Geochemical Assessments and Potential Energy Sources Evaluations Based on Oil Shale and Geothermal Resource in Wadi Al-Shallala—North Jordan

Oil shale deposit is considered as one of the fossil fuel sources in Jordan. Despite that, the needs of renewable energy resources become a must in Jordan. Wadi Al-Shallala oil shale is investigated in this work for geochemical, petrographic features and hydrocarbon potential as a conventional energy resource. Various petrographic and geochemical techniques were applied. Oil shale resource potential is evaluated for cooling and heating Sal village houses. Geothermal heat pumps, as renewable energy resource in the study area, were simulated for comparison purposes. Results show that Calcite is the main mineral component of oil shale. Magnesite, Ferrisilicate and Zaherite are exhibited in the studied samples. Other trace elements of Zinc, Cobalt and Molybdenum were presented, too. Calcium oxide of 41.01% and Silicon oxide of 12.4% are the main oxides reflected in this oil shale. Petrographic features of the analyzed oil shale found that the primary mineral constituent is micritic calcite, while the secondary minerals include carbonate mud and opaque minerals. Furthermore, it’s found that total organic carbon averages 3.33% while the total carbon content averages 20.6%. Moderate TOC values suggest that Wadi Al-Shallala oil shale has a good source rock potential. Even though nitrogen and sulfur are of low contents in Wadi Al-Shallala oil shale, direct combustion of the reserve for electricity generating will increase CO2 emissions by 2.71 Million m. Two systems were simulated to cover Sal village cooling and heating demands. The conventional system is compared with geothermal heat pumps. Geothermal heat pumps are found to save 60% of electricity consumption in heating and 50% in cooling systems. The environmental benefits for geothermal system implementation will be a reduction How to cite this paper: Al Dhoun, H. and Al-Zyoud, S. (2019) Geochemical Assessments and Potential Energy Sources Evaluations Based on Oil Shale and Geothermal Resource in Wadi Al-Shallala—North Jordan. International Journal of Geosciences, 10, 351-365. https://doi.org/10.4236/ijg.2019.103020 Received: February 10, 2019 Accepted: March 26, 2019 Published: March 29, 2019 Copyright © 2019 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/


Introduction
Conventional energy used in Jordan is the major supply source; it satisfies more than 90% of energy demand in Jordan. One of the most important energy resources in Jordan is oil shale [1]. Oil shale reserves in Jordan were evaluated recently by [2] and [3]. They stated that surface and subsurface oil shale rocks in Jordan have a considerable economic potential for Jordan. Their work focuses on central and southern oil shale deposits in Jordan. They presented a brief characterization of four oil shale deposits. Size distribution test and elemental analysis were performed. Hydrocarbon potential evaluations of oil shale are considered as an indicator for this source potential [1]. Furthermore, oil shale evaluations are of utmost importance for future utilization in Jordan. [4] suggested several utilization methods of oil shale in Jordan and worldwide. Most of previous work evaluated Jordanian oil shale in middle and south Jordan ( [1]; [2]; [3]; [4]; [5]). It has been found that oil shale is the most abundant fossil energy resource discovered in Jordan, ranking third after the USA and Brazil in terms of oil shale reserves [5]. In addition, it was concluded that Jordanian oil shale is generally of a good quality, with relatively low ash and moisture contents, a gross calorific value of 7.5 MJ/kg, and a wide range of oil yield of 3% to 12% [5]. Oil shale in north Jordan has very limited evaluation studies. Therefore, this work will evaluate heat potential of oil shale in Wadi Al-Shallala in north Jordan.
On the other hand, the increasing demands of environmentally friendly energy resources convert the attention to other renewable resources. One of the newest renewable energies in Jordan is geothermal energy ( [6]; [7]; [8]). Shallow geothermal energy resources are rather used in Jordan [7]. It can utilize the subsurface temperature as it differs from air temperature. Thus, it would be an environmental and sustain heat exchanger. The ground can be utilized as heat source in winter and cool source in summer. Thus, unlike other energy resources that require advanced technical setups, geothermal energy exploits the natural heat (and cool) from the earth. In order to extract this energy a closed loop of horizontal installed pipes, which filled with heat carrier fluid inside, is circulating in subsurface. This circulation is responsible for heat transfer from/to the subsurface to/from buildings systems, where a heat pump is often applied [9]. Closed loop geothermal system for nearby village of Wadi Al Shallala is International Journal of Geosciences modeled. Sal is located to the east of Irbid city. Its area is about 9 square kilometers with a population of about 12,000 per capita. 2270 houses were considered for their cooling and heating demands in this study. Consequently, this work aims at highlighting the possible energy sources in Wadi Al-Shallala. In parallel with the oil shale, geothermal resource is evaluated for prospective energy production. The possibility of supplying buildings with heat and cool is evaluated. Oil shale is suggested as the first energy supplier, electricity form. Shallow geothermal heat pumps with closed loop are simulated as the second energy supplier. Thus, potential evaluations were calculated for both resources in Wadi Al-Shallala and Sal village.
There is a need and an opportunity for targeted potential energy utilization that support research which connects energy resources development and the available infrastructure. On the other hand, an increased necessity for supporting work that focuses specifically on addressing important gaps in understanding the social, economic and environmental implications of expanding alternative energy systems. The literature was reviewed to identify potential knowledge gaps. This will suggest an immediate path forward: the interpretation of the national literature for the Jordanian energy context. In addition, a key challenge for policy makers and researchers is to understand and acknowledge what we know about the impacts of alternative energy systems and which of those gaps require attention. This will lead to looking for immediate research opportunities: the interpretation of the national literature for the energy context to best identify knowledge, and relevant experiences and cases. Therefore, the present work addressing to fill potential knowledge gaps in energy utilization in Jordan.

Geologic Settings
Wadi Al Shallala is located in north Jordan about 12 kilometers northeast of Irbid  chert. It's of Lower-Middle Eocene age [12]. WSC Formation is 100 m thick of Middle to Upper Eocene age. It consists mainly of chalk, marl and micritic limestone [13].

Oil Shale Characterization
Thirty oil shale samples had been collected vertically along the outcrop. The samples, for technical circumstances, were collected at 20 -50 cm in depth, as fresh as possible. The lower sample was at an elevation of 429 m (above sea level). The samples were collected apart 25 cm from each other. Each sample was approximately 500 gm. The sampling was in summer, at June, thus the samples had a little amount of humidity. The samples were air dried and packed in plastic bags in the field. The sample then had been prepared in the lab for each test independently. Investigated oil shale samples were prepared in the lab to be examined for its chemical composition, mineral constituents and carbon potential. The following analyses were performed; 1) Elemental Analysis (EA), 2) X-Ray Diffraction (XRD), 3) X-Ray Fluorescence (XRF), 4) Scanning Electron Microscope (SEM) and 5) Polarized Light Microscopy Analysis of Thin Section. The analyses were carried out as follows: 1) Elemental Analyzer is used to measure carbon content of the studied samples. The sample is pulverized and chemically treated with hot diluted 20% HCL to remove its inorganic carbon in the form of carbon dioxides CO 2 . After that, the sample is washed free of HCL solution, filtered and collected in a specified International Journal of Geosciences bag then sent to Elemental Analyzer. Organic carbon combustion products of the sample are catalytically converted to CO 2 and measured by Elemental Analyzer [14]. In addition to the organic carbon content, nitrogen, hydrogen and sulfur constituents for organic compounds were measured, too. Total carbon content (TCC) was measured for the examined samples, on 63 μm grained size, using the calcimetry method [15]. Total organic carbon (TOC %) was calculated as illustrated in Equation (1) below; where: W = Dry sample analysis (g) Improving the sensitivity of analysis method with using a wide range of reference standard for calibration curve determination has been developed [16].
2) X-Ray Diffraction is an atomic plane used for phase identification of crystalline material in order to obtain detailed information about their structure samples. Each sample has been grinded to (75 μm) size. The powdered samples were packed into a cavity at a flat surface on the backside of the XRD sample holder.XRD measurements were performed in a Shimadzu Lab X, XRD-6000 X-ray diffractometer using Cu KL2,3 (α1,2) radiation (λ = 1.5418Å, 40 kV) and it ranges from (2˚ to 80˚) 2θ with a step size of 0.05˚ 2θ. The assignment of the minerals was based on the database of the Joint Committee Powder Diffraction Standards-International Centre for Diffraction Data (JCPDS-ICDD) [17].
3) X-Ray fluorescence is applied to determine the major oxides ( and mathematical corrections during data export have been implemented. Automatic fusion technique, for presenting the best homogeneity samples, has been applied. Thus, the examined samples were milled to give a flat surface. The powder reduces particle size effect. The samples then pressed into pellets for best handling fusion with a suitable flux of glass-like beads. This is the best practice for eliminating errors with materials which exhibit varying mineralogical composition [18]. should be mounted to a specimen holder or stub using a conductive adhesive [19]. International Journal of Geosciences 5) Polarized Light Microscopy Analysis of Thin Sections was conducted under polarizing microscope. They had been investigated with two light positions; plane polarized light and crossed polar light with two polarizing filters at the right angle are installed. Thin section s are pre-prepared at 30 µm ± 5 µm thin slice of shale slab, having at least one glass slide glued to one of its sides with epoxy.

Hydrocarbon Potential of Oil Shale Comparing with Geothermal Potential in the Study Area
On the other hand, a suggested geothermal heat pumps for cooling and heating houses in Sal village, the nearest urban area to Wadi Al-Shallala, were modeled. Information about the subsurface temperature distribution in the study area is very limited. One subsurface temperature survey was conducted in central Jordan (about 200 km south to the study area) by [20]. Thus, an initial surface temperature distribution was estimated at 20˚C. The basal heat flow rate is 95 m•W•m −2 according to global heat flow data base [21]. Thermal conductivity of the subsurface is given from previous work as 2.36 ± 0.32 W•m −1 •K −1 [22]. Comparing with available modeled subsurface temperature eastern to the study area [7] and the geothermal gradient in the study area [23] a temperature of 22˚ was assigned to subsurface in Wadi Al-Shallala. To bring this temperature distribution into reality, a comparison with the nearest wells subsurface temperature has been done. Available data was match with the modeled temperature [24]. Shallow geothermal closed loop heat pump system was simulated for its cooling and heating potential. Different scenarios were applied dependent on the intake flow rate and system capacity for the suggested heat pumps. For comparison purposes, oil shale reserve in the study area was estimated. Oil shale heat potential was calculated from oil shale reserve. The average organic matter content is then converted to energy (i.e.; electricity). This amount of energy was modeled for supplying houses with cooling and heating. The two energy types were compared in terms of their supply potential in the study area.

Elemental Analyzer (EA) Results
Total Organic Carbon (TOC) is relatively low to moderate in the studied samples. It ranges between (1.297% and 4.616%) with an average of 3.33%, this is considered as a good hydrocarbon generating potential [25]. Total Carbon Content averages 20.6% and ranges between (10.95% and 27.72%). Hydrocarbon potential could not be generated without originally enough organic matter content in the depositional environment. Therefore, the drop in TCC may be as a result of early organic matter loss at early stages of genesis. The planktonic/benthic ratio exhibits some fluctuations in the oil shale TOC probably as a consequence of relative sea-level changes. This method can be used as a quantitative method to calculate paleo depth based on a formula [26]. Low abundance The decrease in abundance of planktonic foraminifera (52% and 68% in samples 16 and 22, respectively) indicated the presence of shallower environments. Such environments provide more than 50% increase in oxygen. Consequently, this will lead to decline in organic matter accumulation due to aerobic biodegradation [27]. On the other hand, the samples revealed low quantities of sulfur and nitrogen as well. The average sulfur content in the examined samples is 3.5% while the average nitrogen is 1.5%.

X-Ray Diffraction (XRD) Results
XRD analysis of the oil shale indicates that the major mineral constituent is cal-

X-Ray Fluorescence (XRF) Results
The X-ray fluorescence (XRF) analyses show the presence of 41.01% CaO and 12.4% SiO 2 . In addition, high percentage of L.O.I with mean a value of 40.34% was obtained.
Loss on ignition in oil shale depends on the content of moisture organic matter, carbonate and volatile components mainly sulfur (although SO 3 of the studied samples are higher than other Jordanian oil shale). Such lost occur after the samples exposure to a strong heating during the analysis.

Polarized Light Microscopy Analysis of Thin Sections
The microscopic analysis of oil shale reveals that the primary mineral consists

Oil Shale Resource Potential
Oil shale reserve in the study area was estimated for the current comparative study. It has been found that this oil shale thickness averages 40 m [25]. Thus, oil shale reserve is calculated to be about 35.8 Million Ton considering that oil shale density is 1.79 g/cm 3 , using suggested formula by [29] in multiplying the three parameters together. Daily consumption for air condition cooling for each house in the study area is 5.25 KWh [30]. In the study area, the needs for cooling is 3 months a year, thus the annual energy consumption for cooling is 472.5 KWh.
The annual energy consumption for cooling for the 2270 houses in Sal is 1.073 GWh. On the other hand, the daily consumption for air condition heating for each house in the study area is 5.45 KWh [30]. In the study area, the needs for shale. [30] stated that burning one ton of oil shale with 3.33% organic matter will produce 297.

Geothermal Resource Potential Calculation
As stated earlier in the methodology, subsurface temperature for shallow closed loop system was modeled to be 22˚ at about 150 m depth. This depth with assigned temperature will be the heat storage in the suggested closed loop system for the annual cooling and heating supply. The system will use the differences between subsurface and air temperature for satisfying cooling and heating needs.
Geothermal system will reduce the electricity consumption by decreasing the  In summer a reversed process is operated. The subsurface temperature is lower than air temperature. Average room temperature will be 28˚, the liquid used in this system will have the same temperature as the surrounding air. This liquid is pumped into pipes. Pipes loop underground will receive this warm fluid. Heat exchange between this fluid and the surrounding subsurface temperature (22˚) is developed. Cold liquid is pumped back to the infrastructure and reach the heat pump. The compressors supplied by heat pumps will decrease the temperature from 22˚ to 16˚. Cool is pushed by fans out to the houses to decrease room temperature.
In winter subsurface temperature is higher than air temperature. Average room temperature will be 10˚, the liquid used in this system have the same temperature as the surrounding air. This liquid is pumped into pipes. A horizontal loop of pipes underground will receive this cold fluid. Heat exchange between this fluid and the surrounding subsurface temperature (22˚) is developed. Heated liquid is pumped back to the infrastructure and reach the heat pump. The temperature is increased from 22˚ to 30˚. Heat is pushed by fans out to the houses to increase room temperature. In order to model the possible intake flow rates of different houses cooling and heating capacities, three scenarios were simulated for heat pumps system i.e.; 50, 100 and 200 m 3 /d. Annual cooling and heating energy consumptions compared with the annual geothermal heat pumps energy consumptions are listed in Table 3  energy consumption with the annual cooling/heating geothermal heat pumps consumption, it has been found that geothermal heat pumps save 60% of electricity consumption in heating and 50% in cooling systems ( Table 3).
The environmental benefits from geothermal system implementation will be a reduction in energy consumption as electricity and fuel oil through the replacement of the conventional systems. The savings in fuel oil will be about 9.35 Million barrels. While the reduction of CO 2 emotions will be dropped to 1.5 Million

Conclusion
Oil shale in Wadi Al-Shallala is investigated into its minerals, chemical composition and hydrocarbon potential. It is found that Calcite is the main mineral constituents. Some other Magnesite, Ferrisilicate and Zaherite are presented, too.
Trace elements of Zinc, Cobalt and Molybdenum were exhibited in the examined samples. Calcium oxide and Silicon oxide were composed of 53.41% of the studied oil shale. In parallel with that, Calcium, Oxygen, Carbon and Silicon were indicated by SEM results. In addition, the microscopic analysis of oil shale reveals that the primary mineral consists of micritic calcite, while the secondary minerals include carbonate mud and opaque minerals. It's found that total organic carbon averages 3.33% while total carbon content averages 20.6%. Low sulfur contents are noticed in the examined oil shale. Oil shale reserve is estimated to be 35.8 Million Ton. For a nearby Sal village of 2270 houses, assuming direct burning of oil shale, two cooling and heating facilities were evaluated for their energy consumption. Oil shale resource will cover the village cooling and heating demands with generated electricity for more than 200 years if the system is air conditions. Another modern system, heat pumps, is simulated for cooling and heating supply, too. With these pumps, it has been found that oil shale reserve will supply the village with cooling and heating in 35, 18  International Journal of Geosciences tricity consumption in heating and 50% in cooling systems. This will reduce CO 2 emissions to 1.5 Million m 3 . Consequently, geothermal energy offers considerable advantages rather than conventional oil shale potential.