Atlantic Offshore Wind Transmission Study

The Atlantic Offshore Wind Transmission Study, co-led by NREL, 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 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 evaluates 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 northern section 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 farm areas and projects.
The locations of the current U.S. North Atlantic Coast offshore wind projects being considered or developed as of August 2023. Map by NREL
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 farm areas and projects.
The locations of the current U.S. Mid-Atlantic Coast offshore wind projects being considered or developed as of August 2023. Map by NREL

This 2-year study aimed to:

  • 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 considerations
  • 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 are conducting this study, funded by the U.S. Department of Energy Wind Energy Technologies Office, by creating multiple scenarios of interstate and interregional transmission topologies (size, shape, branching, and location of transmission lines) between 2022 and 2030 and 2050.

Project Objectives

The Atlantic Offshore Wind Transmission Study 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
  • 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 closely engage with and draw expertise from a technical review committee, which has been providing input throughout the project on assumptions, scenarios, and the modeling framework.

Project Schedule

Through February 2024, the team has:

  • Created a technical review committee with a range of stakeholders and subject-matter expertise and conducted regular meetings with these stakeholders to solicit feedback throughout the study
  • Established plausible land-based and offshore transmission expansion scenarios for 2030 and 2050—including feasible routing, points of interconnection, and landing points—that consider environmental and community impacts
  • Evaluated system operations, cost, and reliability of the established, plausible scenarios
  • Completed production cost modeling, capital investment estimation, and reliability studies
  • For 2030, performed a stability analysis, a transient fault-behavior analysis, and resilience studies for the land-based and offshore grid.
  • For 2050, performed AC power-flow contingency analysis for the land-based and offshore grid
  • Drafted the final report
  • Presented the final results to the technical review committee.

The Atlantic Offshore Wind Transmission Study Report will be published in March 2024.

TASK 1

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

TASK 2

Transmission Expansion Planning

Envision future grids

TASK 3

Production Cost and Resource Adequacy

Simulate operability

TASK 4

Technology Characterization

Evaluate cost, performance, and siting

TASK 5

Reliability and Offshore Grid

Evaluate reliability of the grid by studying contingency analyses

TASK 6

Resilience and Extreme Weather

Evaluate grid operation during cascading events due to extreme weather

TASK 7

Economic Analysis

Run a cost-benefit analysis for selected offshore tansmission scenarios

TASK 8

Final Report and Final Presentation to Technical Review Committee

Project Tasks

The project will include eight tasks, the first seven of which will be conducted contemporaneously, with ongoing findings influencing the scenario development and sensitivity analysis:

  1. Offshore Wind Data Collection, Modeling Framework Selection, and Technical Review Committee Formation: The team assembled 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 is evaluating the cost-optimal generation and transmission options under a variety of conditions and determining 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 is using PLEXOS to model production costs and NREL's Probabilistic Resource Adequacy Suite to model resource adequacy.

  4. Technology Characterization: The team is conducting 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 is also collecting information to screen for cable routes that avoid military-sensitive areas, fisheries, cultural areas, 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 is using 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. It is also using power systems computer-aided design 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 is using the Electric Grid Resilience and Assessment System.

  7. Economic Analysis: To identify and evaluate quantifiable benefits associated with transmission investments identified in the study and demonstrate replicable and scalable methods to allocate economic benefits of transmission among network users for both regional and inter-regional projects.

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

Offshore Grid Development

Topologies are the layout and connections of transmission lines. This study is modeling four topologies (additional topologies are being identified as the study continues):

  • Radial (one transmission line from each offshore wind plant to an onshore substation or point of interconnection [POI])
  • Interregional (meshed connections between transmission planning regions)
  • Intraregional (meshed connections within transmission planning regions)
  • Backbone (a larger version of the interregional topology that runs the full length of the Atlantic Coast).

The radial topology considers POI and offshore wind connections that attempt to represent an optimal layout for cable costs and lengths, electrical attributes of the POIs, and quality of the connected offshore wind resource. The radial connection topology strategy underpins each of the other three topology strategies; all meshed interlinks connect platforms that exist in the radial topology. The intraregional, interregional, and backbone topology strategies assume that there will still be radial connections to shore; not all offshore platforms are assumed to be meshed.

While viewing the interactive maps on energy.gov, please note that there are potentially other configurations of interregional interlinks that could provide similar benefits. For these proposed interlinks, specific interconnecting POIs were identified based on assumptions about existing coastal generation plant retirements, but it may be possible to use other nearby POIs and still see similar system benefits.

Contacts

Greg Brinkman

Technical Lead

Gregory.Brinkman@nrel.gov

Lanaia Carveth

Technical Resource Committee Communications

Lanaia.Carveth@nrel.gov

Dave Corbus

Offshore Wind Grid Integration Lead

David.Corbus@nrel.gov

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