Search Results (100)

Mining (1) operations in remote areas (2) face significant challenges related to energy supply, high fuel costs, and limited infrastructure. This study investigates the potential for achieving energy independence (3) and resilience (4) in such environments through the integration of renewable energy sources (5) and battery–electric mining equipment. Using the “Studena Vrila” underground bauxite mine as a case study, a comprehensive techno-economic and environmental analysis was conducted across three development models. These models explore incremental scenarios of solar and wind energy adoption combined with electrification of mobile machinery. The methodology includes calculating levelized cost of energy (LCOE), return on investment (ROI), and greenhouse gas (GHG) reductions under each scenario. Results demonstrate that a full transition to RES and electric machinery can reduce diesel consumption by 100%, achieve annual savings of EUR 149,814, and cut GHG emissions by over 1.7 million kg CO₂-eq. While initial capital costs are high, all models yield a positive Net Present Value (NPV), confirming long-term economic viability. This research provides a replicable framework for decarbonizing mining operations in off-grid and infrastructure-limited regions. Full article

Offshore synthetic fuel production and marine carbon dioxide removal can be enabled by direct ocean capture, which extracts carbon dioxide from the ocean that then can be used as a feedstock for fuel production or sequestered underground. To maximize carbon capture, plants require a variety of low-carbon energy sources to operate, such as variable renewable energy. However, the impacts of variable power on direct ocean capture have not yet been thoroughly investigated. To facilitate future deployments, a generalizable model for electrodialysis-based direct ocean capture plants is created to evaluate plant performance and electricity costs under intermittent power availability. This open-source Python-based model captures key aspects of the electrochemistry, ocean chemistry, post-processing, and operation scenarios under various conditions. To incorporate realistic energy supply dynamics and cost estimates, the model is coupled with the National Renewable Energy Laboratory’s H2Integrate tool, which simulates hybrid energy system performance profiles and costs. This integrated framework is designed to provide system-level insights while maintaining computational efficiency and flexibility for scenario exploration. Initial evaluations show similar results to those predicted by the industry, and demonstrate how a given plant could function with variable power in different deployment locations, such as with wind energy off the coast of Texas and with wind and wave energy off the coast of Oregon. The results suggest that electrochemical systems with greater tolerances for power variability and low minimum power requirements may offer operational advantages in variable-energy contexts. However, further research is needed to quantify these benefits and evaluate their implications across different deployment scenarios. Full article

It has been found in engineering practice that the degree of rockburst risk increases when roadway excavation occurs near the stratigraphical boundary of different lithologies. This study uses the 1276 m deep-buried roadway of a lead–zinc mine in Yunnan, China, as its engineering background. Based on a numerical analysis of this case, it investigates the mechanical behavior of surrounding rocks in different lithological formations and explores the causes of excavation-induced rockburst. Additionally, by changing the excavation strategy in a numerical simulation, the influence of the direction of roadway excavation on the degree of rockburst risk in the construction of different lithological formations is assessed. The results are summarized as follows: (1) When the tunnel passes from the C₁b stratum (limestone) to the D₃zg stratum (dolomite), an abnormal stress zone forms in the roof rock strata of the D₃zg stratum (the lower plate of the stratum boundary). The rockburst risk level was evaluated by introducing the numerical rockburst index in this abnormal stress zone, which aligns closely with on-site rockburst investigation results. The rockburst risk is the greatest in the abnormal stress zone, which provides an external energy storage environment for the development of rockburst disasters. (2) Near the stratum boundary, the rockburst risk level when excavating from the D₃zg stratum to the C₁b stratum is greater than that when excavating from the C₁b stratum to the D₃zg stratum. The direction of tunnel excavation significantly affects the rockburst risk level during construction that crosses different lithological strata. These findings can provide a theoretical basis for the construction design of similar underground projects. Full article

Underground mine surveys present unique challenges, including the logistics of deploying an energy source, placing geophones in solid rock, managing reverberation from the adit, and ensuring safety. We present the results of seismic surveying at the historic Deer Trail Mine in south-central Utah (USA). The mine is located along the eastern side of the Tushar Range. The surveys utilised a narrow, mostly horizontal adit, 120–510 m below the ground surface. The country rock consists of highly fractured and mineralised Permian to Pennsylvanian quartzites, shales, and limestones. A short test of a 96-channel common midpoint (CMP) P-wave profile was conducted using an accelerated weight-dropper source. We supplemented the P-wave survey with tests of surface-wave dispersion and horizontal-vertical spectral ratio modelling for shallow S-wave structure. These tests confirmed the capability to map shallow, small-scale structure. A conventional CMP 264-channel survey with an explosive source covered 1728 m. A static recording array was used for both surveys with 4.5-Hz vertical geophones. The conventional CMP profile imaged horizontal and dipping reflectors down to about 2000 m, interpreted as lithologic variations in the bedrock. Our study demonstrates the potential for high-resolution seismic exploration in an unconventional and challenging setting to guide the exploitation of deeply buried mineral resources. Full article

The inspection of sewer pipes in the UK is costly, and if not inspected regularly, they are costly and disruptive to repair. This paper presents the Mega-Joey, a novel miniature, tether-less robot platform that is capable of autonomously navigating and assessing confined spaces, such as small-diameter underground pipelines. This paper also discusses a novel decentralized event-based-broadcasting autonomous exploration algorithm designed for exploring such pipe networks collaboratively. The designed robot is able to operate in pipes with an inclination of up to 20 degrees in dry and up to 10 degrees in wet conditions. A team of Mega-Joeys was used to explore a test network using the proposed algorithm. The experimental results show that the team of robots was able to explore a 3850 mm long test network within a faster period (36% faster) and in a more energy-efficient manner (approximately 54% more efficient) than a single robot could achieve. Full article

To enhance the efficient development of geothermal energy, this study investigates the heat transfer enhancement mechanisms in medium-depth coaxial underground heat exchangers (CUHEs) integrated with corrugated fins, using computational fluid dynamics (CFD) simulations. Nine distinct corrugated fin geometries were modeled, and the streamlines, velocity fields, temperature fields, and turbulent kinetic energy were analyzed across Reynolds numbers (Re) ranging from 12,000 to 42,000. The results demonstrate that corrugated fins significantly promote fluid turbulence and mixing, thereby augmenting convective heat transfer. Compared to smooth inner tubes, the Nusselt number (Nu) is enhanced by a factor of 1.43–2.19, while the friction factor (f) increases by a factor of 2.94–6.79. The performance evaluation criterion (PEC) improves with increasing fin width and decreasing fin spacing. The optimal configuration, featuring a fin width of 15 mm, a spacing of 60 mm, and a thickness of 15 mm, achieves a maximum PEC value of 1.34 at Re = 12,000, indicating a substantial improvement in heat transfer performance within acceptable pressure drop limits. This research innovatively explores the performance enhancement of CUHEs at high Re, systematically elucidates the influence of geometric parameters on heat transfer and flow resistance, and employs the PEC index to optimize the structural design. This provides significant theoretical support for the efficient engineering application of CUHEs in geothermal utilization. Full article

Geothermal resources represent one of the most vital renewable energy sources, offering substantial development potential within the energy sector. Wudalianchi, renowned as one of China’s prominent volcanic clusters, has undergone extensive underground volcanic activities, suggesting a promising capacity for geothermal resource accumulation. This paper is the first to apply the cross-gradient gravity-magnetic joint inversion method to study the shallow structures in the Laoheishan Volcano and surrounding areas of Wudalianchi, based on high-precision measured gravity and magnetic data. The inversion results indicate the presence of a rock body at a depth of approximately 2 km beneath the Laoheishan and Bijiashan regions, which simultaneously exhibits characteristics of low density, high magnetization, and low seismic velocity. Integrating previous research findings, the rock body is interpreted as basalt formed during magmatic activity, retaining remanent magnetism. Furthermore, the rock body contains fractures filled with fluids, thereby excluding the possibility of a shallow magma chamber or dry hot rocks beneath the Laoheishan area. These rock bodies are interconnected at depth and align with the NE and SE fault directions in the Wudalianchi area, confirming that these faults govern the region’s volcanic activities. The inversion results, from the perspectives of density and magnetic susceptibility, elucidate the material distribution in the shallow subsurface of the Laoheishan and surrounding areas, providing new evidence for further exploration of geothermal resources in the region. Full article

The Yinchuan Basin harbors significant geothermal resource potential and could be a clean energy source critical for transitioning to a low-carbon economy. However, the current research primarily focuses on the exploration and development of geothermal water in the sedimentary basins, with limited studies on the deep geothermal formation mechanisms and regional geothermal types. Although geophysical methods provide insights into the types and formation mechanisms of deep geothermal resources in the basin, there is still a lack of a connection between quantitative understanding and direct evidence. A series of algorithms based on thermal parameter characteristics can directly extract underground thermal features from raw geophysical signal data, offering a powerful tool for characterizing the structure and aggregation patterns of deep thermal sources. Therefore, this study employed a Bayesian thermal parameter inversion method based on interface information to obtain the spatial distribution of thermal conductivity, surface heat flow, and mantle heat parameters in the Ningxia Basin study area. Additionally, correlation analysis and global sensitivity analysis were conducted to further interpret the predicted results. A comprehensive analysis of the geophysical inversion results showed that the deep thermal anomalies in the basin are primarily controlled by fault activities and the lithospheres’ thermal structure, while shallow high-heat flow anomalies are closely related to convective circulation within faults and heat transfer from deep thermal sources. The established geothermal genesis mechanism and model of the Yinchuan Basin provide crucial support for sustainable regional geothermal development planning and the utilization of deep geothermal resources, contributing to energy security and emission reduction goals. Full article

Since the heating and cooling sectors consume most of the energy in Europe through fossil fuels, the transition to a low-carbon and sustainable energy system is crucial. Underground Thermal Energy Storage (UTES) systems, such as aquifer thermal energy storage (ATES) and borehole thermal energy storage (BTES), offer promising solutions by enabling seasonal storage of renewable thermal energy, balancing the mismatch between supply and demand. ATES and BTES systems store excess heat or cold for later use, making them suitable for large-scale applications like residual heat storage from industrial or power generation processes by offering flexibility in heating and cooling. This review explores the geological and hydrogeological requirements for ATES and BTES systems, pointing out the importance of basic geological knowledge, laboratory and field investigations, and operational monitoring to optimize their performance. The study highlights the need for Slovenia to use the experiences of other European nations to overcome initial challenges, develop effective site evaluation methods, and integrate these systems into existing energy infrastructure. Full article

Underground cold storage gives rise to special challenges that require innovative solutions to ensure maximum energy efficiency. Conventional energy systems tend to be based on high energy use, so sustainable solutions are crucial. This study explores the novel idea of biomimetics and how it might be used in the planning and building of underground cold storage facilities as well as other infrastructure projects. Biomimetic strategies, inspired by termite mounds, gentoo penguin feathers, and beehive structures, are applied to minimize reliance on energy-intensive cooling systems. These natural models offer efficient thermal regulation, airflow optimization, and passive cooling mechanisms such as geothermal energy harvesting. The integration of naturally driven convection and ventilation ensures stable internal temperatures under varying conditions. Biomimicry was employed in Revit Architecture, coupled with structural optimization, to eliminate urban space’s limitations and further increase energy efficiency. The analytical work for this paper utilized a set of formulas that represent heat flow, thermal resistance, R-value, thermal transmittance, U-value, solar absorption, and G-value. The results pointed to very good insulation, with exterior walls having an R-value of 10.2 m²K/W and U-value of 0.98 W/m²K. Among the chosen 3-layer ETFE cushion with a U-value of 1.96 W/m²K, with a G-value of 0.50, showed good heat regulation and daylight management. Furthermore, bagasse-cement composites with a very low thermal conductivity of 0.10–0.30 W/m·K provided good insulation. This research proposes a scalable and sustainable approach in the design of underground cold storage by merging modelling based on Revit with thermal simulations. Biomimicry has been demonstrated to have the potential for changing subterranean infrastructure, conserving energy consumption, and creating eco-friendly construction practices. Full article

Methane emissions from coal mining remain a significant environmental challenge in the European Union, particularly in the context of climate change commitments and the ongoing transformation of the energy sector. This article analyses methane emissions from surface and underground coal mining, distinguishing between emissions from mining activities, abandoned underground mines, and post-mining activities. A key aspect of the analysis is the methane emissions per 1000 tonnes of lignite and hard coal mined, which allows a comparison of emission intensities between different mining methods. Between 2009 and 2021, methane emissions from coal mining in the EU decrease, with reductions of 2436 kt CO₂ eq. (87 kt CH₄) from surface mining and 16,518 kt CO₂ eq. (590 kt CH₄) from underground mining. However, total methane emissions in 2021 still amount to 25,414 kt CO₂ eq. (908 kt CH₄), with underground mining contributing 84.7% of the emissions. Discrepancies in national emissions reporting and the lack of transparent data on methane emissions from imported coal make accurate assessments difficult. Strengthening international cooperation, improving data transparency, and exploring methane recovery for energy use are essential steps towards achieving the EU’s climate change objectives. Full article

Salt caverns are recognized as an excellent medium for energy storage. However, due to the unique characteristics of China’s bedded salt formations, which contain numerous salt layers and a high concentration of insoluble impurities, significant accumulation at the bottom of salt caverns occurs, leading to the formation of extensive sediment voids. These sediment voids offer a potential space for underground oil storage, referred to as sediment void oil storage (SVOS). Oil recovery process from these sediment voids is a critical process. This paper summarizes the oil recovery technologies for SVOS and identifies four key factors—geological evaluation, stability evaluation, tightness evaluation, and oil storage capacity—all of which influence enhance oil recovery from sediment voids. This paper also outlines the overall oil recovery process, presents oil recovery experiments, and discusses oil recovery methods for enhancing oil recovery from sediment void. Additionally, it addresses the challenges of oil recovery in SVOS and explores its potential advantages and applications. The findings suggest that salt cavern sediment voids, as a promising storage space, provide a new approach to realize oil recovery and can overcome the limitations associated with cavern construction in high-impurity salt mines. The oil recovery from the sediment void is feasible, and China has rich rock salt and other convenient conditions to develop SVOS technology. Full article

This paper explores the innovative application of Geographic Information Systems (GISs) to identify and utilize waste heat sources from railway and highway tunnels for fifth-generation district heating and cooling (5GDHC) systems. Increasing the number of prosumers—entities that produce and consume energy—within 5GDHC networks enhances their efficiency and sustainability. While potential sources of waste heat vary widely, this study focuses on underground car/railway tunnels, which typically have a temperature range of 20 °C to 40 °C. Using GIS software, we comprehensively analyzed tunnel locations and their potential as heat sources in Belgium. This study incorporates data from various sources, including OpenStreetMap and the European Waste Heat Map, and applies a two-dimensional heat transfer model to estimate the heat recovery potential. The results indicate that railway tunnels, especially in the southern regions of Belgium, show significant promise for waste heat recovery, potentially contributing between 0.8 and 2.9 GWh annually. The integration of blockchain technology for peer-to-peer energy exchange within 5GDHC systems is also discussed, highlighting its potential to enhance energy management and billing. This research contributes to the growing body of knowledge on sustainable energy systems and presents a novel approach to leveraging existing district heating and cooling infrastructure. Full article

This paper investigates the flow performance and mechanical properties of underground gelled filling materials made from potash mine tailings, using lime as a gel. It demonstrates the feasibility of using lime as a gel, potash mine tailings as aggregate, and replacing water with potash mine tailings to create filling materials that meet design requirements for flow and compressive strength. The role of lime in the hardening process is explored through X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and infrared analysis. Results show that hydration products vary with lime dosage. With 9% lime (L9), the products are primarily ghiaraite (CaCl₂·4H₂O) and carnallite (KMgCl₃·6H₂O); with 5% lime (L5), tachyhydrite (CaMg₂Cl₆·12H₂O) predominates, along with minor amounts of antarcticite (CaCl₂·6H₂O) and korshunovskite (Mg₂Cl(OH)₃·4H₂O); and with 2.6% lime (L2.6), the products include tachyhydrite, ghiaraite, bischofite (MgCl₂·6H₂O), and korshunovskite. These hydration products form a dense, interwoven structure, enhancing the strength of the filling material. This study offers a theoretical foundation for using lime gel as a filling material in potash mining, with significant implications for sustainable mining practices. Full article

This study investigates innovative solutions for balancing energy supply and demand using long-term thermal energy storage (TES) systems, with a focus on tank thermal energy storage (TTES) for European buildings, which account for approximately 40% of energy consumption in the European Union. Research conducted at the Technical University of Košice explores the potential of TTES systems for efficient and long-term energy storage. The accumulation is carried out in three existing underground tanks of different volumes. Among various outputs, we present the cooling process resulting from covering the water surface and the effect of tank size on cooling. The findings indicate that covering the water surface in the tanks can effectively double the energy retention time, thereby extending the cooling period. A tank with a larger volume cools slower and better ensures the formation of temperature layers. Temperature layering allows for better utilization of the tanks’ potential in terms of energy. The overall result is a significant reduction in heat losses and CO₂ emissions. These results demonstrate the critical role of TTES in stabilizing renewable energy sources, especially solar energy, to support sustainable energy solutions in buildings by providing reliable and long-term energy storage. Full article