Researchers working at the UK Geoenergy Observatory in Cheshire have shown that distributed acoustic sensing (DAS) has the potential to detect subsurface temperature change during geothermal experiments. The research, which was conducted by scientists from the University of Leeds as part of the NERC-funded SmartRes project (grant number NE/X005496/1), used a high-resolution, fibre-optic DAS sensing system installed in boreholes at the Cheshire Observatory.

During two days of surveying in June 2025, over 1000 seismic impacts were made at the ground surface using a controlled seismic energy source. The energy generated by these impacts — essentially sound waves propagating through the ground — was recorded by DAS in the 5Ìýkm fibre-optic network installed in the observatory 100Ìým-deep boreholes. Strong seismic arrivals were visible at all depths, validating the survey set-up and providing an encouraging seismic baseline for future thermal testing. During subsequent tests, researchers will measure whether any variations in the arrival time of sound waves can be detected, as this could indicate where heat is moving in the subsurface.

DAS sensing has proven its credentials in many subsurface settings, but is yet to be widely developed for monitoring shallow geothermal operations. Initial analysis of the data recorded in Cheshire confirms the potential of this technology to provide high-resolution monitoring of the aquifer. This will contribute to wider understanding of geothermal processes and help with the design of efficient heating systems that use geothermal energy. The measurements are one of several datasets that provide a baseline for the acoustic, electrical and thermal properties of the Sherwood Sandstone Group.

It been very exciting to undertake the first DAS survey at the Cheshire Observatory. Fibre-optic technologies like DAS are giving us unprecedented insight into many subsurface processes. For geothermal applications, the insight is really timely: we need to demonstrate to prospective stakeholders that we understand how subsurface properties will evolve under various heating scenarios.

Prof Adam Booth, associate professor of applied geophysics at the University of Leeds.

The UK Geoenergy Observatories have been designed to advance our understanding of energy storage in shallow geological systems. This cutting-edge research undertaken by the team at the University of Leeds is an excellent demonstration of the potential for these facilities to deliver on that promise.

Dr Mike Spence, science and operations lead at BGS for the Cheshire Observatory.

The UK Geoenergy Observatories are a network of custom-built facilities operated by BGS that were designed to enable research in shallow geothermal energy and underground thermal energy storage. The facilities are available to the UK science community for research, innovation and training activities.

For further information, including details on how to access the sites, please visit .

More information

Every city has a story hidden beneath its surface, shaped not just by people but by ancient landscapes and geological forces too. Under our streets, buildings and parks lies an unseen subsurface that has a major influence on how our cities function, grow and adapt.

On World Cities Day, we are highlighting urban geoscience — the study of the ground beneath our towns and cities — and why understanding this hidden world is essential for building safer and more resilient urban environments.

What is urban geoscience?

Urban geoscience helps us to understand the geology and both the natural (for example, ancient river valleys and glacial deposits) and human-made features (for example, old mine workings) beneath our cities. This knowledge helps planners and decision makers to more safely utilise the subsurface — for example, for water, energy and — while avoiding any challenges caused by the complex and sometimes unpredictable geology beneath our feet. As cities develop, urban geoscience offers the insight needed to mitigate risk and plan with confidence.

Examples of how British cities are influenced by geology

There are countless ways in which geology influences the evolution of our towns and cities. Here are four examples from around Britain.

London: shrink–swell clay and the changing climate

Much of London is built on the . This unit has clay-rich deposits that expand when wet and shrinks when dry, a phenomenon known as shrink–swell. This movement can cause cracks in buildings, damage roads and disrupt underground utilities.

With climate change, hotter and drier summers followed by intense rainfall are worsening the effects of shrink–swell. The 51ÁÔÆæ GeoClimate dataset models how these risks may change over time, showing areas most likely to experience future subsidence. Such modelling can allow for preventative or mitigative steps to be put in place to alleviate the effects of the hazard on property and infrastructure.

Glasgow: mining and geothermal energy

Glasgow sits on the Carboniferous-aged and the coal mined from beneath the city powered its industrial growth. The old mine workings have left voids in the subsurface that can collapse and, if the collapse is close to the surface, cause subsidence. However, if potential issues are known, preventative measures can be put in place to reduce the risk.

The 51ÁÔÆæ Mining Hazard dataset helps identify areas where past underground mining might pose a risk, supporting safer planning and development. Old mine workings are also providing new opportunities as warm water in flooded mine workings can be used to supply low-carbon heat and hot water to offices and homes, turning a legacy of coal mining into a .

Truro: radon risk from granite

Truro in Cornwall is a city built on Carboniferous to Permian-aged granite intrusions, which were formed when molten rock slowly cooled deep underground. Granite contains small amounts of the radioactive element uranium, which naturally breaks down (via a series of intermediate, unstable elements) over millions of years to produce radioactive .

In enclosed spaces like homes and offices, radon may build up to levels that pose a health risk, with prolonged exposure to elevated levels of radon increasing the risk of lung cancer. For most people, the risk of developing lung cancer from exposure to radon remains low. However, the advises you to test your home if you live or work in a radon affected area and there are several methods of reducing high radon levels in buildings.

Cornwall is just one of several areas around the UK were radon gas needs to be considered. The 51ÁÔÆæ/UKHSA Radon Potential dataset shows where elevated radon levels are most likely, showing where testing and mitigation are needed around the UK to make homes safer.

Cardiff: complex ground and urban redevelopment

The combination of river sands and gravels, glacial deposits and rocks of the Triassic-aged beneath the city of Cardiff affect drainage, groundwater flow and how easily the ground can be built on. As the city continues to grow and redevelop, understanding the subsurface is key for managing groundwater, avoiding subsidence and planning safe infrastructure.

The 51ÁÔÆæ 3D urban geology model for Cardiff helps to visualise the deposits beneath the city, while the 51ÁÔÆæ Civils dataset provides practical information on ground stability, excavation difficulty and chemical risks to construction materials.

Every city around the world is shaped or influenced to some degree by the rocks that lie beneath its foundations, a changing coastline along its shore or the risks posed by geohazards such as earthquakes, landslides or radon. As cities continue to grow and face new challenges, from a need to become climate resilient to an increasingly crowded subsurface, understanding the ground beneath them becomes more important than ever.

Urban geoscience connects the past with the present, helping us build cities that are not only functional but also resilient.

Understanding how heat moves within the subsurface is important for the development of geothermal energy, including ground-source heat pumps. Determining which geological areas are suitable for their installation is vital. For the first time, scientists at BGS have used time-series data at the , which is run by BGS, to look at long-term trends for subsurface heat.

The geo-observatory monitors 62 boreholes, 49 of which were observed every 30 minutes for four years between 2014 to 2018. The analysed data found previously undetected, localised cracks in the geology in the south of the city, where the subsurface is largely clay at that depth. These newly discovered cracks, which can be caused by plant roots, provide pathways that act as recharge routes underneath the south of Cardiff, allowing rain water to enter and be conveyed to the groundwater below.

While a ground-source heat pump can be highly efficient, installing one in one of these newly discovered areas of cracks could lead to performance issues. Specifically, the constant influx of cooler groundwater could hinder the heat pump’s ability to extract heat effectively and the system could potentially affect the groundwater flow and quality.

For geothermal developers looking to install shallow ground-source heat pumps underneath the capital, it’s important that this new data is carefully considered. The research shows that installing a ground-source heat pump in Cardiff deeper than 8 m will help to maximise the technology efficiency. 

Using time-system data for the first time in Cardiff has provided vital information to further our understanding of what lies beneath our feet. The discovery of geological recharge pockets in an area where they were previously not thought to occur is an important consideration for future infrastructure projects. It essential that geothermal developers take this research into account before installing a shallow ground-source heat pump, to ensure it runs as effectively as possible and is not impacted by recharge.

Ashley Patton, engineering geologist at BGS and research lead.

For more information about the Cardiff Urban Geo-Observatory please email 51ÁÔÆæ Cardiff (bgswales@bgs.ac.uk).

Geothermal technologies, which use heat from the ground, have the potential to decarbonise heating and cooling, playing a role in the energy transition to net zero emissions in the UK. The ability to identify which parts of the subsurface have the necessary conditions to realise this potential is an important first step.

51ÁÔÆæ has launched the , which provides national- to local-scale information on geothermal potential across shallow and deep technology options. It allows users to explore and assess the geothermal potential of an area and make more informed decisions. The platform draws together diverse information and synthesises it to deliver the information needed by heat policy, heat networks, national zoning model and planning specialists. The platform can be used by regulators, developers and researchers.

Included in the platform is an overview of geothermal energy potential for four geothermal technologies (Great Britain coverage):

• shallow, vertical closed-loop with ground-source heat pump
• shallow open-loop with ground-source heat pump
• deep, hot sedimentary aquifers (hydrothermal)
• deep, engineered geothermal systems in granites (petrothermal)

For instance, the platform highlights that closed-loop systems can technically be deployed almost anywhere across Great Britain (local planning and regulatory constraints apply). Up to 55Ìýper cent of the population has the potential to extract up to 15Ìý000ÌýkWh of thermal energy (the typical annual energy of a gas boiler), via a single, 150 m-deep, closed-loop system.

Towns, cities and industrial sites can be assessed for the potential to retrofit geothermal technology and new development zones can be quickly assessed for strategic use of geothermal energy from the start of the development or planning cycle. For example, planned development for the Liverpool–Manchester–Leeds–Sheffield growth corridor can take advantage of multiple geothermal energy technologies.

The openly available platform features a user-friendly map explorer and a data access page that also enables you to view more detailed geoscientific information from several organisations, including BGS, the Mining Remediation Authority, environmental agencies, the North Sea Transition Authority and the UK Onshore Geophysical Library.

For the first time, the UK Geothermal Platform makes a large volume of national-scale geothermal data and information available and digitally accessible.

It supports a wide range of users in understanding at high level the potential for a range of geothermal energy options, supporting decarbonisation of heating and energy security.

Dr Alison Monaghan, head of geothermal at BGS.

The first release of the UK Geothermal Platform has been funded by the UK Government’s Department for Energy Security and Net Zero (DESNZ) through the Net Zero Innovation Portfolio. It is delivered and maintained by BGS.

Decision makers across the UK are today considering new research that reveals areas of the subsurface with outstanding geological potential to boost economic growth. They will help unlock an estimated and energy-transition technologies. The findings identify eight ‘geological super regions’. These are the areas with a subsurface composition that is ‘just right’ to potentially host multiple energy-transition technologies, which will help deliver the UK net zero aspirations as presented in the Government Clean Power Action Plan.

Whilst other parts of the UK benefit from geology well suited to certain net zero technologies, such as shallow geothermal installations or critical minerals occurrences, these geological super regions contain subsurface formations and conditions that are favourable to multiple different technologies within a relatively small area. The geological super regions that could play a pivotal role in the application of sustainable energy production and decarbonisation are:

• Northern Ireland
• the Scottish Central Belt
• north-east England
• north-west England
• the South Yorkshire and Humber region
• the East Midlands and East Anglia
• South Wales
• south-west England

The subsurface has a vital role to play in the energy transition, acting as an enabler and helping deliver economic growth by providing:

• a sustainable heat source for geothermal energy
• geological formations for secure storage of energy and carbon dioxide (CO₂)
• rocks containing important resources for mineral extraction
• suitable geological foundation conditions for onshore and offshore wind power infrastructure projects

The benefits of a stronger renewable sector for UK residents could include improved access to secure, affordable, sustainable energy and subsurface raw materials, contributing to economic prosperity and net zero targets for the UK.

The findings provide crucial insights for decision makers looking to target further research and maximise return on investment in the pursuit of a reliable and sustainable energy future for the UK. Whilst these eight regions display many of the right geological ingredients, further investigation will be required to fully establish each region true potential, ensure safe deployment of each technology, and understand any environmental impact.

The data underpinning this research has been shaped by our current understanding of the subsurface. In some cases, this data is weighted towards existing project development and there is also a correlation with UK industrial clusters. A few parts of the country, such as the north of Scotland and parts of Wales, have been less extensively surveyed and further research is required in order to fully assess their potential.

Matching subsurface technologies and favourable geological conditions is essential for identifying regions with opportunities for investment, providing a roadmap for the UK to reach net zero emissions and ensuring a reliable and sustainable clean energy future. These findings provide a clear and deployable roadmap for decision makers to direct resources to the areas where they can deliver the greatest impact and support the through renewable energy by 2030.

Much of the UK subsurface can support at least one of the energy-transition technologies assessed, but what makes these geological super regions stand out is their versatility and potential to host multiple net zero technologies.

Work still lies ahead to accurately map these subsurface regions and BGS is uniquely positioned to undertake such investigations due to our national remit, recognised geological expertise and national geological data holdings.

Michelle Bentham, BGS Chief Scientist for decarbonisation and resource management.

Geology is a complex and diverse natural resource. Its variable characteristics have the potential to support multiple net zero technologies. Strategic planning and careful management will be vital to ensure safe and secure deployment, especially in locations where technologies may co-exist, whilst also protecting the surrounding environment for future generations.

Regional summaries and maps

Distribution maps by energy transition technology

Notes to editors

As a geologist and geophysicist, my research focuses on understanding whether Scotland radiothermal granites could help unlock a new source of sustainable geothermal energy for the UK. In summer 2024, I conducted a three-week field campaign to study the potential for geothermal energy in the Cairngorms with a team of other geoscientists. 

The Cairngorms: more than just mountains

Geothermal energy is often associated with places like Iceland or other volcanic hot spots, but Scotland ancient granites may also be able to supply sustainable heat. The Cairngorm Pluton, part of the East Grampians Batholith, is one of the UK highest heat-producing granites, with intriguing geothermal potential. My work combines geophysical surveying with laboratory experiments to explore this potential, whilst addressing uncertainties about the region geology. 

Using magnetotellurics to explore below the surface

Magnetotellurics (MT) is a deep-sounding geophysical technique that uses the Earth natural electromagnetic field to produce images of the conductivity properties of the rocks in the subsurface. It can also be used to map features like fluid pathways and fractures located several kilometres below the surface. These pathways are critical for geothermal energy because they act as conduits for the fluids transporting heat. 

During my fieldwork in the Cairngorms, we set up 24 MT stations using instruments on loan from the NERC Geophysical Equipment Facility across the region. These were deployed by a team comprising myself and: 

• 51ÁÔÆæ staff members 

• Heriot-Watt University staff 

• other postgraduate researchers 

• a Cairngorm ranger 

• a University of St Andrews undergraduate student 

The MT equipment uses two types of sensor:  (1) non-polarisable electrodes, which measure the ground electric field, and (2) induction coil magnetometers, which measure changes in the magnetic field. The setup at each site required us to bury the sensors to protect them from the fierce weather conditions.

The data collected from the sensors will allow us to produce images of the Earth electrical resistivity below the surface using a mathematical process called data inversion. Ideally, the images could show zones with lower electrical conductivity, where fractures in the rocks are present within the resistive granite. These could be potential geothermal reservoirs from which heat can be extracted.

Fieldwork challenges and discoveries

Conducting fieldwork in the beautiful but bleak Cairngorms is both rewarding and challenging. With no roads in much of the area, we had to carry our equipment, including a 20 kg battery, over many kilometres of hiking paths and sometimes beyond any trails. Navigating deep bogs, steep bouldery terrain and elevations of up to 1250 m while braving sudden weather changes was an adventure in itself. In June 2024 we had seven consecutive days of snow fall on the mountain!

In addition to the MT fieldwork, I surveyed the geological structures and outcrops and collected samples for later laboratory analysis. One memorable moment came when we discovered a zone of extensive hydrothermal alteration of the granite near Stob Coire an t-Sneachda. This is possible evidence of hot fluids chemically changing the rock many millions of years ago. This alteration is significant because it could enhance the porosity and permeability of the rock, which are crucial factors for geothermal reservoirs.

Why it matters

Geothermal energy offers a constant, low-carbon source of heat, making it a promising candidate for the UK renewable energy mix. Additionally, its small land footprint and minimal surface infrastructure requirements mean it can provide sustainable energy with reduced visual impact, preserving the natural landscape. My research aims to de-risk geothermal exploration in Scotland, providing the scientific basis for future projects that could benefit communities and combat climate change.

Next steps

With my first year of fieldwork complete, I’m back in the laboratory, analysing samples and processing the MT data to build a three-dimensional resistivity map of the Cairngorm Pluton. Combining geophysical models with laboratory-based analyses will bring us closer to understanding the geothermal potential of this region of Scotland.

Thanks

Thanks go to Nathaniel Forbes Inskip and Andreas Busch from Heriot-Watt University and Juliane Huebert from BGS.

All images kindly reproduced with permission. For enquiries about the images within this article, please contact the copyright team (IPR@bgs.ac.uk).

The rocks of the were deposited between 200 and 250 million years ago in the Triassic Period, at the same time as the first dinosaurs walked on land. This rock underlies much of central and southern England as well as several offshore areas, and is the bedrock on which many urban areas and their infrastructure are built.

Core scanning and analysis of a 240 m-long and 100 mm-diameter rock core by the Core Scanning Facility (CSF) at BGS headquarters in Keyworth, Nottinghamshire, will further our geological understanding of the rocks beneath our feet. It will provide new data that feeds into more robust geological models, which will highlight the effectiveness and environmental sustainability of ground-source heat pump technology. This will help to accelerate the energy transition away from fossil fuels, scientists say .

The core was collected and scanned as part of ongoing installation work for a geothermal ground-source heat pump system at the Keyworth site.

Core scanning is a relatively rapid and non-destructive method to gather a large amount of data to maximise the value of core drilled and, together with conventional core characterisation practices, increases our understanding of rock properties and behaviour that will inform subsurface processes.

Magret Damaschke, CSF manager at BGS.

Geothermal energy naturally occurs under the ground and is available to us 24/7 across the UK, but this energy is not currently sufficiently utilised to meet our net zero 2050 targets.

As part of our ongoing geothermal heat pump project, a detailed characterisation of the Mercia Mudstone has been undertaken, using advanced technologies including core scanning and thermal conductivity analysis; this data will provide us with a better understanding of what lies beneath our feet and how much renewable heat could be sustainably extracted.

This information is especially valuable as the Mercia Mudstone can be found underlying much of the UK, so the data gathered will be relevant to a large number of planned geothermal installations and other geoenergy technologies, and could hold the secrets to accelerating the green energy transition.

David Boon, BGS Senior Geothermal Geologist.

Work began on BGS £1.8 million, Government-funded heat decarbonisation project in February 2024. Installation of the ground-source heat pump system, involving 28 boreholes and five heat pumps, continues on-site and is due to be completed in early 2025.

When finished, the project will provide up to 300 kW of clean heating power to two existing buildings and will constitute a ‘living laboratory’, with state-of-the-art fibre-optic sensors deployed in the heat extraction boreholes and buildings. The technology will provide data in real time to help increase the public understanding of ground-source heat pumps and how they can be an effective solution for heating both new and existing buildings in the UK.

The results of the core analysis will be released via the Natural Environmental Research Council (NERC)Environmental Data Service National Geoscience Data Centre. More information is available via .

The project is majority funded by NERC with a further contribution from the Government Public Sector Decarbonisation Scheme (PSDS). PSDS is run by the Department for Energy Security & Net Zero and is delivered by Salix Finance. The heat pump project is being delivered with partners Cenergist, Welltherm Drilling Ltd and Pick Everard.

Further information

For more information, please contact 51ÁÔÆæ press (bgspress@bgs.ac.uk) or call 07790 607 010.

51ÁÔÆæ, the UK provider of geoscientific data and expertise, officially opened the UK Geoenergy Observatory in Cheshire on Tuesday 8 October 2024. The groundbreaking £8.3 million facility delivers unique research infrastructure that will help the UK explore the potential of geothermal energy to decarbonise the energy used for heating its homes and businesses, which is a critical step in tackling climate change.

The underground facility, located in Thornton Science Park, provides researchers and industry with access to at-scale experimental infrastructure. The facilities are needed to optimise and de-risk a range of subsurface energy storage systems, which will help to develop technologies related to utilising geothermal energy.

Heating and cooling of homes and businesses account for over a quarter of the UK carbon dioxide (CO₂) emissions. Geothermal energy has the potential to help the UK meet its net zero objectives as an ultra-low-carbon source of energy.

Geothermal energy already delivers environmental, economic and technical advantages in countries with similar geology to the UK, such as the Netherlands, Belgium and Germany. The UK currently uses only a small fraction of its geothermal heat resources, accounting for approximately 0.3 per cent of the UK annual heat demand. The Cheshire Observatory offers unparalleled opportunities to explore the potential of geothermal energy, including other relevant technologies such as hydrogen storage and CO₂ storage. The facility boasts a unique research infrastructure, providing access to:

• boreholes that can be used to circulate heated and cooled water
• opportunities to investigate the effect of thermal energy storage and extraction
• access to samples of groundwater and drill core for off-site laboratory investigations
• arrays of sensors capable of monitoring changes in subsurface pressure, temperature, water chemistry and physical and mechanical rock properties
• data freely available on the UK Geoenergy Observatories website 

We are thrilled to unveil the UK Geoenergy Observatory in Cheshire, a world-class science and research facility for scientists and innovators working in geothermal heat and subsurface energy storage. The observatory will foster collaboration among researchers and industry experts, enabling us to address key challenges related to decarbonisation and generate the robust scientific evidence needed to inform future energy strategies and regulatory frameworks.

The observatory will be available to the whole of the UK science community for research, innovation and training activities. We thank our partners for their invaluable support in bringing this project to fruition and look forward to the innovative research that will emerge from the observatory.

Dr Karen Hanghøj, director, BGS.

NERC is dedicated to supporting research that not only advances scientific knowledge but also delivers tangible benefits to society. The UK Geoenergy Observatory in Cheshire embodies this mission and we look forward to the valuable insights and discoveries it will yield in the years to come to support the UK journey of decarbonisation.

Louise Heathwaite, executive chair, Natural Environment Research Council (NERC).

Over the last seven years, we have proudly worked alongside BGS on their vision to create the UK Geoenergy Observatory. As their lead designer, our team has delivered remarkable feats of engineering, including the design of 100Ìým boreholes that ensured advanced precision science and monitoring equipment that could reach unprecedented depths below the Earth’s surface.

This observatory not only supports a world-class geoenergy research site, but also plays a crucial role in advancing our efforts towards decarbonisation. We are excited to see the geoscientific discoveries and energy innovations that will emerge from this world-class facility to move the UK towards a low-carbon economy.

Dave Grove, director, Ramboll.

Contact

For more information, please contact contact the BGS Press Office (bgspress@bgs.ac.uk) or call 07790 607 010.