Could hydrogen-powered aeroplanes be the future of aviation?

In 1903, just nine weeks before the Wright Brothers made their first flight, the New York Times estimated that the development of aircraft would take between 1 million and 10 million years. Back then, air and space travel was often portrayed as being impractical or even downright egotistical. 

Over a century following the first flight, air and space travel has come a long way. Mankind has reached the moon and has even established its abode in international space stations, while international flights have become a day-to-day affair. 

However, as humanity reckons with its reckless use of fossil fuels, green and sustainable aviation has become an utmost priority in the twenty-first century. And thanks to the aspiration, tenacity, and ingenuity of many like the Wright Brothers, green aviation might become a reality soon. 

The problem with traditional air travel

At present, 3.5% of total greenhouse gas emissions are caused by air travel. Petrobras Aviation Kerosene (QAV), the fuel of choice for modern aircraft, emits dangerous levels of carbon dioxide (CO2)  into the environment. 

In fact, the fastest-growing global cause of climate change is aviation. The International Coalition for Sustainable Aviation predicts that the number of people flying worldwide will double to 8.2 billion by 2037.

Moreover, up to 22% of all of our carbon emissions by 2050 may come from this industry. 

We are aware that, to reduce global emissions by half by 2030, we urgently need to address the aviation industry's growing impact. Unsurprisingly, scientists have long called for a sustainable alternative.

Hydrogen as an alternative fuel

Apparently, utilising hydrogen as fuel does not release any hazardous pollutants into the atmosphere. In fact, experiments are already underway to demonstrate the efficacy of hydrogen-powered aircraft.

Initial experiments indicate hydrogen-powered aeroplanes can travel just as quickly as conventional ones and can transport more than a hundred people every trip over thousands of kilometres while emitting just water. 

Moreover, hydrogen is also plentiful and will only become cheaper to create, since it can be made from water. By 2030, the price of renewable hydrogen will have decreased by 50%, according to PWC. With on-site hydrogen generation, costs can be reduced further and the system can become completely emission-free.

Additionally, the substitutes, like sustainable aviation fuel, do not address the issue of non-carbon emissions, i.e., nitrogen oxides, particles, soot, and high-temperature water vapour. These molecules can have a greater overall influence on climate change than carbon dioxide does on its own. However, they are not a factor in engines powered by hydrogen.

According to McKinsey, hydrogen-powered electric flying has the greatest potential for reducing climate impact as hydrogen fuel cells are between two and three times as energy-efficient as today's gas-guzzling internal combustion engines.

When will they be available?

According to a paper on hydrogen-powered aviation that was published in the International Journal of Hydrogen Energy last June, hydrogen may perhaps be utilised by 2035 to power a commercial passenger aircraft for up to 3,000 kilometres of flight. A medium-range journey of up to 7,000 kilometres should be feasible by 2040 or later, leaving only long-distance flights to conventional aircraft. 

Initial experimentation with hydrogen-powered aeroplanes has already begun. For instance, the biggest hydrogen-powered aircraft in history took off from a UK airfield earlier this year, flew a 10-mile loop, and then touched down again approximately 10 minutes later. Although the aircraft, a 19-seat Dornier 228 turboprop heavily modified by ZeroAvia, wasn't quite a jumbo jet, it nonetheless represents a major advancement in the fledgling field of zero-emission aviation. The six-seat aircraft that held the previous record for the biggest hydrogen aircraft also belonged to ZeroAvia.

How does the hydrogen-powered engine work?

An electric motor on the left wing of the aircraft is powered by two onboard fuel cells that turn hydrogen into energy. A lithium-ion battery provides additional power during takeoff. 

The aircraft had a traditional kerosine engine powering the second propeller, in case the zero-carbon system failed. The test aircraft had just around 10 kilograms (22 lbs) of hydrogen on board, which was sufficient for a flight time of roughly 30 minutes. 

"We are looking at 80 to 100 kilograms of hydrogen on board for commercial flights. So much further range," says Val Miftakhov, CEO of ZeroAvia.

The firm has more ambitious goals, and this present aircraft is only a first step. A 76-seat regional hydrogen-powered aircraft is presently being developed; it might be completed in 2026.

Airbus has shown three concept aircrafts that, according to the company, may be deployed by 2035. The first is a turboprop (propeller-driven) aircraft that can travel 1,000 nautical miles with roughly 100 people on board (1,850km). 

The second vehicle, a turbofan (jet), could go twice as far with 200 people. Both resemble existing aircraft, but ZeroE (Airbus's zero-emission project)'s third idea has a blended wing that looks futuristic and significantly differs from current commercial versions. 

Airbus claims that this third design may be able to transport more people over greater distances than the other two, but has not yet provided any further information. As hydrogen hybrids, all three of these systems are intended to be propelled by gas turbines that burn liquid hydrogen as fuel and also produce electricity using hydrogen fuel cells.

Possible difficulties on the way

Several variables will affect whether or not we succeed in achieving hydrogen-powered air travel soon. First, to transport enough liquid hydrogen in aircraft for these flights, hydrogen storage technology must evolve. 

It will be necessary to develop new strategies for delivering hydrogen to airports so that aircraft can refuel on runways. Additionally, redesigning the interiors of aircraft will be important to figure out how to include all the requisite systems and tubes for hydrogen-powered commercial aircraft.

Additionally, liquid hydrogen has an energy density that is approximately one-fourth that of jet fuel. It follows that a storage tank four times the size is required to store the same quantity of energy. To accommodate the storage tanks, aeroplanes may either need to carry fewer people or grow considerably. 

Under the first scenario, which pertains to the first two Airbus concept aircraft, ticket sales would decline. The third proposal from Airbus represents the second alternative, which calls for a larger airframe that is more susceptible to drag. Furthermore, storing and transporting hydrogen at airports would need the construction of entirely new infrastructures. 

There is also the issue of hydrogen being generated at scale and at a competitive price without leaving a significant carbon impact. The vast majority of hydrogen utilised in the industry today is produced from methane, a fossil fuel, with the waste product carbon dioxide. Water can be converted into hydrogen by a process called electrolysis that is powered by renewable energy, but this conversion is presently costly and energy-intensive. Currently, just 1% of hydrogen is created in this manner.