A lot of transmission planning today focuses on near-term needs within a utility’s specific service region. Like the scope of the NTP study, there is an emerging trend toward longer term utility planning studies. DOE believes that joint planning between regions over a longer horizon can unlock tremendous value both locally and nationally. DOE and the National Labs will work closely with planners, other regional stakeholders, and Tribes, so that the NTP study’s national results can readily inform interregional dialogue and the exploration of new value propositions. The NTP study won’t replace current planning, but it will test additional transmission options that lie outside current planning.

This study aims to complement and build upon recent national-scale decarbonization studies. This study differs from other recent national-level decarbonization studies in that it integrates a comprehensive range of models in its analysis, including both long- and short-time horizons as well as both zonal and nodal spatial granularity. The study also differs in that a robust public engagement process through the analysis is foundational.
 

The study includes a robust public engagement plan, including:

• Public webinars
• Leveraging existing convener groups such as the Western Electricity Coordinating Council (WECC), Eastern Interconnection Planning Collaborative (EIPC), National Association of Regulatory Utility Commissioners (NARUC), National Association of State Energy (NASEO), and others
• A Technical Review Committee (TRC)

Through this robust engagement plan, DOE can collect stakeholder input and facilitate the integration of the results of the analysis performed by DOE and the National Labs into existing processes to spur the building of transmission lines. The study will also help prioritize DOE funding to support new transmission and upgrades of existing transmission through programs such as the Bipartisan Infrastructure Law’s Transmission Facilitation Program.

From a technical analysis perspective, a change model for this study compared to previous studies is the comprehensive integration of long- and short-term models, including nodal alternating current (AC) power flow analysis. The project baseline is a nodal AC power flow model, the same model used by industry planners. 

Please see the Tribal Engagement section of the FAQ for more information about Tribal engagement.

DOE is partnering with Pacific Northwest National Laboratory (PNNL) and National Renewable Energy Laboratory (NREL) to conduct this study. A geographically and sectorally diverse Technical Review Committee (TRC) comprised of subject matter experts from across the country will provide input to the study.

The study kicked off with the first public webinar on March 15, 2022, and interim results were shared via public webinars in Fall 2022 and Spring 2023. The final results will be shared in Summer 2024 via a public webinar and publication of a final written report.

DOE does not build transmission. We hope that by conducting modeling with input data and assumptions that have been discussed with planners, regulators, other key stakeholders, and Tribes, the results and recommendations of the NTP study will facilitate the building of new transmission that makes the future power grid more economical, reliable, resilient, and net carbon-free. 

DOE supports all forms of clean energy technologies. The study will examine different resource and transmission expansion scenarios to achieve 100% clean electricity by 2035 while maintaining reliability through the transition. Clean energy resources included in the Study are wind, solar, distributed generation, fossil fuel plants with carbon capture and sequestration capabilities, extension of the existing nuclear fleet, new small modular nuclear reactors, storage, and new clean firm resources such as hydrogen gas powered turbine generators.

Achieving the goal of a decarbonized electric system will require increased flexibility at all levels of the grid – generation, transmission, and distribution. Distributed energy resources (DER) will be part of the future energy mix and there are many benefits to increasing their deployment. Utility-scale generation resources that require transmission for delivery will still be needed, however, to reliably serve customers who do not have the financial resources or physical footprint to deploy enough distributed generation to meet their needs.

Furthermore, regional coordination through a robust transmission system will ensure reliable electricity even when drought, cloudy skies, or a lack of wind limits local production. The NTP study recognizes that transmission investments are a complementary investment to distributed energy resources, and will identify optimal pathways to leverage geographic diversity to minimize costs and ensure reliability. This study’s scenario analysis includes varying amounts and locations of DER integration as key sensitivities.

The study is focused on the power sector and therefore is not intended to inform decarbonization pathways across all sectors. However, the scenarios will include a wide range of electrification and demand growth sensitivities including those that are broadly consistent with a pathway toward achieving a net-zero economy by 2050. These trajectories will be based on data available from other studies.  

The NTP study is one of several analyses DOE will rely on to guide the application of funding for programs identified in the Bipartisan Infrastructure Law, such as the Transmission Facilitation Program. 

The study includes a robust public engagement plan, including:

• Public webinars
• Leveraging existing convener groups such as WECC, EIPC, NARUC, NASEO, and others
• A TRC

The NTP study TRC is as open and transparent as possible. We seek input from those who have data, models, and information relevant to the study. The project website shows project updates and provides a place for stakeholder comments. We will make every effort to be comprehensive and clear about the stakeholder process and the technical modeling, including limitations. 

Please visit our National Transmission Planning Study Tribal Engagement page for more information about Tribal engagement.

The study will identify expansion options at several levels of granularity which could include increased transfer capacity between regions, increased transfer capacity between balancing areas, or potential new lines represented in a nodal (bus-branch) model. At all levels of granularity, engagement with stakeholders will be critical to ensure that viable, pragmatic expansion options are identified.

The TRC has a Land-Use and Environmental Exclusion subcommittee which will provide general information on issues affecting the location of transmission and power generators. For example, if it is determined that it would be extremely difficult or impossible to site generation or transmission in a particular area, that would be incorporated into the modeling and analysis. The subcommittee will not site specific transmission line routes.  

The study will use capacity expansion, production cost, power flow (including dynamic analysis), and resource adequacy modeling. Regional Energy Deployment System (ReEDS) is an NREL-built capacity expansion model that is a nation-wide zonal model that co-optimizes transmission expansion and generation expansion subject to input assumptions and constraints. 

ReEDS will be used for capacity expansion modeling. Separate distributed energy resource and load forecasting tools feed into the capacity expansion model. Plexos and GridView are two commercial production cost models that simulate the cost of operating a particular future power system over the course of a year. They will be used for production cost modeling. The power flow model will utilize several industry-standard programs to ensure the system can operate reliably withstand high-stress events. Nodal power system models are based on the WECC and Eastern Interconnection Multiregional Modeling Working Group (MMWG) data sets used by industry.

The NTP study will link long-term capacity expansion modeling, short-term production cost modeling, and detailed power flow modeling to test a number of transmission build-out scenarios. Linking these modeling tiers, which is difficult even regionally, is an important part of how the National Labs will carry out the NTP study. Pushing the frontier of comprehensive, multi-tier modeling will provide a wide range of economic, reliability, and resilience indicators for each transmission scenario. The overall study findings will reflect results from the full suite of modeling tools, along with insights from study experts and external reviewers. 

Moreover, the linkage tools developed for the NTP study can help inform regional transmission planners in their work. This study is detailed in breadth by considering the entire contiguous nation, but less detailed in depth of the specifics of any one geographic region, which is the expertise of regional planners. A cornerstone of the NTP study is robust stakeholder engagement. This engagement will help us capture important reliability and resilience details that may not be initially captured in a national model. 

The NTP study will not develop detailed plans of service or site individual transmission line routes. The results from the NTP study will inform, not replace, utility planning. The study will be particularly informative for interregional and inter-interconnect transmission expansion, which utility planning doesn’t typically address. 

The geographic scope of the study is the contiguous United States (CONUS), and will not include Alaska, Hawaii, U.S. Territories, or neighboring interconnected countries (Canada and Mexico).

Through a collaborative dialogue with stakeholders and Tribes, one goal of this study is to help inform regional planning entities about the reasonable ranges of key parameters (such as electrification, storage integration, DER integration, etc.), and benchmark those ranges against other regions as well as the entire country.

The resilience analysis will focus on extreme weather events (e.g. heat and cold waves). The events will be characterized using the best available atmospheric science research to explore future heat/cold events under a changing climate. The study team will perform zonal resource adequacy analysis and nodal production cost modeling analysis for the weather events over a period of the event (approx. one week).

The assessment of reliability spans several modeling domains that capture regional planning reserve margins, hourly (8760) balance of demand and supply, and probabilistic assessments of resource adequacy using multiple hourly (8760) weather years and climate impacts. The analytics will include some contingency analyses. And extreme weather will be analyzed as described in the resilience FAQ.