Geoelectric Research Articles

Experimental study on dynamic power generation of three ORC-based cycle configurations under different heat source/sink conditions

Organic Rankine cycle (ORC) is used for geothermal power generation, and other two derived cycle configurations, parallel double-stage organic Rankine cycle (PDORC) and organic Rankine flash cycle (ORFC), have been proposed to improve the geothermal power generation performance. However, no experimental comparison have been done before. An experimental device that can switch between three cycles was designed and constructed to compare the power generation performance of three cycles. The operational performance of the three cycles at different heat source and heat sink temperatures are analyzed in this paper. The results show that under the heat source temperature of 90 °C and heat sink temperature of 15 °C, the output power of ORFC is 876.59 W, which is higher than that of the PDORC and ORFC. Moreover, the exergetic efficiency is greater than other two cycles due to the smallest irreversible loss of ORFC. The exergetic efficiencies of the ORC, PDORC and ORFC are 31.87 %, 31.32 % and 34.79 %, respectively. The increase of heat sink temperature is beneficial for the isentropic efficiency of the expander, but not conducive to power generation performance and energy utilization. PDORC and ORFC promote the effective utilization of heat source, outputting more power but with a lower efficiency.

Experimental study of a novel in-tube spray evaporative condenser for geothermal power generation

To enhance the efficiency of medium to low-temperature geothermal power systems, we designed a novel in-tube spray evaporative condenser. Experimental setups for single-tube heat exchange were devised, examining both water-water and working fluid-water configurations. The study analyzed the impact of air volume and hot water flow rate on heat transfer. Economic comparisons were made in laboratory conditions among the novel evaporative condenser, traditional evaporative condenser, water-cooled condenser, and air-cooled condenser. Results indicated: (1) The novel evaporative condenser exhibited 1.5–1.7 times higher heat flux density and 2.0–2.7 times higher mass transfer coefficient, indicating superior heat transfer performance compared to the traditional one. (2) Variations in hot water flow rate within a certain range had minimal impact on condenser performance when the condenser size was constant, providing valuable insights for condenser selection and structural design. (3) Both total power and water consumption of the novel evaporative condenser were lower than the other three types. Its daily operating cost was approximately 3/4 of the traditional evaporative condenser, 1/2 of the air-cooled condenser, and 1/4 of the water-cooled condenser, demonstrating superior economic feasibility.

Investigating the potential of geothermal energy as a sustainable replacement for fossil fuels in commercial buildings

Commercial Buildings release large volumes of greenhouse gases, expediting global warming. The commercial building industry accounts for 37% of global CO2 emissions. Geothermal energy technologies are an intriguing solution that provides a low-impact, emission-free, and cost-effective thermal fuel source for baseload energy production. Geothermal energy systems offer a potential solution to dramatically halt global warming and facilitate the transition to a carbon-neutral civilization. This study develops a framework for assessing the geothermal power capabilities of innovative house and district heating systems. The energy requirements are first assessed, and then the spatial evaluation of district heating infrastructure is carried out using a Python-based program. Economic comparisons between geothermal energy and fossil fuels are made using LCC analysis. Environmental impacts are measured by Life Cycle Analysis (LCA). This study compares geothermal energy to fossil fuels, and the LCA results show that geothermal energy has a low environmental impact. With a Net Present Value (NPV) of 34.81 USD, it displays economic viability as well as a satisfactory financial return. The study's findings show that geothermal energy has the ability to compete with fossil fuels in commercial heating applications while still being environmentally beneficial.

Canada’s Geothermal Energy Update in 2023

Geothermal energy exploration, development, and research have been ongoing in Canada for several decades. The country’s cold climate and the push to develop renewable energy sources have driven interest in geothermal energy. Despite this drive, regulatory complexities and competition with other relatively inexpensive energy sources with existing infrastructure have hindered development. As such, interest has grown and waned with changes in the energy economy over several decades, leaving many projects at a standstill. As of January 2023, there are currently no operational geothermal power projects in Canada. Many hot spring pool and spa complexes remain active, and Canada is a leading country in the installation of ground source heat pumps (GSHPs; also called geo-exchange systems). However, in the last decade, the interest in deep geothermal systems has renewed, with many new projects starting up across several provinces and territories. Moreover, projects that had shown limited progress for many years—such as Mount Meager in British Columbia—have begun to renew their development efforts. Research is also expanding within prominent research groups and universities. The areas of focus include both building upon previous studies (such as thermal gradients and the heat flow in sedimentary basins) and researching new methods and resources (such as GSHPs, closed-loop systems, integrated geothermal operations, and hybrid systems, including heat storage). The development is supported by federal, provincial, and territorial governments through grants and the development of regulatory frameworks. Although challenges still remain for Canada to develop its geothermal energy resources, several power, thermal, and co-production projects, ongoing research, funding, and regulatory acts are all moving forward to support geothermal development. This paper aims to study Canada’s geothermal energy update in 2023 regarding the aspects mentioned above.

Comparative study on the organic rankine cycle off-design performance under different zeotropic mixture flow boiling correlations

Zeotropic mixture utilization enhances the performance of the Organic Rankine cycle (ORC) significantly. For geothermal ORC power plants, the zeotropic mixture flow boiling correlation plays a vital role in both evaporator design and system performance evaluation. Based on the screened zeotropic mixture R1224yd(Z)/R1234ze(E) (0.452/0.548), a comparative analysis of 4 flow boiling correlations is performed to assess their impact on both evaporator design and system performance under off-design conditions. The results underscore a substantial impact of these correlations on determining the plate length, with the largest relative difference being 53.8%, consequently resulting in uncertainties of 31.7% and 23.4% for the evaporator exergy loss and cost, respectively. Under off-design working conditions, the relative difference in net power output varies from 16.43% to 7.67%. The exergy efficiency variation is up to 11.82% and the electricity production cost (EPC) uncertainty is up to 11.2% at the working condition with the maximum difference in net output work. This study provides valuable insights for selecting the appropriate zeotropic mixture flow boiling correlation in practical evaporator design and evaluating the off-design performance of ORC systems.

Design and Fabrication of DSSC and Monitoring Using Embedded System

Fossil fuel shortages, increasing prices of crude oil, and the shunning of conventional energy sources (such as coal or nuclear power plants) are some of the factors that have made sustainable forms of traditional energy gain more attention. Some examples include hydropower, wind power, geothermal power, and biomass processing. Solar power is also a very important source of alternative energy. To comprehend such improving progress in achieving higher solar-to-electricity efficiency and improved long-term operating stability, the development process and basic principles for DSSCs should be understood. An FTO electrode with titanium dioxide (Tio2) is being used here, as part of which we grow dye tuned to give the required color and conductivity. It is called an anode. A pencil was used to graphite the other FTO glass, which would then serve as the cathode. We are presently working on using an iodide electrolyte. Also, current density and voltage were monitored by the ESP8266 kit. Key Words: Dye-sensitized solar cell; Carotenoid Extract; Electrolyte; ESP8266.

Deep Learning Method for Improving Rate of Penetration Prediction in Drilling

Summary The urgent global need to reduce CO2 emissions necessitates the development of sustainable power generation sources. Geothermal power emerges as a renewable and dependable energy option, harnessing the Earth’s natural heat sources for electricity generation. Unlike other renewables, geothermal energy offers uninterrupted power, immune to weather conditions. However, its efficiency hinges on technological innovation, particularly in the challenging realm of geothermal drilling. Rate of penetration (ROP) is a crucial drilling performance metric, and this study explores how deep learning models, particularly transformers, can optimize ROP prediction. Leveraging data from Utah Frontier Observatory for Research in Geothermal Energy (FORGE), we analyze the relationship between drilling parameters and ROP. Traditional drilling optimization methods face limitations, as drilling dysfunctions can disrupt the linear relationship between ROP and weight on bit (WOB). We propose a dynamic approach that allows adapting drilling parameters in real time to optimize ROP. Our experiments investigate optimal sampling intervals and forecast horizons for ROP prediction. We find that a 60-second sampling interval maximizes the transformer model’s forecasting accuracy. Additionally, we explore retraining to fine-tune models for specific wells, improving forecasting performance. Our transformer-based ROP forecaster outperforms deep learning models, achieving a low overall 5.22% symmetrical mean average percentage error (SMAPE) over a forecast horizon of 10 minutes. This model offers opportunities for cost-effective drilling optimization, with real-time accuracy, speed, and scalability. Future work will focus on larger data sets and integration with drilling automation systems to further enhance the model’s practicality and effectiveness in the field.

Implementation of combined hydrogen aqua electrolyser-fuel cell and redox-flow-battery under restructured situation of AGC employing TSA optimized PDN(FOPI) controller

This work addresses the automatic-generation-control of multiple-area and sources under a restructured-situation. Sources within area-1 represent geothermal power plant, thermal, and gas, and area-2 sources represent thermal, hydro, and wind. An original endeavour is brought about to execute a controller with an admixture of proportional-derivative with filter (PDN) (integer-order) besides fractional-order proportional–integral (FOPI). Examination manifests excellence of PDN(FOPI) over integer order controllers likely integral, proportional–integral, proportional–integral–derivative-filter from perspective concerning depleted status of peak aberrations, extent-of-oscillations, and duration of settlement. To attain the controller’s attributes bioinspired meta-heuristic tunicate swarm algorithm is exercised. The occurrence of renewable sources makes arrangements meaningfully improved related to base thermal-gas-hydro arrangement. The action of hydrogen aqua electrolyzer-fuel cell and redox flow battery is examined using a PDN(FOPI) controller, providing noteworthy outcome in dynamic performance. The analysis is conducted under all the schemes of restructured situations.

Demonstration by laboratory experiments of thermosiphon effect in the closed loop carbon dioxide circulation system

The thermosiphon effect has been shown theoretically to exist in the closed loop CO2 circulation geothermal power generation systems. We verified this effect based on previous numerical studies that determined the conditions under which the thermosiphon effect can be established and we developed laboratory experimental apparatus with conditions analogous to those in the previous studies. The results of laboratory closed loop CO2 circulation experiments using this apparatus demonstrated the thermosiphon effect at initial injection pressures from 8.5 to 18 MPa and heater temperatures from 80 to 200 °C. With this experimental apparatus, higher heater temperatures produced higher heat output at the same injection pressures, and that the peak heat output was observed at injection pressures of 12–14 MPa. Furthermore, comparing CO2 with water as the thermal transfer medium indicated that the feasibility of the thermosiphon effect was increased by changing the medium from water to CO2.

Frequency regulation of geothermal power plant-integrated realistic power system with 3DOFPID controller

Frequency regulation of geothermal power plant-integrated realistic power system with 3DOFPID controller

Evaluating Geothermal Power Plant Sites with Additive Ratio Assessment: Case Study of Mount Seulawah Agam, Indonesia

Indonesia, a country rich in geothermal resources, has yet to fully exploit its potential, particularly in volcanic regions like Mount Seulawah Agam. This study investigates the application of the Additive Ratio Assessment (ARAS) method for the site selection of Geothermal Power Plants (GPP) in Indonesia. The ARAS method provides a systematic approach to evaluating and prioritizing geothermal development sites by integrating multiple criteria, including geological, environmental, and socio-economic factors. The study collects data from various sources and weights criteria using the Ordinal Priority Approach (OPA), incorporating expert opinions. The findings demonstrate the effectiveness of the ARAS method in identifying optimal locations for GPP development, ensuring sustainability and feasibility. The study also tests the ARAS method in existing GPP locations in Jaboi, Sabang, Indonesia, to investigate alignment with the results and validate the approach. Furthermore, the study presents recommendations for GPP site selection. This research emphasizes the significance of multi-criteria decision-making techniques in facilitating renewable energy projects. It promotes a more systematic and informed approach to geothermal energy development in Indonesia and other geothermal-rich regions.

Thermodynamic and thermoeconomic analysis and optimization of a renewable-based hybrid system for power, hydrogen, and freshwater production

To address environmental pollution effectively, it is crucial to promote the increased utilization of renewable energy sources. Furthermore, an appealing opportunity arises from enhancing the efficiency of renewable-based power plants while diversifying their product output. This study introduces a hybrid system that revolves around renewable resources, with a primary focus on evaluating power generation, hydrogen production, and freshwater extraction. The designed system seamlessly integrates a flash-binary geothermal power plant with a solar system, incorporating cutting-edge phase-change material storage technology. Hydrogen is generated through a combination of steam-methanol reforming and pressure swing adsorption processes. Freshwater is procured utilizing humidification-dehumidification and multi-effect desalination units. In terms of power generation, the system leverages the capabilities of the geothermal power plant alongside a modified Kalina cycle. The performance of this integrated system is rigorously evaluated through a combination of thermodynamic and thermoeconomic approaches. An exergy-economic optimization scenario is employed to determine the most efficient operational mode. The results of this comprehensive analysis reveal that the system can produce 0.0224 kg/s of hydrogen, 8.017 kg/s of freshwater, and generate 215.9 W of net power. Impressively, it achieves an exergy efficiency of 58.3% at a unit cost of $32.23/GJ in the base mode. Furthermore, the optimal operating state boosts efficiency to 60.59%, with a unit cost of $32.22/GJ. Notably, adjustments in the selling price of hydrogen have a significant impact on the system's financial metrics. As the price of hydrogen rises from $5 to $6/kg, the payback period reduces from 4 to 3 years, and the net present value surges from $5.81 million to $10.16 million.

Numerical simulation of single-well enhanced geothermal power generation system based on discrete fracture model

This study proposes a single-well enhanced geothermal system (SEGS) to mitigate the high-risk of traditional Enhanced Geothermal Systems (ESGs) with two or more wells and enhance the general applicability. A detailed thermodynamic model that couples the wellbore, reservoir, and organic Rankine cycle is built. For the reservoir, a three-dimensional flow and heat transfer model featuring a discrete fracture network is employed. The effects of injection flow rate, injection temperature, branch well length, and branch well spacing on net output work, pump power consumption, thermal efficiency, and exergy efficiency have been investigated. The results indicate that an increase in the injection flow rate improves the shaft power of the expander and the power consumption of the injection pump. An optimal flow rate of 30 kg/s is identified, which maximizes the annual net power output to 1221.2 kW. Additionally, an increase in the injection temperature is found to enhance the buoyancy effect, thereby improving both thermal and exergy efficiency, and reducing the power consumption of the injection pump. The maximum net output power is achieved at an injection temperature of 60 °C. The study also notes that the branch well length has a negligible effect on thermal and exergy efficiency and expander shaft work. However, a longer branch well length contributes to a decrease in the power consumption of the injection pump and an increase in the net power output. Finally, it is observed that increasing the lateral well spacing slows the rate decay of the production temperature. A spacing of 360 m is found to yield a maximum annual net output power of 1259.4 kW. In conclusion, this study offers significant insights and practical guidance for the development and utilization of SEGS, demonstrating its potential as an effective alternative to conventional EGS methodologies.

Comparative analysis of geothermal binary ORC systems: performance and environmental considerations for CO2 andwater as geofluids

This study considers the process simulation of geothermal binary Organic Rankine Cycle (ORC) systems which utilizes CO2 and water as geofluids for electricity generation. The simulation was performed using Hysys v11 software by using Peng Robinson’s fluid property package. Two dry working fluids including isopentane and n-pentane, were used. The effects of geofluid temperature and working fluid mass flowrate on power generation, as well as the maximum pressure of working fluids were evaluated. The result showed that power generation increases with higher geofluid temperature due to enhanced heat transfer. Isopentane outperformed n-pentane, attributed to its superior thermodynamic properties. CO2 showed better performance as geofluid than water highlighting its superiority, observed in the increased power generation. The unique characteristics of CO2 enable efficient heat transfer at lower temperatures, making it an environmentally friendly and effective choice. Contrarily, the use of water as a geofluid poses some implications for local ecosystems and water resources. From an environmental perspective, CO2 shows greater potential for reduced environmental impact, which aligns with the transition to cleaner energy sources. However, the economic considerations suggest a trade-off, as CO2 projects may entail higher upfront costs compared to water-based systems. Regulatory factors and economic feasibility, therefore, play a crucial role in the choice of geofluid for geothermal power generation.

Environmental effects of geothermal energy utilizations: A case study of the Seferihisar geothermal system, İzmir, Türkiye

Geothermal resources are often regarded as environmentally friendly and sustainable resources. They are utilized for different purposes, including energy generation, thermal tourism and greenhouse cultivation. The utilization type depends on the temperature, chemical characteristics and the flow rates of available geothermal resources. In long-term applications, there is a need for research and monitoring process to assess environmental consequences. Also, supervised use of the resource is crucial for both the geothermal system and its environment, as there is a possibility of unpleasant impacts on the environment, as chemical pollution, subsidence, and thermal effects in cases of improper use of geothermal resources. In Seferihisar, current consumption types of geothermal energy are consisting of a geothermal power plant with an installed capacity of 12 Mwe and a few primitive spas. In the Tuzla geothermal field, the geothermal waters ascending to the surface cause the deposition of travertine, where sea water interference to the geothermal system is clearly observed and supported by XRD analysis of the sample collected from the Tuzla travertine. Seismic activities as earthquakes, affect the surface manifestations of the SGS. The temperature measurement values obtained from Tuzla and Doğanbey are higher than the values recorded prior to the installation of the geothermal power plant. The operation of the geothermal power plant has caused the nearby hot springs to dry up and has ceased travertine deposition in the Cumalı geothermal field. The annual mean values of NO₂ and SO₂ for the region are lower than the National threshold value and European Union Countries’ threshold value.

Eco-friendly multi-heat recovery applied to an innovative integration of flue gas-driven multigeneration process and geothermal power plant: Feasibility characterization from thermo-economic-environmental aspect

Sustainable production presents a viable approach that provides an environmentally friendly and integrated method for polygeneration objectives. This method can make the most significant impact in improving the effectiveness of conventional power plants. Furthermore, using renewable energy sources to modify the configuration of conventional power plants is imperative for implementing this methodology. Therefore, the primary objective of this research is to suggest a new method for attaining sustainable production in a power plant by integrating an environmentally friendly multi-heat recovery system. This innovative system allows for the efficient use of the power plant's flue gas for a polygeneration process and a geothermal power plant. The integrated setup comprises various components such as a multi-effect desalination unit, a proton exchange membrane electrolyzer, a cooling and heating generation subsystem, a liquefied natural gas regasification unit, a geothermal-based subsystem utilizing a flash-binary geothermal power plant, a Kalina cycle, and a heating generation unit. The study simulates this process using Aspen HYSYS software and conducts a comprehensive energy, exergy, economic, and environmental analysis. According to the results, the assessment reveals that the total energy and exergy efficiencies amount to 64.82% and 88.57%, respectively. The energy cost index is recorded at 0.028 $/kWh, alongside a specific CO2 emission of 0.211 kg/kWh. This value shows a notable reduction of 59.33% compared to a system reliant on biomass fuel. Parametric assessments are additionally conducted, whereby variations in performance metrics are predicted to exhibit the process performance.

Thermal characteristics of MHD [formula omitted] water nanofluids flow past a stretching/shrinking wedge in the view of Cattaneo-Christov heat flux

Wedge flow has a variety of potential uses, including thermal systems, geothermal power plants, aerodynamics and cooling of nuclear power plants. In this framework, the modified Cattaneo-Christov heat flux is implemented to examine the thermal characteristics in the dissipative flow of a viscous nanoliquid over a shrinking/stretching wedge. The laminar and two-dimensional flow of CoFe2O4/ water over a wedge domain is scrutinized. The self-similar solutions using bvp4c together with the stability analysis are estimated to demonstrate the physical existence of first and second solutions under relevant parameters used in the study. The findings reveals that the reverse flow phenomena, the novel form of decreasing flow exhibits physical existence which is significantly different from those in the stretching flow scenario. Thermal relaxation has a substantial impact on energy flux, which results in oscillatory heat conduction with a narrower temperature. When the volumetric friction of nanoparticles grows from 0.0 to 0.02, the local skin friction coefficients rises. The upper branch elucidation is stable and physically realistic, while the second branch solution is imaginary and having no physical existence. The rise and fall in temperature and velocity is perceived with suction parameter. However, the dropping of velocity is seen with the nanoparticle volume percentage.

On the temperature sensitivity of near-surface seismic wave speeds: application to the Groningen region, the Netherlands

SUMMARY Subsurface temperature measurements play a crucial role, for instance, in optimizing geothermal power plants and monitoring heat-storage systems. Previous studies have demonstrated that time-lapse variations in temperature can be correlated with variations in seismic wave speeds, offering the potential for temperature monitoring via seismic surveys. However, an apparent discrepancy has emerged between field and laboratory experiments. Field studies predominantly report positive correlations between temperature and seismic wave speeds, while laboratory experiments often show anticorrelations. This inconsistency underscores the need for a more comprehensive, physics-based understanding of temperature-induced wave speed changes. In this study, we strive to bridge the gap between field and laboratory findings by examining several mechanisms governing temperature-induced seismic wave speed changes, namely the intrinsic temperature dependency of elastic parameters and thermally induced elasticity. We present a physics-based modelling approach to identify the primary mechanisms responsible for temperature-induced seismic wave speed changes. By considering several end-member models, we find that intrinsic temperature dependency of elastic parameters (negative correlation) compete with thermal pressure effects (positive correlation). The precise initial and boundary conditions and physical parameters of the system under consideration will determine the weight of both effects. Temperature-related dilatation does not seem to play an important role. We apply our approach to loosely consolidated sediments in the shallow subsurface of the Groningen region, where subsurface temperature fluctuations are driven by seasonal atmospheric temperature fluctuations roughly between −5 and $30\, ^\circ$C. For these models, we predict seasonal temperature-induced changes in body-wave speeds of up to 8 per cent in the first few metres of the subsurface, high-frequency (above 2 Hz) surface wave phase velocity variations in the range of 1–2 per cent, and relative changes in site amplification on the order of 4 per cent. These findings contribute to a more comprehensive understanding of the intricate relationship between temperature and near-surface seismic properties, offering insights for applications as subsurface temperature monitoring systems.

The impacts of intellectual capital, market size, and intellectual property factors in geothermal power exploration

The impacts of intellectual capital, market size, and intellectual property factors in geothermal power exploration

Geomechanical modelling of injection-induced seismicity: the case study of the Muara Laboh geothermal plant

SUMMARY In this work, we study the induced seismicity recorded during an injection operation at the Muara Laboh geothermal plant (Indonesia). The swarm, consisting of three bursts activating a normal fault zone, is characterized by rapid earthquake (km d−1) migration. We use a 2-D rate-and-state asperity model to better understand the physical mechanisms controlling the evolution of this induced swarm. The model suggests that the observed rapid seismic migration can be explained by the interaction among asperities through the expansion of slow post-seismic slip fronts. Also, it shows that the amount of seismicity generated by the fluid injection is strongly controlled by the background seismicity of the system, that is by the seismicity determined by the tectonic load charging the fault. This close correlation between natural and induced seismicity suggests that the injection in Muara Laboh principally stimulates critically stressed faults, which release the seismicity determined by their natural seismic cycle.