In September 2020, on behalf of the International Energy Agency’s Ocean Energy Systems collaborative, PNNL released the “2020 State of the Science Report: Environmental Effects of Marine Renewable Energy Development Around the World,” summarizing scientific progress to date on marine renewable energy devices and their potential interactions with the marine environment, including the animals that live there and the habitats that support them. The report can help inform project siting, engineering design, operational strategies, and monitoring program design, and is targeted for use by many different types of stakeholders, such as regulators, engineers, researchers, policymakers, and more. Prior to releasing the final report, PNNL researchers and other authors released a draft report in June, conducted public webinars, and elicited stakeholder feedback.
Although marine energy technologies have the potential to provide a suite of societal benefits—from marine debris cleanup to new drinking water sources—they could also pose some risks if not well-studied and documented. Therefore, monitoring potential interactions between devices and marine animals, habitats, and the environment is vital. Over the past decade, the understanding of potential environmental effects across multiple scales has significantly increased, thanks to environmental monitoring. The “2020 State of the Science Report” represents the most up-to-date knowledge on environmental effects of marine renewable energy, based on studies and monitoring from publicly available, peer-reviewed scientific literature and reports. The study focused on analyzing key potential stressors, including:
- Underwater noise
- Electromagnetic fields
- Changes in oceanographic processes, including circulation, sediment transport, and water quality
- Encounters with moorings and cables
- The risk of a marine mammal or fish colliding with a device.
Funded by WPTO and Ocean Energy Systems, more than a dozen PNNL researchers served as authors, in addition to more than a dozen other authors from around the world. After synthesizing four years of global research, the report found the potential impact to marine life is likely small or undetectable. However, uncertainty still exists around some issues, which will continue to be monitored and studied.
Key report findings include the following:
- To date, no marine mammals, fish, or seabirds have been observed colliding with a marine renewable energy device.
- There was no evidence that underwater noise emitted from marine renewable energy devices will significantly alter the behavior or cause physical harm to marine animals.
- The ecological impacts of electromagnetic fields emitted from power cables from single marine renewable energy devices or small arrays are likely to be limited, and marine animals living in the vicinity of these devices and export cables are not likely to be harmed by emitted electromagnetic fields.
- Overall, changes in habitat caused by marine renewable energy devices and arrays are likely to pose a low risk to animals and habitats if projects are sited to avoid rare or fragile habitats.
- Marine renewable energy cables and lines do not have loose ends or sufficient slack to create an entangling loop, so the risk of entanglement is considered very low.
- The growth of marine renewable energy will result in the increasing use of marine space and the potential for conflict with existing ocean uses, which can be partially addressed through implementation of marine spatial planning.