In September, hydrogen-electric engine manufacturer ZeroAvia achieved the world’s first commercial flight powered by hydrogen fuel cells.
While most people only hear news about the efforts toward zero-emissions in the automotive industry, similar news in the aviation industry—like this feat from ZeroAvia—receives less coverage. This isn’t for lack of progress, however, since many companies are investing heavily in zero-emission flight.
In fact, a Fuel Cells and Hydrogen (FCH) report released this year forecasts that by 2035, hydrogen could power a commercial passenger plane traveling up to 3,000 kilometers. Additionally, the report posits that hydrogen fuel-cell technology could power flights of up to 7,000 kilometers by 2040.
Boeing made history in 2008 with the Fuel Cell Demonstrator Airplane, dubbed the “green machine.” Image used courtesy of Boeing
While Boeing was the first big name to operate an aircraft solely powered by hydrogen in 2008, a more recent announcement in hydrogen-fueled aviation comes from aerospace designer and manufacturer Airbus. The company’s ZEROe program aims to create the world’s first zero-emission commercial aircraft.
What exactly is driving this appeal toward hydrogen fuel cells in aviation?
Hydrogen Fuel Cells: More Efficient and More “Green” Than Batteries?
While the operation of a hydrogen fuel cell is similar to most batteries, the important distinction is that this alternative is entirely carbon-free. Instead, the reactions of a hydrogen fuel cell produce H2O.
In addition, hydrogen fuel cells provide higher efficiencies than a normal combustion engine. According to the U.S. Department of Energy, the efficiencies of hydrogen fuel cells can reach up to 60% compared to 25% in a standard combustion engine.
Hydrogen fuel cells are said to be two to three times more efficient than traditional combustion technology. Image used courtesy of the U.S. Department of Energy
Finally, hydrogen fuel cells run longer than lead-acid batteries and can be refueled in as few as two minutes. Implementing this technology in aircrafts will, in hopes, eliminate the need to maintain, charge, and replace batteries, lowering operational costs and environmental impact.
How Hydrogen Fuel Cells Could Feasibly Power a Plane
Hydrogen fuel cells operate similarly to batteries, except they rely on the chemical reactions of hydrogen and oxygen gasses to create electricity. Originally dubbed a “gas voltaic battery,” these devices are reminiscent of a voltaic cell, consisting of an anode and cathode separated by an electrolyte membrane.
For hydrogen-powered planes to function effectively, they would require four major parts, according to Horizon Magazine:
- A safe storage system for liquid hydrogen
- Fuel cells capable of converting hydrogen to electricity
- Power control device
- Propeller motor
Airbus’ Hydrogen Pod Proposal
Using the pod configuration, an electric current would be formed from hydrogen and air. Power electronics would convert current to power the electric motors and consequently drive the propeller. Image used courtesy of Airbus
The “podded” configuration consists of six, eight-bladed pods underneath each wing of the aircraft. The configuration is a distributed fuel-cell propulsion system with each pod providing the aircraft its thrust.
Individual pods act as a standalone propulsor with each consisting of a propeller, electric motors, hydrogen fuel cells, electronics, liquid hydrogen fuel tanks, and a cooling system.
When Will Hydrogen-Powered Planes Come to Market?
While hydrogen fuel-cells seems like a promising goal for zero-emission flights in theory, bringing this technology to fruition in an eco-friendly way may not be as simple as it seems. This is because hydrogen is most often created by reforming methane from natural gas, which produces carbon dioxide.
Researchers are, however, investigating the possibility of producing “green hydrogen.” This could be achieved by applying an electric current derived from a renewable resource to break down water into oxygen and hydrogen.
Comparison of new aviation propulsion fuels and technologies. Image used courtesy of the FCH
Even Airbus, with its three conceptual prototypes of hydrogen fuel-cell-powered airliners, recognizes the challenges of a solely hydrogen-powered aircraft. The company currently features a hybrid system of combustion turbines and motors driven by fuel cells.
Airbus submitted a patent application for the hydrogen pods 18 months ago and is deciding whether this configuration or other proposals will most effectively accomplish the ZEROe program by 2025.
As with all new battery-like technologies, there will likely be roadblocks on the road to adoption. What design-level hiccups might you foresee from hydrogen fuel cells in aviation?