Deep Geothermal Energy project

The term geothermal means “heat from the Earth”. Geothermal energy comes from the natural heat stored beneath the Earth’s surface. The Earth’s crust contains a virtually limitless amount of thermal energy which is being continuously replenished by heat conduction from the mantle below it. The temperature at the base of the crust is about 1000°C and, as a result, the deeper you go underground, the hotter it gets, on average at a rate of 25°C per km.

Geothermal is normally associated with volcanic regions such as Iceland and New Zealand, as this heat is more easily accessible being closer to the surface. In volcanic areas and places where the Earth's plates meet, the underground heat is much stronger. Just a couple of kilometres below the surface, temperatures can reach several hundred degrees. In some locations this heat creates natural pockets of hot water or steam underground. By drilling into these areas, we can bring the heat to the surface and use it to generate electricity and provide heating.

But geothermal resources exist away from volcanic regions too. Most countries around the world can access geothermal, albeit at lower temperatures, and around 90 countries are now harnessing it for heat or power. Some are drilling much deeper wells in non-volcanic areas to access the temperatures they need because they recognise the environmental benefits of the technology.

Geothermal is a clean, sustainable, renewable, low carbon energy source that has a very small surface footprint and minimal environmental impact. It can be harnessed from just a few metres below the surface or from deep underground and used for heating, cooling, and electricity generation. It is already present across the UK and can be accessed using different technologies to provide low-carbon heat and power.

You can find more information about geothermal energy on the British Geological Survey website and through GeoScience Limited.

Watch the British Geological Survey’s Geothermal Energy Lesson Introductory video.

The climate emergency, along with concerns over energy security and rising fuel costs, makes it clear that our energy systems need a complete transformation. We need energy that is locally produced, affordable, and built to last. At the same time, urgent action is required to tackle climate change—meaning we can no longer rely on fossil fuels.

By 2050, the UK aims to reach Net Zero greenhouse gas emissions. To achieve this, both electricity and heating must be as close to zero emissions as possible. Geothermal energy has the potential to provide renewable electricity and heat 24/7.

Geothermal energy has, but is not limited to, the following benefits:

• Renewable and sustainable: Geothermal energy comes from the Earth’s natural heat, which is constantly replenished, making it a long-term energy source.
• Low carbon and environmentally friendly: Unlike fossil fuels, geothermal energy produces little to no greenhouse gas emissions, helping to combat climate change.
• A constant supply: Unlike solar and wind, geothermal energy isn’t affected by the weather. It provides a constant, 24/7 energy supply.
  Improves national energy security: By using geothermal energy, countries can rely less on imported oil and gas, improving energy security.
• Cost-effective in the long run: While initial setup costs can be high, geothermal energy has low operating costs and provides stable energy prices over time.
  Efficient for heating and cooling: Geothermal systems can heat homes, businesses, and even entire cities efficiently. They can also be used for cooling in summer.
• Small land footprint: Unlike large-scale wind or solar farms, geothermal plants take up very little space to generate power, making them suitable for urban and rural areas.
• Supports economic growth: Investing in geothermal energy provides a multitude of jobs in the green energy sector.

Geothermal energy works by using the natural heat from beneath the Earth’s surface. This heat is captured by drilling wells into the ground to access hot water or steam. The steam is then used to power a plant that generates electricity, or the hot water can be used directly for heating buildings, greenhouses, or even pools. The process is sustainable and produces very little pollution, making it a clean source of energy.

Geothermal heat is the natural heat found within the Earth. This heat exists in various forms and is found beneath the ground almost everywhere. However, it’s unevenly distributed. In places like Iceland and New Zealand, where volcanic activity is common, geothermal heat is close to the surface and can even be seen in hot pools and geysers. In the UK, we need to drill much deeper—usually thousands of metres— to reach the temperatures required for power production or direct heat supply.

Today, geothermal energy can be used for heat and power generation.

Geothermal heat

To meet our commitment to Net Zero by 2050 and the UK's target of a 81% emissions reduction by 2035, we must decarbonise how we generate heat. Geothermal energy is a renewable and low carbon source of heat, which can be used to warm our buildings, workplaces, homes and leisure facilities. It can also be used in district heating systems, where hot water from the ground is circulated to heat multiple buildings in a community or city. Geothermal wells can also be used to store heat in the rocks below for extraction later.

Geothermal power

Geothermal can also be used to produce dispatchable, low carbon electricity. While heat can be extracted from almost anywhere, geothermal electricity generation needs specific geological conditions, which aren’t found everywhere. Geothermal energy can provide reliable, continuous electricity and can also be adjusted as needed, making it a valuable support for both the national grid and local distribution networks. This flexibility is becoming increasingly important as more solar and wind energy are added to the grid.

To access heat from below the ground, boreholes (called ‘wells’) are drilled to intersect permeable rocks at high temperatures. The water within the rocks is pumped to the surface and can be used directly for heating or to produce electricity. Once it has been cooled by the end-use, the water is injected back into the ground to be reheated by the hot rocks, ensuring the system remains sustainable.

Geothermal energy has, but is not limited to, the following benefits:

• Renewable and sustainable: Geothermal energy comes from the Earth’s natural heat, which is constantly replenished, making it a long-term energy source.
• Low carbon and environmentally friendly: Unlike fossil fuels, geothermal energy produces little to no greenhouse gas emissions, helping to combat climate change.
• A constant supply: Unlike solar and wind, geothermal energy isn’t affected by the weather. It provides a constant, 24/7 energy supply.
• Improves national energy security: By using geothermal energy, countries can rely less on imported oil and gas, improving energy security.
• Cost-effective in the long run: While initial setup costs can be high, geothermal energy has low operating costs and provides stable energy prices over time.
• Efficient for heating and cooling: Geothermal systems can heat homes, businesses, and even entire cities efficiently. They can also be used for cooling in summer.
• Small land footprint: Unlike large-scale wind or solar farms, geothermal plants take up very little space to generate power, making them suitable for urban and rural areas.
• Supports economic growth: Investing in geothermal energy provides a multitude of jobs in the green energy sector.

Yes, geothermal energy is renewable. It comes from the Earth's natural heat, which is constantly replenished from the core. As long as the Earth exists, this heat will continue to be available, making geothermal energy a sustainable and long-term energy source.

In contrast, fossil fuels like coal, oil, and natural gas are non-renewable. They take millions of years to form and are being depleted much faster than they can be replaced. When burned, fossil fuels release harmful greenhouse gases into the atmosphere, contributing to climate change and air pollution. Unlike geothermal energy, which is clean and virtually limitless, fossil fuels harm the environment and will eventually run out.

Geothermal energy offers a reliable and environmentally friendly alternative, helping to reduce our reliance on fossil fuels while providing a sustainable source of power for the future.

No it isn’t. The geothermal development project at York involves circulating water through naturally permeable rock or natural fractures. This is not the same process as fracking, which involves injecting large volumes of fluid with complex chemicals at high pressures to create new fractures in solid rock to extract oil or gas. Fracking also raises concerns about waste disposal and contamination.

In contrast, geothermal development uses naturally occurring water in existing fractures and, once the heat is extracted, the water is reinjected into the same formation. All activities are permitted through the Environment Agency.

Yes, geothermal energy is safe. The technology is well-established and carefully regulated to ensure that it has minimal environmental impact. The drilling process and heat extraction are carefully monitored to avoid any harm to the surrounding area. Additionally, unlike fossil fuels, geothermal energy produces very little pollution and carries no risk of explosions or spills. Overall, it is considered a reliable and safe energy source.

Natural seismicity occurs all over the world, all the time. It refers to ground movements caused by natural forces. These movements are sometimes referred to by different names, including earthquakes, earth tremors, earthquakes, and seismic events. For millions of years, the Earth's crust has been shifting, reshaping continents, and forming mountains and volcanoes. The most active areas are along tectonic plate boundaries, where plates collide, slide past each other, or move apart. However, faults exist in various shapes and sizes everywhere—even in places like York! As tectonic plates move, pressure builds up along faults of all sizes. When the stress becomes too great, the rock shifts, releasing energy in the form of a ‘seismic event’. They are usually very deep underground.

Seismic activity is only noticeable if the shock waves are strong enough to reach the surface. For any real damage to occur, the shaking must be powerful enough to move the ground forcefully. Smaller or deeper seismic events often lose their energy as it spreads through the surrounding rock, and may go completely unnoticed.

Explore more about seismicity

Induced seismic events are exactly the same as natural ones, except that the trigger for the movement is human activity, rather than a gradual build-up of geological pressure over time. Testing and developing geothermal reservoirs on York’s campus may cause minor seismic activity. Most of these small events will go unnoticed, though occasionally people might hear a faint rumble or feel a slight vibration. These events are not dangerous and pose no risk to buildings or infrastructure. A seismic monitoring system will be installed before drilling which will allow any vibration to be monitored.

There are several reasons why geothermal projects are not more widespread here:

High initial costs

Building the infrastructure needed to harness geothermal energy requires significant investment. These upfront costs can be prohibitive.

Regulatory challenges

The rules and regulations surrounding geothermal projects are not well-developed, making it difficult for developers to navigate. A lack of clear guidelines can create uncertainty around costs and project timelines, which many investors find risky.

Geographic limitations

Geothermal energy is highly dependent on location. To be effective, the heat source needs to be relatively close to the end user, especially for heating purposes, making it less versatile in areas where such resources are not easily accessible.

We are exploring geothermal energy as a way to reduce fossil fuel use on our campus and contribute to the City’s wider Net Zero goals. Our campus is located above a geothermal resource, which offers an opportunity to integrate cutting-edge research with practical solutions in response to the climate crisis.

A new Geothermal Project Board is being established, chaired by the Dean of Sciences, to manage and oversee its delivery.

The project is an important part of the University’s Sustainability Plan 2030, targeting a 78% reduction in fossil fuel consumption. By exploring this low-carbon energy source, the project hopes to lower the University’s carbon emissions and play a pivotal role in York’s broader efforts to achieve its climate change targets and will directly support the city’s ambitions to become a leader in sustainable living.

Early assessment has already taken place, focused on Campus East. The next steps include going through the planning process and obtaining the necessary approvals. Later in 2025, more geological surveys will be carried out to better understand the underground conditions. This includes a seismic survey, which involves placing thousands of sensors in the ground and using a special machine that vibrates the surface—helping to create a detailed 3D picture of the ground beneath our campus. If all goes to plan, initial groundwork could begin in 2026, with drilling anticipated in 2027.

The geothermal energy site will be located on the east side of Campus East (the exact location hasn't been chosen yet).

The drilling rig chosen will depend on availability when contracts are being issued, which will be after planning consent has been given. However, any rig capable of drilling to 5,000m will necessarily be large. We anticipate using a rig with a maximum mast height of 55m. The rig will not be a permanent structure and will only be on site during the drilling phase of the project (around 1 year).

The impact on the environment and local community is really important to us and is something we will be closely monitoring and keeping to a minimum. The drill rig’s mast will have lighting for health and safety reasons, and a red flashing light to warn of its presence to aircraft. The site will also be lit with working lights to allow 24/7 operation during drilling.

Some minor ground vibration is possible during drilling. However, it would be very localised and unlikely to be noticed outside the site boundary.

The site design and choice of drilling rig will take account of potential noise levels outside the site. A noise monitoring system will be put in place to ensure that any noise is kept within permitted levels.

The drilling rig will operate 24 hours a day but activity will be carefully planned to minimise any noise disturbance and keep within permitted limits.

No, there is no need to worry. Although the testing and development of geothermal reservoirs on York’s campus is likely to cause some seismicity, most induced events will be incredibly small and release very little energy. A full risk assessment will be carried out by experts to help guide the design of the project. Seismic activity will be closely monitored throughout, with operating conditions adjusted as needed to ensure safety and stability.

See geothermal energy FAQs for more information about seismicity.

The project is expected to begin generating heat by March 2028. Once operational, the initial focus will be supplying energy to the campus, with potential for wider use being explored depending on the system’s performance.

The footprint of a completed geothermal project is very small. We will share designs once they become available but it is envisaged that only a small number of surface enclosures and structures will remain after completion. Future phases may introduce additional equipment located at our Energy Centre or elsewhere on Campus.

There has been no new physical testing carried out. Initial studies used existing data from boreholes and historical coal mine exploration. Using this data has given us a good picture which will be refined through a new survey carried out in the second half of 2025.

The geothermal project is supported by a £35 million government-funded grant from the Public Sector Decarbonisation Scheme, run by the Department for Energy Security and Net Zero, and delivered by Salix Finance Ltd. The University of York is also contributing 12% of matched funding to the project.

The funding will be used to contribute to the following:

• Planning, design and construction of the geothermal wells system.
• Integration of the geothermal system as the heat source into our existing district heat network.
• Adding a range of existing buildings to our District Heat network.
• Carrying out insulation and lighting improvements across a range of building.
• Decommissioning a number of gas powered boilers which can be permanently removed.

We envisage creating opportunities for site visits when the site is under construction.

Early assessment has already taken place, focused on Campus East. Next steps include going through the planning process and obtaining the necessary approvals. Later in 2025, more geological surveys will be carried out to better understand the underground conditions. This includes a seismic survey, which involves placing thousands of sensors in the ground and using a special machine that vibrates the surface - helping to create a detailed 3D picture of the ground beneath our campus. If all goes to plan, initial groundwork could begin in 2026, with drilling anticipated in 2027.

Keep an eye out on this web page for project developments.