Commercial airplanes have begun using biofuel or hybrid fuel. That’s undeniably a good step towards a greener future. In the future or years ahead, we might only need hydrogen to power planes. But for now, we can see how it works through a plane prototype called ZeroAvia.
Scientifically speaking, hydrogen contains three times more energy by mass than jet kerosene. It lowers greenhouse gas emissions and it offers a greater range than battery electric propulsion today.
Hydrogen’s energy density is four times lower by volume than fossil fuels and it requires large tank sizes that are impossible to fit in an airplane. However, technology ultimately prevails and two startups have developed what could be the first commercial hydrogen-propelled aircraft.
Massachusetts-based Alaka’i Technologies aims to test fly a hydrogen fuel cell powered multi-rotor aircraft that’s designed to take off and land vertically. The company said that it would have a range of up to 300 miles and they hoped to achieve FAA certification next year.
Meanwhile, the California-based ZeroAvia said that it has flown about 10 test flights of a Piper Matrix retrofitted with a hydrogen fuel cell system. Similar to Alaka’i, this company aims to produce a system for planes or aircrafts that carry up to 19 passengers. ZeroAvia wants to bring it to the market in 2022.
Battery might be a great alternative for cars, however its development is a little too slow when it’s intended to power aircrafts. Val Miftakhov, the CEO of ZeroAvia, stated, “I wanted to see what can be done to bring zero emission aviation to a large and existing segment.”
He also stated, “Using hydrogen produced from local renewable energy is the most practical way to enable zero-emission aircraft of commercially meaningful size on traditional 300 to 500 mile regional missions.”
Miftakhov said that his propulsion system, which used hydrogen to make electricity through proton exchange membrane fuel cells, will generate an electrical output of 700 to 800 watt-hours per kilogram. That’s four times more than the best batteries available today.
Although Alaka’i and ZeroAvia have similar goals, they have different approaches to overcome the density problems of hydrogen. The former plans to use hydrogen that’s cooled into dense liquid form below -252 degrees celsius and stored in a double-walled tank at a pressure of 100 psi (pounds per square inch, a unit of measure for pressure).
On the other hand, ZeroAvia compressed hydrogen to about 5,000 psi. They expect that the safety record established on the road by similar high-pressure fuel cell systems in vehicles like the Toyota Mirai and Honda Clarity will make it easier to pass muster with the FAA.
Phill Ansell, assistant professor of aerospace engineering at the University of Illinois, said that 5,000 psi of compressed hydrogen would take up about three times the volume as an equal amount of liquid hydrogen by energy content. But because liquid hydrogen boils at such low temperatures, it creates challenges for safely storing and venting it if the tank containing it heats up.
Currently, Ansell is trying to create a super-cold cryogenic liquid hydrogen fuel cell system for aircraft in which the low temperatures would be used to enable superconducting electrical systems.
“It will also be more economical than conventional turbine engines or even the battery-based systems, on the total cost basis. We calculate the total costs of operating ZeroAvia aircraft to be close to half of what it costs to fly a conventional turbine aircraft, due to lower fuel input costs, higher powertrain efficiency, and reduced maintenance costs,” said Miftakhov about his propulsion system.
To compensate for the high cost of fuel cells, ZeroAvia plans to lease the system to customers in a “power by the hour” arrangement, which has become common with large turbofan engines, where the operator pays a fee based on usage that includes maintenance.
As mentioned before, ZeroAvia aims to flights of 500 miles (around 800 km), which is about half the range of the aircraft it hopes to become an option for compared to their current conventional propulsion systems.
“About 50% of worldwide departures are less than 500 miles,” said Miftakhov. He believes that the lower operating costs of his propulsion system will open up new markets, enabling more affordable passenger service between smaller cities.
Richard Aboulafia, an analyst for Teal Group, thought that the commuter airlines that operate small planes might be hesitant to limit their fleet flexibility by acquiring planes with a lower range. He said, Is this sort of experimentation worth doing? Sure. But nobody really knows the economics of small planes with hydrogen.”
Aboulafia pointed out that fuel and maintenance are only part of the cost equation for aircraft operations, along with crew salaries, and capital and infrastructure costs. “Just because you can make an uncertain but possible difference in one of those areas doesn’t mean that everything gets revolutionized,” he added.
Additionally, ZeroAvia’s plans to lease the propulsion system on a power by the hour basis also means that it will have to find backers who are willing to finance its sales and wait patiently for revenue to come in.
However, Miftakhov said that he was in talks with private-equity funds interested in backing his sales model. His company has taken several million dollars in seed funding, half self-funded and the rest from investors, including the socially responsible fund SystemIQ.
Jeremy Oppenheim, founding partner at SystemIQ, said, “Aviation is the fastest-growing segment of transport emissions, set to nearly double by 2050 under current trends. Greenhouse gases released at altitude are particularly damaging, so it’s vital to develop and scale zero-emission alternatives,”
“ZeroAvia’s zero-emission drivetrain is the most promising, cost-competitive alternative to incumbent fossil-based technologies today. SystemIQ is proud to be supporting ZeroAvia on their time-critical mission to decarbonize the aviation sector.”
The company is currently seeking to raise a $10 million A Series round. Miftakhov is certain that he can get to market for close to $50 million.
Persisting, the CEO said, “Zero-emission transportation is progressing rapidly to an inflection point. The technology today to decarbonize commercial aviation in a meaningful way, and at ZeroAvia, we intend to lead that charge,”
“With governments around the world calling for a shift towards clean transportation, and predictions that air travel frequency will increase in the future, it is imperative for us as an industry to ensure sustainable aviation is cleared for takeoff.”