Energy Geostructures

Soil mechanics laboratory

The application of environmentally friendly technologies that exploit renewable energy sources is key to follow international agreements and directives for the development of carbon neutral buildings and infrastractures. Energy geostructures are an innovative, multifunctionaltechnology that can be used to address the aforementioned challenge. By coupling the role of the ground structures with that of the geothermal heat exchangers, energy geostructures such as so-called energy piles, energy walls and energy tunnels can serve as structural supports as well as heating and cooling elements for buildings and infrastructures.
The analysis and design of energy geostructures requires the integrated knowledge of various, multidisciplinary aspects in the broad field of engineering. The reason for this is because energy geostructures are subjected to the unprecedented combined action of both thermal and mechanical loads, which govern their energy, geotechnical and structural response via multiphysical interaction with the subsurface.
Typical questions that arise in this framework are as follows: What multiphysical phenomena are associated with the geothermal and structural support operations of energy geostructures? How should energy geostructures be analysed and designed from an energy, geotechnical and structural point of view? What will be the behaviour and performance of energy geostructures over time?
The research we perform at the LMS is centred on, without being limited to, the understanding and solution of these questions and problems. The basis of our work consists of observing, measuring, understanding and predicting how energy geostructures behave from a multiphysical perspective. Our goal is to ensure an optimal energy, geotechnical and structural performance of this technology. As a practical application, our work provides answers to actual questions of practitioners and contributes to the dissemination of the energy geostructure technology.

Research Group for Energy Geostructures:

Professors

Scientific assistants

PhD students

Current Research Projects:

Energy piles are an innovative and environmental friendly way of using renewable energy by combining geothermal heat exchange and structural foundation support. As a result of their unique roles, they are exposed to daily and seasonal temperature variations during their lifetime. Temperatures in the pile and in the surrounding soil fluctuate during the day in between operation and stoppage times resulting in short term temperature changes. Furthermore, there is a seasonal increase in temperatures after episodes of heat injection during summer followed by seasonal temperature reductions during heat extraction in winter. These temperature changes may cause axial displacements, additional axial stresses and changes in the shaft resistance with a daily and seasonal cyclic nature along their lengths. Yet, the primary role of energy piles which is the structural support, should not be jeopardized by the effects of these cyclic temperature changes. The main objectives of this work are from a fundamental perspective to understand the long-term behaviour of energy pile groups subjected to cyclic thermo-mechanical load, for which very limited knowledge remains available to date. The response of soils and soil-concrete interfaces to extensive applied thermal cycles still remains a major challenge and may contribute to the development of reliable, long-term predictions of the behaviour and performance of energy pile groups. From a practical perspective, the current interest in the energy geostructure technology requires the development of simplified, yet reliable analysis and design tools.



Involved persons: Prof. Dr. Lyesse Laloui, Dr. Melis Sutman, Elena Ravera

Sponsors:

Energy piles are one of the innovative and environmental-friendly technologies where piles that are already required for structural support are used for exploiting the near surface geothermal energy for efficient heating and cooling of buildings, with the inclusion of circulation pipes. The dual nature of energy piles eliminates the additional drilling costs compared to traditional boreholes. However, it also leads to unprecedented challenges related to thermally induced effects on pile and soil behaviour, as well as structure-pile-soil interaction. Up to date, the extent of these effects has not been fully understood to this date, which results in uneconomical design of such foundations, preventing their wider use. Currently, there is a lack of rational and practical tools for evaluating the interactions and couplings that occur in a group of energy piles with a slab lying on the soil, which contribute to the response of the foundation.


Involved persons: Prof. Dr. Lyesse LalouiCristiano Garbellini 

Sponsors:

Thermo-active diaphragm walls, also known as energy walls (EWs), are geotechnical structures typically used for multi-floored basements, cut-and-cover tunnels and underground car parks. The thermal activation of walls is made by inserting pipes attached to the reinforcing cage. Such civil structures usually present the top part of the wall exposed to the soil on one side and to the air void on the other side, while the bottom part is embedded in the soil on both sides. Due to the large surface exposed to the soil, these structures show a great potential for geothermal activation. EWs represent a modern and innovative solution to provide heating/cooling to buildings.

This research project aims at tackling energy walls from either a thermal and a mechanical point of view. The goals are to understand thermal performance and propose design guidelines, as well as quantify thermally-induced mechanical effects and propose a design methodology. This project is developed in the framework of the Marie-Curie Innovative Training Network project TERRE and accounts for the collaboration with the industrial partner Nobatek (France).

An in-situ, thermo-mechanical, testing campaign is being performed at one of the under construction stations of CEVA railway (Geneva). The station name is Lancy-Bachet and it is equipped with energy walls and slabs. The goals of such experimental campaign are to understand the thermal potential of the installation, to quantify thermally-induced mechanical actions on the wall structure and to define future scenarios for geothermal exploitation of this thermo-active underground train station. This project is developed in collaboration with Services Industriels de Genève and BG Consulting Engineers.


To former projects and publications

Publications

Books:

publication thumbnail

Analysis and Design of Energy Geostructures,1st Edition: Theoretical Essentials and Practical Application

Lyesse Laloui; Rotta Loria

Analysis and Design of Energy Geostructures gathers in a unified framework the theoretical and experimental competence available on energy geostructures: innovative multifunctional earth-contact structures that can provide renewable energy supply and structural support to any built environment. The book covers the broad, interdisciplinary and integrated knowledge required to address the analysis and design of energy geostructures from energy, geotechnical and structural perspectives.


Academic Press

1st November 2019

Hardcover ISBN: 9780128206232

  

More publications:

2020

A.F.R. Loria, J.V.C. Oltra, L. Laloui, Computers and Geotechnics 120, 103410.

  • Hydrothermal interactions in energy walls

J. Zannin, A. Ferrari, M. Pousse, L. Laloui, Underground Space.

A.F.R. Loria, M. Bocco, C. Garbellini, A. Muttoni, L. Laloui, Geomechanics for Energy and the Environment 21, 100153, DOI: 10.1016/j.gete.2019.100153.

M. Sutman, G. Speranza, A. Ferrari, P. Larrey-Lassalle, L. Laloui, Renewable Energy 146, 1177-1191, DOI: 10.1016/j.renene.2019.07.035.

C. Garbellini, L. Laloui,  Journal of Geotechnical and Geoenvironmental Engineering, DOI: 10.1061/9780784482780.005.

Elena Ravera, Melis Sutman,  Lyesse Laloui, Journal of Geotechnical and Geoenvironmental Engineering, doi.org/10.1061/(ASCE)GT.1943-5606.0002258

2019

C. Garbellini, L. Laloui,Géotechnique, 1-12, DOI: 10.1680/jgeot.19.p.208

Elena Ravera, Melis Sutman,  Lyesse Laloui, Computers and Geotechnics, doi.org/10.1016/j.compgeo.2019.103294

Benoît Cousin, Alessandro F.Rotta Loria, Andrew Bourget, Fabrice Rognon, Lyesse Laloui, Tunnelling and Underground Space Technology DOI: 10.1016/j.tust.2019.102997,  2019

Media:

2019-2020

Tech – Transfer

While shallow geothermal energy represents one of the most dynamic growing industries in the renewable energy market, especially in Switzerland (world leader in terms of density of installations), ensuring the optimised lifetime of those systems in their real operating conditions remains a challenge. The GeoBrain tool uses innovative Machine Learning techniques to supervise and optimise the performance of those systems during their operation and ensure both their energy efficiency and sustainability.
 

ENERDRAPE

We developed the first geo-thermal panel that efficiently captures both geothermal and waster heat in existing indoor environments located in the underground and transfers it for renewable heating and cooling to buildings. Unlike conventional geothermal systems, the technology developed relies on a non-invasive installation, allowing the use of shallow geothermal energy in existing buildings. The modular geo-thermal panels are meant to be installed in existing underground indoor environments such as underground parking, underground transportation hubs, tunnels etc. With the modular geo-thermal panels we facilitate access to renewable shallow geothermal energy to existing buildings while reducing capital investments, operation costs and CO2 emissions.