Nov-2022

Take-off for cleaner skies starts now with SAF (ERTC)

The transportation sector accounts for 14% of the world’s GHG emissions. This is why governments and states worldwide are taking measures to lower GHG emissions through subsidies and legislation, with 137 countries having pledged to achieve carbon neutrality by, for the most part, 2050.

Mikala Grubb
TOPSOE

Article Summary

And with aviation responsible for 8% of the transport sector’s emissions, there is no way the industry can fly under the radar. Change is coming, and that means sustainable aviation fuel (SAF) will be under the spotlight, with projected demand of around 15 Mt in 2030 and 200 Mt in 2050. Eventually, and as is our collective aim, both renewable jet and eJet fuels are expected to overtake fossil jet fuel.

But change has been coming for some time. Indeed, as far back as 2008, airlines have been exploring the potential of SAF. However, uptake has been slow, and by 2019 SAF accounted for just 0.1% of all fuel consumed by the aviation industry. In terms of ambition and tangible action, it has only been the last year or so in which we have started seeing real change.

In 2021 airlines bought every drop of SAF available worldwide, test flights are being run partially or fully powered by SAF, and regulations reducing barriers to entry have come into effect. All of which is great news for efforts to decarbonise aviation.

Routes to SAF certification
Aircraft flying around the world will be fuelled at different airports in different countries, making international fuel specifications for SAF a necessity.

It is a matter of ensuring flight safety and minimising risk of mishandling, but it is also a matter of avoiding having to implement a varied mix of fuel delivering systems at high cost. In addition, current specifications ensure today’s engines and aircraft do not have to be redesigned to run on SAF, thus making the transition even more sustainable. At present, the focus is on SAF as a drop-in replacement to conventional jet fuel. And, with ASTM standards excluding the use of pure SAF in aircraft, a 50% blend is most common, with a maximum 10% blend available in some cases.

There are currently seven approved technology pathways to producing drop-in SAF (see Table 1). Co-processing, as seen in Table 2, is another option for decarbonising aviation and meeting the criteria for the Standard Specification for Aviation Turbine Fuels (D1655). Co-processing, which involves the simultaneous processing of fossil and renewable feedstocks, means you can use existing refining, transport, and storage facilities. This, in turn, makes it possible to convert renewable feedstocks into drop-in, ultra-low sulphur renewable jet or eJet fuel at economically competitive prices.

Topsoe routes to SAF
At Topsoe, we have identified the main routes we consider to be the most commercially advanced (see Figure 1). Firstly, we have HydroFlex^tm, which offers full feedstock flexibility whatever raw material you choose to work with. This technology utilises Topsoe’s hydroprocessing expertise to enable the processing of virgin oils, waste oils and fats, solid biomass, and plastic waste/tyres into HEFA-based SAF with minimal Carbon Intensity (CI) compared to traditional petroleum aviation fuel. HydroFlex also has a high number of running references, offers versatile process design and hardware, and comes with a comprehensive range of proprietary catalysts for renewable fuel production.

But if gasified waste is your source of choice, go the synthetic- and gas-based route with G2L^tm Biofuels. This commercially proven technology utilises Topsoe’s hydroprocessing technologies and Sasol’s LTFT^tm technology to produce Fischer-Tropsch Synthetic Paraffinic Kerosene (FT-SPK). We supply the core technologies and engineering, catalysts, proprietary hardware, and technical services in a single-point license – an industry first – and offer a feed-in/product-out guarantee.

And then we have G2L^TM eFuels, which allow you to produce eFuels from renewable energy via green hydrogen and CO₂ via carbon capture. By combining synthesis gas, Fischer-Tropsch and hydroprocessing technologies, our G2L eFuels solution efficiently produces FT-SPK/eJet and green naphtha. The process integrates newly developed technologies like our fully electrified eREACT^tm into already proven solutions, meaning a viable way to produce eFuels is ready. Now. Furthermore, the Fischer-Tropsch technology is provided by our strategic partner Sasol under a single-point licence.

Feedstock availability can cause turbulence
SAF can be produced from various renewable feedstocks, including vegetable oils, waste oils and fats, solid biogenic waste, industrial flue gases, CO₂, renewable electricity, and water. As the market for and production of SAF increases, so will the need for suitable feedstocks. There are many reasons for this, not least because other segments and industries are pursuing the same feedstocks for their purposes, like road transport, marine fuel, and petrochemicals. That could become a seriously limiting factor in our journey to decarbonising aviation.

But what does this have to do with legislation? The use of feedstocks, in particular first-generation renewable feedstocks, is highly regulated in some parts of the world like the EU, with direct implications for the biofuel production required to supply mandated volumes (see Figure 2).

Inbound: advanced feedstocks
But a third generation of feedstocks is coming: advanced solid waste feedstocks that can be derived from solid biomass waste, rotational crops, and recycled carbon.

Processes for working with solid waste feedstocks naturally differ from those applied to first- and second-generation feedstocks – the principal divergence being solid-to-liquid conversion. And while the technologies for this conversion process are almost ready and the knowledge is there, strict aviation regulations mean these processes still need approval.

Solid waste feedstocks are a much more abundant resource than previous generations and will remain so for years. In all, their emergence is key to decarbonising aviation.

Boundless opportunities
There is no doubt that the demand for SAF will keep growing. With innovative technologies and cutting-edge knowledge enabling the upgrading of advanced feedstocks, fuel production is at the centre of the global transition. Forward-thinking businesses will capture this by moving into new, advanced feedstocks while the opportunity is ripe.

Collaboration is Key
We can see the effort being made by refineries, OEMs, airlines, government bodies and more to propel us to decarbonise aviation. And collaboration will be the final piece in our SAF puzzle, enabling us to push for more legislation, greater feedstock availability, and a Flight Plan Green.

This short article originally appeared in the 2022 ERTC Newspapers, which you can view HERE