Qatar Foundation Annual Research Conference Proceedings Volume 2014 Issue 1

Karst is ubiquitous on the peninsula of Qatar, including depressions, sinkholes, and caves. Aerial reconnaissance indicates that the widespread depressions, sinkholes, and caves reveal NE-SW and NW-SE orientations, similar to the joint and fracture systems. Faulting and fractures play a major role in the development of karst, where fluids find pathways through limestone and dissolve the host rock. The resulting fissures may grow larger as more surface water is funneled through to form cavities or karst. Sinkholes may also form, when cavern roofs collapse, and it is this last characteristic that is of concern to rapidly growing metropolitan areas, that expand in heretofore unexplored regions. Qatar has seen a recent boom in construction, including the planning and development of complete new sub-sections of metropolitan areas. Before planning and construction can commence, the development areas need to be investigated to determine their suitability for the planned project. Of particular concern to construction projects are ubiquitous karst features that are prone to collapse, particularly when surface loading is increased due to construction. In this study, we present a spectral-based analysis to seismically detect the presence of karst-like subsurface void in Doha, Qatar. Seismic waves are well suited for karst detection and characterization. Voids represent high-contrast seismic objects that exhibit strong responses due to incident seismic waves. However, the complex geometry of karst, including shape and size, makes their imaging nontrivial. While karst detection can be reduced to the simple problem of detecting an anomaly, karst characterization can be complicated by the 3D nature of the problem of unknown scale, where irregular surfaces can generate diffracted waves of different kind. In our current project we use an innovative approach to detect and characterize subsurface voids by spectral seismic analysis. We devised an iterative approach to progress from symmetrically shaped subsurface voids with known geometry to more complex geometries and finally to realistic karst features. In the current paper, we present results from a seismic imaging experiment of a vertical water-collection shaft located on the campus of Qatar University. The experiment consisted of four seismic lines, including two geophone and two source lines, oriented in a rectangular geometry surrounding the water-collection shat. The seismic source was a 10 kg sledge hammer, while the geophones consisted of three-component 10 Hz sensors. Seismic source and geophone spacing was 0.5 m, while each line was 15.5 long. The water collection shaft had a diameter of 2.7 m and an approximate depth of 4 m. Seismic waves scattering off the shaft were visible in ambient noise records and in unprocessed data generated by the seismic source. We will present the results of our novel approach using spectral analysis of scattered seismic wave to determine the location and to estimate the volume and dimensions of the water-collection shaft.

Mid-infrared (MIR) spectroscopy is a versatile and important tool for the analytics of liquids. Conventional absorption spectroscopy is based on exact intensity measurements to reveal information about the measured components. Therefore, stable light sources are needed for the detection of weakly absorbing, i.e. diluted substances. Often the strong absorption of the solvent itself makes exact measurements even more difficult. Moreover, it limits traditional spectroscopies using thermal light sources to selected spectral regions and solvents. The development of commercial widely tunable quantum cascade lasers (QCLs) has opened up new possibilities in mid-infrared vibrational spectroscopy. QCLs were first demonstrated in 1994 [1] and offer orders of magnitude (~104) more power compared to thermal light sources. This facilitates the use of measurement cells with path lengths > 100 µm for transmission measurements - an important requirement for fast process analytical applications. For instance a strongly absorbing aqueous solution of the amino acid proline (OD > 3) could successfully be measured [2]. Despite their high optical power and compact rugged design, QCLs are often plagued by intensity fluctuations, which limit the achievable sensitivity in absorption measurements. Here, two spectroscopic methods based on QCLs are presented. Both make use of the total internal reflection and can be adapted for fast process applications like online monitoring of water quality. First an QCL-based version of the so called Fiber Evanescent Field Analysis (FEFA) [3] is demonstrated [4], a special ATR-technique, where the light is guided inside an optical fiber. Due to the good collimation of the radiation emitted by the laser coupling losses can minimized. This makes QCLs an ideal light source for the FEFA-spectroscopy. Shown are the application and the results of this technique to the online-detection of water contaminations with pesticides. The second method is a form of MIR refractometry also making use of the total internal reflection. Changes in the beam profile after the reflection are used to simultaneously determine the refractive index and the absorption of the analyte without the need for an absolute detection of the intensity. This makes the method immune against intensity fluctuations of the laser. The principle is demonstrated with measurement results for dichloromethane (DCM), which exhibits a single absorption band in the examined spectral region. The work was funded by the Fraunhofer program ATTRACT (Grant 692247) and the cooperation project IRLSENS (BMBF, FKZ 13N11034). References: [1] J. Faist, F. Capasso, D. L. Sivco, C. Sirtori, A. L. Hutchinson, A. Y. Cho; Science 264 (1994) 553 - 556 [2] S. Lüdeke, M. Pfeifer, P. Fischer; J. Am. Chem. Soc. 133 (2011) 5704 - 5707 [3] T. Beyer, P. Hahn, S. Hartwig, W. Konz, S. Scharring, A. Katzir, H. Steiner, M. Jakusch, M. Kraft, B. Mizaikoff; Sensors and Actuators B 90 (2003) 319-323 [4] A. Lambrecht, M. Pfeifer, W. Konz, J. Herbst, and F. Axtmann; Analyst 139 (2014) 2070 - 2078 [5] M. Pfeifer, A. Ruf, P. Fischer; Optics Express 21 (2013) 25643 - 25654

It is well known that for solar cell back contacts CdTe forms a Schottky barrier when it is contacted directly to a metal.Therefore an interlayer is needed to provide low ohmic contact resistance. Due to its strong p-type character, narrowing the Schottky barrier and therefore allowing holes to tunnel through, Sb2Te3 is a promising material. Furthermore, the use of such a Cu-free back contact material might enhance the stability of the solar cell. However, the fabrication of Sb2Te3 can be challenging due to Te re-evaporation from the hot substrate, significantly complicating stoichiometry and property control. Therefore, the nanoalloying growth method was used for the first time to fabricate the back contact layers. This method is based on the stoichiometric deposition of element layers on a cold substrate and afterwards the application of a low-temperature annealing process in which compound formation takes place. We discuss the properties of single Sb2Te3 films and present performance studies on superstrate-based CdTe solar cells with nanoalloyed Sb2Te3 back contacts. High quality single-phase Sb2Te3 with large grain sizes, carrier mobilities > 400 cm²/Vs and large Seebeck coefficients was obtained. Changing deposition parameters allows to influence the texture and to adjust the carrier concentration, demonstrating the flexibility of the method. An efficiency of 11.7% was achieved with Sb2Te3/Cu/Mo back contact and with Sb2Te3/Cu/Au contact in a first experimental series with significant potential for further optimization.

Since the design of the first working solar cell in 1954, silicon has been the material of choice for the fabrication of efficient, durable yet cost effective solar devices. The tremendous progress of microelectronic industry made it possible to engineer the properties of the materials and the large scale fabrication of silicon devices at low cost. Yet, the cost of the energy produced by PV technology remains significantly higher than that produced from fossil fuels. Strategies to lower the cost include the reduction of the amount of materials by using thin films, the development of novel fabrication processes that are not based on vacuum technologies and the quest of novel abundant, non toxic alternative materials. Perovskite hybrid cells have recently emerged as potential alternative to silicon based devices. However, major challenges remain before a perovskite cell becomes available on the market. We describe in this work some of these challenges and our recent contribution to enhance the power conversion efficiency by replacing the moisture sensitive hole transport material layer a by more resistant and cheaper organic material.

The authors gratefully acknowledge the support of the Qatar National Research Fund (project n. NPRP 5 - 873 - 5 - 133) It is now widely accepted that investment in renewable energy sources is one of the most effective solutions to amend the emission of greenhouse gasses. By providing emission-free and sustainable energy, these energies are main alternatives to fossil fuels. Yet, notwithstanding the advantages and the fact that they have experienced a substantial growth over the last decade, renewable energy market penetration still remains below the levels judged necessary to effectively curb C02 emissions. Increasing RE penetration requires therefore that concerned actors such as RE companies and policy makers develop a more thorough understanding of the factors that affect the RE diffusion process. To that end, in this study we adopt a new technology diffusion perspective to shed further light on the factors that may hamper or accelerate the diffusion of a specific type of renewable energy: photovoltaic systems (PV). We especially discuss and examine the impact of the following factors: i) the type of PV-related information acquired by individuals before adoption which is either customized (face to face contact, talking, etc.) or non customized information (article readings, ads, etc.); ii) information channel, either commercialized (information from PV suppliers) or non commercialized channels (information from other sources) iii) the total amount of PV-related information acquired by individuals before adoption iv) economic value of PV system v) technological uncertainty and vi) the perceived degree of competition in the PV supply market. We put forth a conceptual model of PV diffusion and we test it using primary data obtained through a survey of the actual clients, prospect and potential customers of a large European utility that also sells PV systems. Both Prospect and Potentials do not have the PV system but prospect asked for the quote. We used a set of logit models to estimate the impact of the above factors on the adoption likelihood for prospect and potential customers, and also to compare clients with prospects and prospect with potentials. The analysis provides interesting insights, particularly with respect to the time value of different information dimensions. The results indicate that the value of information varies over the time. For example customized information has positive effect on the adoption decision, and information coming from commercialized channels has positive effect on becoming a prospect. Second, our results show that, contrary to expectations, increasing the number of market competitors decreases the probability of adoption, possibly because potential adopters defer their adoption decision when the number of available alternatives increases beyond a certain limit. Altogether, our results indicate that - in addition to focusing on improving technological effectiveness and reducing system cost, RE providers should pay a lot of attention to the way they organize their distribution channels and to how they design their marketing campaigns.

Thermal energy storage systems are crucial for reducing dependency on fossil fuels and minimizing CO2 emissions. The building sector is a major sector responsible for producing high levels of CO2 in most countries (including Qatar). Thermal energy storage can be accomplished either by using sensible heat storage or latent heat storage components. Latent heat storage is more attractive than sensible heat storage because of its high storage density with smaller temperature fluctuations.[1] The materials able to utilize latent heat which can undergo phase changes (usually solid to liquid changes) at relatively low temperatures, while absorbing or releasing high amounts of energy are called phase change materials (PCMs).[2] Most promising PCMs are paraffin waxes which contain saturated hydrocarbon mixtures. They are frequently used due to their numerous advantages such as high latent heat of fusion, negligible super-cooling, and chemical inertness.[3,4] In this contribution, thermal properties of the PCMs based on linear low density polyethylene (LLDPE), different types of paraffin waxes with melting points, 25 oC and 42 oC, and expanded graphite (EG) were characterized by unique transient guarded hot plate technique (TGHPT), which allow to identified thermal properties of large sized samples[5] in comparison with commonly used ifferential scanning calorimetry (DSC). It was confirmed that all prepared PCMs were able to store and release huge amount of thermal energy. The 25 % increase of capacity to store and release a thermal energy was observed by PCMs contains paraffin wax with melting point 25 oC in comparison with paraffin wax with melting point 42 oC. Also reproducibility of storage and release heat of the PCMs by repeating of heating and cooling process has been demonstrated. Moreover, the increase of the EG content in the PCMs led to the increase of thermal conductivity from 0.24 W/mK for PCMs without EG to 1.3 W/mK for PCMs contain 15 wt.% of EG. Additionally, life cycle assessment of prepared PCMs has been demonstrated to identify the effects of these new materials on the Qatar environment. Our results indicate that using of PCMs in building industry can reduce emission of CO2 up to 10%. Keywords: phase change materials; latent heat; storage and release energy; thermal conductivity; life cycle assessment Acknowledgement: This contribution was made possible by NPRP Grant # 4-465-2-173 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors References: [1]Soaresa N, Costab JJ, Gaspar AR, Santos P. Energy Build 59 (2013) 82-103. [2]Krupa I, Mikova G, Luyt A.S. Europ. Polym. J. 43 (2007) 4695-4705. [3]Kenisarin M, Mahkamov K. Renew. Sustain. Energy Rev. 11 (2007) 1913-1965. [4]Lachheb M, Karkri M, Albouchi F, Nasrallah S, Fois F, Sobolciak P. Composites: Part B 66 (2014) 518-525. [5]Karkri M, Boudenne A, Ibos L, Garnier B, Candau Y. High Temp.-High Press. 40 (2011) 61-84.

The development of future ultra-low emission combustion strategies is necessary in order to strengthen the security of energy supply and address the rising concerns over the health and environmental effects due to pollutant combustion emissions. The imposition of legislation, which places strict limits on pollutant emissions from combustion systems around the world, is designed to reduce the dependence on petroleum based fossil fuels, and indicates the need to diversify towards sustainable and cleaner burning fuels. Natural gas and hydrogen stand out as two potential alternatives for the currently used petroleum based fuels. Natural gas has the highest carbon to hydrogen ratio than any other fossil fuel and, therefore, releases relatively few by-products (CO2 and particulates) into the atmosphere as pollutants on combustion. Hydrogen is the ultimate a ‘zero carbon emission’ fuel with a relatively high energy density; however, hydrogen is not naturally available in the way that natural gas is and requires and investment to produce, and can therefore be used to complement natural gas combustion. The work presents an experimental investigation of diesel fuel co-combustion with both natural gas and hydrogen, carried out on a modern, naturally aspirated, direct injection diesel engine. The engine was supplied with a range of methane-diesel fuel, hydrogen-diesel fuel and methane-hydrogen-diesel fuel mixtures and the effect on combustion and exhaust emissions was investigated. At low to medium engine loads, the results showed a decrease in particulates, NOx and CO2 exhaust emissions as diesel fuel was replaced by methane-hydrogen mixtures. At high engine loads and relative to diesel only combustion, NOx emissions increased steeply, which was attributed to the combined diesel fuel and methane-hydrogen mixture co-combustion temperatures exceeding the threshold temperature for NOx emissions. In addition, an in-cylinder gas sampling technique was utilised with the research engine to gain a greater level of insight into the process of energy release and emissions formations in the gas of hydrogen methane diesel co-combustion than is afforded by the measurement of engine exhaust. The engine was supplied with a range of hydrogen-diesel fuel and methane-diesel fuel mixtures, and in-cylinder gas sample composition was investigated at two sampling locations; within the diesel fuel spray and between adjacent spray cones. Concentrations of NOx were found to be higher between the two diesel sprays relative to within the spray cone for both hydrogen and methane addition. In the case of hydrogen-diesel fuel co-combustion, the measured particulate levels were observed to be higher in the diesel fuel spray relative to between two sprays; however, in the case of methane-diesel fuel co-combustion, higher particulate levels were measured in the region between the two sprays. This was attributed to methane contributing significant quantities of particulates (unlike hydrogen) to the total particulate concentration produced from the methane-diesel fuel mixture in between two sprays.

Conducting biodiversity surveys is expensive and time consuming and we cannot always invest as much time as needed conducting field work. To compensate for such deficiencies, scientists can benefit from advanced techniques of species distribution modelling. Data on species distribution is essential for the correct conservation and management of the species and their habitats. The objective of this study has been to predict the distribution range of four lizard species in Qatar that were found in few locations during field surveys conducted in 2012-2013, and that we believe that could be present in a larger range. The species examined were: the Schmidt´s fringe-toed lizard, Acanthodactylus schmidti (with 18 field observations), the toad-headed agama, Phrynocephalus arabicus (with 27 field observations), the Arabian sand gecko, Stenodactylus arabicus (with 22 field observations) and the Eastern skink, Scincus mitranus (with 8 field observations). The four species have been only observed in the southern part of the Qatar country. To make predictions about the potential distribution of these lizard species we used climatic data obtained from the WorldClim database, and remote sensing data (Landsat 8 Image), from which we obtained high resolution data as surface temperature, and other features derived from the land surface reflectivity at different wavelenghts. We generated new maps for the four lizard species in Qatar based on different ecological niche models (ENMs). All these models appeared to be ‘good’, with a AUC value >0.8. There are not significant differences between bioclimatic and remote-sensing maps. However the bioclimatic maps were the ones that visually matched better with the observed distribution of the species. Furthermore, bioclimatic maps can be less reliable due to the low number of climatic observatories in the area used to build the databases. We found some differences between the predicted distribution maps depending on the environmental covariates used, being the relative rank between pairs of maps of any species always near 0.5. Despite the limitations of the models, they appear to be a good predictive tool for lizard distribution ranges. Future advances in the knowledge of the environment together with environmental and climatic maps of higher resolution will improve ecological niche modelling in Qatar.

The overall municipal organic waste in Qatar accounts for 57% of municipal waste generated annually. Organic solid wastes such as food, newspapers, packaging, furniture woods and wood from building demolition have traditionally been placed in landfill, which create issues of sustainability for a country like Qatar with small land mass. While the recently opened Doha solid waste treatment facility contributed to alleviating the pressure on Landfill sites through composting and incineration, new value-added use of solid organic waste are needed for environmental and economic sustainability. Fortunately, biochars from mixed organic solid wastes can be used in soil amendment for food security and long term carbon sequestration for environmental sustainability. We hypothesize that deficiencies in depleted Qatari soils can be remedied by the application of biochars that are custom-designed to possess the right physicochemical characteristics suitable to improve soil fertility. Hence, this study was conducted to (1) Optimize production of biochars from mixed organic waste for desired physicochemical characteristics as soil enhancers. (2) Produce and characterize designer biochars using optimum production conditions for testing in soil incubation experiments. Select municipal organic wastes (newspaper, cardboard, woodchips and landscaping residues) individually and in a 25% blend were used as a precursor for biochar preparation. These residues were chosen due to their commonality in municipal solid waste streams. A complete 5 × 3 × 3 factorial design was used in this study with five biochar precursors (the 4 solid waste materials and a 25% blend/mixture), 3 sets of pyrolysis temperatures (350, 500, and 750°C) and 3 sets of pyrolysis residence time (2, 4 and 6 hrs). Data obtained showed that biochar yield was in the range of 21- 62% across all feedstocks and pyrolysis conditions. The highest yield was observed in newspaper-based biochars pyrolized at 350°C for 2 hrs. Key parameters such as pH, electrical conductivity bulk density and surface area, which positively improve water and nutrient-holding capacity in biochar-amended soil, varied depending on the precursors and production conditions. Bulk density was high in woodchips-based biochars but was similar among all other biochars, irrespective of precursors and pyrolysis conditions. The total surface area of biochars was low but showed dramatic increase in all feedstocks at 700°C pyrolysis temperature. The highest electrical conductivity observed in cardboard-based biochars pyrolized at 700C. Biochars produced from selected waste precursors were acidic except those produced at 700°C temperature where pH became alkaline. The wide range of biochar pH suggests potential tailoring to remediate the specific soil acidity. Cumulatively, biochars showed promising results for improving soil fertility parameters such as better water holding capacity, pH stabilization, and increased electrical conductivity of soil for better aggregation. These findings indicate that solid organic municipal wastes hold promising potential as precursors for manufacturing of value-added biochars with varied physicochemical characteristics allowing them to be used not only as an alternative to bio-waste management and greenhouse gas mitigation but also as means to improve depleted Qatari soil as the country embarks on its ambitious goals of ensuring food security and environmental sustainability.