Hydrogen in Aviation
Lighter Than Air
It has been almost a century since we gave up on lighter-than-air aircraft. Until the end of the First World War, hot air balloons and zeppelins were widely used in the military, but ever since the Hindenburg disaster, lighter than air aircraft have been mostly perceived as floating hazards. Well, this may soon change as a result of the use of hydrogen as a source aviation fuel.
The aviation industry is responsible for about 2.5% of global CO2 emissions, and its overall contribution to global warming from other gases is about 3.5%. While these are relatively small, aviation emissions are not getting any smaller. The aviation sector is expected to grow at a rate of 4.3% per year and it’s forecasted to double or triple by mid-century.
A big part of the conversation about emission reductions has mainly considered the availability of technological, operational and infrastructural improvements as well as the compatibility of biofuels with current aircraft. But while these innovations help reduce emissions, these alone will not eliminate them. The trend can be observed in IATA’s 2050 roadmap, which leads to question what “radical tech” may be.
The Big Shot
The smallest molecule may be our biggest shot. A growing number of aviation stakeholders have recently shared their zero-emission goals. The cleanest and potentially most ambitious goal is hydrogen aircraft. Not to be taken lightly, plans to research and develop zero-emission concept aircraft by 2035 have been set in motion by a major aircraft manufacturer, Airbus, with testing occurring as early as 2025.
Hydrogen research and innovation is widespread across industries. With the highest energy per mass of any fuel, hydrogen has traditionally been the fuel of choice for space exploration. The hydrogen molecule holds immense potential in the decarbonization of industries where electrification is impractical, such as aviation.
Presently, about 99% of all hydrogen is produced through steam methane reforming (SMR) to generate gray hydrogen. This technology can be paired with carbon capture and storage (SMR-CCS) to generate blue hydrogen. A greener process uses renewable energy for electrolysis to generate green hydrogen and an even greener process uses SMR-CCS with biomethane, biogas derived from waste and sewage. Grayish hydrogen? The latter can have a negative footprint - in essence offsetting carbon emissions. This could help bridge the gap towards carbon neutrality, repurposing existing infrastructure while renewable energies are developed at scale to support green hydrogen production. The carbon footprint for these processes using different electricity grids for electrolysis can be observed below.
The Chicken or the Egg?
The future of hydrogen looks promising, but its current use in aviation is scarce at best, with only minor uses in the military. Hydrogen’s low volumetric density requires advanced storage methods, its green production is energy intensive, complex aviation regulatory standards impede radical innovation and a consortium of sectors need to be mobilized to adopt hydrogen.
In a world where fossil fuels are cheap and abundant, hydrogen cannot compete as an energy source. Yet as we start to account for the environmental and health costs associated with fossil fuels, hydrogen may stand a fighting chance. In fact, a number of countries in Asia Pacific and Europe have implemented hydrogen strategies. Canada also released its hydrogen strategy with a roadmap to incentivize a hydrogen economy through investment, policy, innovation and awareness.
Back to the airplane, Airbus’ designs include an ambitious flying wing, but we don’t see many of those around and there is a reason for it. In reality innovation in aviation can take decades! The hyper safety focused aviation industry does not make it easy for a new type of aircraft to take off. This results in minor iterative innovation – For example, the Boeing 747 was designed in the 60’s and ever since marginal improvements have been compounding to design the 747 we see today. But with new technology such as electric aircraft and advanced air mobility, it wouldn’t be surprising to see the development of radical aviation tech using hydrogen.
All in all, this is a very complex relationship where there really is no chicken or egg. The development of current hydrogen infrastructure is a delicate partnership from all sectors, where various stakeholders rely on memorandums of understanding to scale up operations. To name a few, hydrogen producers, energy operators, distributors, airports, aircraft manufacturers and policy makers need to continue their efforts to build this complex ecosystem. But perhaps most important of all, passengers need to understand that green aviation may come at a greater cost than the current pricing to which we have become accustomed.