Search Results (1,942)

With the changing picture of global energy supplies and the shift toward the energy transition, it has never been more important to look for alternative sources of energy. Globally there are tens of thousands of abandoned oil fields with considerable reserves left behind. These have the potential to be reactivated to become an energy supply that is cleaner than conventional oil and gas. This can be achieved by the use of in situ combustion and the subsequent exploitation of the inherent increase in temperature and pressure to produce geothermal energy, allied to sequestration of the mixture of produced fluids. In situ combustion (ISC) has conventionally been used as an enhanced oil recovery technique, with a high failure rate that has been recently attributed to poor reservoir selection and project design. We suggest that the failure of many earlier ISC projects is due to insufficient appreciation of how the subsurface geology affects the process. With the use of computer numerical modelling, we aim to ascertain how the geometry and heterogeneity of the reservoir control the success of the process. Here we employ simple three-dimensional sector models to assess a variety of different petrophysical heterogeneities, within a set of different reservoir geometries, on the temperature, velocity, propagation stability and enthalpy rate. These models illustrate that the biggest impact on success of the ISC process for geothermal energy generation, as a function of temperature and enthalpy, is the location of the wells relative to the heterogeneities and the scale of heterogeneities. Metre-scale heterogeneities do not have a significant effect on this. Instead, the biggest contributor to the propagation stability and direction of the fire front is the presence of a large-scale (10 s to 100 s of metres) heterogeneities, such as channels, or the geometry of a tilted fault block; both have a strong control over the direction of the propagation, and therefore are important factors with regards to well placement. Full article

The current demand for heat production via geothermal energy is increasingly rising amid concerns surrounding non-renewable forms of energy. The Dogger aquifer in the Paris Basin (DAPB) in France produces saline geothermal waters (GWs), which are as hot as 70–85 °C, anaerobic, slightly acidic (pH 6.1–6.4), and characterized mainly by the presence of Cl⁻, SO₄²⁻, CO₂/HCO₃⁻, and H₂S/HS⁻. These GWs are corrosive, and the casings of all geothermal wells are carbon steel. Since 1989, these GWs have been progressively treated using petrosourced organic corrosion inhibitors (PS–OCI) at the bottom of the production wells. Currently, there is a great need to test not only new PS–OCIs but also, and above all, biosourced organic corrosion inhibitors (BS–OCIs) to improve the efficiency and environmental friendliness of this carbon-free geothermal energy source. The main objective of this study is to evaluate the potential performance of biosourced corrosion inhibitor candidates (BS–CICs) in terms of their inhibition efficiency (IE) for carbon steel corrosion. This was achieved using a previously established geochemical and electrochemical method to study the mechanisms and kinetics of the corrosion/scaling of carbon steel and optimize short-term corrosion inhibition in standardized reconstituted geothermal water (SRGW) representative of the DAPB’s waters. Four new molecules from the 2-oxazoline family were evaluated individually and compared based on their behavior and inhibition efficiency. These molecules exhibited a mixed nature (i.e., anodic and cathodic inhibitors), with a slight anodic predominance, and showed a significant IE at a concentration of at 10 mg/L during the first hours of immersion of CS-XC38 in SRGW. The average IEs, obtained via the three electrochemical techniques used for the determination of corrosion current densities, i.e., J_corr(Rp), J_corr(Tafel), and J_corr(Rw), are 51%, 79%, 96%, and 93% for Decenox (C10:1), Decanox (C10:0), Undecanox (C11:0), and Tridecanox (C13:0), respectively. Full article

The organic Rankine cycle (ORC) is a valuable method for harnessing low-temperature waste heat to generate electricity. In this study, two dual-pressure auto-cascade ORC systems driven by low-grade geothermal water are proposed in series and parallel configurations to ensure high thermal efficiency and power output. The energy and exergy analysis models for two systems are developed for comparative and parametric analysis, which uses a zeotropic refrigerant mixture of R134a and R245fa. The findings indicate that, with a heat source temperature of 393.15 K, the thermal efficiency and exergy efficiency of the series auto-cascade ORC reach 10.12% and 42.07%, respectively, which are 27% and 21.9% higher than those of the parallel auto-cascade ORC. However, the parallel cycle exhibits a higher net power output, indicating a better heat source utilization. The exergy analysis shows that evaporator 1 and the condenser possess the highest exergy destruction in both cycles. Finally, the parameter analysis reveals that the system performance is affected significantly by the heat source and heat sink temperature, the pinch temperature difference, and the refrigerant mixture concentration. These findings could provide valuable insights for improving the overall performance of ORCs driven by low-grade energy when using zeotropic refrigerant mixtures. Full article

Tibet, with its abundant hydraulic, solar, and wind resources, stands at the forefront of China’s renewable energy development. This paper provides a comprehensive analysis of the current state of clean energy development in Tibet, highlighting the region’s vast potential and the challenges it faces. We find that, while Tibet has made significant strides in harnessing its natural endowments, infrastructural limitations, seasonal fluctuations, and technological hurdles constrain the development of clean energy. This paper offers a multifaceted set of recommendations aimed at accelerating clean energy development in Tibet, including policy reforms, infrastructure enhancements, and technological innovations. Our study’s unique contributions lie in its holistic approach to clean energy development, its detailed analysis of the regional energy policies, and its forward-looking recommendations that balance ecological protection with energy security. By adhering to the principle of ecological priority and conducting innovative research in clean energy development, Tibet can leverage its carbon sequestration capabilities for environmental protection while promoting sustainable economic and social development. This paper provides valuable insights for policymakers and scholars, offering a roadmap for the sustainable development of Tibet’s economy and a reference for similar regions embarking on clean energy transitions. Full article

China’s significant carbon emissions have attracted global attention, and the country has committed to reaching a peak in carbon emissions before 2030 and achieving carbon neutrality by 2060. It is crucial to achieve this goal by effectively controlling the combustion of primary fuels and developing alternative energy technologies. The existing literature has studied the effects of primary energy consumption on CO₂ emissions, alternative energy technology on CO₂ emissions, and energy patents on CO₂ emissions. However, there are few studies on the effects of the relationship between primary energy consumption and alternative energy technology patents. This study analyzes the effects of primary energy consumption and alternative energy patents on CO₂ emission intensity and CO₂ emissions per capita, and their relationship using canonical correlation analysis. Our results are as follows. First, CO₂ emissions from natural gas and liquefied petroleum gas have positive effects (correlation coefficients of 0.102 and 0.275, respectively), while CO₂ emissions from gasoline, fuel oil, diesel, and kerosene have negative effects on CO₂ emission intensity (correlation coefficients of −0.767, −0.420, −0.138, and −0.035, respectively). Second, patents for devices for producing mechanical power from muscle energy have large positive effects on total CO₂ emissions (correlation coefficient of 0.533). Finally, the more the patents utilize waste heat, geothermal energy, hydro energy, and wind energy, the higher the CO₂ emissions from liquefied petroleum gas, gasoline, and crude oil, and the lower the CO₂ emissions from diesel, which are conducive to controlling CO₂ emissions. Therefore, energy policies will be more effective, improve the living environment, and promote sustainable development based on the CO₂ emissions level from primary energy consumption and the control degree of CO₂ emissions by alternative energy. Full article

Shallow geothermal energy (SGE) is a promising green and sustainable energy source, gaining prominence in light of the dual-carbon target. This study investigated the SGE resources in the Yinchuan area. Suitability zones and the potential of SGE resources were determined based on the comprehensive analysis about thermophysical parameters, hydrogeological conditions, and geological environment. Our findings revealed that the effective thermal conductivity in the Yinchuan area surpasses those of other cities, indicating significant potential for SGE. The thermostat layer depth ranges from 40 to 60 m, with a geothermal gradient between 0.81 and 6.19 °C/100 m. Regions with poor adaptability for a borehole heat exchanger (BHE) are mainly distributed in the western and southern parts of the Yinchuan area, whereas moderately and highly adaptable areas are primarily located in the central and eastern areas, respectively. The total geothermal resource of the BHE in the Yinchuan area amounts to 1.07 × 10⁸ GJ/a, generating significant economic benefits of 1.07 × 10⁹ CNY/a and saving 1.09 × 10⁶ t/a of standard coal annually. This initiative leads to significant reductions in CO₂, SO₂, and NOx emissions by 2.61 × 10⁶ t/a, 1.86 × 10⁴ t/a, and 6.57 × 10³ t/a, respectively. Additionally, it results in potential savings of 0.309 × 10⁹ CNY/a in environmental treatment costs. The methods and models used in this study have potential for similar geothermal surveys in arid and cold regions. The results also contribute essential insights for policy formulation and sustainable development strategies related to shallow geothermal resources in the Yinchuan area. Full article

The booming of the building industry has led to a sharp increase in energy consumption. The advancement of zero-energy buildings (ZEBs) is of great significance in mitigating climate change, improving energy efficiency, and thus realizing sustainable development of buildings. This paper reviews the recent progress of key technologies utilized in ZEBs, including energy-efficient measures (EEMs), renewable energy technologies (RETs), and building energy management system (BEMS), aiming to provide reference and support of the wider implementation of ZEBs. EEMs can reduce energy demand by optimizing the envelope design, phase change materials integration, efficient HVAC systems, and user behavior. The renewable energy sources discussed here are solar, biomass, wind, and geothermal energy, including distributed energy systems introduced to integrated various renewable resources and meet users’ demand. This study focuses on the application of building energy management in ZEBs, including energy use control, fault detection and diagnosis, and management optimization. The recent development of these three technologies mainly focuses on the combination with artificial intelligence (AI). In addition, this paper also emphasizes possible future research works about user behavior and zero-energy communities to improve the energy efficiency from a more complicated perspective. Full article

Geothermal energy offers a sustainable way, through heating a salt solution, to generate electricity and extract salt, minimizing environmental impact while supporting clean energy needs. The thermal behavior and vaporization mechanisms of flowing salt solution thin films are investigated in this study using molecular dynamics (MD) simulations. The research focuses on the evaporation dynamics of NaCl solutions at various temperatures (450 K and 550 K) and under different flow conditions, providing insights into the microstructural evolution and the role of ionic interactions. The simulations reveal critical aspects of evaporation, such as the formation and behavior of ion clusters, the impact of temperature on evaporation rates, and the effects of flow on heat transfer efficiency. Key findings include the observation that higher temperatures accelerate the evaporation process and promote ion clustering, while flow conditions enhance heat and mass transfer, leading to more efficient vaporization. These results contribute to a deeper understanding of the thermal dynamics in saline solutions, with implications for industrial processes such as desalination, crystallization, and thermal management. Full article

This study investigates the impact of the Emeishan Large Igneous Province (ELIP) on hydrocarbon formation within the Anyue gas field in the Sichuan Basin. As a major Middle to Late Permian large igneous province, the ELIP hosted intense mantle plume activity that reshaped regional tectonics and thermal structures, indirectly influencing hydrocarbon accumulation. This paper examines three primary factors in hydrocarbon evolution linked to the ELIP: its thermal influence, induced fluid activity, and role in hydrocarbon cracking. Data reveal that the thermal effects of the ELIP extend to the central Sichuan Basin, where an elevated paleogeothermal gradient has driven hydrocarbon evolution in the Anyue gas field. Petrographic characteristics, chronological data, fluid inclusion features, and C–O, S, and Pb isotopic signatures collectively indicate that around 260 Ma, a hydrothermal event occurred in the Sichuan Basin, closely aligned with a natural gas charging event. The combined effects of a heightened geothermal gradient and hydrothermal fluids (with temperatures up to 320 °C) suggest that paleo-oil reservoirs had already cracked into natural gas during the peak ELIP activity. Full article

In many projects, it is important to monitor the direction of groundwater flow, but conventional methods make it difficult. Through streaming potential detection technology, under the action of external pressure, liquid can be forced to flow through solid pores to generate directional flow, and a flow potential can be generated at both ends of solid pores. The phenomenon of different streaming potentials can help engineers determine the direction of fluid flow. In this study, tests were conducted using a core injection system and a streaming potential tester to carry out injections on sandstone samples of two different structures to study the effects of different injection pressures and different salinities on the variation in the streaming potential in sandstone. Moreover, a small-scale field water injection monitoring experiment was also carried out to observe the actual situation of the streaming potential generated during water injection in the field formation structure. The laboratory test results show that the flow potential is accompanied by the liquid injection process in the sandstone sample, and the flow potential produced by the sandstone with different porosities is obviously different, Therefore, the flow potential associated with the actual rock injection process can be used to infer porosity and permeability. This study provides a new method for monitoring underground fluids and is expected to improve the efficiency of oil extraction and geothermal development. Full article

In this paper, a new approach is proposed to improve the performance of the LNG regasification process in a geothermal-transcritical CO₂–LNG cycle by using thermoelectric generators. Energy and exergy analyses were applied to the proposed system and the plant’s performance is compared with the conventional CO₂–LNG cycle. To achieve the optimal solution for the system, a multi-objective optimization technique based on a genetic algorithm is used. This study’s findings revealed that in the conventional CO₂–LNG cycle, the highest exergy destruction occurs in the preheater. However, integrating a thermoelectric generator allows a portion of this destroyed exergy to be converted into power. The proposed system demonstrated 2% less exergy destruction compared to the conventional system. Moreover, the TEG contributes additional power, increasing the net output power of the system by 24%. This improvement ultimately enhances the overall exergy efficiency of the system. The analysis also concluded that, although a lower LNG mass flow rate reduces the system’s net power output, it improves the exergy efficiency. Overall, the proposed system exhibits an 8.37% higher exergy efficiency and a 24.22% greater net output power compared to the conventional CO₂–LNG cycle. Full article

The imperative of achieving net zero carbon emissions is driving the transition to renewable energy sources. However, this often leads to carbon tunnel vision by narrowly focusing on carbon metrics and overlooking broader sustainability impacts. To enable these broader impacts to be considered, we have developed a generic approach and a freely available assessment tool on GitHub that not only facilitate the high-level sustainability assessment of renewable energy projects but also indicate whether project-level decisions have positive, negative, or neutral impacts on each of the sustainable development goals (SDGs). This information highlights potential problem areas and which actions can be taken to increase the sustainability of renewable energy projects. The tool is designed to be accessible and user-friendly by developing it in MS Excel and by only requiring yes/no answers to approximately 60 diagnostic questions. The utility of the approach and tool are illustrated via three desktop case studies performed by the authors. The three illustrative case studies are located in Australia and include a large-scale solar farm, biogas production from wastewater plants, and an offshore wind farm. Results show that the case study projects impact the SDGs in different and unique ways and that different project–level decisions are most influential, highlighting the value of the proposed approach and tool to provide insight into specific projects and their sustainability implications, as well as which actions can be taken to increase project sustainability. Full article

With the advent of the deep mining era, thermal damage in mines has become increasingly significant. The high-temperature environment in underground mines adversely impacts the physiological and psychological health of operators, reduces work efficiency, elevates the risk of accidents, and disrupts sustainable mining operations. Consequently, the development of accurate and reliable methods for classifying thermal hazards is essential for enabling mining enterprises to implement effective prevention strategies. Furthermore, such methods provide a theoretical basis for the sustainable management and utilization of geothermal energy. This study systematically considered factors influencing underground thermal damage and selected 10 quantitative indicators, encompassing both natural and human factors, as evaluation criteria. The CRITIC method was employed to determine the weight of each indicator, which was then integrated with uncertainty measurement theory to develop a novel thermal hazard assessment framework (CRITICUM). This framework enables the classification of thermal hazards in deep mine roadways. The evaluation results generated by the CRITICUM system were subsequently used to train machine learning predictive models. During the training process, the particle swarm optimization algorithm (PSO) was utilized to identify the most suitable prediction model parameters for the complex thermal environment of deep mines by leveraging its capability for continuous iterative evolution. The optimized parameters replaced the original random forest (RF) model parameters, resulting in an enhanced thermal damage prediction model (PSO-RF) with an accuracy of 96.55%, outperforming the standard RF model by 3%. Finally, the prediction model’s accuracy was validated using engineering case data, demonstrating that the results met practical engineering requirements. In summary, the proposed CRITICUM-PSO-RF evaluation and prediction model can accurately classify thermal damage in deep mines and provide a valuable reference for ensuring site safety and supporting the sustainable utilization of geothermal energy. Full article

Geothermal resources are abundant in the Southern North China Basin, which is one of the prospective areas hosting low–medium-temperature geothermal resources in sedimentary basins in China. The purpose of this work is to reveal the formation and storage conditions of the geothermal resources in the western margin of the Taikang Uplift and delineate the range of potential geothermal reservoirs. This paper uses five magnetotelluric sounding profiles for data processing and analysis, including the calculation of 2D skewness and electric strike. Data processing, analysis, and NLCG 2D inversion were performed on MT data, which consisted of 111 measurement points, and reliable two-dimensional resistivity models and resistivity planes were obtained. In combination with drilling verification and the analysis of geophysical logging data, the stratigraphic lithology and the range of potential geothermal reservoirs were largely clarified. The results show that using the magnetotelluric sounding method can well delineate the range of deep geothermal reservoirs in sedimentary basins and that the MT method is suitable for exploring buried geothermal resources in deep plains. The analytical results showed that the XZR-1 well yielded 1480 cubic meters of water per day, with the water temperature of the wellhead being approximately 78 °C, and combined with the results of this electromagnetic and drilling exploration, a geothermal geological model and genesis process of the west of the Taikang Uplift area was constructed. The water yield and temperature were higher than those of previous exploration results, which has important guiding significance for the future development and utilization of karst fissure heat reservoirs in the western Taikang Uplift. Full article

The primary aim of this study is to explore how varying flow rates impact the heat transfer in single fractures, taking into account the effects of surface roughness, aperture and external temperature of the rock. Utilizing COMSOL Multiphysics, the fluid flow and heat transfer through 3D fracture models characterized by different roughness and apertures were simulated with volumetric flow rates ranging from 1 × 10⁻⁶ m³/s to 1 × 10⁻⁵ m³/s. The combined effects of these factors on key metrics, including outlet temperature, thermal breakthrough time, energy extraction efficiency, and heat transfer coefficients were systematically analyzed. The results indicate that water flow rate dominantly influences heat transfer, followed by fracture surface morphology and rock external temperature. Higher flow rates enhance both heat transfer and total heat extraction, while also increasing temperature non-uniformity, which improves overall heat extraction efficiency. Surface roughness significantly affects temperature distribution, leading to heterogeneous thermal profiles, especially in narrower fractures. Additionally, higher external temperatures and flow rates facilitate faster thermal breakthroughs by reducing thermal resistance. The interplay between surface roughness and thermal breakthrough time is intricate, with increased roughness prolonging breakthrough times in smaller apertures but potentially reducing them in larger ones. At smaller apertures, increasing the JRC from 2.29 to 17.33 results in a 1.01 to 1.20 times increase in thermal breakthrough time, whereas at larger apertures, thermal breakthrough time decreases by a factor of 1.01 to 1.29. This highlights the importance of carefully selecting fluid parameter in the design of geothermal projects to optimize heat extraction efficiency. Full article