GrafTech and Antora Are Building a Domestic Energy Storage Supply Chain in Pennsylvania

Eight bake furnaces are running again in St. Marys, Pennsylvania. GrafTech International and Antora Energy announced a strategic collaboration on September 10, 2026 to develop and supply carbon-based materials for Antora's thermal batteries, and the work builds a domestic energy storage supply chain inside an Elk County plant that has produced carbon for generations. Both companies have already hired in St. Marys and are recruiting about a dozen more workers across plant operations, machining, maintenance, and additional functions.

The structure of the deal is the point. One American manufacturer makes the carbon. Another American manufacturer turns it into energy infrastructure. The product ships to American factories, data centers, and utilities.

Two American Manufacturers Hold Each End of the Chain

GrafTech traces its carbon manufacturing to 1886 and is headquartered in Brooklyn Heights, Ohio. The company describes itself as the only major graphite electrode producer vertically integrated into petroleum needle coke, its key raw material, which it produces at Seadrift Coke in Port Lavaca, Texas. It has operated the St. Marys facility since acquiring it in 2010. CEO and President Timothy Flanagan said the collaboration is expected to use a significant portion of the bake furnace capacity at St. Marys and to diversify the company's end markets into domestic energy storage.

Antora Energy, headquartered in San Jose, California, builds the batteries. The company closed a $550 million Series C on July 30, 2026, co-led by G2 Venture Partners and Eclipse, with participation from Ribbit Capital, Salesforce Ventures, Activate Capital, John Doerr, Westly Group, StepStone Group, and Liberty Mutual Strategic Ventures. Bloomberg reported that the round funds a second U.S. factory for Antora's modular batteries. Co-founder and CEO Andrew Ponec framed the GrafTech relationship as an investment in American energy leadership.

What is a thermal battery?

A thermal battery stores low-cost electricity as heat inside insulated blocks of solid carbon and delivers that stored energy around the clock as industrial heat or as electricity. Antora's modules are factory-built and can serve a chemical plant, a food producer, a steelmaker, a data center, or the grid. The company reports that the modules ship without supply-constrained critical minerals or multi-year construction timelines.

The Feedstock Is Already American

The carbon blocks and insulation inside Antora's batteries are produced by heating lower-purity feedstocks such as petroleum coke and coal tar pitch in high-temperature furnaces. The United States makes both in volume. EIA analysis of Census Bureau data puts annual U.S. petroleum coke production at an average of 46 million tons across 2014 through 2023, with roughly 41 million tons exported in 2023 alone. Thermal energy storage gives that domestic byproduct stream a high-value industrial destination inside the country.

Federal data shows what that feedstock position is worth.

Why does graphite import reliance matter for energy storage?

The United States produced no natural graphite in 2025 and has been 100 percent net import reliant on it every year since 2021, according to the USGS Mineral Commodity Summaries 2026. U.S. companies consumed an estimated 71,000 tons of natural graphite valued at $128 million in 2025, and China supplied 46 percent of U.S. imports across the 2021 to 2024 period. A storage technology that runs on American refinery and coking byproducts sidesteps that exposure entirely.

The broader picture is the same. USGS reports the United States was 100 percent net import reliant on 16 nonfuel mineral commodities in 2025 and more than 50 percent reliant on 50 of them. Mineral-reliant industries accounted for $4.09 trillion in value in 2025, more than one-eighth of the U.S. economy. Every supply chain that moves onshore reduces the leverage that mineral exporters hold over American industrial production.

Industrial Heat Is the Largest Prize in the Energy Economy

Process heating accounts for roughly 68 percent of all process energy consumed by the U.S. manufacturing sector, and fuel-based process heating alone consumes about 4.8 quadrillion Btu annually, equal to roughly 51 percent of total industrial primary energy consumption, according to the Department of Energy's Better Plants program. Heat is where American factories spend their energy budget, and heat is the market Antora's modules serve directly.

Antora has a delivered project to point to. Its Big Stone system in South Dakota, a 5 gigawatt-hour installation serving POET's bioprocessing facility, moved from initial construction to delivering energy in under 12 months. Speed at that scale is the variable that determines whether a chemical plant, a steelmaker, or a data center campus can actually be built on a competitive timeline.

Scale Is What Makes St. Marys Possible

A partnership like this requires a manufacturer with 140 years of carbon and synthetic graphite experience, idle high-temperature furnace capacity, a vertically integrated coke supply, and the balance sheet to restart a production line for a new end market. It also requires a counterparty with a gigafactory, a proven multi-gigawatt-hour deployment, and $550 million of fresh capital to buy forward supply. Large integrated American companies are the entities positioned to move at that scale on that timeline.

Rep. Glenn Thompson (PA-15) tied the announcement to Pennsylvania's industrial base, crediting the commonwealth's skilled workforce and infrastructure and welcoming the investment in Elk County. St. Marys is the kind of place where domestic supply chain policy either produces jobs or produces press releases. Here it produced restarted furnaces and open positions.

What Policymakers Should Take From This

Three things are worth carrying into the next supply chain debate.

American industrial byproducts are strategic assets. Petroleum coke and coal tar pitch are outputs of refining and steelmaking that the United States produces in surplus and ships overseas. Thermal energy storage turns that surplus into domestic energy infrastructure, and it does so using furnace capacity that already exists on American soil.

Existing plants are the fastest path to new capacity. GrafTech restarted eight furnaces at a facility it has run since 2010. That is measured in months. Greenfield critical mineral capacity is measured in years, and often in permitting decades.

Scale and integration are what make onshoring real. The companies with the furnaces, the feedstock position, and the capital are the companies that close the loop between raw material and finished energy infrastructure. Policy that constrains their ability to grow constrains the domestic supply chain that depends on them.

The furnaces in St. Marys are the evidence. American carbon, American batteries, American factories running on both.