Unravelling the potential of sustainable aviation fuels to decarbonise the aviation sector

The aviation industry is responsible for approximately 2% of the total anthropogenic greenhouse gas emissions. With an expected four to six-fold growth by 2050, increased attention has been paid to reduce its carbon footprint. In this study, we analyse the requirements to promote Sustainable Aviation Fuels (SAFs) from solar energy to reduce the emissions of the sector. Using a discrete spatio-temporal mathematical description of the region of Spain, we present the key elements required to produce jet fuel via Fischer-Tropsch (FT) and Methanol to fuels (MtF). We have found that solar PV, electricity storage, and alkaline water electrolysis are the key drivers for the performance of solar SAFs while the optimal location of the facilities is driven by the availability of solar radiation, underground H-2 storage, and high jet fuel demand. We show that the constant supply of H-2 requires an over sizing of technologies, which in turn decreases the utilisation of solar panels and electrolysers. While higher usage rates could be attained by a constant supply of electricity (e.g., via the electricity grid), the use of renewable sources is essential to guarantee a reduction in CO2 emissions compared to fossil-based jet fuel. We found that production costs in 2020 per kg(fuel) in Spain varied from 3.90 euro (MtF) to 4.95 euro (FT) using solar radiation as a sole source of energy and a point source of CO2, cutting CO2 life cycle emissions by similar to 25% compared to their fossil-based counterpart (2.5-2.7 kg(CO2eq) per kg(fuel)). Potential technological improvements could reduce jet fuel production costs to 2.5-3.3 euro per kg(fuel) for CO2 point sources while emissions could reach similar to 1.0 kg(CO2eq) per kg(fuel). Ultimately, the impact of these routes in the cost of a flight ticket would result in a minimum increase of 100-150% at present and 40-80% by 2050, accounting for current projections on technologies and carbon prices. This shows that future minimum carbon taxes of 500 euro per tCO(2) would be required for SAFs to become competitive.