The United States boasts one of the most extensive transmission networks in the world. The U.S. Department of Energy’s (DOE) 2023 National Transmission Needs Study[1] (DOE Needs Study) notes a pressing need for new transmission infrastructure to accommodate increasing electricity demand and renewable energy integration and strengthen resilience. To align with regional expansion models, the National Transmission Needs Study forecasts that regional transmission capacity will need to double by 2035. Yet, during the second half of the last decade, transmission investments steadily declined across multiple regions of the U.S.

Across the U.S., the demand for electricity to rapidly increasing with the proliferation of data centers, the revival of domestic manufacturing, and beneficial electrification. To meet this growing demand, grid modernization can be accelerated by optimizing, reinforcing, and expanding current transmission lines.  The discourse on transmission expansion has largely revolved around the challenges of siting, permitting, and constructing new lines. However, it is imperative to expand this dialogue to include how to grow the overall capacity of the nation’s electric grid, including deploying new technologies on existing transmission lines and investing in local distribution systems.

Building New Transmission

Expanding the nation’s transmission network is essential for ensuring a reliable and resilient grid and for integrating new clean energy resources necessary to meet climate goals. The DOE Needs Study notes that nearly every region in the country will see improvements in reliability from new transmission, and new transmission will reduce congestion in large portions of the U.S. New transmission will also reduce electricity prices by connecting cheaper generation to regions with high demand and help meet future demand needs by facilitating interregional transfers.

Exactly how much new transmission we need is a function of complicated model scenarios, but DOE estimates that a reasonable scenario of moderate load growth and high clean energy deployment would require in a 57% increase in high voltage gigawatt-miles by 2035.[2] And while the need for new transmission miles is growing, actual construction has declined from 2,000 miles of new transmission each year from 2012-2016 to 700 miles from 2017 to 2021.[3]  Yet studies consistently show that the benefits of building new transmission exceed overall costs.[4]

Building new transmission faces a host of challenges, from complicated and lengthy siting and permitting processes to difficulties in allocating costs across potential beneficiaries. In the following sections, the GridWise Alliance suggests an approach that can facilitate the construction of new transmission miles while accelerating investments that will defer costs and potentially avoid the need for some new transmission. We emphasize that this is not an either-or approach, but rather a coordinated strategy for maximizing the capacity of the current transmission and distribution system while awaiting the benefits of an expanding transmission network.

Increasing the Capacity of Existing Transmission Lines

The deployment of new technologies can significantly increase the capacity of the existing transmission system. These technologies should be considered not only on existing lines but for all new transmission.

• Grid-Enhancing Technologies (GETs): Implementing technologies such as dynamic line rating and power flow optimization can maximize the efficiency of new and existing transmission lines. Unlike traditional transmission projects that can take five to ten years for planning and construction, many GETs can be implemented in less than a year. GETs can effectively complement new transmission projects by increasing capacity and integrating more resources before new transmission projects can be executed. GETs provide immediate solutions to solve grid issues, while providing more time to plan future transmission projects.
• Reconductoring: Replacing existing conductors with advanced conductors allows the transmission of more electricity without acquiring new rights-of-way. According to the DOE Liftoff report on innovative grid deployment, reconductoring with advanced conductors is estimated to cost less than half the price of building new transmission lines. An estimated 20% of transmission lines across the country could be viable candidates for reconductoring.
• Strategic Storage Deployment: Utilizing energy storage strategically across the system can relieve transmission constraints and provide peak power, further mitigating the need for new transmission lines. Additionally, deploying energy storage technologies can increase the resiliency of the transmission network by providing contingency power support in the event of outages.

Priorities for Transmission Investments

Key considerations for new transmission investments include:

1. Regional Interconnections: The National Transmission Needs Study notes that interregional and cross-interconnection transmission investments will improve system resilience and alleviate resource adequacy concerns by enabling increased access to diverse generation resources across regions. Especially as the country is working towards 100% clean energy by 2035, developing transmission infrastructure between different regions can reduce resource adequacy concerns by unlocking access to resources generated in different climatic zones.
2. Permitting Reform: Streamlining siting and permitting processes across federal, state, and local levels is vital. Congress is currently considering proposals to amend the National Environmental Protection Act (NEPA) and other statutes to improve coordination and alleviate conflicting authorities across overlapping statutes and agencies.
3. Cost Allocation and Benefit Analysis: A comprehensive understanding of the financial benefits from increased transmission capacity to ratepayers is essential. The Liftoff report highlights that many capacity-increasing GETs are low-cost and provide greater value to ratepayers. Currently, the DoE is providing federal funding for advanced grid technology deployment and large scale transmission development to further reduce pressure on rates.

4. Reduce Time for Interconnections: The interconnection queues for large scale renewables, off-shore wind, distributed energy solar and batteries, and charging demands for transportation electrification are all increasing. Transmission and distribution projects can take many years, on average, from planning, permitting, construction to operations, and the projects may go through an ISO or State processes, in order to identify the scope and nature of their electrical infrastructure. Over the next years, there is a need to reduce the total interconnection timeframe, an aggressive target set by some utilities is by half by 2030.
5. Integrated Planning: The interconnected nature of the distribution and transmission systems mandates a holistic planning approach. The implementation of Order 2222, aiming to integrate distributed energy resources into bulk power markets, epitomizes this integrated vision.
6. Transmission Investment Optimization: Transmission operators can utilize technology solutions to implement a transmission loading order approach where increased grid capacity in existing rights of way with GETs or reconductoring is initially pursued, followed by new transmission line construction.

Harnessing the Power of Local Resources

Historically, electric grids were engineered to facilitate power flow from large, centralized generation facilities through transmission and distribution lines, eventually reaching the customer. With the advent of Distributed Energy Resources (DERs), including rooftop solar, storage, and electric vehicles, behind-the-meter resources can now provide additional power and grid flexibility to both the distribution and transmission systems. Harnessing DERs and developing more local resources like community solar can alleviate the need for some new transmission and increase resiliency for communities looking to enhance their control over local energy choices. Local resources will help meet skyrocketing electricity demand while new utility-scale generation and transmission are built.

Integrated Planning Across Transmission and Distribution

With FERC Order 2222 aiming to integrate aggregated distributed energy resources into bulk power markets, investments in the distribution system are imperative. This enhances the connection of customers to wholesale markets, necessitating an integrated planning approach that considers both transmission and distribution system evolution.

According to the DOE Liftoff report, many key commercially available, but underutilized, advanced grid solutions are ready for deployment across transmission networks. These grid solutions are differentiated into four categories:

1. Advanced Transmission Technologies: Advanced conductors and point-to-point high voltage direct current (HVDC)
2. Situational Awareness and System Automation Solutions: Advanced sensors, distributed energy resource management systems (DERMS), advanced distribution management systems (ADMS), volt/VAR optimization (VVO), and more
3. Grid Enhancing Technologies and Applications: Dynamic line rating (DLR), advanced power flow control (APFC), topology optimization, virtual power plants (VPP), energy storage, and advanced flexible transformers
4. Foundational Systems: Communication technologies, data management systems, system digitization and visualization, and alternate timing and synchronization

If these solutions were deployed today, the transmission and distribution capacity could expand to support 20 to 100 gigawatts of incremental peak demand while also improving energy reliability, resiliency, and affordability. These deployments are essential to effectively address accelerating grid pressures.

Role of States in Transmission Planning

States play a pivotal role in steering transmission planning, ensuring that developments are congruent with local needs, regulatory frameworks, and available resources. The need to coordinate across state lines for regional transmission can complicate the planning process, so transmission developers should devote resources for this interstate collaboration early in the planning process. Regarding the use of new transmission technologies like DLR, additive to what FERC may require, states can pursue studies to determine the potential of these technologies, propose requirements for incorporating them in utility planning, and consider incentives to accelerate their deployment.

Recently passed FERC Order No. 1920 establishes specific requirements for transmission providers to plan long-term for regional transmission facilities and consider grid enhancing technologies like Dynamic line ratings in that process. Under this new rule, transmission providers conduct and periodically update long-term transmission planning over a 20-year horizon to address future needs.

[1] National Transmission Needs Study | Department of Energy
[2] DOE study highlights America’s transmission needs, but how do we accelerate buildout? | Utility Dive
[3] Queued Up… But in Need of Transmission | Department of Energy
[4] Queued Up… But in Need of Transmission | Department of Energy