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Optimisation of geothermal resources in urban areas
Get PDFL'abstract è presente nell'allegato / the abstract is in the attachmen
Sistema energetico contro terra e metodo per scambiare calore tramite tale sistema (Geothermskin)
Get PDFrOGER: A method for determining the geothermal potential in urban areas
Get PDFShallow geothermal energy is increasingly adopted for heating and cooling purposes because of the short payback time of initial installation investments. As a result, a relevant concentration of Ground Heat Exchangers is being experienced in urban areas. Planning issues thus arise to manage interferences and optimize the use of underground heat resources without depletion, harm to the environment nor efficiency losses on heat pumps or plant oversizing. This study provides a rational approach to optimise geothermal resources based on the use of Geographic Information Systems and transient 3D Thermo-Hydro numerical models. An optimised semianalytical formula for the assessment of Borehole Heat Exchangers geothermal potential in hydrodynamic conditions is developed through a parametric numerical study. The long-term performances of BHE subjected to groundwater velocity in the range of 0 to 1 m/day were analysed with multiple aquifer thermal parameters. This analytical expression allows a fast and accurate assessment of the potential even in large areas without leading to excessively conservative evaluations. This may serve designers in the preliminary sizing of installations and city planners in the development of appropriate policies for the promotion and management of shallow geothermal resources. An example of the application to the central district of the city of Turin (Italy) is also shown
Development and testing of a novel geothermal wall system
Get PDFShallow geothermal energy systems have the potential to contribute to the decarbonization of heating and cooling demands
of buildings. These systems typically present drawbacks as high initial investments and occupancy of wide areas. In this
study, a novel energy wall system is proposed to overcome the limitations of conventional geothermal applications in urban
areas. The system is characterized by ease of installation, low initial costs and applicability to existing buildings undergoing
energy retrofitting. The paper illustrates the implementation of the prototype of such a system to an existing structure
in Torino (Italy). An overview of the components is given together with the interpretation of an illustrative test carried out
in heating mode. The data from both heating and cooling experimental campaigns allow us to highlight the potential of
the proposed technology. The results suggest that an average thermal power of about 17 W per unit area can be exchanged
with the ground in heating mode, while an average of 68 W per unit area is exchanged in cooling operations. The negligible
impact on the stress–strain state of the wall and the surrounding soil thermal and hygrometric regime is also testified by the
results collected. These aspects are associated with a reduced probability of interferences with other installations in highly
urbanized areas, easiness of installation and affordable cost
Development and testing of an innovative energy wall system in Torino (Italy)
Get PDFShallow geothermal energy (SGE) is increasingly being regarded as a valuable solution for space heating and conditioning because of high efficiency, diffuse availability and low environmental impact. Significant growth in the number of installations is envisaged as a result of energy policies and European Directives. Indeed, the obligations in the construction sector about the share of energy supply from renewable sources is increasingly pushing the design of new and renovated buildings. On the one hand shallow geothermal energy is suitable as a sustainable and distributed energy source. On the other hand, significant installation costs related to drilling of traditional installations represent an hampering factor. Thermally activating geostructures such as piles, diaphragm wall, tunnels and anchors can allow to include these costs in the construction of the structural elements. Moreover, a large availability of operational surface is represented by new and/or existing building heritage in urban areas as most of them have underground levels that can be equipped with heat exchangers.
This contribution introduces a novel modular very shallow geothermal exchanger as part of a Heating, Ventilation and Air Conditioning (HVAC) system. The system concept allows its application not only to new structures and buildings but also to existing ones. While the low depths interested may penalize the heat exchange rates, on the contrary, extremely low installation costs make the cost-benefit ratio of this new technology extremely interesting and promising.
A first prototype consisting of three modules was designed by the authors and installed in an office building in Torino (Italy). External deployment of pipes to the basement wall in two different arrangements was realized in order to test system efficiency. Due to the experimental nature of
the tests, a large number of sensors were placed to monitor the additional stresses and strains on the wall and the thermal regime of the partially saturated ground volume involved in heat exchange.
Preliminary thermal performance tests were performed together with numerical modelling reinterpretation. On the basis of the first tests and interpretation carried out, it was demonstrated that remarkable heat exchange rates of up to 20 and 27 W/m2 could be injected/extracted from the ground in summer and winter respectively. Furthermore, the monitoring records suggest that extremely low affection of ground thermal status is operated by the system with respect to analogous non thermo-active walls. This evidence is extremely promising in the perspective of wide and dense diffusion of this new shallow geothermal energy system in urban areas where thermal interferences should be limited or avoided
Testing of a Novel Energy Wall System in Torino
No full textThe need of renewable energy sources is increasingly pushing the design of new and renovated buildings as a result of compelling regulation in the construction sector. On the one hand shallow geothermal energy is suitable as a sustainable and distributed energy source. On the other hand, significant installation cost related to drilling of traditional installations represent a ham- pering factor. Energy geostructures as piles, diaphragm wall, tunnels and anchors include these costs in the construction of primary or secondary struc- tural elements. Major part of building heritage in urban areas present under- ground levels that can be equipped with heat exchangers.
This paper introduces the concept of a modular very shallow geothermal exchanger as part of a Heating, Ventilation and Air Conditioning (HVAC) system. The system is conceived to externally equip with heat exchangers the earth-contact area of underground walls that are generally widely available in residential and commercial buildings. An experimental site consisting of three modules of the above mentioned technology was designed by the authors and installed in an office building in Torino (Italy). Pipes were placed externally to the basement wall in two different arrangements. A large number of sensors were placed to monitor the additional stresses and strains on the wall and the thermal regime of the partly saturated ground volume involved in heat exchange. A comprehensive view of the main components of the prototype and the related monitoring system are given together with preliminary thermal performance results
Energy Tunnels for Deicing of a Bridge Deck in Alpine Region
Get PDFRoads and paved surfaces in cold climate are exposed to the formation of ice and snow deposition. These phenomena are related to high risks for vehicles and road users due to reduced friction. Deicing techniques are up to now mainly based on chemicals, especially salt. These substances induce chemical decay of concrete infrastructure elements and environmental harm. In order to overcome these drawbacks, the use of embedded hydraulic pipes with a hot carrier fluid below the paved surfaces has been proposed in last decades. This circuit can be part of a Ground Source Heat Pump (GSHP) system. Despite a number of examples of this technology have been proposed, very few of them included the application of energy tunnels. This paper focuses on the thermal activation of a tunnel lining in relation to an application for bridge deck deicing. A theoretical case study along an Alpine road has been considered as representative of a common situation of alternated bridges and tunnels. The numerical results show that the thermal activation of the tunnel lining can provide enough heat to keep the paved surface unfrozen even in protracted periods of low external temperatures
Geothermal potential of the NE extension Warsaw (Poland) metro tunnels
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Geothermal potential of tunnel infrastructures – development of tools at the city-scale of Basel, Switzerland
Get PDFThis work presents preliminary evaluation elements for geothermal potential assessment and thermal influences
of planned tunnel infrastructures for the urban agglomeration of Basel (Switzerland). In dependence of the
tunnel type (motorway or railway) as well as its location related to the geological and hydrogeological settings
different solutions for shallow geothermal energy systems (SGE) are investigated. ‘Passive’ and ‘active’ SGE have
been evaluated, including heat-exchanging segments installed in tunnel lining structures and thermal exploitation
of water circulating in culvert systems.
First results suggest that thermal activation of a planned railway tunnel is most efficient where it is located
within groundwater-saturated zones of the unconsolidated rock deposits. In summer, thermal power of 3.7 and
1.4MW can be exchanged from two 736 and 284 m-long tunnel sections, respectively. Accordingly, in standard
heat pump operating conditions a thermal energy of 10.4 and 3.8 GWh can be delivered for ‘cooling’. In winter,
thermal power of 1.9 and 0.7MW can be exchanged, respectively, and a thermal energy of 5.2 and 1.9 GWh can
be delivered for ‘heating’.
SGE within culverts reveals to be favorable in heating mode only and for sections where the motorway tunnel
runs perpendicular to the regional groundwater flow field and where ambient groundwater temperatures are
high. Under such conditions along a 320 m-long tunnel section thermal power of up to 0.4MW can be provided
in summer and 0.8MW in winter, respectively, and thermal energy of 1.1 GWh in summer and 2.1 GWh in
winter, can be delivered
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