Mine Geothermal Energy

Overview

Mine geothermal energy is a viable, low-carbon heat source to warm our houses. Before installation of such mine geothermal system, it is essential to investigate the potential of local mines using predictive numerical water circulation models. This PhD project aims to investigate mine geothermal systems using numerical models to enable generic recommendations and advise on the potential productivity and risks of specific sites. The project will involve code development and application as well as collaboration with local and national institutes. The student will become part of a vibrant research community at Durham University.

Over half of UK energy demand is used to produce heat, most of this comes from burning gas and most is consumed by the domestic sector. In the past, coal mining directly provided the energy to heat our homes. While coal energy is phased out to decarbonise our energy supply, the water within flooded abandoned mines provide a huge source (2.2 million GWh) of geothermal heat for the future, enough to meet the UK’s heating demand for more than a century. The mine water is only lukewarm (12-20°C), but by using a heat pump, temperatures can be increased to a more comfortable 40-50°C (Bailey et al, 2016). Research has shown that our abandoned mines could meet our heat demands for a century or more and will deliver economic opportunities to former mining areas (Fig.1).

After extracting its heat, the mine water is returned to the subsurface to avoid surface water contamination, and the right location(s) for re-injection of the water is crucial for the thermal evolution of the mine system. In addition, mine water could interact with nearby (drinking water) aquifers, so a proper understanding of the hydrogeological behaviour of the mine system is required. Therefore, numerical modelling of mine water and surrounding groundwater flow and associated heat exchange is an essential first stage for the successful deployment of these geothermal mine systems (Loredo et al, 2016).

Click on an image to expand

Image Captions

mine.png – Figure 1) Schematic representation of a minewater heat pump system.
louisa.png – Figure 2a) Project example: Part of the mine plan under the Louisa Centre, Stanley, County Durham, UK. b) Modelling of the long-term mine water heating for this mine system through abstraction from the Hutton coal seam, and re-injection into a shallower seam.

Methodology

Numerical modelling of mine water flow and heat exchange between the subsurface and mine water will be used to assess whether and under which conditions a mine system can provide long-term heat supply. Model reliability depends on the accuracy of local mine data, appropriate modelling software, and model calibration with experimental data. We will apply those models to prospective production sites.

The project therefore has the following objectives and associated workplan:
1) Data collection. Mine data collection is achieved through collaboration with the Coal Authority and local former mining communities. Collaboration with the BGS and the UKGEOS Glasgow Research centre will provide geological and hydrological data. Links with industrial partners (in county Durham and Heerlen, the Netherlands) will provide data from operating minewater pumping sites. Visits to those collaborators and, wherever possible, field experiments and data collection will be undertaken.
2) Code development. Our bespoke mine geothermal model (Fig.2) will be combined with a BGS hydrogeological model to look at the local heat exchange (Rodriguez & Diz, 2009) between the porous media of unmined bedrock and circulating minewater in the mined system.
3) Model application will provide optimization strategies for prospected geothermal sites in the UK and elsewhere.
4) Dissemination of results through publications, seminars, and conference presentations.

Project Timeline

Year 1

Training in numerical modelling & data; knowledge exchange with regional institutes, county councils and Coal Authority; developing & testing of models; project specific and transferable skills. Secondment to the BGS.

Year 2

Code development; application to targeted test sites; industrial secondment to enhance skill set and future employability; academic publication writing.

Year 3

Collect scientific results that will be written up in the form of several scientific publications; these will be combined with further chapters to integrate into a first draft of the PhD thesis. Secondment to the BGS.

Year 3.5

Project completion: finalizing thesis and submission of scientific manuscripts. Visits to the BGS.

Training
& Skills

This project is suitable for a student with a degree in Earth Sciences, Engineering or Geography (or a related field) who is interested in renewable energy sources and solutions to reduce our carbon footprint.

An affinity with programming and modelling is useful, although not strictly required. The student will be encouraged to participate in relevant workshops for both project specific and transferable skills.

They will attend national and international conferences, networking events and outreach activities, developing an important network for feedback and future employment. The student will become part of IAPETUS2 doctoral training programme, which offers a multidisciplinary package of training focused around meeting the specific needs and requirements of each of our students who benefit from the combined strengths and expertise that is available across our partner organizations. They may join the Centre for Doctoral Training in Energy for additional training activities (e.g. lectures, site visits), while the Durham Energy Institute (DEI) provides opportunities to engage in networking with other energy researchers and professionals involved with industry, policy and governance, as well as with outreach events, competitions and public lectures.

The student will spent a month per year working with BGS co-supervisor, based at the BGS office in Keyworth on modelling groundwater flow and heat transport in the subsurface, but it is expected that the student will also access to wider hydrogeological expertise across BGS. Through the BGS University Funding Initiative (BUFI), the BGS currently supports research training for approximately 130 PhD students across 40 universities. The successful student will become part of this large cohort of researchers.

References & further reading

– Bailey et al. (2016). Heat recovery potential of mine water treatment systems in Great Britain, Int. J. Coal Geol., Volume 164, 77-84, https://doi.org/10.1016/j.coal.2016.03.007.
– Loredo et al. (2016). Modelling flow and heat transfer in flooded mines for geothermal energy use: A review, Int. J. Coal Geol., http://dx.doi.org/10.1016/j.coal.2016.04.013
– Renz et al. (2009). Numerical Modeling of Geothermal Use of Mine Water: Challenges and Examples. Mine Water Environ 28, 2-14 https://doi.org/10.1007/s10230-008-0063-3.
– Rodriguez & Diaz (2009). Analysis of the utilization of mine galleries as geothermal heat exchangers by means a semi-empirical prediction method. Renew. Energ. 34, 1716-1725. http://dx.doi.org/10.1016/j.renene.2008.12.036.

Further Information

For further information on the PhD project, the department of Earth Sciences or doing a PhD in Durham, please feel free to contact Jeroen van Hunen (jeroen.van-hunen@durham.ac.uk).

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