Thermogeological Assessments
Igne’s thermogeological assessments evaluate ground conditions for geothermal systems, ensuring accurate feasibility, efficient design, and long-term performance.
Open Loop Geothermal Drilling
Open loop geothermal systems offer one of the most efficient and sustainable ways to heat and cool buildings using the natural warmth of groundwater.
About
Open Loop Systems
Unlike traditional heating, open loop systems tap into aquifers or underground water sources, transferring heat via ground source heat pumps before re-injecting the water back underground.
At Igne, we specialise in the complete delivery of open loop geothermal systems, from investigation and test pumping through to drilling, construction and reinjection well commissioning.
The explanation
What is Geothermal Energy & How do Open Loop Systems Harness it?
Geothermal energy is the heat stored beneath our feet, constantly replenished by the Earth’s core and radioactive decay within rocks.
In open loop systems, this energy is accessed by abstracting naturally warm groundwater from boreholes. The heat is extracted using a ground source heat pump and the cooled water is then returned to the same aquifer through a separate reinjection borehole.
The key to success lies in the drilling. The boreholes must be located, designed and constructed to suit the geological, hydrological and thermal conditions of the site. That’s where Igne’s drilling and ground characterisation expertise makes the difference.
The process
How Geothermal Boreholes are Drilled & Constructed
Drilling geothermal boreholes for open loop systems requires deep knowledge of subsurface conditions. Igne carries out:
- Detailed thermogeological and hydrogeological assessments
- Test pumping and flow rate verification
- Drilling of abstraction and reinjection boreholes
- Installation of casing, screens, filter pack and headworks
- Pumping tests and system balancing
Abstraction wells are typically between 50 and 400 metres deep, depending on the aquifer’s depth and yield. Reinjection wells must be located at sufficient distance to prevent thermal short-circuiting and ensure long-term system efficiency.
Our drilling teams operate across a wide range of geological conditions, from chalk and limestone to sandstone and mixed glacial deposits. We understand how to manage artesian pressures, sediment build-up, groundwater chemistry and challenging access constraints.
The application
Using Geothermal Energy for Heating & Cooling
Open loop systems can both heat and cool buildings. In winter, the system extracts warmth from the ground. In summer, it reverses, sending excess building heat into the cooler ground.
This makes it ideal for:
- Commercial offices and mixed-use buildings
- Data centres with high cooling demands
- Hospitals and care facilities
- Public buildings, museums and archives
- Agricultural and horticultural operations
- District heating applications
At Igne, we’ve supported projects where open loop systems provide not only heating and cooling, but also process water and comfort conditioning for sensitive environments.
Sustainability
Why Open Loop Geothermal is a Sustainable Solution
Open loop systems are classed as a renewable energy source. They use the constant, natural temperature of the Earth to provide low-carbon heating and cooling. Because the water is re-injected back into the ground with only a small temperature change, there is minimal environmental impact.
Igne works to ensure that all systems are environmentally compliant, with full engagement with the Environment Agency or SEPA for abstraction and discharge licensing. Our designs prioritise thermal sustainability, hydraulic balance, and system efficiency from day one.
Understanding the Benefits & Considerations
Advantages:
- Highly efficient energy transfer
- Minimal land use
- Reduced carbon emissions
- Long operational life
- Low running costs
- Suitable for high-demand buildings
Challenges:
- Requires access to a reliable aquifer
- Higher upfront cost than traditional systems
- Requires abstraction/discharge licensing
- System design must account for reinjection spacing and thermal plumes
Igne supports clients throughout the lifecycle, helping you navigate regulatory approvals, design optimisations and technical delivery.
Ground Source Heat Pumps
Open Loop Systems & Ground Source Heat Pumps
Ground source heat pumps (GSHPs) are the interface between the borehole and the building. In open loop systems, they extract heat from the groundwater and elevate it to a usable temperature. Because the source temperature is stable year-round, GSHPs connected to open loop systems offer better efficiency than air source alternatives.
Igne collaborates with heat pump manufacturers and M&E consultants to ensure your boreholes are matched precisely to the system specifications.
minewater geothermal
What About Minewater Geothermal & District Heating?
Open loop principles are also applied in minewater geothermal systems, where naturally heated water trapped in abandoned mine workings is used as a heat source. Igne is at the forefront of this emerging field, with successful experience in drilling for minewater abstraction and reinjection.
In district heating, open loop geothermal offers scalable, decentralised heating for entire housing estates, campuses or industrial parks. Igne’s deep drilling capability and design expertise ensures your system is futureproofed, balanced, and resilient.
FAQ
Fequently Asked Questions about Open Loop Geothermal
- How far apart should abstraction and reinjection boreholes be?
This depends on the flow rate and aquifer properties. Typically, a minimum of 50 to 100 metres is used to prevent thermal interference.
- Is planning permission needed?
Usually, yes. In addition, you will require an abstraction licence and possibly a discharge permit. Igne helps manage the full permitting process.
- Can I use an existing water well for geothermal?
Sometimes, but it must be assessed for flow rate, yield and temperature stability. We can evaluate and adapt existing wells for geothermal use.
- What kind of buildings suit open loop systems?
Any building with high or continuous heating/cooling demand, especially where space is limited, benefits from open loop geothermal.
- Can the same borehole be used for abstraction and reinjection?
No. Separate boreholes are always required to maintain system efficiency and comply with environmental regulations.
- Why partner with Igne for open loop geothermal drilling?
We’re not just drillers, we’re geothermal system enablers. Igne combines deep technical knowledge with decades of specialist drilling experience to deliver reliable, high-performance open loop systems.
The Next Step
From initial feasibility through to final commissioning, our team supports your success every step of the way.
We understand the science, the regulations, the risks and the realities. Whether you’re heating a single facility or building a multi-borehole energy centre, we deliver performance from the ground up.
From tight urban sites to high-yield aquifers, Igne brings the drilling precision, environmental expertise and geothermal know-how you need to make open loop energy work for your project.
Get in touch with our team today to explore your site’s potential and unlock a future of clean, efficient heating and cooling.
Open Loop Geothermal Drilling
Igne delivers open loop geothermal systems that extract and return groundwater for heating and cooling, combining hydrogeological insight with drilling expertise.
Closed Loop Geothermal Drilling
Igne installs closed loop geothermal systems to deliver efficient, low-carbon heating and cooling without groundwater abstraction.
Minewater Geothermal Boreholes
Igne taps into the heat of flooded coal mines with specialist minewater geothermal boreholes, transforming industrial legacy into low-carbon energy for the future.