Decarbonisation Technology November 2026 issue

electrolysis, the Shell Wax Hydroconversion Process, and key utilities integration. As shown in Figure 1 , the processes are designed to connect different feedstock routes with a common syngas-to-liquids platform. For producers, the choice between BTL, PTL, and hybrid BTL/PTL configurations depends on local and regional factors, such as access

Sustainable biomass, biowaste

Renewable power

CO point sources

Direct air capture

Shell RWGS P rocess

Water electrolyser

Torrefaction

Solids gasication

Syngas (CO + H)

CO + H

Shell Fischer – Tropsch P rocess

Shell Wax Hydroconversion P rocess

e-SAF

Bio-SAF

Figure 1 The Shell XTL processes for bio-SAF and e-SAF production, showing how renewable power, water, CO 2, and biomass feedstocks can be converted into syngas and upgraded into SAF through an integrated process based on Shell’s Fischer-Tropsch technology

produced in the Shell Reverse Water-Gas Shift (RWGS) Process, which is then converted into e-SAF (i.e. SAF produced using electricity as an energy source). When the additional hydrogen required in the BTL process is produced by water electrolysis rather than shifting part of the syngas, the process is called a BTL/PTL or Hybrid XTL process with combined bio-SAF and e-SAF production. Shell is offering a portfolio of integrated XTL processes. At its core is the Shell Fischer–Tropsch Process, supported by other technologies and process steps, including solid biomass gasification, the Shell RWGS Process, water

to suitable biomass, low-cost renewable power, CO₂ sources, infrastructure, and policy support. Meeting regulatory requirements is also key. Regulatory compliance is shaped by the feedstock used, the source of power, and the carbon intensity of the final fuel. For BTL, this means using suitable biomass that is typically residue- or waste-derived, does not compete with food crops, and does not require additional land use. For PTL and hybrid BTL/PTL routes, renewable power, with clear evidence of its origin, are also important. Frameworks such as ReFuelEU aviation ( European Commission 2026 ) and the UK SAF mandate ( UK Dept. for Transport, 2026 ) include carbon intensity requirements as well as e-SAF or PTL sub- mandates, so producers need to assess feedstock, power source, and pathway together. Figure 2 compares the potential economics of hybrid BTL/PTL with standalone BTL and PTL. One advantage of BTL over PTL is that the carbon is already contained within the biomass feedstock, avoiding the need to source a separate CO 2 stream. Hybrid BTL/PTL can offer further benefits through process integration. Combining the two pathways can remove the need for the water- gas shift step required in standalone BTL and the RWGS step required in standalone PTL, reducing the amount of process equipment required. The hybrid configuration can also yield more fuel per tonne of renewable (green) hydrogen than standalone PTL, reducing the scale of electrolysis required and helping to lower the levelised cost of production relative to standalone PTL. Figure

Relative SAF production cost in 2030, $/t (fuel)

Fossil jet fuel (reference)

BTL

BTL + PTL

PTL

Figure 2 Relative levelised production cost of SAF by pathway, comparing fossil jet fuel, BTL, PTL, and BTL/PTL hybrid routes. The line shows a linear interpolation between the standalone BTL and PTL values, with the gap to the hybrid BTL/ PTL value indicating the potential synergy created by combining the two line-ups. Source: Shell