Iron-air cell stack · Pittsburgh line 3 VK—2025 / Q3 commissioning batch

SERIES C $340M raised · led by Breakthrough Energy · Nov 2025

A battery built from iron, water, and the air around it — for the grid we need next.

Iron-air chemistry delivers 100-hour grid storage at one-tenth the cost of lithium-ion. We build them in Pittsburgh and deploy them across North American utilities — turning intermittent wind and solar into firm, dispatchable, multi-day power.

Talk to our utility team See the technology

Cell cost

$18/kWh

vs $138 lithium-ion (DOE 2025)

Duration

100hr

vs 4 hours typical Li-ion

Sites operating

+ 23 under construction

Deployed capacity

1.84GWh

8.1 GWh contracted by 2027

01 / Technology

The chemistry is iron rusting — slowly, reversibly, on demand.

26 55.845 u

Ferrum · Iron

One of the four most abundant elements on earth — held in a charged cell, given back as electricity.

Iron-air cells run on a reversible oxidation reaction that humans have understood for two centuries — the same reaction that turns iron orange in a damp basement. We charge a cell by reducing iron oxide back to metallic iron. We discharge it by letting the iron rust again, harvesting the electrons that move during the reaction.

The result is a battery whose materials cost almost nothing. No lithium, no nickel, no cobalt, no rare earth supply chains. Just iron pellets, water, and air drawn in from outside the container.

Domestic supply chain: Iron is mined and refined at scale in North America. No critical mineral exposure.
Non-flammable, non-toxic: Water-based electrolyte. No thermal runaway, no fire suppression infrastructure required.
Modular containers: 1 MW / 100 MWh units arrive on a flatbed, are connected to the grid in 14 days.
25-year design life: No degradation curve typical of lithium chemistry. Performance is flat for the asset's full term.

02 / Why this matters now

Lithium solves four hours. The grid needs days.

The transition runs into a wall around hour five. Wind farms go quiet for a week at a time. Polar vortexes shut down solar for ten days. Lithium-ion batteries can't economically store energy over multi-day periods — the chemistry isn't built for it. Iron-air is.

Levelized cost of storage by duration $ / kWh discharged · DOE 2025 reference framework · lower is better

Volkern iron-air Lithium-ion (Li-NMC)

4-hour durationDaily load shifting

$0.18 / $0.16

12-hour durationOvernight cycling

$0.08 vs $0.42

24-hour durationDay–night arbitrage

$0.05 vs $0.84

100-hour durationMulti-day reliability

$0.02 vs $3.50

Source — Department of Energy Long-Duration Storage Shot reference architecture, 2025 update. Lithium-ion costs include capacity overprovisioning required to achieve equivalent duration. Iron-air costs include 25-year container, electrolyte, and replacement cycle. Independently audited by RMI in collaboration with NREL.

03 / How a site comes online

From PPA to first discharge in eighteen months.

01 — Months 0–3

Capacity contract & siting

Long-term tolling or PPA structured against the utility's resource adequacy needs. Site selected on existing substation or retiring fossil land — no new transmission required.

02 — Months 3–9

Permitting & interconnection

Iron-air's non-flammable, non-toxic profile means category-shifting permit speed. No NFPA 855 hazardous fire suppression. No critical mineral disclosure cycle. Months, not years.

03 — Months 9–15

iii

Manufacturing & delivery

Containers ship from our Pittsburgh factory on flatbeds. Each unit is a self-contained 1 MW / 100 MWh storage block. A typical 100 MW site is 50 containers on a six-acre pad.

04 — Months 15–18

Commissioning & live

Containers connect to substation in 14 days each. SCADA integration with the utility's EMS, dispatchable like any other generation asset, first cycle within two weeks of energization.

04 / Field operations

Forty-seven sites live. North America, mostly.

Our first commercial cell ran in 2022. Three years later, we have over a gigawatt-hour deployed across utility partners in eleven states and two Canadian provinces — and a contracted pipeline that takes us past eight gigawatt-hours by 2027.

Pittsburgh HQ

Sites: 47 live · 23 building Updated: Nov 11 · 14:32 UTC

Buckeye Energy Park

Cleveland, OH · 120 MW / 12 GWh

Utility: FirstEnergy Ohio

● Live

Llano Wind Pairing

Llano County, TX · 80 MW / 8 GWh

Utility: ERCOT · Apex Clean Energy

● Live

Cariboo Resilience

Quesnel, BC · 60 MW / 6 GWh

Utility: BC Hydro

◐ Commissioning

Antelope Valley LDS

Lancaster, CA · 200 MW / 20 GWh

Utility: SCE / LADWP

○ Contract signed

Empire Reliability Block

Schenectady, NY · 120 MW / 12 GWh

Utility: NYISO · National Grid

○ Contract signed

Iowa Wind Ride-Through

Sioux County, IA · 90 MW / 9 GWh

Utility: MidAmerican Energy

● Live

05 / Team

Eight years of work, by people who know grids.

Two hundred and forty engineers, electrochemists, manufacturing leads, and operators. Most have spent careers at utilities, national labs, or the inside of fossil generation stations. We hire for the experience of running real infrastructure.

Eliana Marquez

CEO & Co-founder

Previously VP of Battery R&D at Tesla. Before that, Argonne National Lab. PhD MIT electrochemistry, 2008.

Wesley Otieno

CTO & Co-founder

25 years at NREL leading long-duration storage research. Co-authored the DOE's reference framework for iron-air cells.

Reka Pataki

Chief Commercial Officer

Formerly VP of Origination at NextEra Energy Resources. Has structured over $14B in utility PPAs.

Daniel Choi

VP of Manufacturing

Built and ran Tesla's Nevada cell plant ramp-up. Before that, Bosch automotive operations across three continents.

If you run a grid, we should talk.

We work directly with vertically integrated utilities, IPPs, and grid operators across North America. Our commercial team can have a preliminary techno-economic analysis back to you in under two weeks.

Request a meeting → Download our white paper