The future disruptive technology envisioned in “Deep U-tube heat exchanger breakthrough: combining laser and cryogenics gas for geothermal energy exploitation (DeepU)” Project is expected to revolutionize the deep geothermal energy sector. The ultimate goal is to create a deep (>4 km) closed-loop connection in the shape of a U-tube exchanger, combining laser and cryogenic gas in a single technological drilling solution. Specific temperature control analysis and innovative laser lenses able to convey the heat and to sustain multilateral drilling will be developed alongside the U-tube creation, guaranteeing liquefaction and vitrification of the rocks from ground surface to greater depths. Then, a U-tube system ready to exchange heat with the underground becomes the main tool to exploit or store geothermal energy, meeting energy needs in power and thermal energy production. Hence, DeepU project targets a novel and ambitious science-to technology breakthrough in the field of geothermal exploitation. The overall aim is the creation in laboratory of a vitrified, waterproof, non-cracked U-tube exchanger for different kind of rocks. This will be achieved by a laser drill head combined with special drill strings sustaining the coupled action of laser and cryogenic gas, responsible for melting, evaporating and cooling even the hardest rocks. Then, (i) the physical-thermal phenomena affecting the rocks, (ii) an evaluation of the legislative aspects and environmental standard related to the innovation proposed, (iii) the modelling of the DeepU geothermal exploitation potential considering some virtual case studies will be assessed. The high-risk innovation proposed has the potential to make geothermal energy systems accessible anywhere in a targeted and demand-oriented manner, offering a complimentary approach and an alternative solution to traditional energy storage and production, decentralizing the power supply also in areas where this is currently deemed uneconomic.

The solutions to apply the shallow geothermy will be different in function of the building type, the climate and the geological conditions of the underground, the geothermal system (drilling methodology, GSHE, grouting,..). The main objectives will be : - identify and where missing develop building blocks solutions in drilling (machines and methods), GSHE types, heat pumps and other renewable energy/storage technologies, heating and cooling terminals with the focus on every type of built environment, civil and historical; - generate and demonstrate the most easy to install and cost-effective geothermal energy solutions using and improving existing and new tools. In the area of shallow geothermy of further innovations are needed to provide a pan – European solution base for all the parameter combinations. More efficient borehole heat exchangers and lower cost drilling methodologies/machines adapted to the built environment will be realised as improvement or innovation related to the previous projects. This approach will bring to a easy applicability in the building refurbishment presenting different constrains, to reduce the overall drilling cost in the given geological conditions, will to avoid replacement of heating terminals constructing modular high temperature heat pumps and hence to reduce the deep retrofit costs. The association with tools (DSS, APPs, etc.) will enable to find the best solution for each combination of building type/climate/geology y. Moreover, the design tools will reduce overall engineering costs, avoid design mistakes and form the basis for a major dissemination effort. Application tools will help the users for different practical aspects. Finally to help knowledge dissemination and formations of the future experts a pan – European network of centres of excellence based on past expertise but complemented with the new developments should become instrumental in breaking down the barriers in shallow geothermal energy in building renovation.