As part of our series celebrating the women researchers behind HOCLOOP, we sat down with Virginie Harcouët-Menou, senior researcher specializing in geothermal energy at VITO, to hear about her work and how the project is helping bring geothermal energy to new regions in Europe. Virginie leads a technical work package focused on potential future demonstrations of the HOCLOOP technology and its broader applicability.
What is your and your organization’s role within the HOCLOOP project?
I coordinate VITO’s activities in the HOCLOOP project. My role includes leading a technical work package focused on laying the groundwork for potential future demonstration projects and assessing how broadly the HOCLOOP technology can be applied.
At VITO, we carry out simulation work, pre-feasibility studies, and preliminary designs of the HOCLOOP concept for the Balmatt industrial site in Mol (Belgium), where we have our own geothermal plant. This plant, connected to a local heating network, also serves as a test site for new geothermal applications.
We’re also using VITO’s strong expertise in heat exchange and heat-to-power technologies to help optimize the heat transfer within the deep coaxial closed-loop system.
What do you find most interesting about working on HOCLOOP?
I really appreciate the collaborative EU framework and the opportunity to work with geothermal and technology experts from across Europe. It’s exciting to contribute to solutions that can be applied in areas where conventional geothermal technologies struggle—either because of geological limitations or social acceptance challenges.
I also value that the project supports wider uptake of geothermal energy in Europe while aiming to reduce its environmental footprint. Finally, I’m a strong supporter of transferring technologies and knowledge from the oil and gas sector to geothermal, and HOCLOOP provides a great platform for that.
What unique challenges does HOCLOOP address in geothermal energy, and how does our approach overcome them?
Conventional systems rely on deep, naturally permeable aquifers to extract heat. HOCLOOP uses a closed-loop, deep coaxial well design, which eliminates the need for fluid circulation underground. This reduces geological risk and avoids common technical problems like corrosion and scaling. It also lowers the environmental impact.
In countries like Belgium, where there are few deep permeable aquifers, closed-loop systems like HOCLOOP could be key to making geothermal energy more widely available.
How could HOCLOOP’s closed-loop system contribute to the global transition to cleaner, renewable energy?
It helps unlock geothermal potential in regions that have so far been seen as unsuitable. It’s a strong alternative to enhanced geothermal systems, especially for heating applications in areas where conventional methods don’t work.
Because it’s a closed system, there’s no risk of fluid contamination or loss, which makes it more environmentally friendly as well.
What makes HOCLOOP’s approach different from traditional geothermal methods? Why is that important?
HOCLOOP allows for the use of alternative working fluids—not just water. These engineered fluids, such as CO₂ or advanced smart fluids, can improve heat extraction and reduce technical issues like corrosion.
We’re comparing water and CO₂ within the project to find the best fit for different subsurface and surface conditions. This flexibility makes the technology more adaptable and efficient.
How do HOCLOOP’s innovations align with Europe’s sustainability goals?
Because HOCLOOP can work in areas without naturally permeable underground reservoirs, it helps make geothermal energy accessible in more places across Europe. That supports regional energy resilience and plays a part in ensuring a fair transition to carbon neutrality.
