PhD Studentship: Investigating (Bio)geochemical Trapping of CO2 on Geological Timescales

Positions available: 1

This is a fully funded PhD project for which, the successful candidate will receive a monthly stipend, have the university fees paid for, and be awarded some money to support lab costs and travel. The annual tax free stipend is set at the UKRI rate (2025/26 rate £20,780). Applications from home and overseas applicants are welcome.

Geological carbon storage will be critical to lowering atmospheric CO2 levels. However, the inability to ensure safe storage and assessing leakage risks has resulted in delays in issuing permits and slowed industry growth1. Ensuring safe storage with low leakage depends on comprehensive understanding of subsurface processes. Research to date has focused on the physical and chemical interactions CO2 undergoes in the subsurface environment. However, recent studies have shown that microbial processes, such as methanogenesis (microbial conversion of CO2 to CH4), is critical in evaluation of a potential CO2 storage sites2,3. Determination and quantification of both microbial and physical processes and how these both evolve through time is essential to evaluate and ensure a long-term ‘safe’ CO2 storage. This will be important for guiding injection, site selection and informing policy and regulation to ensure durable storage.

Within the reservoir, CO2 can mineralise to calcite via both physical and microbial processes, which provides a snapshot of the reservoir at the time of formation. Using the state-of-the-art equipment at the University of Manchester you will characterise the calcite cements and their paragenesis (relative history of cementation) petrographically (transmitted light, cathodoluminescence and SEM) and determine their stable isotope composition of calcite to distinguish the products of physio-chemical and biological processes. You will also undertake geochemical analysis to determine the trace element composition of the cements and assess their suitability for U-Pb dating. If successful, the U-Pb ages of the calcite will be used to determine changes in the relative importance of physio- chemical and biological processes over time. You will also quantify CO2 saturation and noble gas composition within fluid inclusions to gain insights into the composition of the reservoir at the time of formation4. Together these data will be used in combination with conceptual and reactive transport models to determine and quantify the processes that have occurred within the reservoir and model how these have evolved with time, as a proxy for future CO2 storage.

This project will suit students that hold, or about to obtain, a minimum 2:1 undergraduate degree (or equivalent) in Earth Science or a related discipline. A Master’s degree in a relevant subject is desirable but not necessary. Some direct experience of one of the following would be advantageous: mineralogy, geochemistry, or reactive transport modelling, however this is not a requirement since full training will be provided.

To begin an application please contact the main supervisor, Dr Rebecca Tyne (Rebecca.tyne@manchester.ac.uk) for this project. Please include details of your current level of study, academic background (CV) and any relevant experience and include a paragraph about your motivation to study this PhD project.

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