Hyliion’s additively manufactured KARNO selected for US Navy USX-1 trials
Hyliion Holdings Corp, based in Austin, Texas, has announced that the US Navy’s Office of Naval Research (ONR), in partnership with the Defense Advanced Research Projects Agency (DARPA), has selected the USX-1 Defiant as a candidate test vessel for Hyliion’s KARNO energy generating technology. Initial sea trials are scheduled for 2027 under a development programme funded by the ONR to advance the use of KARNO Cores for onboard power generation in US Navy vessels.
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For the USX-1 Defiant sea trials, Hyliion will deliver a drop-in 800 kW power system consisting of four additively manufactured 200 kW KARNO Cores in a keel cooled configuration. The modular architecture is designed to demonstrate reliable, low-maintenance power generation for an unmanned vessel, where onboard servicing is not available. Trials are aimed at highlighting KARNO technology’s scalability and redundancy, with power units that can be distributed across the ship to support mission reliability.
The USX-1 Defiant was developed under DARPA’s No Manning Required Ship (NOMARS) programme, which challenged the traditional naval architecture model by designing a seaframe (the ship without mission systems) from the ground up with no provision, allowance, or expectation for humans on board. The programme is part of a broader effort to modernise the US Navy and optimise surface platforms for autonomous operation, enabling simpler hull designs, improved reliability and survivability, and increased flexibility in payload and power system integration. Measuring about 55 m in length, with a displacement of about 240 metric tons, USX-1 Defiant is designed for long-duration autonomous operation in the open ocean, independently or alongside other naval assets. The vessel is designed and developed by Serco-North America as a full-scale technology demonstrator and is currently undergoing sea trials.
“USX-1 Defiant represents a fundamental shift in how naval platforms are designed, powered, and operated,” said Thomas Healy, Founder and Chief Executive Officer of Hyliion. “As the Navy moves toward unmanned surface vessels, power systems must be efficient, resilient, and capable of operating without human intervention. Our KARNO technology excels in these parameters, and we view USX-1 Defiant as the first of hopefully many naval platforms to be powered by this technology.”
Hyliion’s KARNO Core is a heat-powered linear generator designed for high modularity, efficiency, and low-maintenance operation, making it well suited for unmanned maritime platforms. For the US Navy deployment, the KARNO Cores will operate on F-76 marine diesel and demonstrate its ability to supply onboard power for extended durations with a low thermal and acoustic footprint. The KARNO Core generates direct current (DC) power output at 800 Vdc enabling direct integration into modern ship electrical architectures. The KARNO technology is currently undergoing land-based testing and development using simulated US Navy load profiles.
