Aviation and maritime transport share a structural problem: neither can rely on battery-electric propulsion for most meaningful applications. Batteries are too heavy, energy density is too low, and charging infrastructure on transoceanic routes does not exist and cannot reasonably be made to. Sustainable aviation fuels offer a partial substitute but are costly and in limited supply. Hydrogen occupies a distinct position in this conversation — not as an obvious winner, but as the fuel type whose fundamental properties align most closely with what high-demand transport sectors actually need.
Aviation: Weight Wins, Volume Loses
Aircraft design is dominated by weight budgets. Every kilogram of fuel or storage system that replaces payload or range capacity is a direct commercial cost. Hydrogen’s energy content per unit of weight — nearly three times that of conventional jet fuel — is its decisive advantage in aviation. A hydrogen-powered aircraft can carry more energy for the same mass, which translates to extended range, longer flight duration, or expanded payload options.
The GAO’s April 2026 assessment cites hydrogen aircraft applications in surveillance, wildfire detection and monitoring, weather modeling, telecommunications relay in disrupted regions, and potential military uses. The quiet operation, low thermal signature, and near-zero emission profile of hydrogen fuel cell aircraft make them particularly well-suited for reconnaissance and persistent observation missions. Several companies are developing hydrogen fuel cell platforms for these applications with active flight programs.
The volume problem is serious but not insurmountable in aircraft designed from the outset for hydrogen. Hydrogen cannot be stored in wings — the tanks are too bulky for wing geometry. Options range from fuselage-mounted tanks on adapted existing airframes to complete aircraft redesigns that integrate hydrogen storage into the structural architecture. Future aircraft optimized for hydrogen will likely look different from current tube-and-wing designs. That redesign requirement is a significant barrier for near-term large-scale commercial aviation adoption but a manageable engineering problem for new aircraft programs and smaller platforms.
Cryogenic management adds another layer of operational complexity. Liquid hydrogen must be stored at approximately -423 degrees Fahrenheit. The insulation systems, pressure management, and heat generated by the fuel cells during operation all require engineering solutions that add weight and cost. NASA, which has used liquid hydrogen in launch vehicles for decades, has established safety and handling protocols that the aviation industry can draw on — but adapting those protocols to commercial aircraft operations at scale is not a trivial exercise.
Maritime: Cleaner, Quieter, Better for Science
Hydrogen-powered vessels offer operational advantages over diesel that extend beyond emissions. They are quieter — a property that reduces the acoustic pollution that disrupts marine wildlife and degrades sonar mapping accuracy. They produce no liquid or atmospheric pollution at the point of operation, which matters for operations in environmentally sensitive waters. And for research vessels and wildlife survey operations, reduced noise and emissions improve data quality.
The GAO report documents a 75-passenger hydrogen-powered ferry that completed a six-month demonstration project in San Francisco in 2024 and a cruise line that has announced two hydrogen-powered cruise ships under construction. These are genuine commercial deployments, not laboratory demonstrations. They reflect a segment of the maritime industry that has concluded hydrogen’s operational benefits justify its current cost premium.
Maritime hydrogen adoption faces many of the same infrastructure barriers as other sectors — refueling infrastructure at ports is minimal, and hydrogen production and transport costs vary by region. But maritime routes are relatively predictable, ports are fixed, and fueling operations can be planned in advance. The logistics of hydrogen maritime refueling are more tractable than building out a nationwide consumer vehicle refueling network.
The Common Thread
Aviation and maritime applications share a characteristic that explains hydrogen’s traction in both sectors: they are environments where battery-electric alternatives face fundamental physical limitations, not merely cost disadvantages. A battery-electric transoceanic cargo ship is not an engineering challenge awaiting better batteries — the weight and volume of the batteries required would displace most of the cargo the ship exists to carry. A battery-electric long-range surveillance aircraft faces similar arithmetic. Hydrogen does not face those constraints in the same way.
This does not mean hydrogen will dominate aviation and maritime transport. Sustainable aviation fuels, synthetic fuels, and ammonia-based propulsion are also under active development for these sectors. Hydrogen will compete with all of them on economics, infrastructure availability, and regulatory acceptance. But the physical case for hydrogen in weight-constrained, range-critical, emissions-sensitive transport applications is stronger than in almost any other sector of the economy. That is where serious development attention is appropriately concentrated.