Project Outline

With the global demand for air travel rising and a commitment by the International Civil Aviation Organisation to achieve net-zero by 2050, there is an urgent need to develop more sustainable methods of powering aircraft [1]. The energy density of batteries is currently about 50 times less than kerosene and so are unlikely to replace conventional engines in the near future. As an alternative, sustainable aviation fuels (SAF) derived from used cooking oil, municipal waste, or agricultural by-products are being widely explored [2]. However, reliance on these materials does not discourage the production of wastes; for example, where waste plastics are converted into SAF, they result in adding CO2 emissions to the atmosphere, rather than acting as a carbon store. For this reason, there is a need to develop truly sustainable aviation fuels from biomaterials.

Microalgae, particularly Chlorella strains, have significant potential to act as the biomaterial capable of producing carbon neutral SAF. Recent reports have claimed that the potential yield from microalgae is as high as 91 t / ha / year. This compares to less than 20 t / ha / year of other energy crops such as palm or rapeseed oil [2]. This research project will focus on algal growth, downstream processing, life cycle analysis (LCA), and techno-economic assessment (TEA) of the process developed.

The effect of different growth factors, such as light exposure, nutrient provision, and bioreactor conditions on the algal composition will be investigated. Analysis of the algae will use techniques such as sonication to break apart the cell walls, liquid-liquid separation to recover fatty acids, and bomb calorimetry to quantify the total energy content. Elemental analysis will also be conducted.

Downstream processing will involve the analysis of different SAF production pathways, such as capitalising on the hydro-processed esters and fatty acids (HEFA) platform. Separation techniques which can then be used to recover a high purity of SAF include filtration, liquid-liquid separation, and rotary evaporation. The purity and yield of the SAF produced may then be determined using analytical techniques such as NMR and GCMS.

In addition to this lab-based work, the project will be supported by computer-based research. To ensure that the developed SAF has a lower environmental impact than alternative fuels, a thorough LCA will be completed. The recommended software for this is Sima Pro. The results from this will both inform, and be informed by, the outputs of the lab-based work considering microalgal growth and downstream processing. Recent work has evaluated the current techno-economic status of various SAFs [3], and a similar approach will be applied to the process developed within this project. Doing so will enable the identification of drivers for, and barriers to, commercialisation of this, or similar technologies.

The successful applicant will be based within the School of Chemical Engineering at the University of Birmingham, however, there is a strong focus on multidisciplinary research. There are numerous opportunities for collaboration with the School of Biosciences, and with the University of Sheffield who will provide LCA expertise throughout the project.

References

1. A. G. Romero-Izquierdoa, G.-A. Claudia, I. G.-C. Fernando, S. Hernandez, and J. F. Garcıa-Trejo, “Production of renewable aviation fuel from microalgae,” in 3rd Generation Biofuels, 1st ed.Woodhead Publishing, 2022, pp. 639–664. doi: 10.1016/B978-0-323-90971-6.00042-5.
2. S. S. Doliente, A. Narayan, J. F. D. Tapia, N. J. Samsatli, Y. Zhao, and S. Samsatli, “Bio-aviation Fuel : A Comprehensive Review and Analysis of the Supply Chain Components,” vol. 8, no. July, pp. 1–38, 2020, doi: 10.3389/fenrg.2020.00110.
3. F. Shahriar and A. Khanal, “The current techno-economic , environmental , policy status and perspectives of sustainable aviation fuel ( SAF ),” Fuel, vol. 325, no. June, 2022, doi: 10.1016/j.fuel.2022.124905.

Techniques

• Chemical cell lysis.
• Sonication.
• Liquid-liquid separation.
• Bomb calorimetry.
• Nuclear Magnetic Resonance spectroscopy (NMR).
• Gas Chromatography coupled with Mass Spectrometry (GC-MS).
• Fourier Transform Infrared Spectroscopy (FTIR).
• Scanning Electron Microscopy (SEM).
• Elemental analysis.
• Life cycle analysis.
• Techno-economic assessment.