Atlantic Offshore Wind Transmission Study

The Atlantic Offshore Wind Transmission Study evaluates coordinated transmission solutions to enable offshore wind energy deployment along the U.S. Atlantic Coast, addressing gaps in existing analyses.

State renewable energy targets and the national goal of 30 gigawatts (GW) of offshore wind energy by 2030 show strong government support for offshore wind energy development. Meeting the goal of 30 GW by 2030 could unlock a pathway to 110 GW by 2050. Ensuring adequate and timely transmission access for offshore wind is critical to achieving state and national deployment goals.

The Atlantic Offshore Wind Transmission Study will evaluate multiple pathways to offshore wind goals through coordinated transmission solutions along the U.S. Atlantic Coast in the near term (by 2030) and long term (by 2050) under various combinations of electricity supply and demand while supporting grid reliability and resilience and ocean co-use.

Map of the midsection of the U.S. East Coast, colored by offshore water depth from less than 30 to over 90 meters and overlain with labeled locations of offshore wind project activity as of 4/20/21. Numbered from north to south, the activity areas are: 1. New England Aqua Ventus I off southern Maine; 2–11. Bay State Wind, Park City Wind, Vinyard Wind 1 + Residual, Beacon Wind, Mayflower Wind + Residual, Shell/Atkins/Ocergy Floating Demonstration, Liberty Wind, Sunrise Wind, Revolution Wind, and South Fork off the southeastern coast of Massachusetts and Rhode Island which are all in a lease area; 12. Block Island Wind Farm southeast of Connecticut; 13. Fairways North Wind Energy Area off Long Island, New York; 14. Fairways South Wind energy Area off southern Long Island, New York; 15. Hudson North Wind Energy Area off the Hudson Bay, New York; 16. Central Bight Wind Energy Area further offshore from Hudson North; 17. Hudson South Wind Energy Area east of central New Jersey; 18–19. Empire Wind and Empire Wind II next to Hudson North; 20. Atlantic Shores Offshore Wind off southeast New Jersey; 21. Ocean Wind + Residual just south of Atlantic Shores in the same lease area; 22–23. Garden State Offshore Energy and Skipjack in a lease area just east of Delaware; 24. MarWin + Residual lease area east of the border between Delaware and Maryland; 25–26. Coastal Virginia Offshore Wind – Commercial and Coastal Virginia Offshore Wind – Pilot in a lease area east of Norfolk, Virginia; 27. Kitty Hawk in a lease area off northeast North Carolina; 28–29. Wilmington West Wind Energy Area and Wilmington East Wind Energy Area just southeast of North Carolina; 30. Grand Strand Call Area off northeastern South Carolina; 31. Winyah Call Area in deeper waters off South Carolina; 32. Cape Romain Call Area near the southeastern coast of South Carolina; and 33. Charleston Call Area in deeper waters than Cape Romain off southeastern South Carolina.
The locations of the current U.S. Atlantic Coast offshore wind projects being considered or developed as of April 30, 2021. Image from the Offshore Wind Market Report: 2021 Edition

This 2-year study will:

  • Evaluate coordinated transmission solutions to enable offshore wind deployment along the U.S. Atlantic Coast, addressing gaps in previous analyses
  • Compare different transmission technologies and topologies, quantify costs, assess reliability and resilience, and evaluate key environmental and ocean co-use issues
  • Produce timely results to inform decision making and offer feasible solutions, data, and models that may benefit stakeholders in their own planning processes.

Researchers from NREL and Pacific Northwest National Laboratory will conduct this study by creating multiple scenarios of interstate, interregional transmission topologies (size, shape, branching, and location of transmission lines) between now and 2030 and 2050.

Project Objectives

The Atlantic Offshore Wind Transmission Study, funded by the U.S. Department of Energy Wind Energy Technologies Office, is designed to:

  • Identify scenarios and pathways of offshore wind energy deployment with transmission topologies (such as radial lines, backbones, or a meshed network), sequencing, and build-out in U.S. Atlantic waters between now and 2030 and 2050 that meet or exceed reliability and resilience criteria
  • Quantify impacts—such as economics, reliability, and resilience—of multiple offshore wind energy and transmission scenarios and pathways, including during periods of system stress caused by typical and extreme weather situations
  • Characterize and compare transmission technologies for the different scenarios, including land-based and offshore substations and cabling, as well as cost and benefit trade-offs for high-voltage alternating current and direct current technologies
  • Identify if there is a critical point (either in time or in gigawatts of offshore wind energy deployed) after which the benefits of a coordinated transmission framework will outweigh the benefits of radial generator lead lines (transmission lines from each offshore wind plant to shore)
  • Evaluate reliability and resilience of various topologies, considering component reliability and cable failures
  • Collect data and develop models that are readily usable by the offshore wind energy industry for conducting analyses and studies.

All activities will closely engage with and draw expertise from a technical review committee that will provide input throughout the project on assumptions, scenarios, and the modeling framework.

Project Schedule

In the first year (Nov. 1, 2021–Oct. 31, 2022), the team will:

  • Create a technical review committee with a wide range of stakeholders and subject-matter expertise
  • Establish plausible land-based and offshore transmission expansion scenarios for 2030 and 2050 end dates, including feasible routing, points of interconnection, and landing points that consider environmental and community impacts
  • Identify the critical point at which the benefits of a coordinated transmission framework will outweigh the benefits of a generation lead-line approach and assess how transmission will evolve over time
  • Begin to evaluate system operations, cost, and reliability of the established, plausible scenarios.

In the second year (Nov. 1, 2022–Oct. 31, 2023), the team will:

  • Complete production cost modeling, capital investment estimation, and reliability studies
  • Perform stability analysis, transient-fault-behavior analysis, and resilience studies for the land-based and offshore grid
  • Deliver the final report.


Offshore Wind Data Collection, Modeling Framework, and Formation of Technical Review Committee


Transmission Expansion Planning

Envision future grids


Production Cost and Resource Adequacy

Simulate operability


Technology Characterization

Evaluate cost, performance, and siting


Reliability and Offshore Grid

Evaluate reliability of the grid by studying contingency analyses


Resilience and Extreme Weather

Evaluate grid operation during cascading events due to extreme weather


Review by Technical Review Committee and Final Report

Project Tasks

The project will include seven tasks, the first six of which will be conducted contemporaneously, with ongoing findings influencing the number of iterations needed:

  1. Offshore Wind Data Collection, Modeling Framework Selection, and Technical Review Committee Formation: The team will assemble a technical review committee composed of representatives from regional transmission organizations/independent system operators, utilities systems, state agencies, original equipment manufacturers, and others to provide input, feedback, and guidance to ensure the highest degree of relevance and usefulness of the study results.

  2. Transmission Expansion Planning: The team will evaluate the cost-optimal generation and transmission options under a variety of conditions and determine plausible scenarios using input from the technical review committee and NREL's Regional Energy Deployment System model.

  3. Production Cost and Resource Adequacy Modeling: To simulate operability, the team will use PLEXOS to model production costs and NREL's Probabilistic Resource Adequacy Suite to model resource adequacy.

  4. Technology Characterization: The team will conduct a preliminary feasibility analysis of offshore transmission system technologies, including marine substations, transmission from marine substations to land-based substations, and undersea cabling for the scenarios developed in previous tasks. The team will also collect information to screen for cable routes that avoid military-sensitive areas, cultural areas, fisheries, and other areas of key ocean use to ensure that cable routes meet marine regulations and address environmental considerations.

  5. Reliability and Offshore Grid Evaluation: To evaluate the reliability of the grid, the team will use the Chronological AC Power Flow Automated Generation Tool to translate modeled production costs into hourly power flow models, perform dynamic contingency analysis with the Dynamic Contingency Analysis Tool, and  evaluate dynamic stability impacts of offshore wind generation using an impedance scan tool. They will also use power systems computer aided design (PSCAD) for electromagnetic transient simulations and ETRAN for electromagnetic-transient-phasor cosimulations to evaluate the performance of offshore grid topologies during fault events.

  6. Resilience and Extreme Weather Assessment: To evaluate grid operation during dynamic cascading events due to extreme weather, the team will use the Electric Grid Resilience and Assessment System.

  7. Technical Review Committee Review and Final Report Delivery: The team will prepare a final report for technical review.


Melinda Marquis

Offshore Wind Grid Integration Lead – National Renewable Energy

Henry Huang

Laboratory Fellow – Pacific Northwest National Laboratory