April 16, 2023

On Wings of Hydrogen | Inevitability of Hydrogen-Fueled Planes

 It seems like everything is going green these days but there's one mode of transportation that seems to be clinging to the traditional "Aviation", fuel-loving ways and while commercial aviation has made strides through smarter design and cleaner engines, many of those gains have been nullified by more air traffic. The challenge is enormous and the industry is large it will take decades to convert, surprisingly the good news is that we have a solution as early as three years out that people can get into and start moving towards zero emission. And it turns out that the solution could be all around us Hydrogen.

Green Hydrogen | ZeroAvia | Airbus | Engineering | Cranfield | Universal Hydrogen

This article will be visualizing the promising future of hydrogen as a fuel source through the lens of pioneering scientists and visionary entrepreneurs. Unveiling the untapped potential of hydrogen as a sustainable and clean energy solution, this compelling narrative delves into the latest breakthroughs and advancements in hydrogen technology. From cutting-edge research to innovative applications, explore the trailblazers who are driving the hydrogen revolution forward and reshaping the energy landscape. 

Learn about the bold visions, groundbreaking discoveries, and real-world success stories that are propelling hydrogen into the forefront of the energy transition. With compelling insights and compelling stories, this captivating journey unveils how hydrogen is transforming from a long-touted fuel of the future into a present-day reality with boundless possibilities for a more sustainable world.

Hydrogen is the most abundant element in the universe. And so if we have to use something, it would be great. The only product of the chemical reaction between hydrogen and oxygen is water.

Hydrogen-Powered Aircraft

Looking at the fundamentals of what it would require to take an aircraft up in the air of significant size, over a significant distance, and commercially relevant. Hydrogen Fuel Cells are the best approach from the cost of fuel, the efficiency of utilization of the fuel, and the mitigation of the climate effects.

Jet Engine Fuel vs Hydrogen Fuel

So the beauty about hydrogen in general is that the energy density of hydrogen as a fuel is three times better than jet fuel. So if we see in general that any size of aircraft going for any distance that jet fuel aircraft can go over time. It will just take a significant amount of time to get the industry over, but this technology can scale to all sizes of aircraft we use in commercial service. 

ZeroAvia's Hydrogen Aviation

ZeroAvia is a hydrogen-electric aircraft developer operating in both the United Kingdom and the United States. Serial cleantech entrepreneur Val Miftakhov started ZeroAvia following his previous success in the EV charging industry. The company is focused on developing zero-emission aviation solutions by utilizing hydrogen fuel cells as a means of powering electric aircraft. ZeroAvia's goal is to provide sustainable aviation options that reduce greenhouse gas emissions and contribute to a more environmentally-friendly aviation industry. The company has been actively involved in the development of hydrogen-electric powertrains for regional aircraft, to eventually achieve zero-emission flights for commercial aviation.

How does Hydrogen Airplane Work?

ZeroAvia uses a hydrogen fuel cell to produce electricity to turn a propeller. Unlike a traditional engine which uses combustion to create energy, a fuel cell generates electricity through an electrochemical reaction. In this case, hydrogen and oxygen are combined to generate electricity, heat, and water. ZeroAvia has flown a six-seater aircraft on a hydrogen fuel cell; a world first. Now they're aiming bigger, at 20 seats. That's technically commercial. One side of the aircraft, the left side, will replace the engine with power plants. 

A normal engine on the right side and part of this is, in aviation, you want to ramp up risk profile in meaningful steps. So if calamity happens there will be a second engine as a backup. But even in the first flight test campaign, it has been planned to demonstrate the operation of this aircraft purely on zero emission power on the left side engine. Once it is taken off, we can switch over to completely zero-emission power. Hydrogen is used throughout all sections of a flight, which maximizes the efficiency of the entire operation reduces the weight, and provides for best the sort of mission capabilities, payload, and range.

Building power plants and fuel cells is one thing, creating a whole new infrastructure for supplying hydrogen is something entirely different.

Building the Infrastructure of Hydrogen Fuel Cell

In automotive a big part of the reason why hydrogen did not take off is that the fueling infrastructure needs to be so distributed. For let's say, the United States, you have a hundred thousand fueling stations. Compare that with aviation where 95% or more of traffic in the United States is concentrated in 100 locations. So that's a three-order magnitude difference which makes building out of the infrastructure much simpler. It's much larger, much more concentrated stations, but they're much fewer in quantity. Calling it simpler might be underselling the challenge of distributing hydrogen, which, unlike other fuels that can be easily transported in liquid form, is usually found instead in a gaseous state.

Transportation of Hydrogen

One of the main concerns is the transportation of hydrogen, How do you get the hydrogen from point A to point B? We cannot have pipelines for moving hydrogen around. We do not have all the specialized trucks to move them around and so we got thinking, we need a solution that can be a low capital expenditure solution and that's what the companies are working on.

Modular tank system for the domestic turboprop

John-Paul Clarke is the co-founder and Chief Innovation Officer of Universal Hydrogen, a startup that has designed a modular tank system for the domestic turboprop market. Like ZeroAvia, it allows for retrofitting planes already in use. Each module has two capsules and so what we do is load it into the aircraft as if it was cargo, strap it down, connect it to the aircraft, close the loading door, and that would be it. When you get to your destination, you'd unload it, put it back in a truck, and send it back to the production site to get refills. We needed to come up with something that could both fit in containers and also fit in the aircraft, not require increases in the maximum takeoff weight of the aircraft. 

This compromise is one of the biggest hurdles that may prevent the widespread adoption of hydrogen. You're gonna have to take out some seats because the energy density of hydrogen is less than jet fuel and you can't store it in the wings practically, so you're gonna have to take away some space in the fuselage. In the ultra-fine margins of aviation, removing 10 to 20% of your seats is a tough ask, but that hasn't deterred startups like ZeroAvia or Universal Hydrogen.

Maintenance cost of Fuel Cell System

The maintenance cost of a fuel cell motor system goes down and it goes down significantly because motors and fuel cells have much fewer moving parts than a gas turbine engine. And so the wear and tear are much lower, so the time between overhauls is longer. And so when you put all that together,  numbers indicate that the CASM, (Cost per Available Seat Mile), actually goes down slightly or is at the worst equivalent to what you have now. So what you'll have is a smaller cabin or a smaller number of seats. However, the cost for each of those seats to operate is the same or better than the hydrogen. 

Like ZeroAvia, Universal Hydrogen is also working on engines, successfully testing the two-megawatt iron bird that will allow them to retrofit planes carrying up to 55 passengers. ZeroAvia is aiming for their first commercial hydrogen electric flight between London and Rotterdam with their 19-seater by around 2024. But much like the range anxiety that has plagued some battery-powered electric vehicles on land, hydrogen fuel cells are also fairly limited. At this point, they still can't power a common 100-passenger jet.

University of Cranfield into Hydrogen Airplane

Beyond fuel cells, however, there is another hope for our lightest, most abundant element: Burning it. An expert in gas turbine combustion, Professor Bobby Sethi leads research at Cranfield University in the U.K. According to him, the first eureka moment, is when we see steam in the exhaust because we are thinking to ourselves, "Huh? We're burning something here when you're producing absolutely NOx CO2." Built on a former RAF base, the college runs multiple aeronautical programs. But what Prof. Bobby is focused on is burning hydrogen, as cleanly as possible. So they tested how we can conceive some hydrogen combustion technologies that can be integrated into the next-generation aircraft engines, which will deliver not only zero CO2 emissions but also ultra-low NOx emissions. 

NOx or nitrogen oxides are a significant source of air pollution globally. They're the dirty particulates that cause smog in cities, usually spat out by diesel cars, scooters, and buses.

Why Hydrogen is better for NOx emission?

Hydrogen is characterized by much wider flammability limits, which means we can go to much leaner combustion. And as a result, we can burn at much lower flame temperatures and that's better for reducing NOx emissions. Going leaner means burning fuel with an excess of air in the engine. Using something like gasoline, lean burn emits far fewer hydrocarbons. Doing it with hydrogen also delivers cleaner emissions. While NOx is a pollutant, hydrogen combustion produces up to 90% less nitrogen oxide than kerosene.

Challenges of Water Vapor Emission from Hydrogen Aircraft

So while burning hydrogen isn't technically as clean as using it inside a fuel cell, it's still a huge improvement over jet fuel. Unfortunately, like any radically new idea, there are other potential byproducts of the process that aren't fully yet understood. NOx is one of the main emissions we need to consider, but the aviation community is also asking themselves and the community in general, what about all the water vapor emissions? 

And some studies have shown, albeit(although) there's still a large degree of uncertainty about it, that contrails and cirrus clouds that may be induced from contrails could contribute to global warming about four times the amount than CO2 does. We know that if we are going to be burning hydrogen, we are going to produce a much larger amount of water vapor emissions. And if we are going to be producing a much larger amount of water vapor emissions, then the propensity for contrail formation is also going to increase.

Despite all these challenges, hydrogen is being taken seriously by the broader industry. Companies like Universal Hydrogen and ZeroAvia are gaining the attention of investors looking for viable and eventually profitable solutions.

Airbus 380 Bets on Hydrogen to Deliver Zero-Emission Jets

Industry giant Airbus wants to introduce a hydrogen-powered passenger aircraft by 2035. Recently announced Airbus to use A380 to retrofit a gas-guzzling Superjumbo with a hydrogen-burning engine. The modified aircraft will add a fifth engine, adapted for hydrogen, and will be mounted on the rear fuselage. The A380 is the largest passenger aircraft in existence, so it offers plenty of room to store 400 kilograms of hydrogen.

A Video Demonstration of Airbus 380 ZEROe on Hydrogen Technology

The company's designs for a blended wing concept to store extra hydrogen also offer a glimpse of our flying future. Apart from the complex engineering challenges faced by airplane manufacturers, there are also difficulties in the production of hydrogen itself.

Nowadays, most of the hydrogen used in fuel is derived by splitting it off from molecules of natural gas. But that requires a good deal of energy and also produces carbon dioxide.

To make green hydrogen, the electricity used to run the electrolyzer must come from a renewable resource, which is currently a lot more expensive. As with any new technology, however, initial costs are daunting, but time may be the best remedy here.

Economics of Hydrogen Fuel Production

If you look at the economics of hydrogen fuel production, for example, versus fossil fuels, for instance, the cost of hydrogen is all based on capital expense and very little operating expense. So it's sort of similar to solar power. You put solar panels out there, and they produce power for 20-25 years. The operating expense is relatively low. What that means is that as scale grows, as we've seen with solar panels, the cost of output drops dramatically.

So the first phase is not about the most efficient aircraft. It's not about the aircraft that will deliver the lowest NOx emissions. It's about demonstrating that we can carry hydrogen safely on board, we can burn it safely on board, and can be used to fly a passenger aircraft. The key thing is that we don't try to put everything in the first generation or we're just gonna delay the entry into service. 

If there are some questions on the margin, they're all in the sort of business model and market adoption realm. It is very hard to create a technological argument or impossible to create a technological argument that says, "Well, it's not gonna work." It is going to work.


To summarize, the inevitability of hydrogen-fueled planes is becoming increasingly clear. With the urgent need to decarbonize the aviation industry and reduce greenhouse gas emissions, hydrogen presents a promising alternative to traditional fossil fuels. As advancements in hydrogen production, storage, and utilization continue to progress, hydrogen-fueled planes are poised to become a sustainable and viable solution for aviation and we eagerly anticipate the aviation industry taking flight "On the Wings of Hydrogen" shortly

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