A New Opportunity For Hydrogen is Aviation
The coronavirus pandemic has revealed how dramatically global CO2 emissions can fall when world governments take collective and decisive action. According to the Australia Institute, airlines' carbon emissions could drop by more than one-third this year, given the lack of travel at airports around the world. Conversations are percolating on what steps both commercial and private airlines should take post-pandemic to ensure the industry becomes much more sustainable over time. A number of governments have already indicated that they will be looking into requiring robust sustainability plans from the airline industry that is now looking for government support.
The crisis also makes a lot of people reflect in general on the impact of humans on the ecosystem and our interactions with it. We are feeling optimistic that this more thoughtful attitude towards our planet’s ecosystem will prevail after the storm passes and we will see an increased push for transformational changes in aviation.
As we shared in one of our recent publications, hydrogen power has the unique capability to drive such a transformation to decarbonize aviation. Hydrogen-based aircraft propulsion satisfies the requirements for extreme energy density and high cycle frequency, while avoiding the scalability problems of biofuels, making this a virtual necessity in our carbon-neutral future.
Conceivably even more interesting, we believe that the reverse is also going to be true - that aviation will become the main driving force that finally propels hydrogen into the mainstream as the zero-emission solution of choice for a variety of transportation needs.
While we've seen consistent buzz over the years surrounding the potential of hydrogen fuel, mass adoption still lags. From the very first fuel cell vehicle introduced in 1959 to the work of major Asian automakers bringing production fuel cell cars to the market, we've seen billions of dollars spent on fuel cells. Yet, today's modern battery electric vehicles have outsold hydrogen cars 307 to one in the last 10 years.
Many economists and experts interpret these results as the death spell for hydrogen mobility. With the rise of more disruptive EV vehicle models, we've seen millions of EV advocates encourage the automakers and the governments to stop wasting billions on 'fool cells.' To no surprise, these advocates have a point given the market outcomes of the launch of electric vehicles and the success of EV adoption globally. From the high cost of the fuel cell cars themselves to the mind-boggling expense of the fueling infrastructure to replace all the gas stations, the barriers seem insurmountable.
Are hydrogen discussions dead given the success of electric vehicles? Not so fast. At ZeroAvia, we think that fuel cells have a great future in transportation. It's just that previous efforts have focused on a completely wrong side of the market - light duty road transport. In actuality, it's aviation that will drive the adoption of hydrogen across sectors. Let’s look at it in more detail.
Aviation Matched to Hydrogen’s Energy Density and Low Cycling Costs
As a foundational principle, one should consider the various transportation modes in terms of energy intensity and utilization. The energy intensity can be approximated by what fraction of vehicle weight is allocated to fuel, and utilization - by the percent of the time the vehicle is in motion. These dimensions map well to the critical differences between battery and fuel cell vehicles: energy density, recharge time and cycle costs - allowing us to have a clear, logical discussion of the applicability of various propulsion approaches to various transport types.
Today, the best production battery packs have 200 watt-hours per kilogram (Wh/kg) energy density, 1,000-2,000 cycle life, and recharge time of 45-plus minutes. In contrast, a liquid hydrogen fuel cell system can get to 3,000+ Wh/kg, 15,000+ cycle life, and refuel in 20 minutes. Therefore, the higher the energy intensity and utilization, the more the balance tips towards hydrogen.
When you examine the various transport types in terms of its energy density and utilization, the differences are staggering. Personal cars go into the bottom left corner - low 2% energy intensity and low level of 5% utilization. Light duty commercial vehicles are slightly better -3% energy intensity and much higher 30% utilization.
Next, we have medium-duty delivery trucks that possess 3.5% energy intensity and even higher utilization of 40%. Heavy-duty trucks are even higher, at roughly 11% energy intensity and 50% utilization. And then we come to the pinnacle of the chart: commercial aircraft. Boeing 737-400 has an energy intensity of almost 40%, staying in the air on average approximately 10 hours/day and for 40% utilization.
This analysis makes it clear why hydrogen fuel cell transport to date has mostly failed. Light duty personal vehicles are the worst possible segment, where even the current batteries are good enough. A typical electric vehicle with 200-mile range and 1,000 battery cycles has an excellent 200,000-mile lifetime - more than it needs. In contrast, a Boeing 737 on a San Francisco - Los Angeles service will run eight trips (cycles) / day. Of course, a battery would not work here at all due to weight, but even if it somehow magically did, it would last just four to eight months, requiring an astonishing 30 battery replacements over the aircraft's lifetime. Hydrogen fuel cell systems could last 10 times longer, potentially beating even the current turbine technology. The best case for hydrogen is pretty clear once you look at the fundamentals.
Aviation Supports Most Concentrated and Efficient Fueling Infrastructure
Aviation’s advantages get even more apparent when you consider fueling infrastructure. In the US, there are 110,000 car gas stations and 6,000 truck stations. In contrast, 85% of all commercial air traffic in the US concentrate in just 50 airports, where all these aircraft refuel, as well (the remaining 15% are across only 450 more). Quite obviously, the more extensive the fueling network, the harder and more expensive it is to replace it. Individual stations get smaller, requiring more complex fuel logistics, and resulting in higher amortization costs per kilogram of fuel dispensed. Once again, commercial air transport shines.
Aviation Powertrains are Much Less Price-Sensitive Than Automotive
Finally, the powertrain costs point in the same direction. When a typical car engine contributes only 8% to 10% to the vehicle cost or approximately $3,000 per driver, any competing technology has to compete with that number. A useful metric here is the cost per kilowatt (kW) or propulsion, which is about $30/kW for a personal car. With the current values of fuel cell systems at $200-$300/kW, this is a robust number to beat. Refreshingly, even a small 800 kW aviation turbine costs $1 million, or over $1,000/kW. Again, it is blindingly apparent where the sweet spot is for fuel cells.
Therefore, we believe it is aviation, not cars - and especially not personal cars - that will finally drive hydrogen to become a mass transportation fuel. The sooner the industry and the governments realize that, and align their investments accordingly, the sooner we will have hydrogen fuel scale-up. With the initial high-volume infrastructure built out at the airports, ground transport will get 100-plus large-scale, low-cost production and fueling points.
Airports, as natural transportation hubs, are among the best places for refueling, where more than a billion people show up every year, and millions of vehicles pick up and deliver. From these apparent locations, we will have a further expansion of the fueling infrastructure to cover lighter and lighter duty transport, and possibly, one day in the future, making even personal hydrogen cars viable.
In short, nowhere else is hydrogen more relevant than in aviation. We at ZeroAvia are excited to be a part of this mutually reinforcing transformation, pioneering the first practical aviation powertrain based on the most apparent zero-emission technology for this market - hydrogen fuel cells. We believe as we pursue this endeavor, the lessons learned by a variety of industry players, advancements in cleaner hydrogen sources and the technology improvements that follow these innovations will trickle down to other uses for hydrogen power to reinvigorate the entire sector.
