Energy Extraction Research Articles

Energetics of magnetized Kerr-MOG and Kerr-Taub-NUT black holes within magnetic Penrose process

In this research paper, we have examined the impact of a gravitomagnetic charge on extracting energy from a rotating Kerr-Taub-NUT black hole and Kerr-MOG (MOdified Gravity known as Scalar-Tensor-Vector-Gravity (STVG)) black hole embedded in the magnetic field via the magnetic Penrose process (MPP). Our findings demonstrate that the gravitomagnetic monopole and MOG parameters both significantly influence the extraction of energy from a rotating black hole, exceeding the MPP for the Kerr black hole in terms of energy efficiency. After comparing the results of this study with the observational data, we were confident that our findings on the amplification of MPP by MOG and NUT parameters are nearly in line with the observations of ultrarelativistic particles in the cosmic rays.

Investigation of role of fins in a Francis turbine model's cavitation-induced instabilities under design and off-design conditions

Harnessing hydraulic energy for power generation using Francis turbines presents formidable downstream swirl instabilities, which can lead to pressure surges at part load (PL) conditions. Cavitation-induced issues affect not just the PL operations but also the power generation at the best efficiency point (BEP). To combat these challenges, fins strategically placed on the draft tube (DT) periphery aid in low-pressure recovery, which suppresses the hurdles for stable energy extraction. This ongoing study delves deep into the internal flow dynamics of the turbine, considering various Thoma numbers, and evaluating the impact of fins. The investigation employs numerical simulations utilizing structured and unstructured grids, incorporating the Shear Stress Transport (SST) model and the Rayleigh-Plesset model to model turbulent flow in a two-phase mixture. Preliminary findings reveal that at PL, the presence of fins substantially reduces low-pressure zone formation, minimizing vortex ropes and associated instabilities. The fins positively influence axial velocity, reducing swirl intensity and mitigating pressure pulsations by 60 % at PL. Conversely, at the BEP, the impact of fins appears less pronounced, with zero detrimental effect. In conclusion, with no negative effect at BEP, the incorporation of fins enhances the turbine's operational range and ensures smoother and more stable energy production at PL.

Analisis Ukuran Partikel Nanosilica Pada Proses Alkali Fusion Silica Scaling Geotermal Dieng Menggunakan KOH

One of the characteristics of the Dieng geothermal field is the high silica content in the production fluid which causes the appearance of silica scaling. The presence of silica scaling inhibits the energy extraction process and becomes waste that disturbs the environment. The silica scaling can be utilized as a nanosilica product for use as a reinforcing filler. Nano-sized powder is expected to improve the mechanical properties of a product with denser results. This research aims to synthesize nanosilica from geothermal scaling silica using the alkali fusion method. Nanosilica is obtained by reacting alkali KOH with silica scaling which has been reduced in size using ball milling. The fusion process is carried out using heat treatment at varying temperatures of 400, 450 and 500ºC. The fusion results were dissolved in distilled water for titration using 2M HCl with stirring using a magnetic stirrer until gelation was formed which was dried into silica nanoparticles. Characterization of the size of nanosilica powder using the Particle Size Analyzer (PSA) obtained the smallest size data at a fusion temperature of 400ºC with the size tending to increase as the fusion temperature increased, where these results were in line with the analysis of nanosilica images from Transmission Electron Microscopy (TEM) testing using ImageJ software. Compound analysis using Fourier Transform Infra-Red (FTIR) shows the presence of characteristic silica bonds. The results of X-Ray Diffraction (XRD) do not show sharp peaks so the compound has an amorphous phase.

The particle dynamics around rotating charged black holes with Weyl corrections

In this article, particle dynamics around charged rotating black holes with Weyl corrections is discussed. First, the metric is studied for its horizon structure and scalar curvature invariants. The effects of Weyl corrections on circular motion of the particles is analyzed around central object. We have shown dependency of effective potential, energy, angular momentum and inner most stable circular orbits on black hole parameters. We have also determined center of mass energy expression for collision of two neutral particles. In the Penrose process of energy extraction, it has been found that efficiency is not that much higher as compared to the other modified rotating black holes.

Energy Harvesting from Water Flow by Using Piezoelectric Materials

As a promising energy‐harvesting technique, an increasing number of researchers seek to exploit the piezoelectric effect to power electronic devices by harvesting the energy associated with water flow. In this emerging field, a variety of research themes attract interest for investigation; these include selection of the excitation mechanism, oscillation structure, piezoelectric material, power management interface circuit, and application. Since there has been no comprehensive review to date with respect to the harvesting of water flow using piezoelectric materials, herein relevant work in the last 25 years is reviewed. To ensure that key aspects of the water‐flow energy harvester are overviewed, they are discussed in the context of energy‐flow theory, which includes the three stages of energy extraction, energy conversion, and energy transfer. The development of each energy‐flow process is reviewed in detail and combined with meta‐analysis of the published literature. Correlations between the harvesting processes and their contribution to the overall energy‐harvesting performance are illustrated, and directions for future research are also proposed. In this review, a comprehensive understanding of water‐flow piezoelectric energy harvesting is provided and it is aimed to guide future research and the development of piezoelectric harvesters for water‐flow‐powered devices is promoted.

Pengaruh Struktur Modal Dan Ukuran Perusahaan Terhadap Nilai Perusahaan Pada Perusahaan Sektor Energi Di Indonesia

The energy company is a sector company that sells products and services related to energy extraction which includes non-renewable energy so that revenue is directly affected by world energy commodity prices such as oil mining, natural gas, coal. The purpose of this study is to determine whether the capital structure of firm size has an effect on firm value. The analytical method used is panel data regression through eviews 12. With this research the researcher used a purposive sampling data collection technique. Purposive sampling is a sampling technique with a certain determination, with a total population of 37 energy sector companies listed on the Indonesia Stock Exchange 2019-2022, and based on predetermined criteria, a sample of 30 companies from the energy sector in 2019-2022 was obtained. The results showed that the variable capital structure (DER) has a negative effect on firm value, while company size (SIZE) has a positive effect on firm value. Simultaneously capital structure and company size affect company value in Energy sector companies listed on the IDX in 2019-2022. The ability of the independent variables to simultaneously explain the dependent variable can be said to be included in the level of a strong relationship and this research model is good.

Impact of well placement on heat production from complex fracture networks in enhanced geothermal systems: A semi-analytical model

Understanding of the effective fracture path between a producer and an injector in complex fracture networks plays a key role in successful geothermal heat extraction from an enhanced geothermal system (EGS). Therefore, there is a need to investigate the impact of well placement on EGS heat extraction performance. An efficient thermal model is developed to simulate fluid and heat flow in fractured reservoirs with complex fracture networks. A general Green's function for fractures oriented at any angle is used, which reduces problem dimensions by one. The effect of fracture types on heat production performance is investigated and the impact of well placement on the efficiency of extracting geothermal energy is demonstrated. Results indicate that the rate of energy extraction depends on the number of backbone fractures connecting the injector and producer, emphasizing the need for well placement that creates more backbone fractures to allow for fluid circulation. These findings provide valuable guidance on well placement strategies to optimize geothermal heat extraction efficiency.

Wavelet Based Energy Extraction Method for Determining Power Quality Disturbances

In this paper, energy of wavelet coefficients are used for determining power quality disturbances (PQD) which are important for power systems. These power quality disturbances are voltage with harmonics, transient and flicker. After analyzing energy coeffients based on wavelet transform, these PQD are compared with healty condition. 50 Hz pure sine is chosen as reference. These signals are generated by using MATLAB. Sampling frequency is 25.6 kHz. Energy distribution of detail coefficients are obtained by using 12 level Daubechies 4 discrete wavelet filter. Parseval theorem is applied to wavelet coefficients for obtaining energy distribution of detail coefficients of these relevant disturbances in different resolution levels. Satisfactory results are taken visually when examining energy distrubutions of these PQD. Also it is observed that these PQD can be distinguished visually when their amplitudes are increased. Energy coefficients of PQD and amplitude of PQD are in direct propotion.

Improvement of the production of bio-oil and biodiesel from Egyptian Jatropha seeds by using microwave and ultrasonic

Bio-diesel is used for engine as a replacement of diesel fuel which is characterized by lower emission, low pollution and renewable some of fuel. This study focus on how to enhance the production of bio-oil from Jatropha seeds by using microwave and ultrasonic as pre-treatments. To achieve that, the effects of extraction temperature (60, 80, 100 and 120 °C) and extraction screw speed (60, 90 and 120 rpm) on oil extraction yield and quality, extraction energy requirements and extraction time and were studied. Studying the effect of pretreatments by microwave and ultrasonic on the yield, energy and time of extraction were studied. The results most important indicate that the highest oil yield (25.1%) was recorded at 120 °C extraction temperature and 60 rpm screw speed. The energy required for extraction ranged from 8 to 11.5 W.h depending on temperature and speed of extraction. The results indicated that using both pretreatments improve the oil yield by 5.03% for microwave and by 6.75% for ultrasonic. Finally, the results concluded that to produce 1 kg of biodiesel you need 1.1 kg raw oil and consume from 2052.5 W.h energy requirement.

Continuum modeling of high-temperature (>1000 °C) heat extraction from a moving-bed oxidation reactor for thermochemical energy storage

There is a growing need for efficient and reliable energy storage technologies to expand renewable energy adoption and transit to a decarbonized clean energy future. Thermochemical energy storage (TCES) through reversible gas-solid reactions has exhibited considerable potential. Up to now, TCES has primarily been studied at the material level and within lab-scale reactors. As such, accurate numerical models are needed for further reactor design and scale-up. In this work, a transient three-dimensional heat and mass transfer continuum model was developed to simulate the transport phenomena coupled with exothermic oxidation of magnesium‑manganese-oxide particles in a high-temperature moving-bed reactor for TCES. The reactor included direct heat extraction at temperatures >1000 °C. The predicted temperature distributions, oxygen concentration profiles, and steady-state reactor energy extraction efficiency were in good agreement with measured values from a corresponding experimental setup. The performance of the reactor was further investigated through two parametric studies (varied particle flow rates and gas extraction ratios), which demonstrated a strong dependence of reactor efficiency (varied between 15 %–40 %) on both operating parameters. The present heat and mass transfer model will be valuable in further reactor design and scale-up studies, as well as for selection of operating conditions to maximize efficiency.

Influence of subsurface temperature on cryogenic fracturing efficacy of granite rocks from Kazakhstan

Liquid nitrogen (LN2) is a new stimulation technology suitable for geothermal energy extraction that increases porosity, permeability, and overall contact area in candidate subsurface formations. It is considered appropriate for hot dry rock (HDR) reservoirs. Due to the significant temperature difference between hot rock and cryogenic fluid, extensive thermally induced cracking is anticipated upon contact, which is helpful in future water-steam cycling operations. To examine the degree of rock integrity failure in granite samples as a function of exposure mode, different procedures were followed for comparison. In particular, three commercial granite samples from three regions of Kazakhstan: Kapal-Arasan, Zhylgyz, and Zheltau, were heated to various elevated temperatures prior to immersion in LN2 with variations in freezing time (FT) and numbers of freezing-thawing cycles (FTC). Samples were examined by various methods to quantify the impact of the cryogenic fracturing process. Compression, acoustic emission (AE), and permeability tests were performed on granite with different starting temperatures ranging from 200 °C to 500 °C. Permeability enhancement was generally in the range of 50-90 %. Scanning electron microscopy (SEM) was also used to document the microscopic characteristics of thermally-induced cracks and indicated most induced fractures to be microscale features. Results showed reductions in Unconfined Compressive Strength of LN2-treated samples by up to 76 %. The experimental outcomes demonstrate that LN2 cooling of hot granite induces mechanical rock failure and permeability augmentation. Furthermore, the degree of thermo-fracturing increases with temperature difference and time of LN2 treatment in both freezing time and freezing-thawing cycle methods. This is the first systematic study of its kind to test three commercially available granites from Kazakhstan with this combination of examination tools to assess alternate cryo-fracturing methods for geothermal energy prospecting and contact area enhancement.

Fuzzy Logic-based Power Optimizer for Solar Photovoltaic Power Systems

Solar photovoltaics has become the most popular renewable energy source due to its simplicity in installation and maintenance. However, the dependence on the availability of solar energy at the instant makes its operation non-linear. Various optimizing solutions are proposed to rule out this disadvantage. This paper dwells on a machine language approach to solve this problem. A maximal tracker for power points relies on fuzzy logic control. An embedded power optimizer is designed and tested under different environmental conditions through simulation. The results presented allow researchers to test various artificial intelligence techniques for renewable energy extraction processes.

Charged Particles Orbiting Charged Black-Bounce Black Holes

The detailed and comprehensive analysis of radiation processes in accretion disks consisting of electrically charged particles around black holes may provide powerful information about the spacetime geometry of the central black hole. We investigate the circular orbits of electrically charged particles around an electrically charged black-bounce Reissner–Nordström (RN) black hole, known as an RN Simpson–Visser (SV) black hole. We also study the profiles of the innermost stable circular orbits (ISCOs), energy, and angular momentum of the particles in their ISCOs, as well as the efficiency of energy release processes in the accretion disk in the Novikov–Thorne model. Finally, we calculate and study the effects of the black-bounce parameter as well as the black-hole charge on the intensity of the radiation of ultrarelativistic charged particles orbiting the charged RN SV black hole along circular orbits and falling into the black hole. It is observed that the black-bounce parameter essentially decreases the ISCO radius, and consequently the energy extraction and intensity of electromagnetic radiation.

Towards real-time optimal control of wind farms using large-eddy simulations

Abstract. Large-eddy simulations (LESs) are commonly considered too slow to serve as a practical wind farm control model. Using coarser grid resolutions, this study examines the feasibility of LES for real-time, receding-horizon control to optimize the overall energy extraction in wind farms. By varying the receding-horizon parameters (i.e. the optimization horizon and control update time) and spatiotemporal resolution of the LES control models, we investigate the trade-off between computational speed and controller performance. The methodology is validated on the TotalControl Reference Wind Power Plant using a fine-grid LES model as a wind farm emulator. Analysis of the resulting power gains reveals that the performance of the controllers is primarily determined by the receding-horizon parameters, whereas the grid resolution has minor impact on the overall power extraction. By leveraging these insights, we achieve near-parity between our LES-based controller and real-time computational speed, while still maintaining competitive power gains up to 40 %.

Efficiently harvesting low-speed wind energy by a novel bi-stable piezoelectric energy harvester from vortex-induced vibration and galloping

Designing low-cost and simple harvesters to convert natural wind energy into electricity is regarded as a promising method to realize the self-powering of node sensors in the Internet of Things. However, the inherent challenge lies in the typically low and fluctuating speeds of environmental wind, making efficient energy harvesting a difficult task. To address this challenge, this study introduces a novel bi-stable wind energy harvester designed to undergo inter-well oscillations through the synergistic effects of vortex-induced vibration and galloping. The bi-stability is achieved by incorporating three magnets. To enhance the extraction of energy from low-speed wind, a square-sectioned bluff body is affixed to the cantilever beam's tip, accompanied by two foam balls. Simulations elucidate the fluid dynamics around the bluff body and foam balls, revealing that the induced vortex causes swinging in the balls, subsequently driving the piezoelectric beam to oscillate and jump. The study establishes the potential energy and force–displacement relationship of the proposed harvester to provide insights into the flow fields. A physical prototype of the harvester is fabricated and subjected to verification experiments in a wind tunnel. Results indicate that the proposed harvester exhibits snap-through or inter-well oscillations, generating a desirable energy output at wind speeds exceeding 1.3 m/s. Notably, even at very low wind speeds, the proposed harvester, despite exhibiting the same intra-well motion as its linear counterpart, achieves significantly higher output voltage due to magnetic interaction and bi-stability. Demonstrating superior performance with a voltage output of up to 10.5 V at a wind speed of 1.6 m/s, compared to the mere 0.7 V from its linear counterpart, the proposed harvester shows the advantages of bi-stability and snap-through motion in low-speed wind energy harvesting.

A Feasibility Assessment of Heat Energy Productivity of Geothermal Wells Converted from Oil/Gas Wells

The mitigation of greenhouse gas emissions necessitates a shift from fossil fuel to environmentally friendly energy, such as geothermal energy. It is advantageous to retrofit end-of-life oil/gas wells for geothermal energy extraction. Prior to repurposing depleted wells into geothermal wells, it is imperative to conduct the heat-energy potential assessment. In this work, an analytical model was developed for this purpose. A case study was conducted using the model and the data from a well in North-west Louisiana for a feasibility assessment. A sensitivity study was performed with the model to identify major factors affecting well productivity. The result of the case study shows that reverse circulation is 35% more efficient than direct circulation for improving the heat-energy productivity of geothermal wells converted from oil/gas wells. The sensitivity analysis revealed that well productivity increases with higher injection rates and greater horizontal wellbore lengths. Additionally, well productivity rises in correspondence with reservoir temperature as well as the temperature of the injected water. However, well productivity decreases as the thermal conductivity of the tubing insulation increases. Counteracting this trend, well productivity increases with thicker tubing insulation layers. This study furnishes engineers with an easy-to-use tool for predicting the heat-energy deliverability of wells converted from end-of-life oil/gas wells.

Geo thermal energy - Clean, safe and renewable - A review study

The rising demand of energy and exhausting sources of fossil fuels has compelled people all over the world towards a renewable, clean energy source i.e. geothermal energy. Geothermal resources are reservoirs of hot water that exist or are human made at varying temperatures and depths below the Earth’s surface. In side the great depths of the Earth, the temperature (1,250 °C) and pressure is sufficient to melt rock into magma which is termed as lava (750°C) once it comes out of the crust. This heat content is harnessed as geothermal energy and utilized for heat applications as well as generation of power. The majority of the world’s geothermal resources are located in the tropical Pacific Rim (Ring of Fire). The types of geothermal resources are categorized as convective hydrothermal systems; EGSs; conductive sedimentary systems; coproduction, with water from oil and gas fields; geopressure systems; and magma energy. Mostly, geothermal fluid can be used directly or indirectly depending on the enthalpy. High-temperature geothermal resources are primarily used for energy production, whereas low to medium ones are particularly equipped for non-electric applications. The extraction of geothermal energy from the grounds leads to a release of greenhouse gases like hydrogen sulfide, carbon dioxide, methane and ammonia etc. However, the amount of gas released is significantly lower than in the case of fossil fuels. Moreover, geothermal energy has proven its capacity to be a reliable, clean, and uninterrupted sustainable renewable energy.

A multisource energy harvesting circuit for vibration and light energy with MPPT

SummaryThe article presents a multisource energy harvesting circuit (MEHC) for vibration and light energy with maximum power point tracking (MPPT). The MEHC has a cold start capability and extracts energy from piezoelectric transducers (PZTs) and photovoltaic cells (PVs) simultaneously when the multi PZTs reach their peak open‐circuit (OC) voltage, detected by the peak voltage detector and the PV1 cell voltage exceeds the MPP voltage (MPP voltage is approximately 0.7 times the PV cell's OC voltage) during the off‐peak time of the PZTs. The experimental results indicate that the output power of the MEHC is 2.8 mW under certain conditions, and the maximum energy extraction efficiency of the PVs is about 75%. The output power of the MEHC is 4.59 times of that without PVs.

Multi-objective optimization of a pipe energy pile with heat exchanger pipes subjected to chaotic advection

Shallow geothermal energy extraction through an energy pile system relies on the constant temperature available below the earth's surface at shallow depths. The energy pile system transfers the heat stored in the earth to a place of utility for space heating and cooling through fluid circulation, thus extracting geothermal energy. In this study, a 3D energy pile model comprising a helical heat exchanger pipe (HHEP) was developed and validated with the existing experimental data using a FEM-based software package. Further, it was hypothesized that replacing HHEP with a chaotic configured helical heat exchanger pipe (CHEP) would enhance thermal performance. The numerical analyses supported the hypothesis, where there was about a 15 % increase in heat release rate for energy piles containing CHEP. The above results form a basis for exploring the simulation results through laboratory scale model tests. Thus, an experimental setup was fabricated to conduct geothermal energy tests on a scaled pipe energy pile (PEP) model. The investigation was carried out by considering three design-input parameters: flow rate, pitch, and inlet temperature at three different levels with water and ethylene glycol as heat exchanger fluid (HEF) in a 4:1 ratio. The heat release rate of the PEP (Qp), heat flux per unit length of HEP (qpl), soil excess temperature (θs), total thermal resistance (TTR), and energy consumed (EC) were analyzed. Furthermore, multi-objective optimization using the MO-Jaya algorithm and multiple attribute decision-making (MADM) R-method were used to predict an optimal set of design-input parameters. Finally, a confirmation test was conducted to test the competence of the predicted parameters. The percentage variation between the predicted design input parameters and the experimental values was below 10 %.

Numerical modelling of an advective geothermal system in the Central Andes: Sustainable utilization through borehole heat exchangers

The utilization of low-enthalpy geothermal resources emerges as a promising solution for district heating in the Central Andes region. Focused on the Pismanta field, a representative example of the prevalent advective geothermal systems in the area, this study investigates into the intricate dynamics of the geothermal reservoir. Situated within a fault-controlled basin, the Pismanta field undergoes deep infiltration of meteoric water, leading to peak temperatures of up to 90 °C. Numerical simulations conducted at varying scales yield critical insights into the characteristics, efficient exploitation, and potential repercussions of energy extraction from the reservoir. A comprehensive approach is adopted to facilitate the optimal management of this geothermal resource and a strategic closed-loop system comprising 10 shallow interconnected borehole heat exchangers (BHE) is proposed. This recommendation takes into account the specific basin geometry and the intricate interplay of pressures within the confined geothermal reservoir. Extensive simulations over a 10-year period show the sensitivity of the system to operating flow rates. By employing the suggested configuration, it is anticipated that a maximum thermal power extraction of 1 MW can be achieved. The circulating water within the system is projected to maintain a temperature of approximately 26 °C.