The overall aim of DeepU is to create a deep (>4 km), closed-loop, vitrified, waterproof, non-cracked U-tube heat exchanger by combining laser and cryogenic gas into a single technological drilling solution. The developed fast and effective drilling technology is tested at the laboratory scale in different rock types to verify its capacity to liquefy and vitrify the rocks, leaving the borehole ready for heat exchange immediately after drilling. The demonstration at the laboratory scale produces the information required for assessing the technological, environmental and economic sustainability and defining the potential and commercial attractiveness of the proposed solution.