Optimizing the Grid: How PJM, GETs, and a $1.9B DOE Push Are Unlocking Transmission Capacity
In early March, mid-Atlantic grid operator PJM Began using Ambient Adjusted Ratings to better determine how much power can flow through its lines based on actual weather conditions. In addition, the DOE announced it will award billions for quick and effective upgrades to the transmission system.
First we have to fix the broken interconnection issue. For all projects seeking interconnection to the grid from 2008 through 2019, only 19% of the projects actually flowed power by the end of 2024. The typical project built in 2025 took 55 months to get through the queue, compared with 36 months in 2015.
But even if all of that new supply capacity could be processed through interconnection queues, there are simply not enough transmission lines to accommodate the planned resources. And few new lines are being built: less than 1,000 miles of 345 kV+ transmission lines were completed in 2024 – far less expansion than is needed, especially in the face of enormous new data center demand.
The biggest challenge is permitting for new rights-of-way, which can take well over a decade. There is a glimmer of hope that the federal government may reform the permitting process prior to the mid-terms, but it’s unlikely.
Grid-enhancing technologies, or GETs, can offer some relief by doing more with existing transmission. In addition, there is the growing potential for reconductoring.
The GETs technology with the greatest near-term is dynamic line rating, or DLR. As power lines move more power, they heat up. Lines are limited in terms of how much they can energy move by static ratings, based on worst case weather assumptions, such as 100 degrees F with no wind.
Such conditions rarely occur, but with static ratings flows cannot exceed those pre-set amounts. Most days, one could move much more power through that line, if one were
using DLRs - a combination of software and sensors. DLRs measure ambient temperatures and wind (wind wicks lots of heat away from the line, as well as how much sunshine is warming the wires. Sensors also measure how much the wire is physically sagging at any given moment. This information helps operators move more power without hitting “thermal violations.”
A 2024 case study showed static ratings could be exceeded 100% of the time, with average capacity increases of 81%. In summer, one could exceed the static ratings 94% of the time, with average increases of 27%.
A less capital-intensive approach that doesn’t require physical sensors and uses weather data, but also fails to measure the impact of wind, is called Ambient Adjusted Rating or AAR. AARs automatically predict transmission line capacity on an hourly basis.
The Federal Energy Commission’s 2021 Order 881 mandated AARs for grid operators by July 2025. But nobody met that deadline. PJM was first, going live on March 4. It will use hourly ratings from real-time to as far as 10 days out and employ monthly seasonal ratings for longer-term studies 12 months out.
Meanwhile, the DOE announced funding of approximately $1.9 bn to “accelerate urgently needed upgrades to the nation’s power grid.” The DOE specifically calls out reconductoring –stringing new and more efficient lines along the same or upgraded poles.
Since rights of way are the single largest limiting factor to expanding transmission capability, it makes sense to fully exploit existing ROWs. Reconductoring can cost-effectively double transmission capacity within existing ROWs and save billions.
We’ll still need to build many new transmission lines. But it will take many years for new lines to get built. In the meantime, it’s essential to do as much as possible with the infrastructure we have. These two recent developments are a start.