Geological maps (Fig.1) and building energy load profile were developed as databases. Thermal and physical properties on rocks and unconsolidated materials from the test sites have been measured complementing literature data and previous analysis. A new method to measure these parameters on gravel has been developed. A methodology to create €/kW maps (Fig.2) compares the innovative borehole heat exchangers to the traditional ones at municipal level.
Helix type ground source heat exchangers (GSHE) (Fig.3) were developed with diameters in the range of 350-400 mm, i.e. smaller than the state of art, typically around 500 mm. The purpose is to facilitate drilling at larger depths which are today 3-5 meters. In combination with an evolved auger based dry drilling method these were installed in 4 demonstration sites at depths ranging from 8 to 14 meters.
Co-axial heat exchangers (Fig.4) out of stainless steel with an enlarged diameter and an insulated internal tube were developed. A drilling machine was built to pile these GSHE's faster and deeper into the soil. Different design improvements of these co-axial GSHE's were simulated. The most optimal GSHE's have been installed with the new drilling machine in record time in the pilot test field. In the demonstration cases, basic feasibility of the methodology was proven in certain types of soil and the speed of installation confirmed. Important learnings were made during the drilling in these sites for future large scale exploitation. All demonstration sites demonstrated important gains of thermal energy exchange when compared to the state of art. These factors combined lead to the targeted cost reduction in unconsolidated soils where borehole stabilization is needed. A patent request has been submitted.
A new HP with CO2 as refrigerant for high temperature terminals (Fig.5) has been designed and installed in the Technical Museum Nicola Tesla in Zagreb. This two-stage heat pump avoids the replacement of the terminals at high temperature in building refurbishments, in particular in historical ones. A patent request is pending.
The development of software and modelling tools, including the sizing of ground source heat exchangers and the selection of heat pumps, has been completed and is feeding into the "Decision support system" (Figs. 6&7).
This DSS enables the end-users to choose the best geothermal technology for their case. The DSS, with an engine that estimates the building's energy consumption, characterizes the different shallow geothermal plant combinations taking also into account the climatic and soil conditions. This tool, freely usable on the web site, is to be an accelerator for technical offices, architects, ESCO’s, building owners and investors to introduce the novel technologies. Also non-expert users can use a simplified version to assess the feasibility and economic returns.
6 real and 10 virtual demonstration cases where the technological innovations and tools were installed and applied provided learnings and data for future exploitations.
A detailed legislative and regulatory analysis of each case study site (Fig.8) was made and a comparative study of the current regulatory conditions for GSHP system completed. An environmental impact assessment demonstrated the low impact of the new technologies. A LCA for each site compared the project technologies against other GSHP technologies. The co-axial heat exchanger design was introduced in the European Standard (CEN-TC 451-WG2) currently being drafted.
An action plan supporting the market introduction of Cheap-GSHPs technologies and exploiting the project results has been developed.
Project website flyer, brochure, 2 videos, newsletters, fact sheets were realised. Social media, congresses, conferences, etc., and fairs were used for dissemination. A technical brochure and a technical training manual in 8 languages, and a technical handbook in 3 languages focused on historical buildings, were realised as basic material for the national workshops. They are freely available in the web site.
