Transforming aviation to serve a climate neutral society @TU Delft

"We are aiming to be the first continent that's climate-neutral," said Ron, referring to the EU Green Deal. "Climate neutrality will impact every human activity. Ducking this ball is not an option for the aviation sector."

Some might question, why does Europe have to be the first? To this, Ron said, "we started this problem through the industrial revolution roughly two generations before anyone else. And we benefited massively as a result, so we have a moral incentive to be first."

He then outlined the efficiency gains that aviation has already made - an impressive reduction of 97.5% of fuel per revenue passenger kilometre (RPK) since the dawn of post-war international aviation and perhaps even more impressively, still over 80% since the era of 'mass travel' started with the eponymous Boeing 747 'JumboJet'. But that's not enough, he explained.

"While the aviation system has quadrupled in the thirty years up to 2019, our emissions have 'only doubled'. But 'only doubled' is no longer acceptable," he said. "We cannot congratulate ourselves. We need to do a lot more."

Ron stressed that neither technology alone nor sustainable aviation fuels alone will lead to climate-neutral aviation. Everything from new technologies within aircraft, to new aircraft configurations, to new engines, to new fuels and new operating paradigms must be explored and improved upon.

"We need skip-a-generation technology," he said. "And while we can't rely on technology alone, we can't rely on sustainable aviation fuels alone either. And it isn't 'one size fits all': It's never been a singular choice between propellers vs jet engines or turboprops vs turbofans. We need to balance our efforts across a spectrum of innovations and accept that there will be 'horses for courses'. We need to do more to optimise aircraft for their use in the transport system."

This has traditionally been Clean Sky's approach - exploring a wide range of technological options in the search for sustainable solutions.

On the oft-publicised view that we should be replacing short flights with rail transport, Ron said "frankly, it's hogwash. Short-haul flying is here to stay. Politicians say we will use rail instead, but there will never be an effective railway connection between Rome and Zagreb for instance, or between Amsterdam and Oslo, or between Berlin and Stockholm. There are many connections which are neither convenient, economically justifiable nor particularly sustainable by dedicated rail connections. For instance, if you have only a few hundred passengers per day on a particular route, an aviation link is economic and can be environmentally optimal when you consider the infrastructure as well as the operations. High speed rail needs several 10,000 passengers per day to recoup the infrastructure, not just in economic terms but even in terms of the carbon footprint."

Looking beyond Europe where we are fortunate to have an excellent rail network, it is even more obvious in other continents that air mobility will remain key.

However, we will have to readjust how we look at future transport systems. "If our aim is to address aviation's climate impact, then focusing on urban air mobility is like building a shed in your backyard while your house is on fire," said Ron, explaining that at this point investing in urban air transport is just supporting a new mode of air mobility that aims to complement or compete with short range ground transport, and does not address the 'mainstream' passenger or cargo movements by air in the current air transport system.

Looking to the future, Ron pointed to hydrogen as being "the only truly zero carbon solution" that is on the horizon. He warned against using drop-in fuels that rely on 'point source' CO2 and claiming these were 'net-zero'. "Otherwise, it's like saying you've stopped smoking because you're using your neighbour's cigarettes. Or as the CEO of EasyJet Johan Lundgren recently quite correctly noted, drop-in fuels relying on a carbon cycle are really a sophisticated carbon offset mechanism."

To close, Ron told the alumni: "The journey towards the next generation of aircraft needs to start today. But we need to realise the overall system will need to change too. We need to stop thinking that flying from Helsinki to Tokyo via Munich is normal. It's not. Europe can lead the transformation and it must."