1. Project Summary

Flooded mine workings can provide ambient temperature storage. Geothermal potential of abandoned coal mines in the UK is a greener energy solution. Energy generated from geothermally heated mine water can be used in district heating schemes to produce clean and renewable heat energy. However, most mine workings are currently abandoned, and not considered as significant in supporting UK’s transition to low-carbon energy solutions. The urban areas of Leeds and West Yorkshire have such legacy mine workings. Local authorities and businesses are interested in the potential of their use. Thus, these areas are ideally suited for an in-depth assessment.

2. Proposed Research

This study aims to investigate the feasibility of extracting geothermal energy from abandoned coal mines that are characterised by a flooded network of galleries and shafts at various depths in the West Yorkshire Coalfield area between Leeds and Sheffield. Specific research objectives, which can be adjusted to reflect the interests of the candidate, include:

- Investigation of the stability of the mines and open cavities to assess the risk of possible eventual collapse and consequent ground-surface movements such as the development of sinkholes, micro-earthquakes or groundwater impacts. Geophysical data analysis and experimental testing of representative samples may provide additional data on aquifer rebound mapping, and modelling via seismic/resistivity surveys. The long-term stability assessment is crucial. This is essential because both pumping and re-injection of water can deteriorate the mechanical behaviour of the shafts and might cause stability issues affecting the in-situ stress conditions due to the impact of aquifer rebound but also on roadway/goaf settlements. Numerical analyses (FEM, FDM models) to capture the hydromechanical and geothermal effects on the geomechanical behaviour of the coal and surrounding rocks will include a sensitivity analysis, assessing also the possible remnant gas saturation identification as a drilling hazard or from abandoned mine methane (AMM).

2.1 Project's Objectives

– Estimation of the geothermal energy potential of selected areas utilizing available mine records, their associated geological data and archive seismic reflection profiles augmented with targeted geophysical and geological data acquisition. It may also be possible to conduct new geophysical surveys (including seismic refraction and resistivity methods, possibly extending to distributed acoustic sensing) to enrich the interpretation of the site.

- Subsequent assessment of the long-term sustainability of the source as well as optimal use of available geothermal energy based on local demand and supply.

The ultimate goal is to provide local authorities with a scientifically well-founded set of recommendations.

The project will examine the feasibility of extracting geothermal energy from abandoned coal mines. The candidate will access data available from existing boreholes and past reports. The candidate will visit the coal mine sites wherever possible. A critical requirement is to investigate the flow within the mine water in the void spaces. Another crucial component of the investigation is the increased permeability of host rock resulting from past coal mining activity.

The proposed research project aims to investigate the geomechanical behaviour of rock materials by performing several laboratory tests. The experiments will take place at Rock Mechanics, Engineering Geology and Geotechnical Laboratory RMEGG.

We anticipate working with external collaborators (partners) such as The Coal Authority, Leeds City Council and the British Geological Survey.

3. Applicant's Eligibility

Applicants should have a BSc degree (or equivalent) in geology, earth sciences, geophysics, civil/mining engineering or a similar discipline. An MSc in engineering geology, geological/geotechnical engineering or applied geoscience (or similar) is desirable. Skills in field-based geological data collection and sedimentology, stratigraphy and structural geology are desirable. Experience using numerical analysis software would be useful, though not essential.

4. Training

This PhD will commence on 1st October 2025 and run for 3 years. During this period the student will be eligible for all the postgraduate training typically provided to students attending the University. The student will receive thorough training in the critical appraisal of subsurface data, experimental rock mechanics and FEM modelling. This multi-disciplinary training will place the successful student in an ideal position to work in the industry or academia. The candidate will have the opportunity to present their findings to national and international conferences during this period.