York County, Pennsylvania

York Energy Storage

Reliable Renewable Electricity for PJM Interchange Customers from Hydro Pumped Storage

858 MW
Generating Capacity
10 hrs
Generation Duration
80%
Round-Trip Efficiency
FERC ✓
Permit Approved Nov 2024
Project At a Glance
Capacity
858 MW
Location
Chanceford Township
York County, PA
Lower Reservoir
Lake Clarke
(Susquehanna River)
Round-Trip Efficiency
80%
Generation Output
8,580 MWh / 10-hr cycle
Regulatory Status
✓ FERC Preliminary Permit Approved
November 21, 2024
Docket No. P-15332-000

Project Description

At 858 MW, YES would rank among the largest long-duration energy storage projects in the eastern United States — with a single 10-hour cycle delivering 8,580 MWh, enough to supply over 715,000 homes simultaneously.

The York Energy Storage (YES) project is an 858 MW open-loop, long-duration pumped hydro storage facility planned in Chanceford Township, York County, Pennsylvania. It leverages Lake Clarke — an existing Susquehanna River reservoir — as its lower reservoir, paired with a newly constructed 580-acre upper reservoir at 680 feet of elevation holding 26,000 acre-feet of storage.

An underground powerhouse will house three reversible pump-turbine-generators (286 MW each), connected by a 44-foot diameter shaft and steel-lined supply tunnels. The facility will connect to the PJM grid via an above-ground 500 kV switchyard.

The project is expected to achieve 80% round-trip efficiency, generating 8,580 MWh over a standard 10-hour operating cycle — providing flexible, dispatchable clean power exactly when and where the grid needs it most.

The powerhouse, penstock, and major infrastructure are hidden underground, and the lower reservoir uses an existing body of water — minimizing surface disturbance and visual impact.

Grid & System Benefits


  • Prime Location — Strategically positioned near the center of the PJM grid; independently cited as the best pumped storage site in the eastern United States.

  • Proven Technology — Pumped hydro accounts for 94% of all long-duration grid-scale energy storage worldwide. A 100-year track record with a 50–100 year operating lifespan — far exceeding battery alternatives.

  • Environmental Advantage — No emissions, no mining, and no solid or liquid waste. A genuinely green technology superior to batteries, gas turbines, or any currently known storage alternative.

  • Grid Resiliency — Instantly dispatchable by the PJM Control Center, providing critical inertia and stability as fossil generation retires from the grid.

  • Long-Duration Load Balancing — Unlike short-duration batteries, YES delivers sustained output over a full 10-hour cycle — managing voltage, frequency, power factor, black starts, and transmission congestion.

  • Minimal Surface Footprint — Powerhouse and penstock are fully underground; lower reservoir uses existing Lake Clarke; upper reservoir on lightly developed land.

Community Benefits


  • Economic Development — 300 to 500 construction jobs and 25 to 50 permanent positions, with billions of dollars in regional investment flowing into York County during construction.

  • Lowest Life-Cycle Cost — Lower long-term cost than battery storage, gas turbine peakers, or any other currently available energy storage alternative.

  • Clean & Green — Powered entirely by water. Produces zero air, liquid, or solid waste. Simply the power of gravity and water — the world’s oldest and cleanest form of energy storage.

  • Tax Contribution — $30 million in annual tax revenue to York County and the Commonwealth of Pennsylvania, with the potential to reduce local real estate and school taxes.

Regulatory Status

The YES project is currently in the Assessment Phase, focused on securing all required regulatory approvals from FERC and PJM.

YES filed for its FERC Preliminary Permit on February 14, 2023 and received approval on November 21, 2024 — granting site control and the first right to apply for a Construction License.

For PJM approval, YES must complete a grid analysis demonstrating project benefits to PJM customers and no adverse impact on downstream Susquehanna River hydro facilities.

Feb 14, 2023
FERC Preliminary Permit Filed
York Energy Storage filed with the Federal Energy Regulatory Commission for a Preliminary Permit for the YES project.
Nov 21, 2024
FERC Preliminary Permit Approved ✓
FERC granted the Preliminary Permit (Docket No. P-15332-000), giving YES four years of site control and the first right to file for a Construction License.
2025–2028
Assessment & Development Phase
Active phase: PJM grid analysis underway, feasibility studies ongoing, and preparation for the FERC Construction License application in progress.
Next Milestone
PJM Grid Analysis & Approval
Demonstrating project benefits for PJM customers and no negative impact on downstream Susquehanna River hydro facilities.

Visuals


Site plan showing the York Energy Storage project boundary

Topographic map of the York Energy Storage site area

Profile diagram of the York Energy Storage pumped hydro facility

History of the Site

The YES site has a 50-year history of recognition as the premier pumped storage location in the eastern United States — studied and pursued by multiple entities across three separate development efforts before York Energy Storage, LLC acquired all prior work and moved forward.

1970s
Site First Identified
Pennsylvania Power & Light and Baltimore Gas & Electric identified the site as the preferred pumped storage location in the mid-Atlantic region — no action was taken at the time.
Early 1990s
Mid-Atlantic Energy Engineers
Mid-Atlantic Energy Engineers, Ltd. formed and obtained FERC Preliminary Permit No. 10868-000. Harza Engineering of Chicago — a national leader in hydroelectric projects — retained to assist, citing the site as “the best location for a pumped storage project in the eastern United States.”
Late 1990s
Project Shelved
At the conclusion of the six-year permit period, the project was deemed too large and long-duration for the changing, deregulating power market. No further action was taken.
2011
Third-Party Application Withdrawn
A third party filed for a new FERC Preliminary Permit. The application was subsequently withdrawn for undisclosed reasons.
2023
York Energy Storage, LLC Formed
YES acquired all prior engineering, environmental, feasibility, geologic, and cost-estimate files from Mid-Atlantic Energy Engineers and filed with FERC for a new Preliminary Permit.
Nov 2024
FERC Preliminary Permit Approved
FERC approved the Preliminary Permit (Docket P-15332-000), granting YES site control through 2028 and the first right to apply for a Construction License.

Get in Touch

York Energy Storage, LLC welcomes inquiries from qualified development partners, investors, and interested parties. Contact us to learn more about the project, partnership opportunities, or our FERC licensing process.

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