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MPhil in Engineering for Sustainable Development

global challenges, engineering solutions

Flight in the net-zero era: Assessing limitations on the deployment of sustainable flight in the UK

As net-zero goals rapidly approach, attention has been devoted to “hard-to-abate” sectors from academics and industry alike. Specific attention has been paid to the potential of Liquid Hydrogen and Biofuel-based Sustainable Aviation Fuels (SAFs) to decarbonise future flight, despite their high resource requirements. This research develops a flexible model to estimate the land, water, energy, and carbon footprints and capital expenditure, including those from system feedbacks, implied by fulfilling a given fuel demand using SAFs produced by HEFA, Fischer-Tropsch BtL, Fischer-Tropsch PtL, or Alcohol-to-Jet, through any of ten biomass feedstock pathways, or liquid hydrogen from steam methane reforming and carbon capture and storage, or electrolysis from renewables to allow industry and governmental stakeholders to effectively consider these factors during decision-making.

A major contribution of this research is that system feedbacks, especially those required to recapture all carbon emitted through direct air carbon capture and storage (DACCS), are found to be important inclusions for decarbonisation planning. The inclusion of feedbacks for DACCS, for instance, is found to increase energy, blue water, capital, and installed capacity requirements per tonne CO2 recaptured by 25%. Due to this, higher carbon fuels are found to require much more energy and blue water than expected. Trade-offs are evaluated for all fuel feedstock pathways. Biomass-based fuels are found to require more land and green water than their counterparts, while hydrogen and PtL are more energy intensive. BtL FT fuels are found to be preferable to HEFA fuels when system feedbacks and carbon recapture are included, with gaps in capital requirement narrowing. Expected gaps in capital and blue water requirements between green and blue hydrogen are found to narrow with the inclusion of feedbacks. Eleven policy scenarios for UK aviation decarbonisation are evaluated using the generated model for all flights leaving the London Airport Cluster. Results indicate that all scenarios will require significant resources, trading off carbon footprint for water, land, and energy use. Fuel pathway choice is found to be influential on the distribution and scale of environmental footprints; aviation growth and FEI assumptions are found to influence their scale.


Course Overview


The need to engage in better problem definition through careful dialogue with all stakeholder groups and a proper recognition of context.


An ability to work with specialists from other disciplines and professional groups acknowledging that technical innovation and business skills also must be understood, nurtured and combined as precursors to the successful implementation of sustainable solutions.


An understanding of mechanisms for managing change in organisations so future engineers are equipped to play a leadership role.


An awareness of a range of assessment frameworks, sustainability metrics and methodologies such as Life Cycle Analysis, Systems Dynamics, Multi-Criteria Decision making and Impact Assessment.