Transmission is one of the most important — and least understood — parts of our electric grid. People see the tall steel towers lining highways, but few realize how essential they are to keeping our lights on, our factories running, and our energy bills stable. As electricity demand surges across the Mid-Atlantic and PJM faces unprecedented challenges, understanding transmission isn’t just for engineers or regulators anymore — it’s at the heart of how we maintain reliability, support new industries, and keep energy affordable. In this sit-down with our Executive Director, Evan Vaughan, we break down what transmission is, why it matters, and how a modernized system can help solve the grid and cost pressures facing our region.
What Exactly is Transmission?
Transmission is the part of the power system that moves electricity over long distances at high voltage. It’s how we get electricity from big sources of power to the places where people actually live and work.
Here’s a simple way to think about it. Transmission lines are the interstate highways of the grid; think of tall steel towers and big wires you see along highways or crossing open fields. Distribution lines are the local streets, the wooden poles on your block that directly connect to homes, schools, and small businesses.
Transmission and distribution lines both do the same basic job of moving electricity from one place to another, but they differ in
- Voltage: Transmission runs at very high voltages so power can travel far with less loss. At substations, transformers step the voltage down for the local distribution system, and then again for use in buildings.
- Role: Transmission focuses on regional reliability and efficiency across many counties or states; distribution focuses on local service.
- Regulation and Ownership: Transmission is generally regulated at the federal level by FERC and operated by the regional grid operator (in our case PJM), while distribution is mostly overseen by state utility commissions and owned by local utilities.
Why is Transmission Useful?
At its core, transmission is useful because it helps grid operators keep electricity supply and demand in balance every second of every day across a huge geographic footprint.
Think of a bike on a hill and imagine everyone who uses electricity riding the same bicycle together. On flat ground, you pedal at a steady effort and move along just fine. When the road tilts uphill — a big factory comes online, everyone turns on their AC; a new data center spins up — you suddenly need more power to keep the same speed.
That’s what grid operators see every day: When demand rises, frequency on the grid starts to fall. If it drifts too far from the normal range, generators can trip offline. If too many units trip, you can get widespread outages.
Transmission is how operators keep that system balanced without needing a power plant in every neighborhood. When you don’t have enough transmission, it’s like having only one bridge into a city — a single crash can back up traffic for hours. On the grid, that congestion shows up as higher prices (because cheap power can’t reach the load), and reliability risks, because too much strain piles onto the few lines that exist.
What Problems is PJM Facing Because of Outdated Transmission?
PJM’s biggest challenge is that its current transmission planning approach is too reactive and too short-term for the amount of change hitting the system.
Local distribution system planning is performed by the utilities and transmission owners (TOs), each operating independently within its own service territory. Most of this planning focuses on replacing aging infrastructure and meeting projected load growth. TOs then submit their local plans to PJM, which integrates them—along with transmission upgrades identified through the generator interconnection process—into a rolling, five-year Regional Transmission Expansion Plan (RTEP) that evaluates system reliability across the entire region.
In very simple terms, RTEP looks back each year and projects over the next five years at where the system showed reliability problems. Examples include:
- Breakers at substations that tripped more often than they should;
- Lines and equipment that are overloaded under stress conditions.
And then RTEP proposes regional transmission fixes for the problems laid out above. Examples include:
- Upgrading a high-voltage substation so it can handle more current or building;
- Reconductoring a high-voltage regional line to relieve a cross-region bottleneck;
- Upgrading a breaker so it can handle more current;
- Building or reconductoring a line to relieve a local bottleneck
That is “whack‑a‑mole” planning. It treats each reliability –based violation as an isolated issue, instead of starting from the question, “Given how much load is coming and where new projects want to build, what does a smart, efficient grid look like 10–20 years from now?”
It’s like remodeling a bathroom one piece at a time. In year one, you replace the shower. In year two, you redo the tile. In year three, you swap out the vanity. You might spread out the spending, but you lose the efficiency of a coordinated project. You might mess up the tile when you swap out the vanity. In the end, you often pay more than if you’d planned once and done it right.
Other factors add more challenges: fast‑growing demand, especially from data centers and electrification, retiring fossil plants that PJM historically counted on for capacity, and huge volumes of clean energy and storage trying to connect.
Because the planning hasn’t anticipated these shifts, we’re seeing more frequent and more expensive local fixes, and the generator interconnection process has turned into a major bottleneck.
How Can Building Transmission Help Our Energy and Affordability Crises?
Transmission buildout is one of the best tools we have to get out in front of the crunch instead of chasing it.
Done well, it:
- Lowers long‑term costs. Transmission costs show up on rates whether we plan or not. Transmission can look expensive on paper because the projects are big. But in region after region, we see that the benefits are 2–3 times the costs over the life of the lines. In PJM’s own data, transmission is not the main driver of recent rate increases; fuel and energy costs have played a much bigger role. The choice is between:
- Planned, regional upgrades that capture economies of scale and connect us to cheaper resources, or
- Endless rounds of patch jobs and emergency measures that often cost more over time.
- Makes it possible to connect more projects. More transmission = more choice. It lets PJM tap cheaper power plants, wind, and solar farther away, instead of leaning on the most expensive plants close to load. If PJM and the states plan backbone upgrades, meaning the big, shared lines and substations, then:
- New wind, solar, storage, and even gas plants plug into a grid that already has room for them.
- Their interconnection upgrades shrink to more manageable local fixes.
- More projects can afford to reach operation, which eases supply constraints and stabilizes prices.
- Strengthens reliability in a changing grid. As older plants retire and extreme weather becomes more common, transmission:
- Creates more paths for power to flow around damage,
- Lets us lean on a broader mix of resources,
- Reduces the number of times we skate close to the edge during heat waves and winter storms.
- In other words, new transmission isn’t a luxury add‑on. It’s the backbone that lets all the other solutions — renewables, storage, demand response, even new gas — actually work together at scale.
Aren’t We Already Taking Action to Address This?
There’s important work underway, but it has clear limits. On the plus side, PJM does upgrade aging lines and equipment each year through RTEP. There’s growing interest in “grid‑enhancing technologies” (GETs), which offer better sensors and forecasting, dynamic line ratings, and advanced power flow controls. Those tools can squeeze more capacity out of existing wires, help operators run the current grid more efficiently, and delay some upgrades in the short run.
But they cannot fully substitute for new, large‑scale transmission.
Much of our grid infrastructure was built for a different era, before today’s level of digital load, electrified transport, and long‑distance clean energy. Software can’t change the fact that a 50‑year‑old line has a fixed thermal limit and may sit in the wrong place for the grid we need now.
So yes, we should use every low‑hanging fruit we can. But tuning up the old system is not the same as building the larger, smarter system we actually need.