Geothermal drilling at Stormont gets the ‘green’ light!  

Conor Lydon, lead GeoEnergy NI contractor from specialist consulting and engineering firm Tetra Tech, discusses the next phase of the GeoEnergy NI project.  

The GeoEnergy NI project has reached another important milestone as Belfast City Council approves plans to explore shallow geothermal potential through exploratory drilling and testing on the grounds of Stormont Estate. 

This represents an exciting stage of the overall GeoEnergy NI demonstrator project which is examining both shallow and deep geothermal potential in two locations in Northern Ireland.  

We all know the importance of decarbonising our economy and tackling the heat sector is a particular challenge in doing so. Geothermal energy can play an important role in how we decarbonise our energy sector in pursuit of net zero carbon targets by 2050 and is a relatively untapped resource here compared to other countries. That is why the GeoEnergy NI project is exploring and showcasing Northern Ireland’s geothermal potential – literally helping us ‘discover the heat beneath our feet’.  

At Stormont, the feasibility study is examining shallow geothermal potential and its possible future application to provide sustainable low carbon, renewable heating and cooling systems for a number of pre-identified buildings on the Estate. It is hoped the project will result in a future geothermal heat network that will replace the current fossil fuel heating systems at some of the buildings on the Estate.  This location has been chosen because it sits on top of a productive aquifer with good shallow geothermal potential for both closed-loop and open-loop geothermal systems. The same aquifer underlies Belfast, Lisburn, Antrim and other large towns in Northern Ireland and we are confident that the results of this study will both increase our understanding of this aquifer and help inform future geothermal projects in this wider area.

A geothermal drilling rig set-up to show how it will look on site.

A geothermal drilling rig set-up to show how it will look on site.


With planning permission granted, the drilling and testing phase of the Stormont feasibility study can now progress. We hope to commence the study within the next month and it is estimated that this phase will take approximately 6 months. It will involve the drilling and testing of five boreholes, four of which will be hydrogeological boreholes around 250 metres deep, and one borehole will be cored to 500 metres depth. A series of tests and analyses including down-hole geophysics will then be carried out on the boreholes to identify the optimum numbers and depths of boreholes required to deliver low carbon and renewable heat. The boreholes will be predominately located in private areas near government buildings west of Stoney Road and the area around Dundonald House, Castle Buildings and Stormont Castle and therefore will present minimal disruption to users of the Estate.  

We are very excited to reach this important stage and we have a detailed plan in place to manage the various studies and we will work closely with local stakeholders and users of the Estate to minimise any disruption during this time.  Our very popular interactive GeoEnergy Discovery Centre will be based on the Estate during much of the drilling phase and we hope to create a viewing area at one borehole location so visitors can see the geothermal demonstrator project in action. Together they will help explain the importance and potential of geothermal energy in Northern Ireland and inform people about how we access it. Keep up to date on activity at the Stormont Estate by following our social media channels!