise pollution in the marine environment, policies are needed to mitigate the sounds of sonar equipment, seismic air guns, pile driving, and construction, as well as propeller noise from ships. Quieter technologies also need to be developed, and innovative technologies and artificial intelligence can be used to reduce and monitor noise pollution.

Environmental effects of tidal barrages

The environmental effects of tidal barrages are complex and multifaceted. As a form of renewable energy, tidal power generated through barrages has the potential to significantly reduce carbon dioxide emissions and combat climate change. However, there are also concerns about the potential negative impacts on aquatic wildlife and ecosystems.

One of the main concerns is the impact of underwater noise pollution on marine life. Tidal barrages involve the use of large turbines that can generate significant amounts of noise. In the ocean, sound travels farther than it does in air, and marine animals depend on sound for communication and navigation. The noise from tidal turbines could potentially interfere with the natural sounds of the ocean, such as whale song and the snapping of shrimp, and impact the behaviour and communication of marine species. For example, research in Kaipara Harbor, New Zealand, has raised concerns about the potential impact of noise pollution on crustaceans, which rely on auditory cues to navigate to the shore during a critical stage of their life cycle.

In addition to noise pollution, tidal barrages can also cause habitat changes and disruptions to tidal patterns. The construction and operation of tidal barrages can alter water flow, salinity levels, and ambient conditions, which can have cascading effects on plant and animal life. For example, changes in salinity levels within lagoons created by barrages can harm both plant and animal life. Additionally, the presence of large structures and turbines in the water can pose a risk of collision for marine animals and fish, with rotating turbine blades presenting a potential hazard.

However, it is important to note that the impact of tidal barrages can vary depending on the specific site and local geography. Some companies, such as Tocardo, are developing innovative turbine solutions that aim to minimise the environmental impact. For example, the Subhub platform is designed to be seabed-mounted, maintaining the seascape and navigation channels while also being beyond the diving depth of most birds. Additionally, studies in the Netherlands have suggested that porpoises may be able to use the sounds produced by turning turbines to locate and avoid them, reducing the risk of collisions.

Overall, while tidal barrages have the potential to provide a significant source of clean, renewable energy, more research is needed to fully understand and mitigate their environmental impacts. Achieving cost reductions, developing durable devices, and minimising environmental effects are crucial to improving the commercial viability of tidal energy and harnessing its benefits sustainably.

Ecological impact of construction

The ecological impact of constructing tidal energy infrastructure can be significant. Firstly, the construction process itself can result in high vessel traffic, noise, and disturbance of the seabed. This can have immediate consequences for marine life, especially in sensitive habitats such as estuaries, lagoons, and spawning areas. For example, the noise generated during construction can interfere with marine animal communication and navigation, which are crucial for their survival.

Secondly, the physical presence of tidal energy infrastructure can alter the ambient flow field and water quality. Large turbines placed in tidal streams can disrupt the natural flow of water and affect water salinity levels, which in turn can harm plant and animal life. The rotating turbine blades also pose a risk of collisions with marine animals and fish, further threatening their habitats.

Thirdly, electromagnetic fields from power cables associated with tidal energy infrastructure can deter sensitive species from the area. The electromagnetic interference can impact marine animal behaviour and navigation, leading them to avoid the area. This can have a cascading effect on the ecosystem, disrupting food chains and ecological balances.

Additionally, the construction of tidal barrages or dams can cause significant land disruption within the tidal range. Barrages are structures placed across rivers, bays, or estuaries to capture tidal energy. The operation of these barrages involves controlling water levels and flow through sluice gates, which can alter natural tidal patterns and impact the surrounding environment.

While tidal energy offers the promise of renewable and clean energy, the ecological impact of its construction and operation must be carefully considered and mitigated. More research is needed to fully understand the potential environmental consequences and develop strategies to minimize any negative effects on aquatic wildlife and their habitats.

Noise pollution and navigation

Noise pollution is a significant concern with the development of tidal energy. The construction and operation of tidal energy arrays based on large underwater structures may negatively impact sea life and their habitats. The ambient flow field and water quality may be affected, and there is a risk of wildlife collisions with the rotating turbine blades.

The noise produced by tidal energy devices can disrupt the communication and navigation of marine animals, which rely on sound for these essential functions. In the ocean, light does not penetrate far, but sound travels farther than through air, so marine life depends heavily on sound. The noise from tidal turbines could potentially drown out natural sounds in the sea, such as whale song and the clacking of snapping shrimp.

Research on the noise produced by wave and tidal power is still limited, partly because the technology is new, and it is not yet widely expected to be a significant problem. However, marine biologists like Matt Pine are studying the potential impact of noise pollution on marine life. Pine's research in Kaipara Harbor, New Zealand, where tidal power generators are being considered, focuses on the potential effects on crustaceans, especially during their larval and juvenile stages, when they need to hear cues from the shoreline to reach safety.

The potential noise pollution from tidal energy devices must be carefully considered, as it could have significant ecological impacts, particularly on bird feeding areas and estuarine ecosystems. The selection of renewable energy sources for power plants must be done carefully to avoid causing harm to the environment.

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