Mounting pressure on the global aviation sector to reduce pollution and hit net zero emissions targets by 2050 is sparking an exciting new wave of innovation, which some observers have described as the industry’s ‘third revolution’.
Emerging technologies for smaller and sometimes uncrewed air vehicles, such as drones and air taxis, are suited to rechargeable battery power due to their short duration hops. Meanwhile, larger aircraft from regional turboprops to single-aisle airliners need a denser form of energy that is more akin to that provided by jet fuel. Long-haul giants are a long way from being able to decarbonise due to the nature of their missions, as long endurance flights carry many passengers or heavy cargo. These can’t ditch kerosene just yet. Instead, they will look to carbon offsetting using systems of credits, as well as making use of sustainable aviation fuels, which should become more widely available.
For the mid-market challenge, hydrogen is streaking ahead as the potential answer. Aerospace giant Airbus abandoned work on a hybrid-electric demonstrator based on a BAe146 jet. It found that the sheer number of battery cells required to power just one of the aircraft’s four engines would take up the entire passenger cabin and the cargo hold. So, it’s now preferring to focus on the potential of hydrogen propulsion. In February, Airbus’s plans to use a giant A380 to test hydrogen-powered jet engines made headlines as the airframer continues to pursue its aim of delivering a zero-emissions aircraft, albeit much smaller than the superjumbo, into service by 2035. Airbus is exploring engines powered by hydrogen combustion through modified gas turbine engines and hydrogen fuel cells, as well as a range of potential future aircraft shapes.
Driving such initiatives are both push and pull factors. Although there is growing concern and awareness about the impacts of climate change, governments have stated that we can’t rule out air travel all together to combat emissions. Before the COVID-19 pandemic grounded most of the world’s fleet of airliners, aviation accounted for about 2.5% of global emissions. But that number is set to rise as other emitters decarbonise faster than aviation can keep up with. Witness, for example, what’s happening in the automotive sector where the mass adoption of battery and hybrid-electric vehicles is already taking place.
Aircraft manufacturers’ airline and freight customers are also driving the change. Among the airlines, easyJet has been one of the most vocal. Its young customers are increasingly keen to know when they can expect to book a flight on a greener aircraft, prompting the group’s chief executive, John Lundgren to pledge its commitment to reducing easyJet’s environmental impact. The company is already partnered with Wright Electric, which specializes in zero-emission technology, and with Airbus. EasyJet’s website states that by the mid-2030s, a flight with a range of 800 miles could be made on a hydrogen-electric or hydrogen powered aircraft, which could open up popular city connections such as London to Barcelona to zero emissions travel.
Just this month hydrogen’s potential for aviation was given a major endorsement by the UK’s Aerospace Technology Institute with publication of the first report from the FlyZero research project to investigate a zero-carbon emission commercial flight. The initiative brings together experts from across the UK to assess the design challenges, manufacturing demands, operational requirements, and market opportunity of potential zero-carbon emission aircraft concepts.
The FlyZero report concluded that green liquid hydrogen is the most viable zero-carbon emission fuel with the potential to scale to larger aircraft using fuel cell, gas turbine and hybrid systems. In their introduction, FlyZero’s project director Chris Gear and ATI chief executive Gary Elliott wrote: “The aircraft being manufactured today are more efficient than ever before and will increasingly operate using fossil fuel alternatives representing great strides towards our global climate commitments on carbon emissions. But what if we could eliminate carbon emissions altogether? A new era for aviation is on the horizon.”
While the scale of the challenge is huge, the ambition to succeed is strong with investment funding pouring into research and development of the key technologies. But it is not just the new breed of aircraft themselves that need to be created. Infrastructure, wider capabilities, and the regulatory and certification frameworks needed for hydrogen to enter commercial passenger air transport services must also be rapidly developed if large aircraft are to be flying us around by 2035. Particular areas of focus include cryogenic hydrogen fuel systems, gas turbines and airframes for ground and airborne demonstration, the FlyZero report explains. And in parallel, the industry must continue to advance technologies required for sustainable aviation fuels, which is needed alongside hydrogen if we are to meet the net zero by 2050 goal.
FlyZero concludes that it is feasible to hit the 2050 target for regional, narrowbody and midsize market segments but the optimum route to get us there is through acceleration of a large (narrowbody and midsize) commercial aircraft into service. This machine would be able to reach all destinations in the world in a single stop, it says, adding that such an approach would be less commercially risky than developing a narrowbody first and would allow infrastructure development to be focused on fewer, but larger international hub airports.
What if this isn’t achieved? The threat is clear. If aviation fails to decarbonise quickly enough, measures to restrict the industry are likely to protect the planet, with the knock-on effects for national and regional economies dependent on business and leisure flying. But the great prize, FlyZero reports, is that this approach would quickly reduce aviation’s global CO2 emissions, which would occur if 50% of the world’s commercial fleet are hydrogen-powered by 2050.
It’s not going to be easy to hit this target. We are at a significant turning point for aviation, the like of which has not been witnessed since the dawn of the Jet Age transformed the possibilities of flight. The whole sector must play its part in limiting the impacts of climate change and given the development times for new aircraft, we must act now. We owe it to future generations to explore the art of the possible.