Eolian Breaks Ground on 1.06 GWh Flint Grid BESS, PJM's Largest Battery Storage Project
Construction has begun on Flint Grid, a 200-megawatt, 5.3-hour duration battery energy storage system in Jersey Township, Licking County, Ohio. At 1.06 gigawatt-hours, it is the largest battery storage project to clear PJM Interconnection's 2027–28 residual capacity auction and the first grid-scale BESS permitted by the Ohio Power Siting Board. The project sits adjacent to the New Albany datacenter corridor, one of the fastest-growing concentrations of AI infrastructure in the United States.
Eolian, the Boston-based energy storage developer, announced the milestone July 29. The company committed hundreds of millions of dollars to the project years before current demand forecasts made headlines. Flint Grid is expected to enter commercial operation before the 2027–28 PJM capacity year begins.
Ohio's Grid Gets Its Largest Battery
The Flint Grid project represents a new scale for battery storage in the PJM footprint, which spans 13 states and the District of Columbia. At 200 MW with 5.3 hours of duration, the system can deliver 1.06 GWh of energy — enough to power roughly 80,000 homes for over five hours. It cleared the residual capacity auction as the single largest battery resource, representing more than 50 percent of all new battery storage capacity awarded for that delivery year.
The Ohio Power Siting Board's approval sets a precedent. Until now, no grid-scale battery project of this size had navigated Ohio's siting process. The board's decision creates a template for future storage development across the state, where interconnection queues are swelling with renewable and storage projects.
Aaron Zubaty, Eolian's founder and chief executive, framed the project as a response to wasted grid capacity. "There's growing consternation about how the US can rapidly scale infrastructure to support America's growing electricity demand, but not nearly enough conversation about how to use existing technology to free up the wasted capacity that already exists on the grid," Zubaty said. The Flint Grid project demonstrates how strategically located storage can increase effective transmission capacity in constrained corridors with rising load.
Why PJM and the Capacity Market Matter
PJM's capacity market exists to ensure enough resources are available to meet peak demand. Generators and storage operators bid into auctions years in advance, locking in revenue for making capacity available when the grid needs it most. The 2027–28 residual auction, held in early 2026, was the first where a battery project of this scale cleared as the dominant new resource.
Flint Grid's participation signals a shift. Historically, capacity auctions were dominated by thermal plants and, more recently, by solar paired with storage. A standalone 200 MW, 5.3-hour battery clearing as the largest new resource marks the first time a storage-only asset has played that role in PJM. The project qualified under PJM's Effective Load Carrying Capability (ELCC) methodology, which assigns capacity value based on a resource's actual contribution to reliability during high-risk hours.
For battery developers, the auction result validates a business model that has been theoretical until now: build merchant storage, bid it into the capacity market, and earn enough revenue to justify the capital expenditure without a long-term power purchase agreement. Eolian's bet — that the capacity market would value long-duration storage in a constrained load pocket — paid off.
The Datacenter Connection
The project's location is no accident. New Albany, just northeast of Columbus, has become a magnet for hyperscale datacenters. Google, Meta, and Amazon have all invested billions in facilities there, drawn by fiber connectivity, relatively cheap land, and a cooperative regulatory environment. The resulting load growth has strained local transmission.
Flint Grid sits directly in that load pocket. By charging when demand is low and discharging during peaks, the battery can relieve congestion on the existing transmission system, effectively increasing its capacity without new lines. That "grid freeing up" effect is the core of Eolian's thesis: storage as transmission alternative.
The economics are compelling. Building new high-voltage transmission takes a decade and billions of dollars. A 200 MW battery can be permitted and built in two to three years for hundreds of millions. In a region where datacenter load is growing faster than transmission can be approved, storage becomes the fastest way to keep the lights on.
Solid-State Research Cracks the Dendrite Problem
While projects like Flint Grid deploy today's lithium-ion technology at scale, researchers are closing in on the next leap. A team at the Max Planck Institute for Sustainable Materials published findings in Nature this month that solve a decades-old mystery: how soft lithium dendrites penetrate hard ceramic solid electrolytes.
The answer, it turns out, is hydrostatic pressure. During charging, lithium metal dendrites grow from the anode toward the cathode. As they elongate inside a crack, the confined lithium generates enough internal pressure to fracture the surrounding ceramic — like a waterjet cutting through rock. The discovery rules out the competing theory that electron leakage along grain boundaries drives the failure.
Dr. Yuwei Zhang, who leads the Chemo-Mechanics of Battery Materials group at the institute, described the mechanism in an interview. "The soft lithium metal is able to penetrate the stiff ceramic electrolyte, like a continuous waterjet that penetrates a rock. We calculated that hydrostatic stress in the dendrite leads to brittle fracture of the solid electrolyte in the end."
The finding opens concrete engineering paths. Researchers are now testing tougher electrolyte compositions that resist cracking, microscopic void patterns that redirect dendrite growth, and protective anode coatings that suppress dendrite formation altogether. If any of these approaches work at scale, solid-state batteries could finally move from lab prototypes to commercial production — offering two to three times the energy density of today's lithium-ion cells.
What This Means for Grid Storage
The Flint Grid and the Max Planck breakthrough operate on different timelines but point to the same conclusion: battery storage is moving from niche to backbone. Today's lithium iron phosphate and nickel-manganese-cobalt chemistries are already cheap enough and durable enough for multi-hour grid applications. Tomorrow's solid-state cells could shrink the footprint of a 1 GWh project by half while improving safety.
For PJM and other wholesale markets, the implication is clear. Storage is no longer a pilot or a peaker replacement. It is a capacity resource that can be sited precisely where the grid needs it most, permitted faster than transmission, and dispatched in milliseconds. The 2027–28 auction was the first to reflect that reality. It will not be the last.
Eolian's Zubaty put it bluntly: "As policymakers consider changes to competitive electricity markets, it's critical that they avoid undermining the long-term investments already underway that will make better use of existing transmission infrastructure and that create a bridge to further long-term supply expansion."
For more on grid-scale storage trends, see our Battery Tech coverage. For the intersection of storage and AI infrastructure, see Cloud & Edge Computing.
According to Eolian's announcement, Flint Grid represents more than 50 percent of new battery capacity in PJM's 2027–28 auction. The Max Planck Institute study on dendrite fracture mechanics was published in Nature in August 2026.