ZeroAvia recently presented at the Paris Air Show and is working intensively on certifying its motors and systems in the United Kingdom. Their two motors are now joined by several components, including a liquid hydrogen fuel management system. This system comprises a “lightweight metallic tank design and associated systems for filling, storing, and distributing the fuel as hydrogen-electric technology is increasingly applied to larger aircraft,” according to the company.
Here, Val Miftkhov explains the workings of the company at this year’s Paris Air Show. Of special interest, he compares the positives and negatives of sustainable aviation fuel (SAF) with those of hydrogen fuel cells, a matter of competitive importance.
The Motors
ZeroAvia has a pair of motors in the 600 kilowatt (804 horsepower) and 2,000 kilowatt (2,680 hp.) range, the ZA600 nearing certification in the UK and the ZA2000 attracting buyers in the regional airliner world. The company claims several advantages for its motors. They include, “90% Lower life cycle emissions compared to turbines. 40% lower fuel and maintenance costs compared to turbines. 75% lower hourly maintenance costs. 250 – 1000 [Newton Meters] (appreciable torque). Ranges covering 95%+ of missions flown today, including reserves. We will focus on the ZA600 for the remainder of this entry.
With this motor seemingly focused on the Cessna Caravan, the market is sizable, 2,600 such craft potentially awaiting a motor-for-turbine swap as the venerable PT-6 turboprops come up for overhaul or replacement. AV Buyer reports a new Pratt & Whitney PT-6 60A (used for valuation purposes) costs around $1 million, and a complete overhaul of all life-limited components (LLC) will total about $500,000 after around 3,800 hours of service. That’s a little over $131 per hour. If ZeroAvia’s numbers are correct, the equivalent value for their electric replacement would be $32.75 per hour, or $124,450 for the same 3,800-hour period. If similar savings accrue for the hydrogen fuel cells’ operating costs, this would be a significant operational saving, especially for fleet owners.
Interestingly, ZeroAvia calls the ZA600 an “entry-level” powertrain, which seems strange to those of us who think of “graduating” to “big” aircraft such as Cessna 182s or light twins. In the jumbo-jet airline world, though, a Cessna Caravan is an entry-level airliner or cargo hauler, and Zero Avia promotes that application in promoting the ZA600.
These same motors are used on aircraft such as the DeHavilland Twin Otter and the Beechcraft King Air 360, among others. Savings would double for such craft.
The Associated Components
Inverters
EZA600 uses four inverters that convert the direct-current charge from the fuel cell to alternating current in the motor. The four 400 kilowatt inverters offer a high degree of redundancy. The “birdirectionally convert the fuel cells’ high-voltage DC into three-phase AC. “Advanced thermal management technologies and integration enable reliable hight performance at atltiude.” According to ZeroAvia, their inverters “are 98-99 percent efficient vs. load and speed and operate at 450kW max power.”
ZeroAvia lists maximum power for an individual inverter at 225 kW (301 hp.), leading to a power density of 20 kW per kilogram, or 18.7 kW per liter, light and compact by comparison with equivalent earyh-bound units.
The combination of lightweight, energy-dense motors and inverters enables ZeroAvia to offer powerplants that equal a turbine’s output with compact efficiency and aerodynamic cleanness.
Fuel Cells and Stacks
Rudolph Coertze, Chief Technology Officer for Hydrogen, explains the workings of the hydrogen fuel cells
An individual ZeroAvia PEM (Proton Exchange Membrane) fuel cell can proiduce a peak gross power of 175 kW (235 hp.) at sea level and decreasing continuous net power with altitude ending with 85 kW (114 hp.) at 25,000 feet. Since his would not be enough “fuel” to keep a Caravan aloft, cells can be “stacked” into a “SuperStack Flex” to provide additional power and redundancy.
Necessarily compact, each fuel cell measures 619 x 670 x 414 millimeters (24.4 x 26.3 x16.4 inches) and weighs 170 kilograms (374.8 pounds)
Control power to the system is from a 28 Volt DC battery, typical on many aircraft. Networking is through a CANbus interface that enables expansion of the system.
The company looks beyond certification of the system to bigger things. “Once approved, the company plans to install the new propulsion system in a Cessna Caravan aircraft, and to acquire supplemental type certificates (STCs) to convert similar-sized airframes such as Twin Otters, as it advances development of the larger ZA2000 for aircraft such as the 40-80 seat ATR family of regional turboprops, 20 of which are operated by Loganair.”
Other components are dealt with in white papers and data sheets on the ZeroAvia website.
The Hydrogen Airport Ecosystem
ZeroAvia goes far beyond merely powering the flight vehicle. Just as at the turn of the 20th century, infrastructures had to move from support for horses and buggies to filling the needs of the new automobiles. The company is working with several organizations to create “green” hydrogen for its aircraft, and other suppliers to help create the fuel distribution and airport systems necessary to support hydrogen-electric flight.
illustrations and vidoes show wind turbines and solar panels flanking the airfield, ready to produce the energy to make green hydrogen, gaseous of liqiuid – liquid increasing the enegy density of the H2 contained in the aircraft’s pressurized tanks. Because this is a critical factor in hydrogen-electric flight, ZeroAvia will build a manufacturing plant near Glasgow Airport to produce and test fuel cell stacks and their associated components.. ZeroAvia’s Hydrogen Centre of Excellence will help meet the company’s nearly 3,000 orders by airlines and others for powerplants and components.
ZeroAvia has additionally signed a Memorandum of Understanding with Loganair to “work towards potential adoption of hydrogen electric engines” to deliver zero-emission flights across its mostly-UK network. The airline operates aircraft including Twin Otters and ATR 42 and 72 commuter planes.
ZeroAvia already has a long-standing partnership with Glasgow Airport to investigate hydrogen fuel infrastructure, and its new hydrogen fuel cell manufacturing plant will be developed close to both the airport and the airline’s headquarters.
New funding from the UK government supports the introduction of liquid hydrogen for future powertrains and aircraft. This will help fund the £10.8 million ($14.4m) Liquid Hydrogen System Integration & Flight Test (LH-SIFT) project, which will end in the installation, “Of a novel lightweight fuel system into a Dornier 228 before a series of flight tests.”
ZeroAvia claims this, “Is the world’s first liquid hydrogen flying commercial airframe testbed that will enable later projects to develop and test cryogenic aviation fuel system components in flight.”
Chief Strategy Officer, James McMicking. says, “Liquid hydrogen is needed to achieve the volumetric and gravimetric energy density required by larger zero-emission aircraft that no other solution offers.”
RVL Aviation, based at East Midlands Airport, will operate UK freight flights using a Cessna Caravan 208B converted from conventional propulsion to a ZeroAvia ZA600.
Future Flight Paths
Pushing new discoveries in its drive to creating an integrated ZeroAvia has earned 45 patents in the last five years, leading a list of remarkable achievements. It’s also coordinating with new partners who wish to applyh hydrogen-electric power to their craft.
Horizon Cavorite
A most unique electric Vertical Takeoff and Landing configuration, Horizon’s Cavorite, recently test as a reduced=scale demonstrator, iw working wiith ZeroAvia to power the full-scale version. The Canadian company has been developing this craft for several years.
Jetcruzer International
A former French company now headquartered in California, Jetcruzer seemed to disappear for a few years, only to return with an agreement with ZeroAvia to power their six-seat canard. According to Aerotime.aero, “Jetcruzer International is developing the Jetcruzer 500E, a six-seat hydrogen-electric aircraft, and further into the future the 1250E in 2030. ” Although destined to be powered by a ZA600, the taziing machine in the French language video appears to have turboprop engine.
ZeroAvia seems to be willing and able to take on any challenge from six-seats up to 100 with their hydrogen-electric power systems and associated infrastructure. That they are getting responses from American and European clients shows a potentially heady future for the firm.