Hydrogen Power – HRL Advances Quiet Undersea Propulsion Innovation
MALIBU, Calif. April 2, 2025— HRL Laboratories, LLC, has demonstrated proof-of-concept on a unique approach to achieve a silent pumping system that replaces traditional mechanical moving parts with an electric current and a magnetic field. This work is being performed under Defense Advanced Research Project Agency’s (DARPA) “Principles of Undersea Magnetohydrodynamic Pumps (PUMP)” program.
HRL’s new device uses a recirculating electrochemical hydrogen cell which enables a prototype magnetohydrodynamic (MHD) pump that could be 70% efficient as well as highly reliable – with a lifespan of more than 5 years. Key design benefits:
- Nearly eliminates gas bubbles – producing 95% fewer bubbles than traditional electrolysis cells – to deliver quiet, gas-free pumping
- Produces no oxidative or corrosive elements (O2 or Cl2) which degrade electrode performance over time
Magnetohydrodynamic (MHD) pumps:
MHD pumps, which generate force from a magnetic field acting on an electric current flowing through seawater, require no rotating mechanical components. This approach significantly reduces noise while simultaneously increasing reliability in comparison to conventional propeller- or impeller-based systems. In a typical MHD pump, a DC electrical current is passed through a volume of seawater, which interacts with an applied magnetic field, resulting in a Lorentz force on the ions in the water. As the ions accelerate, they drag the water molecules and generate thrust.
HRL’s concept includes uniquely tailored gas-diffusion electrodes in its MHD model. This innovation ensures that the hydrogen gas generated at the cathode does not form bubbles but instead diffuses-out to the back side of the electrode. The resulting H2 gas is then routed to the back side of the anode where it diffuses-in and is consumed. This completes the recirculation loop while preventing corrosive oxygen and chlorine bubbles from forming at the anode.
Jason Graetz, principal investigator at HRL Laboratories, said:
With the successful demonstration of a viable method to achieve an efficient, quiet and reliable MHD pump, we hope that HRL will next have the opportunity to build a complete prototype test system for the U.S. Navy for further testing,
History of magnetohydrodynamic (MHD) drive technology:
Since the 1960s, academic, commercial and military researchers have attempted to realize a novel form of maritime propulsion involving no moving parts – no propeller, no drive shaft, no seals – just magnets and an electric current that silently propel a marine vessel through water. Developers have had some success over the decades demonstrating MHD drive technology on a small scale, but it has been inefficient and impractical for full-scale systems. HRL’s new approach to MHD offers a promising solution to overcoming some of these challenges.
Notable partners:
- General Atomics will design and build the high-temperature superconducting (HTS) magnets required for the MHD pump.
- University of Illinois will provide experience in electrochemical and corrosion modeling to develop a modeling and simulation toolset that will guide the electrode design to meet the project’s specifications.
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