New Report Provides Update on Environmental Effects of Marine Renewable Energy

In the drive toward clean and reliable energy goals, the ocean offers potential for power generation from waves, tides, ocean currents, and temperature and salinity gradients. Yet there are lingering questions and data gaps around the potential environmental effects of marine renewable energy (MRE). The 2024 State of the Science report was released today,  providing the most up-to-date global information on the potential ways MRE may affect the marine environment and to support consenting, or permitting, processes for the responsible development of MRE technology.

“This work represents the best available science on the environmental effects of marine renewable energy,” said Tim Ramsey, program manager for marine energy at the Department of Energy (DOE) Water Power Technologies Office. “Information like this can help accelerate deployment, paving the way toward decarbonization, as well as helping to meet energy needs, such as for remote coastal communities.” 

The report is released by OES-Environmental, a working group focused on examining the environmental effects of MRE, under the International Energy Agency’s Ocean Energy Systems (OES). OES-Environmental is led by DOE and implemented by Pacific Northwest National Laboratory (PNNL), with participation from 16 of the 22 OES countries. OES-Environmental work is also supported by Tethys, a knowledge management system developed and managed by PNNL that provides access to information and research about the potential environmental effects of offshore wind and MRE development.

2024 State of the Science report development

The report serves as an update to the 2020 State of the Science report, highlighting new research and levels of understanding gained over the past four years. The report also examines potential social and economic effects of MRE and provides tools that adapt scientific information into accessible forms for general understanding, workforce development, and regulatory processes. In developing this report, OES-Environmental identified 86 MRE projects globally for which significant environmental assessments and monitoring have taken place: 40 tidal, 39 wave, 2 ocean current, and 5 riverine. 

The report was funded by DOE’s Water Power Technologies Office and OES. Spanning eight countries, there were more than a dozen experts who served as authors, including seven PNNL researchers, and an additional two dozen experts who contributed to the report. The report also had a comprehensive review process that entailed both an expert review of individual chapters and a public review of the draft report. There were almost 70 reviewers from 12 different countries.

Updates on key device-environment interactions

The 2024 State of the Science report summarizes findings around potential stressor-receptor interactions, such as effects of underwater noise, electromagnetic field emissions on sensitive marine animals, displacement of marine animals, as well as potential changes in marine habitats. Most of the available information is derived from research and monitoring around single MRE devices or small arrays and indicates that, for most interactions, harm is limited or unlikely. Further research and monitoring are needed to determine the risk from other environmental interactions, such as the risk of collision to marine animals from tidal or riverine turbines, and to understand potential effects of larger arrays. 

Using existing research to “retire” certain risks

Researchers have built evidence bases for each of the key stressor-receptor interactions, so that past research can help streamline regulatory processes for current and future MRE projects. Several stressor-receptor interactions and their associated evidence bases have been vetted by experts to determine that they can be “retired” for small numbers of devices (one to six). These interactions are underwater noise, electromagnetic fields, changes in habitats, and changes in oceanographic systems. 

The risk retirement process, as developed by OES-Environmental, allows for determining which interactions can be considered retired or low risk and may not require data collection for every new MRE project. Instead, regulators, advisers, device developers, consultants, and others can use data from other deployments or jurisdictions to help support the assessment of new projects. The report includes case studies that demonstrate the effective application of such information to justify retiring certain stressor-receptor interactions, reducing the amount of data that needs to be collected at each new site and allowing resources to be focused on those interactions that are less certain.

Tropical and subtropical ecosystems

As MRE development expands into tropical and subtropical regions, potential environmental effects on the unique habitats and species need to be assessed. While there is no stressor-receptor interaction specific to tropical and subtropical ecosystems, MRE technologies may differ—such as extracting power from temperature gradients, which is unique to these regions. 

Additionally, these ecosystems are characterized by high biodiversity and contain unique and sensitive habitats. To better understand the environmental effects of MRE in these regions, all the species of an ecosystem and the interactions between species and MRE devices need to be considered. In tropical and subtropical regions, the development of MRE may also have significant socioeconomic effects if the communities’ needs are not considered from the inception of a project.

Education and outreach

Researchers are conducting outreach with various audiences to increase awareness of MRE and how it can be beneficial. Outreach and educational resources for understanding this renewable energy source range from worksheets for students to informational podcasts to career panels for the future workforce to understand the capabilities of MRE and its field of research. As the MRE industry continues to expand, there will be a growing need to develop a skilled and diverse workforce. Providing educational opportunities can help increase awareness and build career pathways for students to join the MRE industry, suggestions for which are covered in the report.

What’s coming with the next wave of research

The release of this report marks the completion of the fourth phase of OES-Environmental, which has been conducting research over the past 14 years (2010–2024).

OES-Environmental is starting the fifth phase of research that can expand research in the following areas:

• Environmental acceptability
• Environmental effects of off-grid MRE applications
• System-wide effects (testing larger arrays of devices)
• Social and economic effects of MRE.

“This report gathers the sum of international knowledge that will help the ocean energy industry innovate and advance technologies while assuring the health of the oceans,” said Matthijs Soede, OES chair.