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Geothermal Campus

Dave Healy, Emma Bramham, and Fleur Loveridge introduce the Living Lab for Geothermal Energy, a multidisciplinary project probing the potential of geothermal energy production beneath the University of Leeds

Words by Dave Healy
2 September 2024
Emma Bramham
Fleur Loveridge

The ‘living lab’ at the University of Leeds will explore the potential to heat the campus using geothermal energy (© iStock)

To reach our net-zero targets, we must change the way we manage heat and accelerate the use of more sustainable, low-carbon energy across the UK. Using geothermal systems for heating, cooling, and energy storage could be a key part in this process. However, to enable wider and faster uptake across the UK, it is essential that we de-risk the costs, viability, and sustainability of geothermal projects to provide a more informed decision-making process. De-risking geothermal energy in the UK urgently needs pilot studies across a range of geological and end-use scenarios. Geosolutions Leeds – a research centre at the university that aims to deliver a holistic approach to the energy transition (including geothermal energy, hydrogen storage, wind energy, sustainable minerals, and carbon capture and storage) – is leading the way. The team is developing an urban research laboratory to test the viability of harnessing geothermal energy, both under the campus and more widely in the city, while providing researchers and students with an on-site ‘living lab’.

Heating the UK

Heating buildings emits 23% of the UK’s carbon emissions, with emissions from cooling buildings due to rise as climate changes (DESNeZ & BEIS, 2021). UK heat generation remains heavily reliant on fossil fuels, with only 5% of energy demand met by low-carbon sources. For the UK to meet its legally binding target of net-zero emissions by 2050, we must shift away from our reliance on fossil fuels, yet myriad issues complicate the UK’s energy mix. Not least, recent geopolitical instability has brought the security of energy supply into focus; rising energy prices have dramatically increased fuel poverty and associated health issues, while fossil-fuel based heating continues to exacerbate air pollution.

Extracting heat from shallow (less than 500 m) geothermal sources is a potentially attractive option across much of the UK because this approach depends on relatively well-known geology alongside tried-and-tested technologies, such as heat pumps and borehole heat exchangers. These methods also avoid any risk of induced seismicity. Experience in the UK and further afield shows that to gain maximum long-term benefit from shallow aquifers and aestifers (rock that stores or transfers heat) a thorough characterisation of the local hydrogeology is critical (Banks, 2009). But equally important as the geoscience is a holistic approach – one that incorporates effective solutions and specialist technologies from engineering and scientific disciplines with policymaking, investment decisions, and end-user engagement. Heating and cooling must operate in synergy with existing infrastructure and the ongoing decarbonisation of transport, electricity, and other urban services, rather than in competition.

The Living Lab

The University of Leeds Climate Plan, which was approved in 2021, has dedicated £174 million over the next decade to decarbonising the campus using collaborations between academics, students and professional staff. To help deliver the plan, Geosolutions Leeds, a research group that brings together the combined expertise of geoscientists, social scientists, and engineers from across faculties (Environment, Engineering and Physical Science), has launched the Living Lab for Geothermal Energy Project. Many years in the making, the initiative aims to develop an urban lab that will provide a platform to explore how aquifers can be harnessed for heating and cooling – not just beneath the University of Leeds campus, but also across the region and the wider UK.

Figure 1: Diagram of an open-loop geothermal doublet. A borehole drilled into a subsurface aquifer extracts existing warm water. At the surface, an exchanger extracts the heat and a pump brings it up to a useful temperature to heat buildings. The cooler water returns to the aquifer via a second borehole. Importantly, the water never leaves the pipe. (© Dave Healy)

To shape plans for the current investigations beneath the campus, geoscientists from the university developed an initial geological model. The ground conditions beneath Leeds – interbedded sandstones, mudstones, and siltstones of the Coal Measures – are not typically thought of as a major aquifer. However, a borehole pumping test carried out in 2007 showed that sufficient flow rates and temperatures could be achieved from an open-loop ground source heat pump (GSHP) system, which extracts and often reinjects groundwater from the aquifer (Fig. 1). Although not adopted at the time, changes in the political and economic landscape now make a shallow geothermal solution one of the key parts of the university’s plans.

The Living Lab for Geothermal Energy Project will explore how aquifers can be harnessed for heating and cooling

A viable system

So far, eight boreholes, or wells, have been drilled. In February 2024, a pair of reversible extraction and reinjection wells (a geothermal doublet) was drilled, and the initial results looked very favourable. To obtain additional information for the new wells, two pilot wells were drilled and fitted with downhole geophysical sensors for long-term monitoring. Four closed-loop wells, where the fluid used for heat transfer is re-circulated, were drilled and used to test the thermal response of the system using fibre optic distributed temperature sensors (DTS) and distributed acoustic sensors (DAS).

The thermal response tests returned values for effective thermal conductivity that suggest substantial natural groundwater advection rates, in addition to high pumping test yields from the two pilot wells. These results show that a shallow geothermal system would be viable in this area.

Given the locally heterogeneous geology, core acquisition and analysis was invaluable, enabling the identification and mapping of the lateral extent of specific aquifers within a sequence and aiding the design of permanent casings for the wells. The pilot wells and thermal response boreholes were drilled at different locations across campus to aid understanding of the wider subsurface picture and enable development of a dynamic geothermal model across the fault-bounded blocks that underlie the campus.

Core from a campus borehole. Diverse sedimentary structures are found at different depths and in different lithologies. Left: Fractures are crucial for fluid flow in the sandstone aquifer (~10 cm across; © J Kelly). Right: ~1 m of core with sedimentary structures and a fracture (© E Bramham).

This information will constrain the design of the heat-pump systems and provide baseline monitoring data. These data will enable the development of dynamic models to ensure the sustainability of the reservoir, optimisation of a heating, cooling, and heat storage strategy, and applicability across a wider area of both the campus and the city of Leeds.

The in-situ testing phase drew to a close in summer 2024. The next step is to design and construct a new energy centre. Currently, most buildings on the University of Leeds campus are fed by a steam-based heat network that is shared with an adjacent hospital. The plan is to use geothermal heat in a hybrid system with air source heat pumps, to take the university engineering buildings and an adjacent student residence off this legacy steam network and connect them to the stand-alone energy centre. High-temperature heat pumps will be required to meet space heating delivery temperatures, as priority has been given to decarbonisation of supply as the most cost-effective way to reduce emissions in the short term.

Partnerships

Throughout this project, the Geosolutions Leeds team has engaged with both the University Sustainability Team, who were tasked with progressing the University Climate Plan, and the Facilities Directorate, who have responsibility for implementing the new heating systems. This partnership has reduced risks for the commercial project and developed a synergy with the core remit of the university: student education and research. Data from subsurface instrumentation will be combined with monitoring of the mechanical engineering heat system to deliver a living lab, with applications for both student teaching and academic research projects.

More widely, Geosolutions Leeds has partnered with Leeds City Council and the Department for Business, Energy & Industrial Strategy (BEIS, which recently split to form the Departments for Energy Security and Net Zero, DESNeZ; Business and Trade, DBT; and Science, Innovation and Technology, DSIT), to investigate more far-reaching opportunities from geothermal energy in the Leeds City urban environment.

Leeds is included in a UK Government pilot scheme that aims to identify low-cost, low-carbon heat networks (DESNeZ & BEIS, 2022), which may be supported by geothermal energy. Inclusion in the pilot led to two on-going policy projects funded by Research England, which combine interdisciplinary expertise across geoscience, engineering, and social sciences to develop policy frameworks for geothermal uptake in the urban environment.

Shallow geothermal schemes are being developed by other organisations such as the British Geological Survey, Keyworth, and TU Delft, Netherlands. Such schemes provide an emerging and exciting role for universities and non-governmental organisations to lead the way by delivering projects that range in scale from pilot studies to full-scale heating systems, with embedded living labs for teaching and wider public engagement. Real-time open-access data feeds from instruments within boreholes can drive innovation in this growing sector. Tangible progress on campus – evidenced by activity visible to students and employees alike – can simultaneously de-risk shallow geothermal energy systems and accelerate their wider adoption in the UK and globally.

Acknowledgements

Geosolutions Leeds thanks the University of Leeds for investment from the £174 million Climate Plan. We thank Dr Frin Bale, Dr Arka Sarkar, Dr David Barns, Nick Shaw, and Joe Kelly for their contributions to this work.

Prof Dave Healy

Geosolutions Leeds, University of Leeds

Dr Emma Bramham

School of Earth & Environment, University of Leeds

Prof Fleur Loveridge

School of Civil Engineering, University of Leeds

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