Marine renewables unlikely to harm sea life

Assessing the environmental effects of marine energy is an important step in the permitting process before deploying devices.

To help reduce potential impacts, scientists are researching the acoustic impacts to fish and marine mammals and the effect of electromagnetic fields from power cables and devices.

Studies also investigate the potential for whales, dolphins and other marine mammals to entangle in mooring lines, and the impact of tidal power turbine blade strike on marine mammals and fish.

To that end, marine scientists from around the world spent the last four years reviewing numerous studies and other data on the possible environmental effects of marine renewable energy (MRE) devices and found that the potential impact to marine life is likely small or undetectable.

The above mentioned 4-year research aims to help streamline consenting processes and support the responsible development of marine energy around the world.

MRE systems can provide sustainable, predictable, low-carbon energy to coastal areas and large river basins. The energy can be generated locally, providing energy security, and stability for electrical grids in remote areas, as well as supplying power to areas that rely heavily on diesel fuel.

MRE devices can provide a new source of power at sea for applications that have relied on diesel, like offshore aquaculture, or on batteries, like ocean observation platforms and navigation aids.

Scientists also highlight that new uses, like desalination to produce freshwater for remote coastal areas and islands, and providing power to isolated resorts for electric boats and dive tank refills, could all be addressed with power generated by MRE devices.

MRE development also has the potential to bring employment to areas that are often far from other industries, ranging from jobs with the MRE companies, supply chain companies, environmental consultancies, as well as government regulators and advisers.

Like all renewable energy forms, MRE development aids in mitigating climate change by lowering greenhouse gas emissions compared to conventional power sources, and reducing the acceleration of ocean acidification, rising seawater temperatures, and rising sea levels that affect marine animals as well as coastal communities that depend on the ocean.

Wave and tidal devices can act as artificial reefs and refuges for fish and other marine organisms, sometimes providing new types of habitats.

If MRE project sites are set aside for specific uses, such as prohibitions against fishing, they may act as marine protected areas, allowing fish, shellfish like crab and lobster, and other sea life to thrive, sometimes spilling over into outside areas and boosting fishing opportunities.

In addition to the benefits of MRE development, the recently-released report said that a careful study must be undertaken to understand and minimize harm to marine animals, the habitats that support them, and the oceanographic and ecosystem processes that provide them life.

Only by understanding the risks from MRE can we assure that development occurs responsibly to protect valuable resources and allow them to continue to support the needs of humans in coastal communities and beyond.

The areas where MRE projects are sited are among the most energetic and least-understood areas of the oceans.

These areas present challenges to observing and documenting how marine animals might interact with the devices, mooring lines, cables, and other infrastructure, or how these installations might affect seafloor or open water habitats.

According to the report released by Ocean Energy Systems (OES)-Environmental, marine energy devices likely pose minimal impacts to marine life.

“We believe that small numbers of operational marine energy devices are unlikely to cause harm to marine animals, including marine mammals, fish, diving seabirds, and benthic animals; change habitats on the seafloor or in the water significantly; or change the natural flow of ocean waters or waves,” said Andrea Copping, an oceanographer with the U.S. Department of Energy’s Pacific Northwest National Laboratory (PNNL) and lead author of the report.

PNNL leads OES-Environmental for the United States on behalf of DOE. PNNL also manages Tethys, a knowledge management system that provides access to information and research about the potential environmental effects of offshore wind and MRE development.

The 30 scientists who authored the report investigated potential stressors, including: Underwater noise; Electromagnetic fields; Changes in oceanographic processes, including circulation, wave height, sediment transport patterns, water quality, and marine food webs; Encounters with moorings and cables; as well as the risk of a marine mammal or fish colliding with a device.

They found out that the risk to marine animals from underwater noise generated from MRE devices, along with electromagnetic fields (EMFs) emitted by export cables and MRE devices, may be candidates for retirement, because the evidence bases for these stressor-receptor interactions indicate that the actual risk to marine animals is low for single or small numbers of devices.

However, the report says that there is still uncertainty around some issues, as there have been relatively few sizable deployments of MRE devices around the world where data can be collected.

Scientists believe that as larger commercial MRE projects are developed in arrays, some of the above mentioned potential risks will need to be revisited.

The risk of marine mammals and fish colliding with moving parts of tidal and river turbines continues to be the greatest concern for regulators and stakeholders.

“Despite our findings, we still need more data about what might, or might not, happen to animals swimming close to operating turbines underwater. In the years to come, we will continue to focus our research on examining this issue and building our knowledge base to help progress this important renewable energy industry,” Copping said.

Tidal and river energy devices may pose a risk of collision to marine mammals, fish, and diving seabirds.

To date, there have been no observations of a marine mammal or seabird colliding with a turbine, and the limited number of interactions of fish in close proximity to a turbine have not resulted in obvious harm to the fish.

It is expected that collisions, if they occur, will be very rare events that will be difficult to observe in the fast-moving often murky waters.

In addition, the likely consequences of a collision are not known, with outcomes ranging from injuries from which the animal may recover to the death of the animal.

There is limited evidence and understanding of how marine animals behave in the presence of underwater structures; it is difficult to determine how well marine mammals, fish, and seabirds may be able to sense, react to, and avoid an operating turbine.

In the absence of this behavioral information, most progress in understanding collision risk focuses on understanding the presence of marine animals of interest in the vicinity of turbines, supported by computer modeling that simulates potential collisions.

It is clear that as the sector evolves and we see more projects roll out at sea, the industry will gain more knowledge on potential collision risks with underwater turbines and other subsea infrastructure.