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How sustainable fuel will help power aviation’s green revolution


True or false? Garbage, cooking oil, old clothes and woodchips are some of the raw materials that can be used to make aviation fuel.


All true. And not just fuel, but sustainable aviation fuel. These so-called SAFs are being touted as an elixir that will offer aviation a way out of a big carbon problem. SAFs have the potential to become a significant part of new approaches to enable an industry that relies entirely on fossil fuels today to lower carbon pollution tomorrow.


Historically, fuel has not been a big strategic issue for commercial aviation – it is simply a costly essential, representing 30% or more of an airline’s total cost base. It is also a volatile cost, skyrocketing and plummeting in response to wars, global crises or, as we are seeing today, a pandemic.


But that is changing. Fuel is turning into a strategic asset as the aviation industry, with varying degrees of enthusiasm and reticence, joins the global movement to lower its carbon emissions and play its part in tackling climate change.


Most estimates say aviation produces about 2% of total global greenhouse gas emissions – but this may be magnified by other factors, with research pointing toward the significance of the non-CO2 climate impact from aviation, such as NOx, soot and contrails.


The industry’s common target is to reach net zero emissions by 2050, with many airlines having announced their commitments to achieving net zero, and many more set to follow.


Scott Kirby, the chief executive of United Airlines, is prominent and outspoken on this topic. In a LinkedIn post in December, he said: “We’re embracing a new goal to be 100% green by 2050 by reducing our greenhouse gas emissions 100%. And we’ll get there not with flashy, empty gestures, but by taking the harder, better path of actually reducing the emissions from flying.”


The problem for aviation is this is easier said than done. Today, the only fuel source is fossil-based and there is no obvious way of quickly slashing emissions. Carbon offsetting is one option – and although this does something, many see this approach as no more than a temporary sticking plaster.


ELECTRIC AVENUE


Aircraft powered wholly by electricity are gaining prominence. This technology offers the potential to deliver sustainable short-haul flying using aircraft with up to 50 seats in the second half of this decade. Hydrogen fuel is another much-discussed candidate, but that is thought unlikely to become viable until well into the 2030s.


Most agree that the only realistic alternative power source, especially for heavier aircraft, is sustainable aviation fuel. In its November 2020 report Blueprint for a Green Recovery, aviation environmental coalition the Air Transport Action Group (ATAG) describes a rapid and worldwide scale-up of SAF as “perhaps the single largest opportunity to meet and go beyond the industry’s 2050 goal”.


The World Economic Forum November 2020 report, Clean Skies for Tomorrow, concluded that “there is no ‘silver bullet’ overarching approach for aviation’s decarbonisation, but SAF is a necessary asset in the transition”.


The key word in SAF is sustainable – because this fuel is not pollution free. The improvement comes as a result of the fact that the SAF production process itself absorbs CO2, according to a recent report from consultancy McKinsey.


“If you look at our product the reduction is up to 80% on a life-cycle basis,” says Sami Jauhiainen, vice-president, business development, renewable aviation at Finnish renewable fuel producer Neste.


According to ATAG, SAF can be described as reducing emissions on a life-cycle basis because the CO2 that is absorbed by plants during the growth of biomass is roughly equivalent to the amount produced when the fuel is burned in a combustion engine, which is then returned to the atmosphere.


While there are several terms used to describe sustainable or alternative fuel, the term SAF has become a catch-all for non-fossil-based aviation fuels. The first phase of SAF uptake happening now is being driven by use of bio-based waste and residue raw materials.


In time these will be complemented with e-fuels or electro-fuels. These alternatives are manufactured with captured CO2 in a reaction with hydrogen and using renewable electricity.


BURNING ISSUE


While it is true that burning SAF causes the same carbon emissions as burning regular jet fuel, the avoidance of using fossil fuel in the first place is key, says Lauren Riley, managing director, global environmental affairs & sustainability at United. The airline has been using SAF daily on its flights at Los Angeles International airport since 2016.


“SAF and carbon capture are the two known pathways today for airlines to decarbonise,” says Riley. “My vision for 2050 is 100% of our planes fuelled by SAF and significant carbon sequestration to mitigate the emissions from the past.”


The industry has been quietly working on SAF development since 2006. The Commercial Aviation Alternative Fuels Initiative (CAAFI) was formed that year by US aviation bodies including the Federal Aviation Administration and Airlines for America to foster the development and commercialisation of SAF.


“The aim is that blended SAF is a ‘drop-in’ jet fuel, so no changes are required in aircraft or engine fuel systems, distribution infrastructure or storage facilities,” says Steve Csonka, CAAFI executive director. “As such, blended SAF can be mixed interchangeably with existing jet fuel.”

This is the case for industry-approved SAF production pathways today at blend levels of up to 50% with regular jet fuel. Work is under way on higher blend levels that will enable SAF to deliver deeper carbon reductions, Csonka says.



In recent months, Rolls-Royce has conducted tests with a Trent 1000 and a Pearl 700 turbofan exclusively powered by SAF. “Our aim is to give the industry confidence that we can continue on to 100% SAF certification,” says Simon Burr, director of engineering & technology at R-R. “The engines behaved exactly as expected.”


DEMONSTRATION FLIGHT


Boeing flew dozens of 100% SAF test flights in the late 2000s, but it was a Virgin Atlantic 747-400 demonstration flight from London Heathrow to Amsterdam – with founder Sir Richard Branson’s typical razzmatazz – that brought greater publicity to alternative fuels.


SAF development has continued steadily throughout. The latest breakthrough, which came in February, saw a SAF produced in a “lower-carbon pathway” power the first commercial flight with an e-fuel blend. This significant move was achieved with a SAF made by Shell from synthetic kerosene (from CO2 and hydrogen, not biomass) and powered a KLM service from Amsterdam to Madrid.


Tests and demonstration flights aside, several front-running airlines have been using SAF for five years in regular operations.


Cathay Pacific started researching the nascent SAF industry in the USA for use in its transpacific operation in the early 2010s. It was attracted to California-based Fulcrum Bioenergy’s strategy of “low-carbon fuel made from trash”. To secure access to Fulcrum’s SAF, Cathay invested in the firm in 2014. Others, like United and BP, followed suit.



Over recent months Cathay has developed a SAF deployment strategy as part of its net zero commitment, says Yee Chow, the airline’s biofuel manager.


“We are producing a roadmap of what percentage of SAF we can achieve at what cost, by when,” he says. “There are plenty of unknowns, but it is all about putting a stake in the ground.”


However, such pioneers are currently something of an exception in the industry. The adoption of SAF in air transport has been slow when compared with other sectors, which have latched on to sustainable options much faster.


“Aviation’s use of SAF has progressed a lot slower than road transport’s use of sustainable fuel – it’s 15 years behind, even though the product is not in reality any different,” says Neste’s Jauhiainen.


The main barriers to SAF adoption have been high cost and limited availability. SAF is three to five times the price of jet fuel today. That will fall as SAF production rises and incentives for its use arrive.


Currently the uptake of SAF is minuscule compared with the volume of jet fuel burnt in a normal year. Airlines used about 300 million tonnes in 2019. SAF only made up about 0.1% of this.

But that is changing. Over the past year, SAF has become a hot topic. “It’s a once-in-a-century chance for an industry to develop new energy sources,” says Darrin Morgan, head of growth and investment at SkyNRG, a Dutch outfit that KLM helped found in 2010 to develop the SAF market. “We see it not as a defensive activity but as an opportunity.”


SAF producers are using the same business models as the traditional energy industry – including renewable sources such as wind and solar power – to bring investors to the table. “Long-term offtakes facilitate project financing – it makes perfect sense,” says Morgan. Offtakes is the jargon used where airlines commit to a multi-year fuel deal with producers. However, less than a dozen airlines have taken the plunge so far with such SAF agreements.


While rising SAF production will bring the cost down and usage up, policy change will be essential too. “There needs to be a highly effective set of measures led