Net Zero Aviation: Impact of emissions from Sustainable Aviation Fuels on local air quality

Year
2024
Primary Supervisor
Ruth Purvis <ruth.purvis@york.ac.uk>
Institution
University of York
Possibility of becoming a CASE project
No
Collaborative Project
No
Academic Supervisors
Alastair Lewis <ally.lewis@york.ac.uk> (University of York, Wolfson Atmospheric Chemistry Laboratories)
Research Themes
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Research Keywords
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Relevant Degree Courses
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Introduction

Aviation fuel conventionally derives from crude oil-based kerosene (Jet), however there is critical global need to enhance the adoption of sustainable aviation fuels (SAF), addressing environmental, social, and economic challenges. Sustainable Aviation Fuel (SAF) is a key part of the UK Governments Jet Zero Strategy which is a framework for achieving net zero for the aviation industry by 2050.  As SAF is more readily used to, local emissions profiles and compositions will change. Research is needed in this area as a change in emissions could lead to inventory differences and inaccuracies in local air quality (LAQ) modelling and projections.  Furthermore, as the ground transportation sector electrifies, the emissions from airports will become, proportionally, a larger contributor to detrimental LAQ. Projections from the UK National Emissions Inventory (UK-NAEI) show that by 2027 there will be more NOx associated with UK aviation landing and take-off cycle (LTO) than all Heavy Goods Vehicles (HGV’s) (Figure 1).

Figure 1: Projections of total NOx emission by sector. UK-NAEI

When looking at the main sources of air pollution at an airport the largest share is from aircraft operations on the ground (on stand power, taxing and take off). Currently, aircraft are regulated on 4 LTO thrust points (7% (taxi), 30% (approach), 85% (climb) and 100% (take off)), but whilst on stand, aircraft will often run at sub-7% (ground idle) to save fuel. At these low thrusts, the engine non-CO2 emissions (Unburnt HydroCarbons: UHCs, CO, particle matter) can increase due to the low engine temperatures and inefficient combustion, resulting in local pollution effects. Detailed chemical speciation of the gas and aerosol phases, linked to fuel profile and engine condition is alongside research into ageing and processing beyond the airport fence is also needed. This will inform impact on LAQ resulting from a transitioning to SAF.

The project

In 2025 / 2026  a series of experiments will take place to get the most comprehensive emissions database to date from SAF and JET fuels across the full range of two engine technologies. The database will include;

  • Ground based emissions from an engine test facility for standard Jet and SAF fuels direct.
  • Ground based emissions from aircraft engines at an airport for standard Jet and SAF fuels direct from engine and downwind to allow for ageing and processing in th plume.
  • Real time emissions from aircraft from an aircraft chase experiment.

This project will use the database, concentrating on gas phase emissions (VOC, NOx, SO2, CO), to answer key questions such as:

  • How do gas phase emissions differ between SAF and traditional JET and how may these impact on local air quality.
  • Are emission inventories accurate for aircraft emissions and will they need major changes due to the uptake of SAF?
  • What differences are there in ageing aircraft plumes between SAF and JET?
  • How do the different stages of the aircraft cycle affect the gaseous emissions of SAF?
  • How representative are the aircraft emissions regulation tests on the ground to real world emissions?

The project will use the comprehensive dataset already obtained from the NERC funded GRIM-SAF project – a consortium with National Centre for Atmospheric Science, University of Manchester, University of Cardiff and Manchester Metropolitan University and the student will work closely with scientists from different institutions. Opportunity may arise to take further measurements in the field by ground based mobile measurements using the WACL mobile platform or on the FAAM research aircraft.

The student will be based in the Wolfson Atmospheric Chemistry Laboratories (WACL), in the Department of Chemistry at the University of York. WACL is the largest atmospheric chemistry facility in the UK, providing access to state-of-the-art facilities and a wide range of interdisciplinary expertise. The student will benefit from research training and events tailored for atmospheric chemistry students, including training courses provided by the National Centre for Atmospheric Science.