Darbytown Pilot

Executive Overview

The Darbytown Storage Pilot Project is a 5 MW / 500 MWh Form Energy iron-air battery demonstration at Dominion Energy's 336 MW Darbytown Power Station in Henrico County, Virginia. Virginia's State Corporation Commission approved the pilot in May 2024 as part of Dominion's compliance with the Virginia Clean Economy Act, which mandates 3.1 GW of energy storage by 2035 and 100% clean electricity by 2045. Construction began in late 2024 with commercial operation targeted for late 2026. The deployment is Dominion's first long-duration energy storage project and Form Energy's first deployment in Virginia. Dominion serves approximately 7 million customers across 15 states and has stated a target of 1,000–3,000 MW of storage capacity over the next 15 years.

How It Works & Differentiation

The Form Energy iron-air system uses the reversible oxidation and reduction of iron in an aqueous electrolyte to store and release electricity over 100-hour cycles. During charging, metallic iron is oxidised; during discharge, iron oxide is reduced back to metallic iron, releasing electrons to the grid. The storage medium — iron, water, and air — is earth-abundant, non-toxic, and non-flammable, with no lithium, cobalt, or other critical minerals. The 100-hour discharge duration is approximately 25 times longer than the 4-hour average of batteries in Dominion's current fleet and across the U.S. grid. Form Energy has cited a target system cost of less than one-tenth that of lithium-ion BESS at commercial manufacturing scale.

Commercialization & Traction

The Darbytown pilot results will directly inform Dominion's future storage procurement programme. Virginia's electricity sector currently operates at less than 1% storage penetration by real-time output, compared to approximately 20% in California — representing a large addressable market for long-duration storage as the Clean Economy Act drives renewable buildout. The total approved cost for Dominion's approved long-duration storage pilots is approximately $90 million. Form Energy's other commercial deployments include the Cambridge MN (1.5 MW / 150 MWh), Sherco MN (10 MW / 1,000 MWh), Pine Island MN (300 MW / 30 GWh with Google/Xcel), and Georgia Power (15 MW / 1,500 MWh) projects.

Scalability & Strategic Context

The Darbytown Pilot is strategically important because it brings iron-air storage into the regulated utility context of the PJM mid-Atlantic grid, where storage penetration is lowest in the country. Dominion's scale and regulatory reporting requirements under Virginia's Clean Economy Act mean the pilot's performance data will influence procurement decisions not only at Dominion but across the mid-Atlantic utility sector. The 500 MWh capacity of the Form Energy system — the largest single iron-air deployment in Virginia — provides meaningful operational data at a scale relevant to future grid-scale procurements in PJM.