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Assessment of Environmental Effects and Monitoring Efforts for Ocean Wave, Tidal, and Current Energy Systems

Start: 2010 | End: 2024

OES-Environmental (Task 4), led by the U.S. with the Pacific Northwest National Laboratory (PNNL) is an international collaborative project amongst member nations of the International Energy Agency's Ocean Energy Systems (OES) collaborative which synthesizes information and scientific research about MRE and the environment on a global scale into collaborative reports and documents. Additionally, OES-Environmental hosts workshops and webinars to bring researchers together around environmental effects research and supports environmental effects tracks at international conferences.

The U.S. Department of Energy partnered with the International Energy Agency's Ocean Energy Systems (IEA OES) initiative to create Tethys, a database and knowledge management system which hosts OES-Environmental and provides access to information and research about the potential environmental effects of offshore wind and marine renewable energy development.

Phase 1: 2010-2013
OES-Environmental (the task formerly known as Annex IV) member countries collaborated to create a searchable, publicly available database of research and monitoring information to evaluate environmental effects. The database, housed in the Tethys Knowledge Base, includes data from MRE projects, research studies and case study reports. Two international scientific workshops were held to provide input for the database and to inform the 2013 Final Annex IV Report.

Phase 2: 2013-2016
OES-Environmental (the task formerly known as Annex IV) was continued for a second phase, continuing the collection, analysis, and dissemination of information on environmental effects of MRE development. During Phase 2, additional emphasis was placed on creating a collaborative space or commons for interaction among researchers, developers, regulators, and stakeholders. Phase 2 culminated with the preparation of the 2016 State of the Science Report, and partnership with the EWTEC 2015 international conference.

Phase 3: 2016-2020
OES-Environmental was approved for a 4-year extension consisting of three interrelated tracks: (1) information gathering and analysis, (2) information dissemination, and (3) engaging the community to support research and monitoring needs. Phase 3 culminated with the completion of the 2020 State of the Science Report.

Phase 4: 2020-2024
OES-Environmental has been approved for Phase 4 and will continue its efforts.


The OES-Environmental 2020 State of the Science Report: Environmental Effects of Marine Renewable Energy Development Around the World compliments and serves as an update to the 2013 Final Report for Phase 1 of OES-Environmental and the 2016 State of the Science Report. Its content reflects the most current and pertinent published information about interactions of marine renewable energy (MRE) devices and associated infrastructure with the animals and habitats that make up the marine environment. It has been developed and reviewed by over 60 international experts and scientists from around the world as part of an ongoing effort supported by the OES collaboration that operates within the International Technology Cooperation Framework of the International Energy Agency (IEA).

The 2020 State of the Science Report on the environmental effects of MRE development begins with a set of environmental questions that define investigations (Chapter 2) and continues with specific information about stressor/receptor interactions of importance (Chapters 3–9), delves into technologies for monitoring interactions with marine animals (Chapter 10), addresses a series of management and planning measures that may assist with responsible MRE development (Chapters 11–13), and concludes with a potential path forward (Chapter 14). The Executive Summary provides a broad overview of the material in the full report and the Short Science Summaries provide highlights from each chapter. 

Individual Chapters: 

Download the Full Report

Executive Summary

Supplementary Material 

Some of the chapters in the 2020 State of the Science Report contained more information and technical details than could be accommodated in the main report. These materials appear as supplementary materials, which are linked within the 2020 State of the Science Report itself and available for download on the 2020 State of the Science Report Supplementary Materials page.


Tethys is a database and knowledge management system which hosts OES-Environmental and provides access to information and research about the potential environmental effects of offshore wind and marine renewable energy development.

f you would like to contribute by submitting a project site or research study metadata form, please visit here


Tethys Stories feature information on news, events, research, and projects relevant to wind and marine renewable energy development activities across the globe. Stories are contributed from individuals working in the field, and provide insight into advancing the energy industry in an environmentally responsible manner.



Dissemination of information is presented at various conferences and workshops.

Here you can assess the list of past conferences and workshops

Tethys also hosts regular webinars as a means to effectively disseminate new information and research efforts to a large international audience of stakeholders. Anyone is welcome to attend these live webinars and participate in a live question and answer session with the presenters. 

You can assess the webinar archive here

You can sign up to receive invitations to new live webinars here

The OES is organised under the auspices of the International Energy Agency (IEA) but is functionally and legally autonomous. Views, findings and publications of the OES do not necessarily represent the views or policies of the IEA Secretariat or its individual member countries.