In a Utility Dive opinion piece published Feb. 21, 2025, GridLab technical education director Cassady Craighill argued that the United States is sitting on a near-term fix for its interconnection backlog: reusing the grid connections that already exist at aging power plants. Citing research from GridLab and the University of California, Berkeley, the piece says about 800 GW of clean energy projects could be plugged into the interconnection infrastructure at more than 1,000 existing thermal plants, with roughly another 200 GW available by 2030 — a combined figure the author describes as roughly equivalent to today’s total US installed generating capacity.
The piece points to regulatory movement already underway: FERC approved a PJM Interconnection proposal to update its surplus interconnection rules, the Southwest Power Pool expanded its surplus interconnection service, MISO is cited as having roughly 4,000 MW in its queue tied to the approach, and Xcel Energy and PacifiCorp have used it to deploy solar and storage in the Western Interconnection. The author estimates the approach could avoid about $200 billion in new infrastructure spending.
Executive Summary
Interconnection — the process of getting a new power plant physically and contractually attached to the transmission grid — has become the binding constraint on US electricity supply. Queues run years long, and the network upgrades assigned to new projects can cost more than the projects themselves. Surplus interconnection sidesteps much of that by letting a new resource share the interconnection rights of a generator that is already connected but rarely runs. The op-ed’s analogy is a mall leasing out floor space it is not using.
The economics are straightforward and, on their face, hard to argue with. The op-ed states that thermal plants around the country operate at less than 20% capacity factor — meaning their transformers, substations and transmission ties sit idle most of the year while fully paid for. Adding solar or batteries behind that same connection point uses an asset ratepayers have already funded, and it puts new supply on sites that have land, water rights, roads and a local workforce.
What makes this worth tracking rather than simply celebrating is the gap between a tariff change and an energized megawatt. FERC has approved rule updates and several RTOs have created surplus interconnection products, but surplus service is typically subordinate to the host generator’s rights — which raises real questions about how bankable it is. The measure that matters over the next two years is not technical potential; it is signed interconnection agreements and steel in the ground.
Reusing the Wire Is Cheaper Than Building the Wire
When a developer requests interconnection the conventional way, the grid operator studies what the addition does to power flows across the network and assigns the developer a share of any upgrades required — new transformers, reconductored lines, sometimes entirely new substations. Those studies take years, the cost estimates move as neighboring projects drop out, and the resulting bill routinely kills otherwise viable projects. Surplus interconnection changes the question being asked. Instead of “what does the network need in order to accept this plant,” the question becomes “can the connection already built at this site accommodate another resource behind it.” That is a far narrower study.
The physical logic rests on capacity factor — the share of the year a plant actually generates versus its theoretical maximum. A gas peaker rated at 500 MW that runs a few hundred hours a year still holds a 500 MW connection to the grid for all 8,760 of them. The op-ed’s claim that US thermal plants collectively operate below 20% capacity factor is the entire basis of the opportunity: the wire is the scarce asset, and it is mostly empty. Pairing an underused thermal plant with solar or storage also has a seasonal complementarity argument in its favor, since gas units are most exposed during extreme winter conditions.
The winners here are specific and identifiable. Owners of aging coal and gas plants hold something the market now prices very highly — a permitted site with an existing grid connection — and surplus interconnection lets them monetize it without retiring the host unit first. Developers who can strike site deals with incumbents get to skip the queue. Ratepayers benefit if new low-marginal-cost output displaces expensive thermal running hours. The parties with less to gain are developers holding greenfield land with no interconnection position, who now compete against rivals with a structural head start.
The Capacity Number Deserves an Asterisk
The article’s framing moves between two different units in a way readers should catch. It says surplus interconnection “could nearly double the generation in the United States by 2030,” then notes that 1,000 GW “is roughly equivalent to the installed generating capacity in the United States today.” Those are not the same claim. Capacity is how much a fleet can produce at one instant; generation is how much energy it delivers over a year. A gigawatt of solar produces materially less annual energy than a gigawatt of combined-cycle gas, so 1,000 GW of predominantly solar and storage nameplate would not double US electricity output. The technical potential figure may well be sound; the doubling-of-generation phrasing overstates what it means.
A second asterisk applies to the nature of the interconnection right itself. Surplus interconnection generally gives the new resource conditional access that is subordinate to the host generator — if the existing plant dispatches, the newcomer may have to back down. That is exactly what makes the study process fast, because nothing new is being promised to the network. But conditional output is harder to finance than firm output. Lenders and offtakers price curtailment risk, and how each RTO defines the sharing arrangement will determine whether these projects clear investment committees or stall at the term-sheet stage.
None of this is a reason to dismiss the analysis, and it is worth being explicit that this is an advocacy piece from an organization that works on clean energy deployment. The underlying mechanism has been endorsed by a notably broad coalition — the op-ed notes the PJM proposal was backed by utilities, clean energy advocates, environmental groups and independent power producers alike, and frames the concept as consistent with Energy Secretary Chris Wright’s “energy addition” order and his stated aim to “expand energy production and reduce energy costs.” Broad support is meaningful evidence. It is not the same as evidence about deliverable megawatt-hours, and the op-ed does not publish the methodology behind either the 800 GW estimate or the roughly $200 billion in avoided infrastructure costs.
Why Data Center Developers Should Be Paying Attention
The load growth story running through the entire US power sector — data centers, electrification, reshored manufacturing — is currently gated by interconnection, not by the availability of generating equipment on paper. The op-ed puts the tension plainly: clean electricity sits in queues waiting for new interconnection while utilities turn away technology companies seeking power for new data centers. Both problems have the same root cause, and surplus interconnection addresses it from the supply side without requiring a new transmission corridor to be sited, permitted and built.
Timing is what makes this relevant to infrastructure buyers right now. Utility Dive has separately reported that GE Vernova’s gas turbine backlog reached 116 GW with reservations being taken for 2031 deliveries — a queue of its own, and one that no regulatory filing can shorten. Against that, a solar-plus-storage installation behind an existing interconnection point is one of the few supply options with a realistic path to energization inside a typical data center construction cycle. Sites with existing grid rights have become a category of real estate in their own right.
Demand-side discipline is tightening at the same time, which cuts both ways. Exelon has told investors there is a “high probability” its data center load pipeline falls about 40%, to 11 GW, as transmission security agreements screen out speculative projects; and PJM’s market monitor found data center load accounted for 9% of PJM wholesale costs so far in 2026. For operators, the message is that speculative queue positions are losing value while genuinely deliverable power is gaining it — which is precisely the arbitrage surplus interconnection targets.
From Tariff Language to Energized Megawatts
The real test of this proposal is administrative, and it is already running. FERC’s approval of PJM’s updated surplus rules, SPP’s expanded service, MISO’s cited pipeline and the Xcel and PacifiCorp deployments are the input side of the ledger. The output side — interconnection agreements executed, projects financed, capacity energized — is what will show whether surplus interconnection is a structural unlock or a niche product used by a handful of vertically integrated utilities that happen to own both the host plant and the new resource.
Three implementation details will decide it. First, whether host plant owners have any incentive to lease their surplus to a third party that would compete against them in the same market, or whether uptake concentrates among owners developing on their own sites. Second, how curtailment and cost allocation are written into each RTO’s tariff, since that determines financeability. Third, how the process interacts with queue reform generally — a fast lane only stays fast if it does not fill up with the same volume of speculative requests that clogged the main queue.
There is also an honest limitation worth stating: surplus interconnection reuses capacity at fixed points on the network. It does not move power between regions, relieve congestion between load pockets and generation, or serve load that happens to be nowhere near a retiring coal plant. It is a complement to transmission expansion, not a substitute for it, and the strongest version of the argument is the modest one — that it is among the very few levers that can add meaningful supply inside a few years rather than a decade.
Background
Interconnection is the regulated process by which a new generator joins the transmission grid. In most of the country it is administered by regional transmission organizations — PJM in the mid-Atlantic, MISO across the Midwest, SPP in the central plains — under rules set by the Federal Energy Regulatory Commission. Over the past decade those queues have swelled with far more proposed projects than can be studied, and the network upgrade costs assigned to individual developers have grown large enough to cancel projects outright. Queue reform has been a central FERC preoccupation as a result.
Surplus interconnection service is a tool within that framework rather than a workaround of it: it allows an existing interconnection customer to make unused portions of its connection rights available to another resource at the same point. GridLab, a nonprofit that provides technical analysis on grid and clean energy questions, has advocated for wider use of the mechanism alongside researchers at the University of California, Berkeley. The urgency behind that advocacy is the load growth now arriving from data centers, electrification and manufacturing — the first sustained increase in US electricity demand in roughly two decades.
Source: Leveraging surplus interconnection could unleash 800 GW of energy the US needs today — a Utility Dive opinion piece by GridLab’s Cassady Craighill, published Feb. 21, 2025, citing GridLab and UC Berkeley research on reusing existing grid connections at underused thermal plants.