Why the path to dynamic line ratings starts with FERC 881.
The clock is ticking for power grid operators across the US as the July 2025 deadline for FERC Order 881 is closing in. The order mandates utilities to switch from Static Line Ratings to Ambient Adjusted Ratings (AAR), in an attempt to increase grid capacity. Many utilities are dragging their heels to comply, while others are even filing extension requests – suggesting that achieving AAR is a daunting task.
This begs the question: Is introducing Ambient Adjusted Ratings as difficult as these delays might make it seem?
The answer is no.
In fact, introducing AAR can be achieved in as little as two weeks by integrating new software into the utilities’ existing infrastructure. However, AAR is just the stepping stone towards a much more effective and future-proof solution: Dynamic Line Ratings (DLR). Whatever path a grid operator takes to introduce hourly AAR ratings right now should also support their move toward real-time DLR ratings.
In other words, meeting FERC’s AAR requirement by July 25 is only step one on the necessary journey to maximizing the transmission capacity of their existing infrastructure. DLR is the second step.
From ambient adjusted ratings to dynamic line ratings
Nearly every power line today is operated without real-time – or even daily or monthly – insights into the factors influencing power line capacity, such as wind, sun, and ambient temperature. Instead, they’re relying on seasonal ratings, which are no more than region-wide estimates based on historical data.
Not knowing what’s happening on a specific day, at a specific time, or particular points across their power lines forces companies to be very conservative in how much energy they can transmit through a given line. As a result, they’re leaving up to 40 percent of their grid’s capacity untapped.
The mandated AAR will, to a limited extent, begin to fill this gap with hourly updates. However, the only way for power grid operators to gain a holistic view of how much capacity each power line has at any given time is through DLR. DLR provides real-time insights into the conditions affecting each line that makes up a grid. This is important, considering that a single line can span different terrains and be exposed to differing weather events.
This was the case with Great River Energy earlier this year. 
Minnesota’s Great River Energy offers a look at what’s possible
In March 2024, Minnesota-based Great River Energy launched the United States’ largest DLR project after conducting a study to identify the lines with the highest congestion costs and running a pilot project on the most congested line. It was on that line that Great River Energy installed the first four of Heimdall Power’s neurons, colloquially known as ‘Magic Balls’ to gain real-time insight into actual capacity and reduce congestion.
Through the sensors, Great River Energy could monitor the effect on capacity from real-time wind conditions as well as current, temperature, and other weather conditions. Heimdall Power’s software then leveraged machine learning algorithms to synthesize the data and provide a more accurate estimate of the power lines’ real transmission capacity. Knowing this, they could now confidently and safely transfer more power through lines previously considered at full capacity based on conservative assumptions.
The initial six-month pilot on one line showed that capacity gains through DLR exceeded what the company had previously realized, unlocking 42.8 percent more capacity on average. Following this discovery, the company this year expanded its work with Heimdall Power, launching the largest DLR initiative in the US. Dozens more sensors were installed by drones on power lines spanning Minnesota, to unlock additional capacity on more lines and gather information necessary to avoid potentially hazardous situations.
Achieving grid optimization at scale for the country’s largest grids
While Great River Energy’s grid optimization project is the largest in the US to date, achieving the same results for some of the country’s larger utilities would potentially require thousands of sensors to be installed across thousands of miles of grid. For utilities, a project of this scale might seem like a years-long initiative. Hence their delays in beginning the process.
While it’s true that if sensors were installed one-by-one by linemen, it could take years to deploy thousands of sensors, Heimdall Power’s cutting-edge autonomous drone installation technology allows each sensor to be installed in less than ten seconds, reducing the time to deploy large-scale projects from years to months.
Beyond FERC 881
The upcoming FERC 881 order is merely the first requirement in a slew of upcoming enhancements that utilities will need to make to keep up with the increasing demand for electricity. Utilities can use FERC Order 881 as a launch-off point to start deploying technology that will unlock transmission capacity they’ve never been able to access before. Those who view this moment as an opportunity will be ahead of the curve. Starting with DLR now, will future proof the grid to deliver on high demand while waiting for new infrastructure.
By Jørgen Festervoll
For a list of the sources used in this article, please contact the editor.
Jørgen Festervoll is CEO of Heimdall Power, a grid enhancing technology company that specializes in making the world’s grids smarter, more capable and more sustainable. Heimdall Power’s technology is in use by over 40 power grids in 17 countries, across Europe, Asia and in the United States. It has successfully increased power grid capacity for companies like Swissgrid, Austrian Power Grid, TenneT and Great River Energy by as much as 40 percent. The company designs and develops industrial devices and smart software solutions in support of its mission to enable swift, secure and affordable energy transitions around the world.