Hydrogen Fuel Cell Cars, No; Combat Drones, Yes

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Despite years of trial and error, hydrogen fuel cell electric cars have yet to carve out a substantial role in the global vehicle electrification movement. However, military researchers and defense suppliers have been poking into fuel cell technology throughout the 21st century. Their work is beginning to show up in airborne, ground, and seaborne unmanned vehicles on the battlefield, raising the potential for a new wave of civilian applications in the mobility field as well.

Fuel Cells & The Hydrogen Conundrum

Fuel cells produce electricity through a chemical reaction between air and hydrogen, or hydrogen-containing fuels. The only emission is water vapor. That tidies up the tailpipe end. However, the global hydrogen supply chain is larded with carbon at the source, which primarily consists of natural gas. Gassified coal also contributes a measure of hydrogen to the global market.

The changeover to a more sustainable, localized hydrogen supply chain has been slow. Back in 2015 I visited the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland to learn about the thin film solar research under way there, and researchers at the school also described their work on power-to-gas systems. Also called “solar refineries,” power-to-gas refers to electrolyzer systems that deploy solar-sourced electricity to jolt hydrogen gas from water. Wind, biogenic resources, and other renewables are also in play (see lots more water electrolysis background here).

Today, “green” hydrogen is commonly used to describe hydrogen produced with water electrolysis and renewable energy. Power-to-liquid systems have also emerged in recent years, meaning the liquid electrofuels that can be synthesized from green hydrogen and captured carbon.

The economic case for green hydrogen and e-fuels is a tough one to make when the cost of conventional hydrogen is low. However, the Iran war has narrowed the cost gap while also accelerating the security case for locally produced fuels that deploy renewable resources at hand. Last week, for example, the leading German defense supplier Rheinmetall announced next steps in its plan for distributing hundreds of electrolyzer facilities across Europe in order to secure a reliable supply chain for military e-fuels.

Green Hydrogen & The Robot War Of The Future

Another advantage from the military perspective is the scalability of electrolysis systems. They can be combined with solar arrays or other locally sited renewables in transportable microgrids, bringing green hydrogen to remote staging areas while avoiding the dangers, obstacles, and excessive costs of transporting conventional fuel over long distances.

The microgrid solution surfaced on the CleanTechnica radar last fall, when the US drone manufacturer Heven Aerotech partnered with another domestic innovator, Sesame Solar, to pair Sesame’s rapid-assembly, transportable “Mobile Nanogrid” green hydrogen generating and storage system with Heven’s UAVs (unmanned aerial vehicles).

In March, Heven earned a streamlined acquisition status from the US Army for its unmanned Z1 UAV and hydrogen solutions, too. “The contract vehicle enables Army units to place future orders without renegotiating basic terms and conditions,” Heven explained in an article posted on UAS Magazine.

The Fuel Cell Drone View From Heven

Last week I had a chance to speak with Dr. Karen Swider-Lyons, the VP of Hydrogen Technology and Strategy at Heven. In a wide-ranging conversation about the past, present, and future of fuel cell drones, Dr. Swider-Lyons noted that she began flying fuel cell UAVs with the US Naval Research Laboratory back in 2004. She formerly headed the lab’s alternative energy section and she also served a stint as Senior Principal R&D Engineer at the US hydrogen and fuel cell firm Plug Power.

Swider-Lyons describes the progress of the vehicle electrification movement as a process of catching up to — and then surpassing — incumbent fossil fuel ecosystems. Oil companies have had more than 100 years to forge a closely entwined relationship with automakers and the aviation and marine industries, too. Still, Swider-Lyons points out that enabling technologies can tip the balance towards rapid changeover. She cited the contribution of Nvidia’s gaming chips to the AI boom. Another example is the invention of blue LEDs in 1993, which went on to spark a wave of innovation in lighting and communication technology.

If you can describe some noteworthy enabling technologies in the vehicle electrification field, drop a note in the discussion thread. Before you do, consider how drone warfare has brought the advantages of electrification to the forefront. In the aviation field, for example, drones are small, lightweight, relatively cheap, and disposable. They don’t require on-board pilots, and they don’t require the runway infrastructure of conventional aircraft.

Electric propulsion adds the key military advantages of low noise and a low heat signature. “Regular [internal combustion] engines on small planes are like lawnmower engines,” Swider-Lyons observes, referring to the contrast between electric propulsion and the noise, heat, and inefficiency of conventional ICE (internal combustion engine) systems.

As for the additional cost of electrification, that can be absorbed into the overall economy of drone warfare. “The military does not care about the cost,” Swider-Lyons adds. “Drones are smaller and there is a cost reduction in the reduced need for manpower.”

The Long March Of The Fuel Cell Drone

Overall, the takeaway from the conversation is that two decades’ worth of R&D threads are beginning to come together in military applications. Here are two examples from the CleanTechnica archive:

2009: Fuel cells are trialed in the 28th annual Cobra Gold multilateral exercise in Thailand. “The lightweight, portable fuel cell system was developed by DARPA’s Robust Portable Power Sources program.”

2012: The US Navy advances a system for producing jet fuel from seawater. The system was patented in 2016. “With all the ingredients for making synthetic fuel at hand, the Navy anticipates being able to produce practically any kind of fuel it needs from seawater.”

And, more recently:

2021: “The US Air Force has been nosing around the area of fossil-free jet fuel for years…If all goes according to plan, the jet fighter of the future will grab renewable fuel on-the-go from modular systems that tease hydrogen and carbon from water and air.”

2024: “The US Army has been demonstrating a versatile new zero emission hydrogen fuel cell electric rescue truck, capable of going 1,500 miles before it needs a refill.” The project includes a transportable green hydrogen microgrid.

Overall, Swider-Lyons describes drone electrification systems through the lens of a career fuel cell researcher, explaining that “people see hydrogen as the missing piece of the puzzle.”

She’s not the only one. Last summer the Naval Research Laboratory recapped its progress on a transportable, stationary fuel cell system called H-SUP, for Hydrogen Small Unit Power. Initially designed for recharging batteries in the field, H-SUP is producing a knock-on effect in other applications.

“The use of hydrogen in key applications can lead to increased electrical efficiency and energy density, increased operational range, reduced thermal and audible signature, and reduced maintenance requirements,” NRL added.

Next Steps: Technology Transfer

Swider-Lyons advises that niche applications are not the same as widespread commercial use. “There is a lot of work to be done around cost and scale-up,” she notes.

Still, the confluence of drone warfare, green hydrogen, and chaos in global market for conventional fuels can act as accelerators. Out of necessity, for example, Ukraine has emerged as a global leader in drone warfare, with fuel cells and green hydrogen both beginning to emerge.

Despite the sharp U-turn in federal policy making last year, innovation and adoption also continue apace in the US, Heven’s new contract status with the US Army being one example.

Photo: The US drone manufacturer Heven Aerotech has earned a streamlined contract with the US Army for its hydrogen fuel cell UAV and associated hydrogen systems (cropped, courtesy of Heven).