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One century ago, Italian aviator Francesco de Pinedo was attempting the unprecedented feat of crossing the Indian subcontinent in a flying boat. He eventually landed on the Tiber in Rome to widespread recognition, having journeyed through Asia towards Australia and returned after a seven-month period, taking off and landing in water 80 times.

Aviation has been marked by stop-start journeys on hitherto uncharted courses to unlikely, if not unreachable, destinations. The current shared belief – amid much scepticism – is in following an uncertain path to sustainability, through green fuels that are not yet manufactured at scale.

Sector Dedication and Obstacles

The majority within the airline sector, if only for their own benefit, are on board with the theory. Regarding the required reductions in emissions for net zero, 70% rely on sustainable aviation fuels, or SAF. “Lacking this,” notes Tim Alderslade from Airlines UK, “achieving net zero by 2050 becomes nearly impossible.”

In the current year, initial measures were mandated in the European Union and United Kingdom, demanding that 2% of aircraft fuel be eco-friendly – by the year 2030, this rises to 6% in the EU and 10% in the UK.

Diverging Opinions Among Airlines

Nonetheless, carriers have raised doubts about whether supplies will be available and at what price. A division is emerging between companies that have locked in SAF supplies and funded technological advancements, and those intensely focused on financial performance.

Ryanair’s CEO Michael O’Leary dismisses SAF as nonsense. He says: “It is all gradually dying a death, which is what it deserves to do. We have just about met our 2% mandate. There is no possibility of meeting 6% by 2030; 10%, not a hope in hell. We’re not going to get to net zero by 2050.”

More measured voices among SAF’s champions share apprehensions. Willie Walsh, director general of the worldwide airline trade body Iata, had pushed for fuel tanks to contain 5% SAF by 2030. He admitted last week to disappointment in progress, adding he did “not believe that target can be achieved given where we are in terms of SAF production”

Public Sector Efforts and Manufacturing Challenges

Britain is attempting to establish the structure with a guaranteed income system. Legislation now moving through parliament will guarantee a price for SAF, to stimulate manufacturing investments. In July, the Transport Department assigned £63 million to 17 companies looking to make SAF in Britain. A spokesperson said there were “encouraging early signs regarding compliance with the mandate”. However, only Phillips 66 in Humberside is producing SAF extensively, while the five facilities pledged under the “jet zero” plan remain unrealized.

Incentives and penalties are essential, with big oil companies having ever less incentive to go green while encouraged to pursue profitable drilling. Shell’s choice to halt a biofuel facility in Rotterdam, anticipated as a major European waste-to-jet-fuel converter, will make SAF rarer and dearer. Meanwhile, Donald Trump’s “big beautiful bill” slashes US incentives for SAF production introduced by Joe Biden’s Inflation Reduction Act – although, in a concession to American crop farmers, some subsidies on homegrown SAF feedstocks will continue for two more years.

International Views and Forward Projections

Philip New, a former BP alternative energy executive and government adviser on SAF, says: “I’m very pessimistic about SAF in the US. There’s no mandate or regulations or reason to use it.”

Beyond the US, geopolitics could weigh on supplies in various ways, he says. Tariffs could divert more Chinese cooking oil for SAF in Europe; simultaneously, Asian nations enacting their own requirements and limits may not want to export.

New maintains that SAF will eventually materialize but warns: “It is going to be a lumpy transition.”

Technological Advances and Environmental Considerations

Present UK and EU regulations can be fulfilled solely with HEFA-derived SAF, made from sources such as recycled cooking oil – despite concerns about its origins. The bigger hurdles come as governments demand second generation SAF, made of feedstocks such as household rubbish.

Alderslade says production of 2G is “the great unknown”. Missing the mandate, he says, will bring financial penalties “which inevitably will be passed through to passengers”.

New says: “In theory this is a really great way of getting rid of our waste.” The difficulty lies in securing appropriate backing to back up the very high-risk first generations of these technologies.” Despite public support, 2030 goals for 2G are probably unattainable, he adds.

Funding and Sustained Feasibility

Notwithstanding the dangers, funders recognize future potential. One global asset manager, who declined to be named stated that the US is unusual in retreating from net zero, as regulations emerge in Asia and Europe. “For oil majors, SAF is lower priority, it’s hard – some people are giving up. However, carriers cannot forsake it. It’s going to be bumpy – but is it all coming down? No.”

Differing views among airlines, he suggests, could relate to SAF availability and cost at the airports they use: “There’s no shortage in the hubs.”

Corporate Strategies and Regional Efforts

IAG, the parent company of British Airways, affirms a “dedicated long-term plan”, based on past actions – it revealed intentions in 2011 for a groundbreaking waste-to-fuel facility in Essex, although it admitted defeat by 2017. IAG says there will be enough SAF to meet EU and UK mandates until 2030. However, a representative noted: “Advanced SAF generations need greater funding and development assistance … Regulations help drive demand but manufacturing investment is crucial.”

Positive developments continue to emerge: a Belfast company, Catagen, last month launched patented modular technology capable of generating required SAF volumes near regional airfields, an innovation supported by Ryanair.

Airport-Specific Implications and Environmental Debates

Regarding British Airways’ main hub, the discussion is especially pressing: if the sustainable aviation roadmap crumbles, Heathrow’s third runway becomes ever more politically difficult.

Matt Gorman, director of carbon strategy at Heathrow insists: “SAF is not hypothetical. Heathrow currently leads worldwide in SAF utilization, 17% of the world’s SAF in 2024 was used here. This is real progress, not a future promise.”

Certain eco-activists, while remaining firmly against Heathrow expansion, have shifted on SAF, accepting it as a potential route to future decarbonisation – despite concerns it may mask current ecological issues. Yet numerous advocates and researchers doubt SAF’s basic principles and its emission reduction claims.

Aircraft will still release CO2 from engines – and in the broader context, will still be depleting resources. Matt Finch, in an Aviation Environment Federation analysis, said: “The blunt truth is that there is not a single SAF feedstock cannot be utilized elsewhere for beneficial ecological results. Often, waste is already applied toward those ends.”

Advanced Fuel Types and Economic Realities

That caveat applies even for the gold standard fuel, third generation, or e-SAF, created via CO2 capture and renewable electricity. It has been manufactured in limited amounts, and tested in a Swiss “solar fuel” flight this July. But e-SAF requires green hydrogen, resources that, Walsh notes, are “scarce and costly”. Investors in e-SAF right now, according to the City insider, “will probably lose their money”.

Historical Context and Future Predictions

Historical patterns indicate uncertain technological trajectories. De Pinedo was to die eight years after his seaplane feats, in a standard aircraft departing from a New York runway in 1933. Seaplanes were replaced by jet planes introduced during WWII.

“Predicting the future will always involve some uncertainty,” Gorman says. “However, our actions are not speculative. It’s based on evidence, expert consensus, and a clear roadmap.”