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be sustainable Can flying Professor Stephen Dooley , Associate Professor of Energy Science and head of the Trinity College Dublin SAF Research Facility at SMBC Aviation Capital, looks at what’s involved in making aviation sustainable and why Trinity is a leader in the field T he acronym for sustainable aviation fuel is SAF. If this isn’t yet a household acronym, it is only a question of time: as of next year, the EU has mandated that fuel uplift for all flights originating at EU airports must contain at least 2% SAF, and will increase year by year, with mandates of 6% by 2030, 20% by 2035, and 70% by 2050. Japan recently announced similar mandates, as has the UK. The US has incentives, rather than mandates, and is the global leader in SAF research. Currently, just 0.05% of the almost 100 billion gallons of fuel used annually by the global aviation industry is SAF, so the mandated increases will necessitate a quantum leap in the testing, proving and scaling up SAFs. Trinity is set to play a leading role. Building on the success of the Ryanair Sustainable Aviation Research Centre, established in Trinity in 2021, the university’s research in sustainable aviation received significant investment this year: Ryanair has donated a further €2.4 million to the Centre, on top of its foundational gift of €1.5 million. Aircraft Leasing Ireland (ALI), the Ibec group representing the industry, is funding a four-year study [€560,000], led by Trinity and the University of Limerick, to identify ways for Ireland to establish a viable supply chain for SAF raw materials and to scale up SAF production. Aircraft leaser, SMBC Aviation Capital, has announced the Trinity College Dublin SAF Research Facility at SMBC Aviation Capital, located at SMBC’s new landmark offices in Dublin city centre [€1.5 million].
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Collectively, these gifts and investments are enabling Trinity to take on more PhD students in SAF and hire another assistant professor. And with the new SMBC facility, which I am heading up, we have a purpose- built laboratory. Ireland is the leading global centre for the aircraft leasing industry - this has been an impetus for Trinity’s focus on sustainable aviation, as has the university’s general mission in sustainability. The European Union Aviation Safety Agency (EASA) has now appointed Trinity to lead the EU SAF Clearing House, which is coordinating the process of proving the airworthiness of SAFs produced in the EU. This is a real endorsement of Trinity’s leadership but the challenges are considerable: SAFs have to be proved to be sustainable, safe, scalable and affordable. First, we have to show that SAFs save significant quantities of carbon dioxide relative to fossil fuels. SAFs are biofuels made from plant waste matter. It would be easy to make them from oils, fat and lipids but in the EU we can’t use, or import, plant matter that could be deployed for food or animal feed. We are restricted to the plant parts that have no further use, like residues, leaves, grass cuttings. As well as biomass, SAFs can be produced through the Fischer-Tropsch process in which a mixture of carbon monoxide and hydrogen, known as syngas, is converted into liquid hydrocarbons. The carbon monoxide in this process has to be biogenic in nature or to come from recycled carbon fuel. Second, after we’ve proved sustainability and CO2 savings, we have to prove that the fuel is safe for use in aircrafts. This process is analogous to how a drug or vaccine is approved and is highly data-intensive and time-consuming. It takes two to three years just to gather the data, and every time we come up with a new SAF compound, involving different types of plant matter, we have to evaluate it all over again, from ground zero. The minimum number of measurements that we need to do this is 64. Fortunately, our new laboratory at SMBC has the equipment needed to make those measurements. The formal safety approval process for SAFs is led by the American Society for Testing and Measurement, where the original equipment manufacturers, like Boeing, Airbus, General Electric, Pratt and Rolls Royce, sit. Once aviation fuels get mixed together, they're inseparable, which means that every original equipment manufacturer – and there are around 40 – has to approve each SAF for use. If any one of them rejects an SAF, it’s not getting deployed. The approval process requires hundreds of litres of fuel so to save on that, we do pre-screening. As the lead for the EU SAF clearing house, Trinity is the lead service provider for the pre-screening service. Once a SAF is approved, the final piece of the puzzle is scalability and affordability: we have to show that we can make the SAF affordably, at around €2 per litre, and at scale. Each step of the way is exceptionally rigorous, which is reassuring, obviously, since this is air travel. In terms of CO2 savings, my colleagues and I have already published papers to show that the greenhouse gas savings with SAFs are approximately 78 to 82%. In terms of safety protocols, we are developing tools and methodologies to make it easier for the original equipment manufacturers to come to an agreement. And in terms of scalability, we have a highly sophisticated agricultural industry in Ireland, as well as renewable energy, which should give us the capacity to produce biofuels. It is vitally important to complement our research capacity with more education and training: in July next year Trinity will host the first ever international conference on Sustainable Aviation Research. It will be annual, oscillating between the United States and Europe. We need to ensure that everyone working in this sphere is made aware of the research facts and challenges. SAF is just one of Trinity’s sustainable aviation research priorities. The second area, led by Professors Stephen Spence and Charles Stewart at the School of Engineering, is in novel low emission aviation propulsion, which is about designing more efficient aircrafts that need less fuel. And the third area is non- CO2 warming effects – that’s warming induced by aeroplane contrails. With the support of Ryanair, we’ll be hiring a new assistant professor to research into this. Sustainable aviation is a challenge but the rewards are huge: aviation is a big organised industry with very technical requirements. If we can decarbonise it, we can decarbonise other industries. I look forward to the tools and methods and information that we learn in this space getting propagated to other spaces.
