ExxonMobil Corp. is facing expanded antitrust claims in a Texas court, accused of leveraging its dominant carbon dioxide pipeline network to stifle competition in the emerging blue ammonia market.

The amended lawsuit, filed in Texas Business Court by startup Clean Hydrogen Works, adds the oil giant as a defendant in a year-old legal battle originally launched against Denbury Carbon Solutions. 

The petition describes Exxon’s tactics as a “Rockefeller-style power play” intended to protect its own market share.

At the heart of the dispute is the Ascension Clean Energy (ACE) project, a $7.5 billion blue ammonia facility in Louisiana. To operate, the project requires access to specialized infrastructure to transport captured carbon emissions. 

Clean Hydrogen Works alleges that after ExxonMobil acquired Denbury in 2023, it forced the subsidiary to terminate agreements that would have granted the ACE project access to Denbury’s 1,300-mile pipeline network.

That network is currently the largest liquid CO2 pipeline system in the United States, spanning the critical Gulf Coast industrial corridor.

“Control over these networks could significantly influence which projects ultimately reach completion,” industry analysts noted, as the sector faces a bottleneck in transportation and storage capacity.

The lawsuit claims ExxonMobil blocked the startup’s pipeline access to favor its own competing low-carbon hydrogen and ammonia plant in Baytown, Texas. However, in a shift of market fortunes, ExxonMobil paused its Baytown project in late 2025, citing high costs and weak global demand.

Before the acquisition, Denbury had secured exclusive rights to transport and sequester up to 12 million metric tons of CO2 annually from the ACE site. The startup argues that losing this access unraveled years of strategic planning centered on the pipeline’s proximity to the Mississippi River.

ExxonMobil has declined to comment on the pending litigation. The case is expected to set a legal precedent for whether carbon capture infrastructure must function as an open-access utility or can be used as a competitive moat by the companies that own the steel in the ground.