Systematical, experimental investigations on LiMgZ (Z= P, As, Sb) wide band gap semiconductors

This work reports on the experimental investigation of the wide band gap compounds LiMgZ (Z = P, As, Sb), which are promising candidates for opto-electronics and anode materials for Lithium batteries. The compounds crystallize in the cubic (C1_b) MgAgAs structure (space group F-43m). The polycrystalline samples were synthesized by solid state reaction methods. X-ray and neutron diffraction measurements show a homogeneous, single-phased samples. The electronic properties were studied using the direct current (DC) method. Additionally UV-VIS diffuse reflectance spectra were recorded in order to investigate the band gap nature. The measurements show that all compounds exhibit semiconducting behavior with direct band gaps of 1.0 eV to 2.3 eV depending on the Z element. A decrease of the peak widths in the static 7Li nuclear magnetic resonance (NMR) spectra with increasing temperature was observed, which can directly be related to an increase of Li ion mobility.Comment: 8 page

Synthesis and Structural Characterisation of Neutral Pentacoordinate Silicon(iv) Complexes with a Tridentate Dianionic N,N,S Chelate Ligand

A series of novel neutral pentacoordinate silicon(iv) complexes with SiClS

Pastoralist Way of Life Under Threat: : Assessing the vulnerability risks faced by pastoralist communities as well as their potential to adapt to climate change in the Horn of Africa

The aim of the thesis was to examine the main causes of pastoral  vulnerability to climate change as well as assess their adaptive capacity to withstand future climate disturbances in the Horn of Africa. By studying two of the most iconic pastoralists’ communities in Africa – the Somali and the Massai’s in Kenya, the study intended to use the communities as representative to the overall pastoralist’s situation in the Horn of Africa. The study used the 2007 IPCC Vulnerability Assessment framework that entails exposure, sensitivity and adaptive capacity to climate change as a guiding instrument to comprehend the complexities of the pastoral livelihood. The participants of the study included pastoralists, officials from the government, NGO’s and research Institutions. Major findings of this study were, in addition to climate manifesting in destructive forms, pastoralism faces political marginalization, shrinking pastureland, sprawling urbanization, exponential growth of population and conflicts. Despite the challenges, the study also finds strong adaptive capacity by the pastoralists. Adaptation strategies include traditional methods of rangeland management and migration. The study also shows new modern methods adaptation to climate mainly instigated by the pastoralists with assistance from external actors, these methods include; Ecological Based Adaptation and technology driven approaches as well as a mixture of agriculture and pastoralism – agro-pastoralism. It was also found that the two communities studied face different climate challenges and adaptation approaches

Application of a method for the sustainable planning and management of ground source heat pump systems in an urban environment, considering the effects of reciprocal thermal interference

The “Most Easy, Efficient and Low Cost Geothermal Systems for Retrofitting Civil and Historical Buildings” (GEO4CIVHIC) project aims to accelerate the deployment of shallow geothermal systems for heating and cooling purposes when retrofitting existing and historical buildings. Analyzing the implementation process of borehole heat exchangers (BHEs), allows the understanding of how to promote the long-term sustainability of shallow geothermal energy systems. The thermal interference between BHE systems represents a problem, especially due to the increasing deployment of this technology and its spread in densely built-up areas. The main goal of this paper is to propose a conceptual model and to apply this to different case studies. The methodology includes phases to adopt an integrated approach for preventing long term thermal interference in neighbouring borehole heat exchangers, by providing management strategies and technical suggestions for design and operation. The method developed follows the following steps: 1) literature review to determine what are the main drivers for thermal interference between shallow geothermal systems, in the context of the GEO4CIVHIC project case study sites; 2) to create a conceptual model to limit thermal interference at both design and operational phases; 3) to apply the developed method to real and virtual case studies in countries with different regulatory frameworks and to test its main strengths and weaknesses. The application of this conceptual model to specific case studies provides evidence of critical planning and operational characteristics of GSHP systems and allows the identification of measures to mitigate impacts of thermal interference to be identified

New tools to support the designing of efficient and reliable ground source heat exchangers: The Cheap-GSHPs databases and maps

The final aim of the EU funded Cheap-GSHPs project is to reduce the total installation cost of closed-loop shallow geothermal systems. As part of the project a Decision Support System (DSS) has been developed and released on the web, in order to support the design of new closed-loop geo-exchange systems. The Cheap-GSHP project addresses all the aspects involved in planning and dimensioning a new borefield and therefore, the DSS is composed of several databases and tools that collect and elaborate the preliminary data and information that are necessary during the sizing phase, such as the geological and drilling aspects as well as the heating and cooling building demand. This paper briefly introduces the content of the databases and the mapping methodology developed for the Cheap-GSHPs DSS. All these researches are further deepen in the EU project GEO4CIVHIC, with a special attention to the application of shallow geothermal systems for building conditioning to historical buildings

Soil thermal behavior in different moisture condition: an overview of ITER project from laboratory to field test monitoring

The thermal properties of soils can be considered one of the most important parameters for many engineering projects designing. In detail, the thermal conductivity plays a fundamental role when dimensioning ground heat exchangers, especially very shallow geothermal (VGS) systems, interesting the first 2 m of depth from the ground level. However, the determination of heat transfer in soils is difficult to estimate, because depends on several factors, including, among others, particle size, density, water content, mineralogy composition, ground temperature, organic matter. The performance of a VSG system, as horizontal collectors or special forms, is strongly correlated to the kind of sediment at disposal and suddenly decreases in case of dry-unsaturated conditions in the surrounding soil. Therefore, a better knowledge of the relationship between thermal conductivity and water content is required for understanding the VSG systems behavior in saturated and unsaturated conditions. Key challenge of ITER Project, funded by European Union, is to understand how to enhance the heat transfer of the sediments surrounding the pipes, taking into account the interactions between the soil, the horizontal heat exchangers and the surrounding environment. In order to obtain reliable data for modelling, an interdisciplinary approach is used. In laboratory the physical-thermal properties of more than 15 soil mixtures, consisting in (i) natural soil, (ii) pure sand and (iii) mixtures of pure sand and clay additives, have been tested under different water content percentages and different consolidation degree. Then the same parameters are monitored in the project case study, in Eltersdorf, (Germany), where five helix collectors are installed in horizontal trenches filled in with five different mixtures already tested in laboratory. In addition, a monitoring system allows to record every 15 minutes, by means of devoted sensors, values related to ground temperature (undisturbed, inside and outside each helix), fluid temperature and flow running in the collectors, volumetric water content at 20 and 60 cm depth. Moreover, a meteorological station provides climatic data acquisition as rainfall, wind speed, relative humidity and air temperature. The main results achieved until now are useful for future modeling because shed new light (i) on the differences between data collected in laboratory and in the field and (ii) on the influence of the technical solution adopted in situ to fill in the trenches, able to create a non-homogeneous distribution of the soil bodies around the helix.Abstract 5th International Conference Novel Methods for Subsurface Characterization and Monitoring: From Theory to Practice, NovCare 2017, Dresden, Germany, 06-09.06.201

Shallow Geothermal Energy for existing buildings – overview and status of project GEO4CIVHIC

A major obstacle to decarbonisation in the building sector is the comparably low share of new construction, and the specific problems encountered when supplying heat and/or cold from renewable energies (RES) to existing and in particular older/historical, buildings. Without a solution to the problem of RES in refurbishment, however, the decarbonisation of the building stock will simply take too long. Shallow geothermal technologies have contributed substantially to decarbonisation in new construction. However, for a wider deployment in existing buildings, particularly in historical ones, the technologies need further development and innovative ideas must be tested and brought to the market. Within the EU-funded project GEO4CIVHIC a survey was done to identify and understand all other possible barriers to install Borehole Heat Exchangers (BHE) in existing building environment, be they technical or socio-economic, and the project partners work on suggestions for suitable solutions. Based upon this survey, the further work addressed two principal barriers, which are construction of ground heat exchangers under constrained site conditions, and adaption of heat pumps and other components to older heating/cooling systems. A specific emphasis is given to historic buildings, i.e. those dating from before the mid of the 20th century, including listed buildings, where the constraints are even more severe. Development work is done to provide technical solutions for overcoming these barriers, e.g. with novel drilling tools and enhanced heat pumps. Several demonstration cases are undertaken to test the solutions found (4 real sites in Belgium, Ireland, Italy and Malta, and 12 “virtual” sites, where theoretical case studies for renovation with borehole heat exchangers are performed on real, existing buildings). The COVID 19 pandemic hampered drastically the project timeline, resulting in delays of more than one and a half years. At the time of writing this abstract, two real demonstration cases are finished and started operation (Belgium and Italy), while the other two are scheduled to be operational by July 2022. This paper gives an overview of the project, the rationale behind it, and the findings of the initial survey of barriers. It presents the experiences with less invasive, less costly and quicker drilling and installation methods for borehole heat exchangers (BHE), as developed within the project and tested both in the real demonstration sites and in dedicated test fields at some of the project partners. First results of monitoring and results from the "virtual" sites are presented. Other papers within the project also submitted to EGC 2022 address specific aspect in more detail, and are referenced in this overview paper