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[Display omitted] • The environmental effects of nuclear and geothermal energy are explored. • The Novel Quantile ARDL method is employed for the period 1990Q1-2019Q4. • Nuclear and geothermal energy raises the environmental footprint at the majority quantiles. • Urbanization contributes to a sustainable environment only with low environmental degradation. • Agricultural-based activities reduce the environmental footprint in the long run. The global issue of atmospheric variations and global warming caused by diverse anthropogenic behaviors is a global concern. There is apprehension about preserving an uncontaminated atmosphere and attaining optimal nuclear and geothermal energy utilization with agriculture sector development. In this regard, this paper investigates the influence of nuclear energy, geothermal energy, agriculture development, and urbanization on carbon emissions and ecological footprint from 1990Q1 to 2019Q4 in the case of China. The findings of unit root tests reveal that all variables are stationary at first integration order, and cointegration test findings confirm the presence of long-run relationships among series. The quantile autoregressive distributive lag (QARDL) method findings demonstrate that nuclear energy, geothermal energy, and urbanization statistically correlate with CO2 emissions and ecological footprint across all quantiles, indicating that these determinants have contributed to environmental degradation. Whereas agricultural development has a statistically significant and negative influence on the environment, implying that agriculture has a pollution-mitigation impact. Based on these empirical findings, several policy implications are presented to preserve environmental quality to achieve the 2030 Sustainable Development Goals (SDGs) target. [ABSTRACT FROM AUTHOR]

Ground-motion models (GMMs) typically include a source-to-site path model that describes the attenuation of ground motion with distance due to geometric spreading and anelastic attenuation. In contemporary GMMs, the anelastic component is typically derived for use in one or more broad geographical regions such as California or Japan, which necessarily averages spatially variable path effects within those regions. We extend that path modeling framework to account for systematic variations of anelastic attenuation for ten physiographic subregions in California that are defined in consideration of geological differences. Using a large database that is approximately doubled in size for California relative to Next Generation Attenuation (NGA)-West2, we find relatively high attenuation in Coast Range areas (North Coast, Bay area, and Central Coast), relatively low attenuation in eastern California (Sierra Nevada, eastern California shear zone), and state-average attenuation elsewhere, including southern California. As part of these analyses, we find for the North Coast region relatively weak ground motions on average from induced events (from the Geysers), similar attenuation rates for induced and tectonic events, and higher levels of ground-motion dispersion than other portions of the state. The proposed subregional path model appreciably reduces within-event and single-station variability relative to an NGA-West2 GMM for ground motions at large distance (RJB > 100). The approach presented here can readily be adapted for other GMMs and regions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Special difficulties of geothermal drilling, completion and fracturing are reviewed. • Commonly used geothermal drilling and completion technologies are investigated. • State-of-the-art geothermal fracturing methods are reviewed and compared. • Novel heat extraction methods & their applicable reservoir conditions are concluded. Global warming induced by excessive carbon dioxide emission generated from fossil fuels consumption is becoming increasingly severe. Development and utilization of clean and renewable energy is a significant measure to contribute for the carbon neutrality. Geothermal resource is an important clean and renewable energy, because of its advantages of abundant reserves, exploitation without restrictions from the climate and season. Extracting heat from the high temperature geothermal reservoir requires well drilling, completion and fracturing. However, due to some particular conditions in geothermal development, such as high temperature, erosion, leakage, and hard rocks, traditional petroleum well drilling and completion technologies are not well applicable in the geothermal industry. In this paper, the state-of-the-art geothermal drilling, and completion technologies as well as several fracturing methods, such as foam drilling, air hammer drilling, hydrothermal jet drilling, expansion casing technology, high temperature resistant drilling fluid and cement, chemical stimulation and thermal stimulation are comprehensively reviewed. Besides, heat extraction performances of water and CO 2 as working fluids in the geothermal system are discussed. A few novel heat extraction methods including closed loop, open loop, enhanced geothermal systems are compared and analyzed. This review is expected to provide suggestions for research fields worthy of study for geothermal drilling and exploitation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Availability of RES in the MENA region was summarized. • Suitable renewable energy storage systems in MENA was introduced. • Desalination plants powered by RES in MENA were investigated. • Al-khafji solar seawater RO plant in KSA was discussed. The Middle East and North Africa (MENA) countries are rapidly growing in population with very limited access to freshwater resources. To overcome this challenge, seawater desalination is proposed as an effective solution, as most MENA countries have easy access to saline water. However, desalination processes have massive demand for energy, which is mostly met by fossil fuel-driven power plants. The rapid technological advancements in renewable energy technologies, along with their gradually decreasing cost place renewable energy-driven power plants and processes as a promising alternative to conventional fuel-powered plants. In the current work, renewable energy-powered desalination in the MENA region is investigated. Various desalination technologies and renewable energy resources, particularly those available in MENA are discussed. A detailed discussion of suitable energy storage technologies for incorporation into renewable energy desalination systems is also included. The progress made in implementing renewable energy into power desalination plants in MENA countries is summarized and analyzed by describing the overall trend and giving recommendations for the potential amalgamation of available renewable energies (REs) and available desalination technologies. Finally, a case study in the MENA region, the Al Khafji solar seawater reverse osmosis (SWRO) desalination plant in the Kingdom of Saudi Arabia KSA, is used to demonstrate the implementation of REs to drive desalination processes. [ABSTRACT FROM AUTHOR]

The electrical energy needs grow every year, increasing awareness and use of renewable energy even higher. Geothermal power plants (GPP) are even ogled as a renewable energy source that has a lot of potential worldwide. Technology for GPP continues to evolve. However, tools for analyzing a system of GPP are still inadequate. In this study, a simple analysis tool was designed. The usefulness of this analysis tool is to be able to know the state of the GPP works. This tool will help simulate the conditions that may occur in the plant system. The simulation results will also be known operating conditions that may occur, so the operator can determine what should be done if things happen. Modeling started using Microsoft Excel, which has been equipped with thermodynamic properties. Modeling includes turbine, condenser, cooling tower, and extraction systems non-condensable gas. After validated, the model run simulation in variations that may occur such as decline in the condition of the condenser and cooling tower and environmental conditions, represented by relative humidity. The simulation with variation of condition will decrease the power generated from turbine 3 - 5%. [ABSTRACT FROM AUTHOR]

In the present research, energy derived from the geothermal uid is utilized to generate power. In the first case of power generation, the model of the geothermal double-effect instantaneous evaporation cycle is employed, while in the second one, the single-effect evaporation combined cycle and Rankine cycle with different organic uids are utilized. The effect of several organic uids in the combined cycle is then examined. The SPECO method was then incorporated in the economic analysis. According to the mentioned analysis, net power generation reached its maximum value for the combined cycle with water vapor and its minimum value for the double-effect instantaneous evaporation cycle with a considerable difference. Throughout the experiments, increasing the separator pressure at the constant evaporator temperature reduced the power generation cost for combined cycles. The lowest power generation cost was attributed to the combined cycle with operating uid R113 while the highest amount of power generation cost was related to the combined cycle with ammonia uid. The exergoeconomic coeffcient, i.e., the ratio of the purchase price components to the sum of costs associated with total exergy destruction as well as the cost associated with purchasing cycle components, was also the highest in the combined cycle with R113 and the lowest in the double-effect instantaneous evaporation cycle. [ABSTRACT FROM AUTHOR]

This study aims to calculate and analyze the energy requirement and improve the efficiency and sustainability of greenhouse (GH) agriculture by integrating renewable energy sources (RES) and advanced control systems into a hybrid solar-GH heating and cooling solution. The proposed system incorporates both geothermal and photovoltaic (PV) energy to optimize performance, particularly during the colder seasons. The analysis focuses on three widely used double-layer polyethylene materials in Canadian GHs, Thermax, SolaWrap, and SunSaver, evaluating their thermal insulation and light management properties. For a practical test, a typical 1000 m 2 GH is designed to calculate the energy requirements for heating and cooling, specifically tailored to the climatic conditions of Regina, using the three types of polyethylene. An energy and cost analysis is performed considering various energy sources to meet these demands. The research calculates and compares the power generation from building-integrated photovoltaics (BIPV) with traditional maximum power point tracking (MPPT) PV systems and integrates a 5-stage controller with HVAC damper control to further optimize energy consumption under different scenarios. The simulations performed using TRNSYS and SketchUp provide detailed monthly energy consumption and cost breakdowns for each polyethylene type. Additional insights include monthly power generation from both PV and BIPV systems, as well as contributions from geothermal energy. The findings present a comprehensive energy analysis, highlight potential cost savings and system efficiencies, and offer valuable information to advance sustainable GH agriculture in cold climates. • Integration of BIPV, ground heat exchanger, and heat pump in a greenhouse HVAC system. • Comparative analysis of power between BIPV and MPPT PV systems of the same size. • Control system optimizes HVAC damper performance using ambient and greenhouse temperatures. • Results show data on temperature dynamics, energy consumption, and system performance. [ABSTRACT FROM AUTHOR]

The significance of devoting attention to environmental pollution control strategies is widely recognized as an effective means of mitigating the harmful environmental effects caused by fossil fuels in industrial and power plant sectors. Carbon dioxide (CO 2) capture and recovery technologies have opened up the possibility of utilizing this pollutant gas. Hence, the current study suggests a methodology for the CO 2 hydrogenation of the flue gas leaving a power plant. This approach facilitates methane generation via a methanation reactor, subsequently is utilized as fuel for a power plant. For this purpose, a cryogenic method using liquefied natural gas cold energy facilitates CO 2 recovery. Moreover, the whole system utilizes geothermal energy to launch a power plant for power generation and supply the power demands of a hydrogen production unit, relying on a water electrolysis process. The hydrogen generated is employed for CO 2 hydrogenation, while the oxygen produced is utilized for the combustion reaction. Heating provider units and an absorption chiller are also included in the design. The system is modeled utilizing Aspen HYSYS software. This study incorporates a sensitivity analysis alongside energy, exergy, environmental, and economic assessments. The energy and exergy efficiencies, as determined by the thermodynamic analysis, are 30.87 % and 48.61 %, respectively. Additionally, according to the economic study, the levelized energy cost amounts to 16.65 $/MWh, demonstrating a substantial reduction of 87.6 % compared to the power generation mode. One notable merit of the suggested system lies in its zero CO 2 footprint framework, showing a noteworthy supremacy when compared with previous studies. [Display omitted] • Simulating a novel eco-friendly CCHP process using geothermal energy and CO 2 recovery. • CO 2 hydrogenation via cryogenic process and water electrolysis for methanation process. • Using Aspen HYSYS for simulation and conducting thermo-enviro-economic analysis. • The whole system exhibits energy and exergy efficiencies of 30.87 % and 48.61 %. • Levelized energy cost equals 16.65 $/MWh; 87.6 % lower than power generation mode. [ABSTRACT FROM AUTHOR]

This article investigates a geothermal energy-based cycle to produce power, cooling, and fresh water, using humidification-dehumidification technology. Energy, exergy, and exergo-economic analysis have been performed for a geothermal cycle and a proposed cycle that is an improvement of the basic cycle. Comparative analysis for the new cycle has been extracted and exergy-economic parameters have also been calculated. Moreover, by using artificial neural network and multi-objective optimization, optimal parameters of the system have been extracted. The primary novel part of this study is that different subsystems combined in a way generate different products and the optimum performance parameters are introduced based on the multi-objective optimization. The obtained results show that the highest exergy destruction is related to heat exchanger 1 (HX1) with a value of 670.5 kW. The proposed system can produce 1.104 kg/s fresh water and its net power production capacity is 2251 kW. Also, the exergy destruction in the proposed system is 964.4 kW higher than the basic cycle. Based on the multi-objective optimization, the optimal point is selected based on the ideal result of 32.35 % efficiency and 2322.32 kW exergy destruction, and the parameter unit cost of product is 8.81 $/kW. • Introduce a new geothermal based system for providing power and refrigeration • Making a comparative analysis of the new introduced system with the basic system • Heat exchanger 1 with 670.5 kW determined as the most irreversible component • Achieving the energy efficiency of 32.35 % with multi-objective optimization [ABSTRACT FROM AUTHOR]

Several reliable and extensively applied traditional geochemical, mineralogical, and petrography methods exist for identifying hydrothermal alteration of rocks. However, many of these methods require tedious and laborious sample preparation and analysis procedures. Therefore, there is a need for faster methods and reliable in their application. Binary diagrams of felsic vs mafic components, Na 2 O content, porosity, and permeability of the rocks are newer methods that are faster in their application and more reliable and have the potential to be considered for this purpose. These methods are successfully applied to the surface rocks of Cerritos Colorados Geothermal Field (CCGF) providing consistent results that are comparable to those obtained by extensively applied and highly reliable mineralogical and geochemical methods. Most of these altered rocks are from the formation of the Post-Tala Quaternary Lacustrine Sediments and are located near the faults and fumaroles. Evaluation of the results obtained by all applied methods confirms that the new methods are easy to measure and reliable, which can be useful as additional tools during the initial stage of geothermal exploration in identifying altered rocks and zones of hydrothermal alteration. Mass change values reveal the highest mobility for the major elements and the lowest mobility for the trace elements in the rocks of the study area. • The mass change values calculated for major, REE, and trace elements indicate a net loss for all elements except one element Ta. • The highest mobility for the major elements and the lowest mobility for the trace elements in the rocks of CCGF. • The new methods can be useful as additional tools during the initial stage of geothermal exploration [ABSTRACT FROM AUTHOR]

Geothermal energy has emerged as a transformative renewable resource in Kenya's energy landscape, offering immense potential for sustainable power generation in the current century. This review paper aims at identifying challenges experienced in geothermal energy in Kenya with environmental and health impacts from the output through a review study. The study used a descriptive systematic approach with consideration of existing relevant journals, Energy Act and policies and other grey reports from international bodies. A total of 132 peer reviewed journal articles were considered in the study depending on the themes considered. Currently, the extraction of geothermal energy is at 889 MW from the potential 10,000 MW from 14 potential sites. The findings from the study show that environmental challenges can be experienced in site preparation, plant construction, during the operation and during the decommissioning. During the process, environmental impacts such as surface disturbance, solid and liquid waste, seismic activities, impact on air quality, air pollution, forest and biodiversity and chemical pollution from waste and surface disruption have been experienced. During the drilling process, the exposure of geothermal fluids leads to fouling of heavy metals and gases potential of health challenges such as eye irritation, respiratory, neurological effects when safe thresholds are exceeded. The findings show that despite the increase in exploration, the health effects remain within the standards set by the WHO. The environmental effects are not widespread, indicating that geothermal energy's impact is manageable and within containable limits. • Geothermal extraction causes environmental issues like waste, pollution, and seismic activities. • Kenya's geothermal potential is 10,000 MW, with current extraction at 889 MW. • Geothermal drilling consumes 2000 l of water per minute, raising contamination concerns. • Geothermal fluids cause microbial-induced corrosion, requiring effective microbial management. • Impact assessments for geothermal projects lack thorough health and long-term community evaluations. [ABSTRACT FROM AUTHOR]

Multi-energy coupling heating and cooling technology is of great significance to the establishment of an environmentally friendly society. In this study, the CCHP+PVCU+GSHP coupling model was used to obtain the optimal configuration scheme of the multi-energy heating and refrigeration system, which includes the cumulative energy supply ratio of the four subsystems throughout the year. We analyzed the hourly optimized operation strategy of the typical day in the heating season and the cooling season, and simulated the hourly mixed operation energy supply mode throughout the year. The contribution of renewable energy in terms of economy and environmental protection was verified through comparison with conventional energy supply methods. The results showed that: in terms of optimized configuration, the capacity configuration of the multienergy heating and cooling system that prioritizes natural gas energy is more balanced. The cumulative heating and cooling power of renewable energy increased from 17,270 kW to 20,881 kW, an overall increase of 20.9%. In terms of optimized operation strategies, the annual cumulative energy supply of natural gas and geothermal energy accounts for up to 70.5%, which is the main energy supply system for the multi-energy heating and cooling system. In the daily hourly power supply, the CCHP system needs to operate all day in the heating season. The average heating capacity is about 1,800 kW per hour. Among the five typical heating and cooling systems, the integrated multi-energy heating and cooling system of geothermal energy + natural gas + solar energy has the best overall performance. [ABSTRACT FROM AUTHOR]

The Acoculco Caldera Complex is considered a promissory hidden high-temperature geothermal system in Mexico. To support the geothermal prospection of this anomalous area, a comprehensive programme of soil CO 2 flux measurements was performed. A long-term measurement programme was conducted to determine the baseline of natural soil CO 2 effluxes. Significant efforts were devoted both to measuring the CO 2 fluxes between 2015 and 2022 and interpreting their origin. Eighteen soil gas surveys of CO 2 were carried out by using the accumulation chamber method. >1200 diffuse CO 2 fluxes were measured in six different areas of the Acoculco Caldera. Two areas (Los Azufres and Alcaparrosa) exhibited cold degassing sites, acid-sulphate springs, and gas bubbling in surface water bodies. The soil CO 2 fluxes ranged from 1 to 26,000 g m−2 d−1, whereas lower fluxes <29 g m−2 d−1 were determined as the degassing baseline. A total CO 2 output of 492 t d−1 km−1 was estimated using an integrated SGS-GSA approach, where the highest total soil CO 2 fluxes were obtained for Alcaparrosa (299 t d−1 km−2) compared with Los Azufres (164 t d−1 km−2), and Surroundings (29 t d−1 km−2). Such results agree well with those values measured in other worldwide volcanic and active geothermal ecosystems. The range of CO 2 isotopic composition values from −28.83 ‰ to −3.11 ‰, together with their statistical distribution, suggests multiple CO 2 production sources feeding soil degassing. The combined interpretation of flux and isotopic data allowed us to identify two distinct gas sources: endogenous and biogenic. The present study highlights the importance of using soil CO 2 monitoring to determine baseline emissions at the early exploration stage of geothermal systems. • A long-term measurement programme was conducted to determine the baseline and origin of natural soil CO 2 effluxes. • A maximum threshold of 64 g m-2d-1 was suggested for the degassing baseline in the Acoculco Geothermal System. • Three geochemical groups were consistently identified by applying the GSA method. • The Alcaparrosa zone was the largest source of CO 2 fluxes in the Acoculco geothermal system. • The total emission of the Acoculco geothermal system was estimated at 492 t d-1 km-2. [ABSTRACT FROM AUTHOR]

As a domestic and non-intermittent resource, geothermal energy offers countries a clean and sustainable energy option while setting their energy mix strategies. Turkiye, endowed with rich energy fields, stands out as one of the fastest-growing countries in geothermal energy. The dramatic installed power capacity increase and significant expansion in the geothermal energy market, particularly after 2010 following the initiation of the incentive scheme, are pretty remarkable. Nonetheless, it is also evident that geothermal energy investments in the country have shown a decreasing trend in recent years. At this point, this paper aims to reveal the opportunities and challenges in the development of geothermal energy as the first comprehensive qualitative analysis for Turkiye. Furthermore, it evaluates the diffusion of geothermal energy in Turkiye based on the Technological Innovation Systems (TIS) framework to gain insight into the Turkish geothermal sector. According to the interviewees, financial and political barriers such as high investor costs, insufficient incentives for power generation, and the lack of incentives for direct utilization, along with lengthy and exhausting permitting processes, still hinder the prevalence of geothermal energy utilization in the country. Respondents find that Geothermal suggests a huge opportunity for the Green Energy transition in Turkiye and aids economic development through increases in employment opportunities and household welfare using combined uses in district heating, electricity, and greenhouse usage. • Geothermal energy is essential in Turkiye's' green transition to net zero. • Semi-structured interviews are conducted to identify opportunities and challenges of geothermal energy in Turkiye. • The main challenges are financial and political barriers along with lengthy and exhausting permitting processes. • Geothermal energy suggests a considerable opportunity aiding economic development through increases in employment opportunities and household welfare. [ABSTRACT FROM AUTHOR]

Geothermal heat exchanger (GHE) can be used in energy system for greenhouse gas reduction, which has been recognized as one of important devices for renewable energy application. In order to enhance the GHE heat transfer efficacy, various nanomaterials are employed as the thermal fluids and the backfill materials in the energy systems. As a result, this paper reviews and summarizes the state-of-the-art of the GHEs with different nanomaterials (such as carbon nanotubes, graphene nanoplatelets, graphene oxide, silver, copper oxide, titanium dioxide, aluminium oxide and silicon dioxide suspended in based-fluid) and their ground tube configurations (like serpentine tube, spiral coil tube, twisted tape coil tube, swirl coil tube, tree-shaped bifurcation tube, louvered winglet tapes tube, coiled flow inverter tube and centre tapered wavy tape tube). Some critical aspects concerning influences of nanomaterial size, volume fraction, stability and sedimentation, and compatible base fluid and thermal properties on pumping power, soil temperature fluctuation, and heat transfer coefficient of the GHEs system, are produced for ameliorating geothermal energy system efficiency. Additionally, the effects of the ground buried tube structure on the GHEs system pressure drop, entropy production and long-term continuously operating are explored. Finally, the viewpoints, advices and future studies regarding the GHE corrosion and erosion, nanoparticle migration, magnetic and biological nanofluids utilizations, are deliberated to conquer the obstacles and challenges for the actual application. Hence, this comprehensive review will be beneficial for researchers, engineers and academics to comprehend the remarkable impact of various nanomaterials on heat transfer in the GHEs system. [Display omitted] ● The applications of various nanomaterials in geothermal heat pump systems are investigated in detail. ● Various parameters affecting the performance of geothermal heat exchangers are analysed. ● Various pipe arrangements within the geothermal heat exchangers are highlighted. ● Tackling the economic-policy-environmental-legal effects would pave way for widespread utilizations. ● Future uses of magnetic and biological nanofluids within the geothermal heat exchangers are clarified. [ABSTRACT FROM AUTHOR]

The North America CO 2 Storage Atlas is based on criteria for maximizing safety and minimizing costs. In Mexico, tectonically stable sedimentary basins on the East portion of the country have been identified as potential sites for carbon storage. Here we depart from this view to look into what high heat flow and tectonically active areas can offer to geological carbon storage. We present a Reactive Transport Numerical model to assess the effect of injecting 20 kg/s of CO 2 during 10 years in a sedimentary formation related with the origin of Baja California peninsula. The numerical scheme evaluates the flow regime and chemical changes during injection and up to 500 yr ahead. The conceptual model is built on field evidence of the so-called pre-Comondu sandstones, as documented from geothermal exploration of the Las Tres Virgenes geothermal field. The geochemical composition of the target reservoir is described from available petrophysical studies. The initial speciation of the water residing in the formation is modeled from batch (static) water-rock simulations based on NaCl solutions, since direct analysis is not available. Three fluid speciations are numerically obtained considering three different concentrations of NaCl in order to analyze the sensitivity of the result to this variable. Results show that after 500 yr 84% of the injected CO 2 is already mineralized, mainly in the form of calcite, and dawsonite and siderite to a lesser extent. CO 2 migration and mixing – flow system – are controlling factors for mineralization since they define the extension of a low pH zone in the reservoir, that in turn triggers reactions. • Opportunities for geological sequestration of CO 2 in Mexican geologic settings. • Numerical assessment of geological sequestration of CO 2 in two dimensions in high heat flow areas. • Evaluation of salinity of reservoir fluid in the mineral carbonation capacity of a sandstone reservoir. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) capture, utilization, storage (CCUS), and High-temperature aquifer thermal energy storage (HT-ATES) have been considered as effective advanced techniques that could remarkably contribute to renewable energy and mitigating global warming. Thus, this study tries to combine these two concepts. We investigate the potential for storing & extracting the heating from deep aquifers by utilizing CO 2 as a working fluid. To compare the performance of CO 2 and traditional HT -ATES working fluid water (H 2 O), two parallel HT-ATES cycling simulations are employed in DuMux based on a real geology model, identical well doublet design, and pump performance to test the behavior of H 2 O HT-ATES and CO 2 HT-ATES. The 30 years cycling simulation shows CO 2 HT-ATES have similar reliable performance to H 2 O HT-ATES, but there is some difference worth noting: The traditional H 2 O HT-ATES (76–90 °C) have a higher and more stable extract temperature than CO 2 HT-ATES (73–90 °C) because of water heat capacity is larger. The CO 2 HT-ATES (27.3–28.3 kg/s) have higher flow rates than H 2 O HT-ATES (20.8–24.3 kg/s) since the viscosity difference. The CO 2 HT-ATES could form the CO 2 gas cap, thermal conduction and convection to the caprock less than H 2 O HT-ATES, which leads to less heating loss during the heating store stage. H 2 O HT-ATES (4000 TJ) have more total energy input/output volume than CO 2 HT-ATES (3000 TJ), but the energy efficiency of CO 2 HT-ATES (92 %) is superior to H 2 O HT-ATES (85 %). Besides, CO 2 HT-ATES can sequester a certain amount of CO 2 yearly, over 1.6 Mt CO 2 will be sequestered in the aquifer after 30 years of operation. • Using CO 2 as a working fluid to drive the High-temperature aquifer thermal energy storage. • CO 2 HT-ATES performs similarly in the heating stored & extract process just as H 2 O HT-ATES. • CO 2 HT-ATES have better performance at production flow rate and energy efficiency. • CO 2 HT-ATES could sequester a certain CO 2 annually. • CO 2 HT-ATES have the potential to be a heating solution for arid regions. [ABSTRACT FROM AUTHOR]

Under the climate change crisis evolving from greenhouse gas (GHG) emissions, society is seeking ways to produce energy with zero or minimal emissions. Currently, carbon capture, utilization, and storage and low or zero emission renewable energy sources are options that are being considered to reach our goals to constrain global warming. Optimal technologies would be those that both sequester GHG and generate energy, for example, combined geothermal energy production with carbon dioxide sequestration. Here, we expand on previous work on carbon dioxide plume geothermal processes where we examine the potential to combine both underground CO 2 sequestration and geothermal energy harvesting from the low temperature (∼100 °C) and low permeability Basal Cambrian Sandstone Unit in Alberta, Canada. In the proposed process, carbon dioxide injection is used to produce hot brine to surface with the goals of keeping the carbon dioxide sequestered while realizing geothermal energy at surface. Consistent with prior work, the results from our study confirm that both CO 2 sequestration and geothermal operation is possible and could have commercial value and environmental benefits. • Net zero greenhouse gas (GHG) emissions energy systems are needed. • Examine combined GHG sequestration and geothermal heat extraction operation. • Geothermal system examined is the Basal Cambrian Sandstone Unit in Alberta, Canada. • CO2 injection used to produce hot water to surface while sequestering all CO2. • Results demonstrate that both CO 2 sequestration and geothermal operation possible. [ABSTRACT FROM AUTHOR]

Abstract Thought a waste heat recovery system is one of key technologies for sustainable energy, the initial cost of the system is too expensive to introduce for small and medium-sized companies, such as a Japanese hot spring inn. Since the cost for research and development accounts for a large share of total cost of the system, the cost can be reduced if the system is composed of mass-produced commercial components. In this study, an analytical result and an experimental result for two waste heat recovery cycles composed of components dismounted from a commercial heat pump unit are shown. In the analytical study about a supercritical CO 2 Rankine cycle, the thermal efficiency of the cycle was calculated to be 6.77 % if it could be assumed that all of the components delivered the equal performance compared with the original heat pump system. In the experimental study about the Organic Rankine Cycle (ORC) with R245fa which uses the fin-tube heat exchanger dismounted from the heat pump, we found that the air cooled fin-tube heat exchanger performed well at the room temperature and this ORC system had an ability to generate the small amount of positive power from the exhaust heat from hot spring water. [ABSTRACT FROM AUTHOR]

Abstract The interest in harnessing renewable sources of energy for space heating in residential applications has increased in recent decades due in part to their cost benefits and an increase in environmental awareness. The proposed system uses shallow ground as an energy reservoir; able to absorb heat during the summer and release it during the winter respectively. This paper presents by means of a mathematical model an analysis of such a system using real temperature profiles and compares them to idealized fitted functions. A validated two-dimensional multiphase model describing mass, momentum, turbulence and conjugate heat transfer between the bayonet tube and the ground is used to compare the effects of using a simplified fitted function to represent the ambient temperature with that of hourly temperature readings from a weather monitoring station. The results indicate that the strong random nature of the temperature variations complicates the analysis. It is shown that fitted functions can over predict the overall performance of the system, however under-predict the performance on the short term due in part to cold snaps, heat waves and variations in temperatures. While the benefits and capabilities of the system under real loads show the potential of the system, work on thermal buffering or real-time intelligent control systems for quality control will be necessary to maintain constant temperature for thermal comfort and optimum energy extraction. [ABSTRACT FROM AUTHOR]

Abstract The geothermal water reinjection temperature should keep at a high level to avoid silica oversaturation but the permissible reinjection temperature varies with geothermal source characteristics. The reinjection temperature directly affects geothermal source and working fluid temperature profiles, and then affects the organic Rankine cycle (ORC) thermodynamic performance. This work optimized the evaporation temperatures for dual/single-pressure ORCs using isopentane as working fluids to maximize the net power outputs and analyzed the effects of the reinjection temperature on ORC thermodynamic performance. The net power output of a dual-pressure ORC decreases with increasing permissible reinjection temperature. The low-temperature geothermal heat can be more efficiently used by a low-pressure evaporation in a dual-pressure ORC than a single-pressure ORC, but the benefit in power output for a dual-pressure ORC over a single-pressure ORC is lower for higher reinjection temperatures. The evaporation exergy destruction rates for dual-pressure ORCs are considerably lower than single-pressure ORCs for higher reinjection temperatures and geothermal water inlet temperatures. [ABSTRACT FROM AUTHOR]

Abstract To expand the application range of medium-low temperature geothermal water, a high temperature heat pump system with refrigerant injection technique for steam generation is developed. Four working fluids of R123, R141b, R245fa and R1234ze(Z) used in the high temperature heat pump cycle are analyzed and evaluated. Besides, the effects of evaporation temperature, injection ratio of the compressor and condensation temperature on the system performance are also discussed. The results of thermodynamic analysis indicate that the system obtains the optimal performance when uses R141b as working fluid. As the evaporation temperature is 55oC, the condensation temperature is 125oC and the flash evaporation temperature is 100oC, the COP of the system reaches 3.8 and the steam mass per kWh (MkW) is 1.4 kg/kWh for R141b. [ABSTRACT FROM AUTHOR]

Abstract The cost to implement geothermal energy is extremely high, due to the requirement of drilling production and reinjection wells. One method to overcome this problem is to retrofit abandoned oil wells with a closed loop system, eliminating the need for drilling entirely. This study is conducted to evaluate the heat transfer performance of the wellbore heat extractor with the triangular protrusions. A two-dimensional axis-symmetry computational model for fluid flow and conjugate heat transfer in the wellbore is developed. The effect of protrusion height, pitch and volume flow rate are evaluated and discussed in view of numerical results. The results suggest that triangular protrusions offer higher heat transfer rate. However, careful consideration should be taken as the pumping power required is higher due to higher pressure drop. The outcome of this study provides a new insight into the development of geothermal energy, especially on the utilization of abandoned oil wells. [ABSTRACT FROM AUTHOR]

Abstract The borehole heat exchanger (BHE) has been widely used for geothermal development, but its heat production is limited. To enhance the heat transfer, an open loop geothermal system (OLGS) is proposed to exploit hydrothermal resources. For OLGS, the injection and production intervals are perforated in upper and lower wellbore and an insulated inner tube is installed in the wellbore. The OLGS provides a hydraulic circulation in a single well. The working fluid is injected into the reservoir from the injection interval, then extracts heat from the reservoir, and finally returns to surface through production interval and insulated tube. Currently, few studies were conducted to comprehensively investigate the performance of OLGS. Hence, a 3D unsteady-state numerical model considering fluid flow and heat transfer processes of borehole and reservoir is established. Subsequently, the dynamic response of temperature field, pressure field and velocity field are analyzed. The results indicate that the OLGS has a larger impact scope than conventional BHE, which acquires greater heat extraction performance. And a longer injection interval is beneficial to reduce the injection pressure. Then, the elastic energy plays a remarkable role in the fluid production and the change of reservoir pressure. Furthermore, a high-velocity region occurs near the wellbore, which can lead to the serious thermal breakthrough. Therefore, there is a need to improve the local permeability away from the borehole. The main findings of this study can offer guidance for the optimal design of OLGS. [ABSTRACT FROM AUTHOR]

Highlights • Re-harvest of the heat leaked through the buildings below grade envelope into the ground in urban areas can favorably impact the geothermal energy piles functionality. • If the mitigation methods can be applied for meeting the thermal balance of the ground, geothermal energy piles can be well suited in urban areas. • Length of the piles and the operational strategy of the them can significantly affect the thermal balance of the ground and further efficiency of the geothermal energy piles. • Solar water heater unit (SWHT) can efficiently be used as an auxiliary system which aids meeting the thermal balance of the soil. Abstract In this paper, the performance of a proposed geothermal energy pile system for the energy demand of an institutional building is investigated. The building studied in this research is situated in the Fort-Garry campus of the University of Manitoba in the southernmost portion of Winnipeg (MB) in Canada. In an urban area, underground temperatures are substantially higher than the surrounding rural areas due to the buildings heat leakage to their underneath ground. In this study, this heat loss is harvested through geothermal piles and rejected to the building for the HVAC system utilization. The underground thermal imbalance, which is the most common problem encountered while utilizing the geothermal energy in cold regions, is extensively studied. It is concluded that despite the heat leakage through the basement enclosure, thermal balance of the soil, in case of supporting the total energy demand of the building by geothermal piles, cannot be met. The application of some auxiliary heat sources is proposed. Finally, the amount of energy harvested from the ground is calculated by maintaining the thermal balance of the soil and preventing the freezing at the soil-pile interface which affects adversely the structural performance of geothermal piles. [ABSTRACT FROM AUTHOR]

Highlights • Comprehensive investigation of the geothermal heating and cooling systems. • Recognition and accommodation of factors that can enhance installation soundness of geothermal heating or cooling systems. • Overview of GSHPs and GHEs in the geothermal heating and cooling systems. Abstract Geothermal heat is an energy source that is local, reliable, resilient, environmentally-friendly, and sustainable. This natural energy is produced from the heat within the earth, and has different applications, such as heating and cooling of buildings, generating electricity, providing warm/cold water for agricultural products in greenhouses, and balneological use. Geothermal energy is not dependent on weather or climate and can supply heat and electricity almost continuously throughout the year. It may even be possible to use geothermal projects as "thermal batteries", wherein waste or collected heat is stored for future use, even seasonal use, making geothermal energy "renewable" at a time scale of years. Extensive research has been carried out on different technologies and applications of geothermal energy, but comprehensive assessment of geothermal heating and cooling systems is relevant because of changing understanding, scale of application, and technology evolution. This study presents a general overview of geothermal heating and cooling systems. We provide an introduction to energy and the environment as well as the relationship between them; a brief history of geothermal energy; a discussion of district energy systems; a review of geothermal heating and cooling systems; a survey of geothermal energy distribution systems; an overview of ground source heat pumps; and, a discussion of ground heat exchangers. Recognition and accommodation of several factors addressed and discussed in our review will enhance the design and implementation of any geothermal heating or cooling system. [ABSTRACT FROM AUTHOR]

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In this research paper, the sub-surface heat flow of a part of the Chad Basin, in North eastern Nigerian was estimated using spectral analysis. This was obtained from twenty (20) digitized High Resolution Aeromagnetic (HRAM) data sheet covering the study area. Regional-residual separation using first order polynomial fitting method with three coefficients was carried out on the data map before the application of statistical spectral analysis. Result shows that the centroid depth varies between 9.39 km and 18.31 km. The depth to the Curie temperature isotherm varies between 15.14 km and 33.46 km below the mean sea level. It was also found that the Curie temperature isotherm within the basin is not a horizontal level surface but an undulating surface with geothermal gradients and heat flow ranging between 15.77 and 38.31°C/Km, and 39.41 and 95.77 mwn-2 respectively. Thus, the calculated average geothermal gradient and heat flow for this area are 23.39°C/Km and 58.47mwn-2 respectively. Since average heat flow in thermally normal continental region is 60 mwn-2 and the values in excess of 80 mwn-2 - 100 mwn-2 are associated with anomalous geothermal conditions, hence the study area can generally be considered as a thermally normal region. But, the northeastern part of the study area with values in excess of 80 mwn-2 is recommended for further investigation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • CO 2 and H 2 S mineralization within geothermal reservoir is geochemically feasible. • Carbonates and sulfides form within basaltic to silicic reservoirs in few days. • This abatement method can be scaled up worldwide and over at least 50 years. • The re-injection of CO 2 and H 2 S is five time cheaper than the H 2 S-only abatement systems. Abstract Geothermal fluid utilization is considered one of the green energy sources. Yet, mitigation strategies must be applied to reduce the associated pollutants like carbon dioxide (CO 2) and toxic hydrogen sulfide (H 2 S) emissions. One suggested method is the re-injection of the two gases back into the geothermal reservoir wherein carbon and sulfur are expected to mineralize naturally for a long-term underground storage. However, CO 2 and H 2 S mineralization rates for natural systems are not well defined. To address the feasibility of such sequestration, experiments were conducted at 250 °C for several reservoir rock types, ranging from basaltic to silicic. Analysis of solution composition and secondary mineralogy confirmed the precipitation of Fe-Ca carbonates and Fe sulfide for all the rocks within days. The measured mineralization rates indicate that ∼0.2–0.5 t of CO 2 , and ∼0.03–0.05 t of H 2 S can be sequestrated annually per cubic meter of rock, depending on reservoir lithology and surface area. Calculations show that a total rock sequestration capacity of ∼0.03 km3 would be sufficient to store the annual world CO 2 and H 2 S geothermal emissions. These findings indicate efficient abatement of CO 2 and H 2 S at field conditions, confirming the strategy potential for at least the typical 50 years-lifetime of geothermal power plants. [ABSTRACT FROM AUTHOR]

Abstract Geothermal energy is one of the well-known types of renewable energies that can be considered as a promising alternative to fossil fuels in order to mitigate the CO 2 emission in atmosphere. Geothermal energy has recently been used for heating and cooling systems in many countries of the world. Therefore, studying such kind of energy seems important and necessary. This paper studies the heat transfer processes in a borehole heat exchanger (BHE). The flow of fluid in a BHE has been considered with different geometries and heat transfer processes are modeled numerically and in a finite volume method through convection and conductivity. First, a single U-shaped BHE was modeled and its thermal properties were investigated and then other geometries were studied to obtain the best geometry and heat transfer efficiency. In order to increase the heat transfer in the inner part of the pipes, the fin with the given specifications was used and the modeling was carried out and the thermal parameters were compared for three BHE’s with different geometries. In the final part, optimization results are presented, and the interaction of parameters on the Nusselt number and friction coefficient have been investigated. Also, the desirability of optimization and reliability is given to the results presented in percentage terms. Comparing the results of this article with the results of previous research shows a very good agreement and therefore the applied method is reliable and accurate. [ABSTRACT FROM AUTHOR]

A supervolcanic eruption of 10 15  kg could block the sun for years, causing mass starvation or even extinction of some species, including humans. Despite awareness of this problem for several decades, only five interventions have been proposed. In this paper, we increase the number of total possible interventions by more than an order of magnitude. The 64 total interventions involve changing magma characteristics, venting magma, strengthening the cap (rock above the magma), putting more pressure on the magma, stopping an eruption in progress, containing the erupted material, disrupting the plume, or provoking a less intense eruption. We provide qualitative evaluations of the feasibility and risk of 38 of the more promising interventions. The two most promising interventions involve putting more pressure on the magma and delaying the eruption with water dams or soil over the magma chamber. We perform a technical analysis, accurate to within an order of magnitude, and find that water dams and soil and could statistically delay the eruption for a century with 1 and 15 years of effort, respectively. All actions require essentially untested geoengineering challenges along with economic, political and general public acceptance. Further work is required to refine the science, provide cost estimates, and compare cost effectiveness with interventions focusing on adapting to a supereruption. [ABSTRACT FROM AUTHOR]

A substantial part of the energy demand of residential buildings is due to fossil fuel powered space and domestic hot water heating. Reductions in the energy use of these buildings can be achieved by improving the thermal envelope, installing efficient building energy systems and improving user behavior. Alternatively, it may be possible to use hydro, solar, wind or geothermal to meet the energy demand. This paper presents a study of energy refurbishment measures and a direct geothermal powered district heating system for a neighborhood of existing residential buildings in Groningen, Netherlands. The study uses detailed thermal simulation models that rely on accurate building typologies and thermal characteristics, outdoor air infiltration data and occupant behavior profiles taken from an existing comprehensive survey of Dutch home user behavior. The predicted energy savings and costs show that both the geothermal and the energy refurbishment approaches are economically viable and result in large reductions in the environmental impact of space heating. Applying all refurbishment measures results in an 86% reduction in yearly gas consumption for heating with an investment payback time of fifteen years. The energy refurbishment approach has lower costs and lower financial risk while the geothermal grid has the lowest environmental impact. [ABSTRACT FROM AUTHOR]

The interest in the underground seasonal thermal energy storage system as a renewable energy option for residential applications increases in the recent decades. The system, basically, uses the shallow ground as an energy reservoir that absorbs and release the heat in the hot and cold seasons, respectively. This paper presents, by means of a mathematical model, a novel open-loop ground thermal storage configuration using a network of bayonet tube heat exchangers. A validated two-dimensional multiphase model describing mass, momentum and conjugate heat transfer between a bayonet tube and surrounding ground have been used to study the influence of air inlet velocity and pipe length on the performance of the storage system. The results indicate that the air inlet velocity and the pipe length have proportional and inversely proportional relations with the amplitude of the air outlet temperature, respectively. These parameters, therefore, have a significant impact on the extracted or stored energy in the ground. The benefit of the open-loop storage system conducted here is to predict, prior numerical computation, the important characteristics such as heat transfer, pressure drop, and energy saving, correctly. [ABSTRACT FROM AUTHOR]

Shallow subsurface resources are progressively used for the production of geothermal energy, i.e. for the installation and operation of a broad variety of Geothermal Energy Systems (GES). Additionally, in many urban areas there is a surplus of heat from large buildings and constructions reaching into the groundwater saturated zone. Likewise, groundwater is more often used as a cheap cooling medium. As a result, significantly increased subsurface temperatures have been observed in many urban areas. Several studies investigated how the so-called "Subsurface Urban Heat Island" (SUHI) effect and how current thermal subsurface regimes developed. However, a sustainable management of subsurface resources requires a general understanding on how “current thermal states” of subsurface and thermal regimes developed in context of different urban settings and boundary conditions. These aspects yet are mostly unexplored. In practice mitigation measures are generally taken for individual projects. Thereby, a consideration of the broader context of hydrogeological and thermal processes and boundaries and the interacting thermal activities could lead to a more sustainable use of subsurface energy resources. Besides providing an overview of subjects related to the thermal management of urban subsurface resources this review paper summarizes the results from different research projects that have been realized in the densely urbanised area of Basel in north-western Switzerland. [ABSTRACT FROM AUTHOR]

In order to give reasons for further advanced multi-faceted research of geothermal utilization, geothermal energy utilization and its integration in urban planning in the long run in the City of Nis were analysed. Regional aspect of this utilization is considered, which is novelty in the planning of the city. The arguments are supported by expert opinions on geothermal utilization acquired abroad and in Serbia that suggest geothermal use within proposals for an eco-city. [ABSTRACT FROM AUTHOR]

Due to rising energy demand, the awareness of environmental problems caused by fossil fuels and the aim of reducing greenhouse gas emissions, interest in shallow geothermal use is increasing. The ground source heat pump (GSHP) technologies are favorable owing to its high efficiency and relatively low operating costs. Some researchers have noticed the environmental problems caused by shallow geothermal use; however, most studies focus on open groundwater heat pump systems. The underground environmental risks caused by closed GSHP systems have not been widely concerned. In this study, based on literature review, field investigations and temperature measurements, the potential risks including thermal pollution and groundwater contaminations, and the preliminary solutions to these problems are discussed. The results of this study may help to improve quality and safety controls of GSHP systems and it is also important for sustainable use of shallow geothermal energy. [ABSTRACT FROM AUTHOR]

Analyzed characteristics of heat and moisture transfer and condensation. Deep duct heat and moisture transfer model is established. The function of heat and mass transfer during condensation was added to the corresponding control equation as a source term which took advantage of the user-defined-functions of FLUENT software. The three-dimensional simulation on transient conditions was carried out considering coupled heat and moisture transfer of air in the tunnel. Simulated results with different inlet parameters given show that air temperature difference between inlet and outlet of the tunnel, quantity of condensation and heat flux are all increased as the air inlet temperature rises, while the air temperature difference decreases and the quantity of condensation and the heat flux increase as both inlet relative humidity and velocity increase. Lay the foundation for prediction of temperature and humidity during ventilation, calculation of heat and moisture load, and utilization of geothermal energy in underground constructions. [ABSTRACT FROM AUTHOR]

An ecosystem services perspective can provide a useful means of understanding, in human well-being terms, the type, scale and value of environmental impacts deriving from the deployment of renewable energy technologies. This paper provides the first thematic review of the ecosystem service impacts commonly associated with developing geothermal areas for power projects. In this study, the typical ecosystem service impacts of geothermal power projects are classified using the Common International Classification of Ecosystem Services (CICES) typology. Next, in order to develop a guide for future practitioners, an analysis is conducted of the most suitable valuation methods for the respective ecosystem service impacts. A pluralist approach is advised to aide decision-making, involving the use of monetary and non-monetary information. A number of non-market valuation studies may be required to estimate the total economic value of affected geothermal ecosystems, likely including the contingent valuation and travel cost methods. The more intangible ecosystem services associated with geothermal areas, such as artistic inspiration and landscape aesthetics, are best valued using non-monetary approaches, including deliberative methods. Finally, in recognition of the importance of having a strong physical basis underpinning non-market valuation techniques, this paper critically assesses the merits of the most appropriate data sources for future environmental economists working in a geothermal context. A literature review reveals that neither Environmental Impact Assessments (EIA) nor Life Cycle Analysis (LCA) studies in a geothermal context have embedded an ecosystem service perspective into their processes. EIA are closest to fulfilling the needs of environmental economists, encompassing the majority of ecosystem service impacts, yet further methodological progress is recommended to ensure that all project stakeholders are given voice and arbitrage in the data-gathering process. [ABSTRACT FROM AUTHOR]

The successful exploitation of geothermal energy for power production relies on the availability of nearly zero emission and efficient technologies. Two zero emission flash plant layouts, with full reinjection of the geothermal fluid (non-condensable gas included), are considered. This paper focusses on the CO2 issue, and therefore only the carbon dioxide is considered as non-condensable gas present in the geothermal fluid; the CO2 flow is separated, compressed, and reinjected with the geothermal fluid. Both the reservoir and the power plant are simulated. A first scheme of plant presents a conventional layout in which the CO2 is separated and compressed after the condenser. The second scheme presents a plant layout that allows the separation of the CO2 at higher pressure with respect to the conventional layout, thus reducing the requested power consumption. The conventional plant scheme performs always better at higher temperature and at lower concentration of CO2. The new layout results better for low temperature and higher gas content. [ABSTRACT FROM AUTHOR]

A major component in the transition from fossil to renewable energy is the demand for district heating where geothermal energy can be a substantial option. We present results on the controlling factors for the deep thermal field below a large urban area, the city of Berlin. Therefore we analyze 3D thermal models considering conductive and mixed convective heat transport mechanisms as well as different boundary conditions. Of the controlling factors, heterogeneous thermal and hydraulic physical properties of geological units at different depths are key. That data density decreases with depth poses challenges for model assumptions for which we propose solutions. [ABSTRACT FROM AUTHOR]

Geothermal heat pump is an efficient application derived from geothermal energy. It exploits earth as a heat provenance to extract heat from it and heat space in winter, or it uses earth as heat sink to transform heat to it and cool the space during summer. This paper presents a parametric study to investigate the effects of inlet and outlet water temperatures and ground temperature on the length of the pipe of a horizontal geothermal heat pump system during cooling process. The type of the considered pipe is Poliplex - PE100 Series 1 – polyethylene of 16 mm inner diameter and 20 mm outer diameter. The obtained results revealed that at 30 °C water inlet temperature, 27 °C water outlet temperature and 21 °C ground temperature the length of pipe needed is 716 m. Also, the results showed that higher water inlet temperature and ground temperature increases the required pipe length; however, higher water outlet temperature decreases the needed length of the pipe. [ABSTRACT FROM AUTHOR]

Partnering in Innovation, Inc. (Pi-Innovation) offers a novel aqueous gas separation and carbon capture approach. Specific features in the design uniquely integrate multiple energy recovery processes and the potential for contaminant removal (i.e., oxides of sulphur (SOx), nitrogen (NOx), selenium (SeOx), and mercury (HgOx). CO2-DISSOLVED is an ANR multi-national project led by the BRGM, with Phase II funded as one of the first Geodenergies projects. Phase I explored the techno-economic feasibility of geothermal energy production combined with CO 2 injection using a simplified version of the Pi-Innovation technology. Here we review the Pi-CO2capture process and the integration with dissolved injection applications. [ABSTRACT FROM AUTHOR]