Why Utilities Aren’t Using GETs to Unlock Capacity for Large Loads — And How to Fix That

By: 2025 New York Fellow Jill Rathke

Utilities could unlock transmission capacity in months, not decades, by deploying Dynamic Line Ratings (DLR). DLR uses sensors to measure conductor temperature and weather provide real-time ratings, rather than decades old static assumptions. The grid often appears “full” on paper even when physical headroom on transmission lines remains. One DOE report states that DLR typically increases capacity by 10–30%, and real deployments show even more. For example, Great River Energy recorded a 49% rated summer capacity increase on one transmission line. Further, these capacity increases come at relatively modest cost to the ratepayers, making them high ROI investments relative to billion-dollar upgrades that take years to complete.

The Q4 2025 Grid Strategies report forecasts 166 GW of new U.S. load by 2030 (6x more than expected just three years ago) driven largely by data centers (90 GW). Without smarter use of the existing system, load interconnections will be further delayed and pass on higher energy costs and worsening reliability to all of us, especially during extreme weather. The DLR barrier is no longer the technology. It is (1) utility culture, (2) risk allocation, and (3) regulatory misalignment.

Barrier #1: DLR reveals aggressive and frequently unsafe static assumptions

Most utilities still rely on static line ratings, which are fixed thermal limits assigned to transmission lines using worst-case assumptions. One FERC staff paper found many utilities static ratings assume extreme conditions that rarely reflect real life, such as 104 F degrees temps and low wind speed (2 ft/s). Static line ratings both under and overestimate grid capacity; on some lines, DLR shows static ratings to be too conservative whereas on other locations, DLR reveals that some lines run much hotter or sag closer to clearance limits than planners expected with static data. DLR shows that lines are both underutilized and operating unsafely.

This transparency often triggers criticism of long-time staff and requires operational changes. Yet this visibility is essential as heat waves intensify across the U.S. Static ratings may either understate risk (causing overloads) or overstate it (causing unnecessary curtailment and expensive upgrades), whereas DLR provides accurate time- and place-based ratings.

Barrier #2: DLR variability reveals operational risk for utilities and large loads

DLR is dynamic by design. A transmission line’s capacity rises with wind and cool weather, and falls during high temperatures or low-wind conditions. Studies show that DLR can dip below static ratings during certain hours, such as in high heat without wind.

Hyperscaler loads, in contrast, require firm, predictable capacity. No utility wants to interconnect a GW-scale campus to a line whose available capacity fluctuates with wind speed. As a result, utilities gravitate toward long-lead, capital-intensive transmission upgrades and new peaking generators — not because they’re cheaper or cleaner, but because they are firm.

Barrier #3: Misaligned regulations and incentives prevent DLR deployment

FERC Order 881 (approved in 2021) requires Ambient-Adjusted Ratings (AARs) but still omits wind data, which accounts for up to 50% of conductor cooling. Full DLR remains optional. ISOs like PJM and CAISO are actively implementing AAR, but many others requested extensions out to 2028. The focus on complying with just the AAR deadlines distracts ISO from integrating DLR into their interconnection studies or capacity accreditation, where it would provide the most value for load growth.

Utilities also have divergent financial incentives. They earn regulated returns on large capital projects, not small sensor deployments. In its Future of Energy report, EY notes DLR can be installed for <10% of reconductoring cost, but utilities see little upside when regulators reward bigger assets.

In this unprecedented time of large loads surging, the industry looks to maintain a reliable grid with reasonable costs while also keeping up with new data center interconnections. Here are some potential solutions to use DLR to do so.

Solution 1: Require GETs evaluation before approving major upgrades

Public Utilities Commissions (PUCs) could require utilities to evaluate DLR before pursuing expensive upgrades on congested or heat-stressed lines. National Grid UK demonstrated that DLR on a 275 kV line could unlock 600 MW of capacity and avoid £20 million in network upgrade costs. Mandating the evaluation of DLR as an alternative to building new transmission in the U.S. would prevent overbuilding where cheaper (and most importantly faster) operational tools exist.

Solution 2: Deploy DLR during extreme weather for safety

In wildfire-prone or heat-stressed regions of the country, regulators and other stakeholders could require DLR during summer peaks. Real-time monitoring of conductor temperature and sag can prevent local outages and avoid over-conservative deratings that delay load interconnections, while reacting to changing ambient temperatures. As extreme heat becomes more common, static ratings do not capture the ever-changing real-world risks to the grid.

Solution 3: Create firm transmission products using DLR + storage

DLR plus battery storage offers a credible path to firm capacity. Existing research shows batteries can “firm up” DLR variability by injecting power during low-rating hours and capturing excess during high-rating periods. Without this, utilities will never trust DLR for firm service and hyperscalers won’t rely on it.

AES Indiana & Ohio deployed sensors on one 345-kV line that show the DLR exceeded its static rating 97% of the time. With strategically located storage covering the remaining 3%, utilities could treat DLR-enabled capacity as firm and bring major loads online faster.

Solution 4: Standardize DLR data for interconnection and accreditation

Finally, FERC must expand beyond AAR and set consistent standards for DLR, including wind data. ISOs need uniform rules for incorporating DLR into interconnection studies, capacity accreditation, and reliability planning. Utilities that deploy DLR should not be penalized for having more accurate ratings. As major drivers of grid investment, hyperscalers could accelerate adoption by pushing utilities to evaluate DLR in the same way they’ve pushed for innovative tariffs.

Conclusion

DLR has already proven that it can unlock significant capacity, reduce costs, and improve safety as the grid becomes hotter and more heavily loaded. With unprecedented load growth coming from hyperscalers, DLR is an essential tool to unlock this new capacity. We don’t lack technology. We lack alignment.