Geoelectric Research Articles

Reducing Fossil Fuel Dependence and Exploring Just Energy Transition Pathways in Indonesia Using OSeMOSYS (Open-Source Energy Modelling System)

Indonesia’s commitment to the Paris Agreement and its Nationally Determined Contribution (NDC) is not adequately reflected in the significant CO2 emissions from fossil-fuel-intensive energy sectors, despite the enormous potential of renewable energy sources in the country. The ongoing coal regime has led to electricity oversupply and air pollution problems. Despite the huge challenges for Indonesia, a just energy transition away from fossil fuel is crucial. This study aims to explore the ideal energy mix and key emission reduction pathway in Indonesia in achieving a just energy transition using the least-cost optimisation energy modelling tool OSeMOSYS. Six scenarios are modelled over the period 2015–2050 including coal phase-out, NDC, the Just Energy Transition Partnership (JETP), and carbon tax implementation. The results highlight that solar power, geothermal power, and hydropower are the alternatives for coal decommissioning. Despite the large-scale investment in renewable energy under the NDC and JETP scenarios, emissions could be reduced by 55% and 52%, respectively, by 2050. Moreover, Indonesia’s current carbon tax rate will not lead to a significant emission reduction. Three recommended policies include (1) accelerating CFPP retirement; (2) imposing an aggressive carbon tax rate; (3) prioritising investment in solar technologies.

Harnessing Bangladesh's Undeveloped Geothermal Potential: A Case Study of the Barapukuria Coal Basin

Despite its vast potential, geothermal energy still needs to be tapped in Bangladesh. This study addresses this gap by employing a data-driven, systematic approach to evaluate the Barapukuria Coal Basin as a candidate reservoir for the nation's first geothermal power plant. While existing research mainly focuses on resource identification, this work utilizes geotechnical data from the well-studied Barapukuria region to conduct a comprehensive and thorough analysis. The aim is to quantify the available geothermal power and assess the project's lifetime, energy output, and capacity. The methodology leverages the high geothermal gradient (>48°C/km) observed in the area and existing information on reservoir and fluid properties. This enables the estimation of the recoverable thermal energy and subsequent validation of geothermal system models with empirical data. With no operational or planned geothermal plants in Bangladesh, this study represents a crucial step toward unlocking the resource's potential. The initial results are promising, suggesting the Barapukuria basin is a viable location for transitioning toward cleaner baseload power generation.

Unsteady MHD Nanofluid Flow Through a Divergent Conduit with Chemical Reaction and Radiation

Inefficient heat transfer rates have resulted in high energy consumption costs in heat exchanger systems. In this study, unsteady MHD(Magneto-hydrodynamics) Nanofluid flow (Silver-water) through a divergent conduit with chemical reaction and radiation is investigated. The chemical reactions taking place within the Nanofluid are considered to be of first order with the radiation effects being in a steady state. The governing partial differential equations have been transformed into ordinary differential equations using similarity transformations. The resulting system of non-linear ordinary differential equations is then solved using the spectral collocation method and implemented in MATLAB software. The results for velocity, temperature, and concentration profiles are presented graphically and discussed. It was observed that increasing the Reynolds number and Hartmann number led to an increase in the velocity profile. Increasing the Eckert number and Joule heating parameter increased the temperature profile while increasing the radiation parameter led to a decrease in the temperature of the Nanofluid. The concentration of the Nanofluid increased with an increase in the Soret number and Chemical reaction parameter while the concentration decreased with an increase in the Schmidt number. The findings have practical applications in designing and optimizing heat exchangers by maximizing heat transfer thus contributing to the sustainability of geothermal power generation in the energy industry.

Advanced EIS-Based Sensor for Online Corrosion and Scaling Monitoring in Pipelines of Geothermal Power Plants

Corrosion and scaling in metal pipelines are the major issues in the exploitation of geothermal sources. Geothermal fluids are complex mixtures consisting of dissolved gases and high-salinity solutions. This creates very aggressive environments primarily due to the high concentrations of carbon dioxide (CO2), hydrogen sulfide (H2S), chlorides, and other chemical species. Besides, the high temperature of the brines also increases corrosion rates, which can lead to failures related to stress and fatigue corrosion. On the other hand, reinjection of cooled brine exiting the heat exchanger favors the onset of scaling, since the chemicals dissolved in geothermal waters may tend to precipitate promoting inorganic depositions on the casing. Corrosion and scaling phenomena are difficult to detect visually or monitor continuously. Standard techniques based on pH, temperature pressure, electrical resistance measurements, chemistry composition, and physical properties are habitually applied as indirect methods for corrosion rate control. These methods, however, lack enough robustness for accurate and reliable measuring of the corrosion behavior of materials. To address this issue, a novel system has been proposed for the continuous monitoring of corrosion degradation caused by the effect of the geothermal brines. The present work aims to design, develop, and validate a dedicated electrochemical-based test system for online and onsite monitoring of the corrosion rate and scaling growth occurring on different materials exposed to real operating conditions. This system uses non-standard methods based on electrochemical impedance spectroscopy (EIS) to obtain quantitative data related to the material quality. It can be used to track the condition of the pipeline, reducing the operation and maintenance (O&M) costs and shutdown times. By providing early corrosion rate data, this system allows the prediction of failures in critical units of the plant.

An ultra-sensitive SARS-CoV-2 antigen optical biosensor based on angiotensin converting enzyme 2 (ACE-2) functionalized magnetic-fluorescent silica nanoparticles.

This work reports on the design and synthesis of an angiotensin-converting enzyme 2 (ACE-2) functionalized magnetic fluorescent silica nanoparticles (Fe-FSNP) as a biosensing platform to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen. Iron oxide (Fe3O4) nanoparticles were synthesized via ultrasonic-assisted coprecipitation and then coated with fluorescent silica nanoparticles (FSNP) through thesol-gelmethod forming the Fe-FSNP samples. Silica obtained from local geothermal powerplant was used in this work and Rhodamine B was chosen as the incorporated fluorescent dye, hence this reports for the first time ACE-2 was immobilized on the natural silica surface. The Fe-FSNP nanoparticle consists of a 18-25 nm magnetic core and a silica shell with a thickness of 30 nm as confirmed from the transmission electron microscopy image. Successful surface functionalization of the Fe-FSNP with ACE-2 as bioreceptor was conducted through hydrosylilation reaction and confirmed through the Fourier transform infrared spectroscopy. The detection of SARS-Cov-2 antigen by Fe-FSNP/ACE2 was measured through the change in its maximum fluorescence intensity at 588 nm where fluorescence- quenching had occurred. The biosensing platform showed a rapid response at 30 min with a linear range of 10-6to 10-2μg ml-1. The magnetic-fluorescent properties of the nanoparticle enables an ultra-sensitive detection of SARS-Cov-2 antigen with the limit of detection as low as 2 fg ml-1.

Review of NORM occurrence and application of a tailored graded approach for the radiation protection in geothermal plants

In the present paper, the general methodological approach developed to manage legislative requirements for NORM involving industries was fitted to the geothermal industrial sector, which is in the indicative list of the European Directive 2013/59/Euratom (EU-BSS). A review of the state of the art about the radiological characterization of NORM in geothermal plants have been performed with the aim to identify matrices and exposure scenarios of radiological concern. From the analysis of collected data, it results that radiological content of NORM residues generally depends on the characteristics of the geothermal fluid as well as on the type of the plants. In several plants, residues (both scales and filtering materials) show generally high activity concentrations, especially for Ra-226 and Ra-228 decay segments, exceeding Exemption Levels of the EU-BSS. Several tables have been presented as tools to support the stakeholders in the application of the legislative requirements regarding radiation protection in the geothermal sector.

Proposal and simulation of a geothermal-driven water electrolysis unit integrated with a CO2 methanation process toward a novel sustainable framework

This paper presents a novel multigeneration structure powered by geothermal energy, featuring a geothermal power plant, water electrolyzer unit, methanation reactor, fuel and utility production unit, supercritical-carbon dioxide cycle, and both high-temperature and low-temperature organic Rankine cycles. Simulated in Aspen HYSYS software and analyzed from energy, exergy, economic, and environmental (4E) perspectives, the process, under base operating conditions, is capable of producing 20,940 kW of power, 620.70 kg/h of hydrogen, 4,913 kg/h of oxygen, 12.35 kg/s of domestic hot water, 5.293 kg/s of chilled water, and 2.659 kg/s of carbon dioxide with over 99% mole purity. Efficiency assessments reveal energy, exergy, and electrical efficiencies of 10.69%, 48.53%, and 3.73%, respectively, with a total unit product cost of $3.11/GJ and a net present value of $67.40 million. The water electrolyzer unit, with an 88.94% exergy efficiency and a 10% contribution to total system irreversibility, is identified as the most efficient subsystem. The geothermal power plant accounts for the highest system irreversibility at 61%, while the combustor in the fuel and utility production unit contributes 11,250 kW of irreversibility. Environmentally, the system operates with zero emissions and significantly reduces annual CO2 emissions compared to coal, oil, biomass, and natural gas power plants by 453.14 × 106, 576.80 × 106, 111.92 × 106, and 344.10 × 106 kg, respectively.

A Theoretical Study on the Thermal Performance of an Increasing Pressure Endothermic Cycle for Geothermal Power Generation

In this study, a power cycle (IPEC), with an increasing pressure endothermic process in a downhole heat exchanger (DHE) and a CO2-based working fluid mixture, was developed for geothermal power generation. The increasing pressure endothermic process, which cannot be achieved in a conventional evaporator on the ground, was realized using the gravitational potential energy in the DHE. The parameters of the power cycle and the structural size of the DHE were optimized simultaneously. Using CO2-R32 as the working fluid of the IPEC provides the highest net power output. The net power generated with the IPEC was compared with a single-flash (SF) system, a trans-critical CO2 (t-CO2) system, and an organic Rankine cycle (ORC) under the same heat source and sink conditions. Six selection maps were generated for choosing the optimum power cycle for electricity production, in which four power generation systems (ORC, t-CO2, IPEC, and SF) were included, and two DHE diameters (0.155 m and 0.22 m) were investigated. It was found that the IPEC system had more net power output than the other three systems (ORC, t-CO2, and SF) under the conditions that the geofluid’s mass flow rate was less than 10 kg/s and its temperature was lower than 180 °C.

Geothermal power generation and positive impact in the greater bay area: a case study of Huizhou City, Guangdong Province.

Geothermal resources, as abundant renewable and clean natural resources on Earth, have been utilized for geothermal power generation in 29 countries. Guangdong Province, as one of the most developed, economically vibrant, and attractive investment regions in China, has experienced rapid economic growth. However, further development is constrained by resource limitations and severe ecological environmental pressures. The issue of energy consumption and economic growth imbalance needs to be urgently addressed. Geothermal energy, as a clean and stable form of energy, can reduce reliance on fossil fuels, decrease dependence on imported energy, and enhance national energy security. In this study, geological survey, geophysical survey, geochemical survey, remote sensing detection and drilling were carried out in the Shiba-Huangshadong area of Huizhou, and by analyzing the data on geothermal energy reserves in the study area, the available geothermal energy and its potentials in the study area were identified and its impact on the current energy consumption in Huizhou City was assessed, to validate the feasibility of the detailed application of the geothermal energy in the Greater Bay Area, which will enable the energy structure of Huizhou City optimize the energy structure.

The Potential of Renewable Energy to Replace Diesel Power Plants in Supporting Energy Transition in Indonesia

The Indonesian government is committed to reducing greenhouse gas emissions under the Paris Agreement. One form of this commitment is the program to replace diesel power plants with renewable energy plants in the electricity sector. Fossil-based diesel power plant operations have disadvantages, such as relatively expensive generation costs and greenhouse gas emissions. There are three renewable energy technology options as potential substitutes for diesel power plants: a solar photovoltaic (PV) power plant integrated with a battery energy storage system (BESS), a small-scale geothermal power plant, and a micro-hydropower plant. This paper will analyze the prospects of each technology option based on its economic and environmental impact. Various technical parameters, including renewable energy potential and intermittent factors, as well as economic parameters such as investment and generation costs, are important factors for selecting prospective renewable energy generators. The analysis was carried out by calculating the levelized cost of electricity (LCOE), CO2 emissions, and oil fuel consumption for four different scenarios. The results of the analysis show that replacing the diesel power plants with micro-hydropower plants can reduce LCOE by 0.24 USD/kWh to 0.12 USD/kWh. The use of a solar PV power plant integrated with a BESS has the most potential to reduce CO2 emissions, which account for 54% of emissions from diesel power plants. Meanwhile, the potential for oil fuel reduction from this program can reach an annual average of 0.85 million kl.

GIS-AHP APPROACH FOR A COMPREHENSIVE FRAMEWORK TO DETERMINE THE SUITABLE REGIONS FOR GEOTHERMAL POWER PLANTS IN IZMIR, TÜRKİYE

Geothermal energy is gaining more reputation and importance around the world. Correspondingly, suitable location selection is a critical step and has become necessary for the successful installation and operation of geothermal power plants. This study investigated suitability of İzmir region, located in the Aegean part of Türkiye, in terms of geothermal power plants applications by using the combination of Geographical Information System and Analytic Hierarchy Process. Based on the request of power plants, thirteen important criteria were evaluated under three main categories named as physical (C1), environmental (C2) and technical (C3). Moreover, expert’s opinions were taken into consideration to calculate the importance of these criteria. Key results showed that İzmir was suitable for geothermal power plants. The final suitability map layer pointed out that %8.73 (1.037 km2) of total area were determined as highly suitable regions in terms of installation. In addition, the obtained suitability map layer was compared with actual geothermal power plants. Based on the comparison study, power plants in Seferihisar were moderately suitable for geothermal power plants while the location of Balçova power plant was highly suitable. Regarding the suitability assessment in the present study, the location of Dikili power plants had the least suitability score.

MHD second-grade nanofluid slip flow over a stretching sheet subject to activation energy, thermophoresis, and Brownian effects

In this work, the magnetohydrodynamic flow of two engine oil-based second-grade nanofluids Copper (Cu) and Titanium oxide (TiO 2) over a penetrable stretching sheet is studied. The flow, heat and mass transfer characteristics in the existence of activation energy, inclined magnetic field, Brownian diffusion, elastic deformation, and thermophoresis are examined. The coupled nonlinear model equations are formulated by implementing the Modified Buongiorno model and then are non-dimensionalized by the similarity transformation technique. The non-dimensional equations are simulated numerically using the bvp4c solver. Graphs are plotted to study the flow behaviour of nanofluid with the rate of entropy generation and Bejan number. The outcomes of skin friction coefficient, Nusselt number and Sherwood number are exhibited via surface plots. From the analysis, a higher inclination of the magnetic field decays the velocity and amplifies the temperature profiles. The heat transport rate diminishes with the Brownian diffusion, thermophoresis and elastic deformation parameters. The mass transport rate is accelerated due to the activation energy parameter. The entropy generation rate is enhanced with the Brinkman, Biot and local Reynolds numbers. Furthermore, it is seen that engine oil-based TiO 2 nanofluid has larger velocity, temperature and rate of entropy generation than engine oil-based Cu nanofluid. The current examination has applications in automobile radiators, microchips, biomedical engineering, and extraction of geothermal power.

Ground source cooling to increase power generation from geothermal power plants

The utilization of geothermal resources for electricity generation relies heavily on appropriate power plant technology, which is linked to the resource's enthalpy potential. Moderate and high-enthalpy resources often find application in binary (Organic Rankine Cycle) plants, flashing-type plants, or even hybrid configurations. Among the crucial elements determining plant efficiency is the cooling system. By maintaining low turbine exhaust pressure, an effective cooling system facilitates enhanced power output. Traditional options include wet-type and dry-type cooling systems, both with established roles in geothermal applications. This study focuses on mitigating the detrimental impact of high ambient temperatures during summer months on geothermal power plant performance. Specifically, we propose the first-ever implementation of ground source cooling for a combined geothermal power plant in Western Anatolia, Turkiye. This innovative approach aims to counteract the decline in electricity generation observed during summer and maintain stable output throughout the year. The TOUGH + RealGasBrine V1.5 was employed to model the heat transfer dynamics between the buried pipes of the ground source cooling system and the surrounding ground. The simulated system underwent a three-month injection phase followed by a nine-month shutdown period to allow for a return to initial temperature conditions. This comprehensive modeling approach provided valuable insights into system behavior and performance. The simulations revealed a highly encouraging outcome: ground source cooling has the potential to enhance the power generation performance of the geothermal plant by over 10% during summer conditions. This significant improvement underlines the feasibility and effectiveness of the proposed approach. Furthermore, a sensitivity analysis was conducted to assess the influence of pipe diameter on temperature transient behavior and overall system feasibility. This analysis provides valuable information for optimizing the design and implementation of ground source cooling in future geothermal projects.

Geothermal Power Generation: Harnessing Electrical Energy Through The Organic Rankine Cycle (ORC) System

The research employs a thermodynamic simulation method using an Engineering Equation Solver (EES), relying on theoretical calculations. This method is integrated into a geothermal power plant, precisely focusing on geothermal source temperatures of approximately 95ºC. The investigation centers on the heat transfer process within a high-temperature heat transfer fluid from geothermal sources, conveying stored heat to the Organic Rankine Cycle (ORC) evaporator. Three specific working fluids, R134a, R11, and R22, examine working fluid selection for ORC at 95ºC. The results highlight the R11 organic fluid as an optimal compromise, excelling in two crucial criteria. Firstly, R11 exhibits the highest net mechanical power, = 34.81 kW compared to alternative fluids. Secondly, it boasts the best energetic efficiency of the cycle, registering = 16.01%, outperforming both R134a ( = 13.17%) and R22 ( = 12.64%). In summary, this study conducts a focused analysis of the energy aspects of an Organic Rankine Cycle (ORC) for electricity production using geothermal sources and organic fluids. Operating at a geothermal source temperature of 95ºC with a water flow rate of 80 lt/s and environmental conditions at 20ºC, the parametric study emphasizes the superiority of the R11 organic fluid. R11 emerges as the optimal choice, demonstrating the highest net mechanical power and superior energetic efficiency compared to alternative fluids, thereby contributing valuable insights to advancing sustainable and efficient energy technologies.

Life cycle CO2 emission assessment of an organic Rankine cycle based geothermal power plant

Abstract Geothermal resources are well-recognized as a clean and low-carbon emission energy resource for power generation and heat supply. However, CO2 emissions occur during the construction, operation, and decommission stages of geothermal power plants. In this work, the life cycle CO2 emission characteristics of a geothermal power plant based on the organic Rankine cycle are systematically evaluated. The effect of the organic working medium and the recuperative cycle on CO2 emissions of the whole system are analyzed. Sensitivity analysis is conducted by varying the parameters of output power and the sources of the substituted electricity. Results reveal that a considerable amount of CO2 would be released due to the construction of geothermal wells and plants; however, the production of electricity could offset a much larger amount of CO2 emission. The net CO2 emission of the considered geothermal system during its lifespan reaches approximately −300 thousand tCO2e. In addition, the total amount of CO2 emission reduction relies heavily on the output power and the substituted electricity sources.

The 4E emergy-based analysis of a novel multi-generation geothermal cycle using LNG cold energy recovery

Over the last decade, the increasing demand for sustainable energy sources has led to the development of innovative approaches in geothermal power plant cycles. In this study, a novel combined geothermal power plant cycle (GTPPC) that integrates the Kalina cycle, transcritical Carbon Dioxide (T-CO2) cycle, with the injections of the Liquid Natural Gas (LNG) stream and geothermal water (GTW) stream is proposed in order to provide cold and hot sources of the system. The performance of the system is evaluated using emergy analysis, an evaluation factor based on thermodynamic principle and solar energy with the aid of emergoeconomic and emergoenvironmental factors. The injection of LNG stream leads to significant improvements: enhancing the net output power and overall emergoeconomic and emergoenvironmental efficiencies of the cycle. By conducting improvement priority and parametric studies, crucial stream points and the system's performance's optimization is identified. Our results indicate that the Kalina sub-cycle has a greater impact on performance, and the exergy destruction in the LNG stream will be minimized. At the optimal point, the GTPPC achieves high thermal efficiency and emergy-based metrics, indicating its sustainability and viability as a geothermal power generation solution. By the injection of LNG stream, the net output power, and overall emergoeconomic and emergoenvironmental efficiencies of the cycle, improved by 1.79 MW, 14 %, and 16 %, respectively. According to the obtained results, the performance of the Kalina sub-cycle has more effect than the Carbon Dioxide sub-cycle, and destructing exergy in the LNG stream will have irreparable effects on the operation of the GTPPC. At the optimum point of the system performance, the GTPPC will operate with the thermal efficiency, ψ, and φ of 15.4 %, 94.3 %, and 98.5 %, respectively.

Evaluation of the energy and exergy of a trans‐critical CO2 cycle driven by a double flash geothermal power plant

AbstractFacing the dual challenges of environmental impact and the finite nature of fossil fuels, the shift toward sustainable energy sources is imperative. Geothermal energy, a renewable and underutilized resource, offers a promising alternative. This study ventures into a novel domain, exploring the integration of trans‐critical CO2 (tCO2) cycle with a double‐flash geothermal (DFG) cycle, an area not extensively covered in existing research. This study aims to develop a recovery system that utilizes a tCO2 cycle powered by a DFG cycle. A crucial part of this study involves conducting a sensitivity analysis to evaluate the system's energy and exergy performance. This analysis focuses on understanding the impact of changes in key system design parameters, such as energy efficiency, exergy efficiency, net power output, and total exergy destruction rate, to determine the optimal values for these parameters. The results indicate that the recovery system shows a significant improvement of 22% in energy efficiency over the basic cycle. However, there is a decrease in exergy efficiency in the recovery system, which represents a 5.26% decline. As a result, this study paves the way for innovative approaches in geothermal energy use, suggesting potential breakthroughs in renewable technologies.

Assessment and optimization of a single flash geothermal system recovered by a trans‐critical CO2 cycle using different scenarios

AbstractIn the evolving landscape of sustainable energy, optimizing geothermal power systems presents a critical challenge. This study explores the energy and exergy efficiencies of a power production system utilizing a single‐flash geothermal cycle integrated with a trans‐critical CO2 cycle. The study's methodology involves a detailed examination of key performance parameters—separator pressure, CO2 turbine intake pressure, and steam turbine output pressure. Utilizing the EES software environment, the study innovatively employs a combination of Genetic Algorithm (GA), Nelder–Mead Simplex (NMS) method, and Direct algorithm (DA). When using GA, NMS and DA, the system's exergy efficiency increases from 32.46% in the default operating mode to 39.21%, 36.16%, and 38.82%, respectively. One of the notable outcomes is the identification of optimal separator pressure for maximum energy efficiency. Furthermore, the study reveals that increasing the CO2 turbine's inlet pressure adversely impacts the system's efficiency. The study's results contribute significantly to the field of renewable energy, offering practical guidelines for enhancing the performance of geothermal power systems.

PESTEL Analysis on Renewable Energy Generation in Indiastudy Based on Tata Power Solar, Suzlon Energy and Renew Power

In recent years, India as a country has been developing rapidly in renewable energy sectors. Many start-ups are coming up to invest in renewable energy sector. They are playing a vital role for adoption of renewable energy sources. They investment mainly in – wind, solar and geothermal power. The need to invest in renewable energy sector arises due to emerging challenge of climate change. In this scenario the present study seeks to analyse various external factors that influence the renewable energy sector in India using.

Sintesis dan Karakterisasi Nanosilika dari Limbah Silica Scaling PLTP Dieng Melalui Metode Alkali Fusion NaOH

Silica scaling is the main problem that arises in the operation of geothermal power plants (PLTP) in Dieng. Silica scaling can disrupt electricity production and cause a buildup of waste in the environment. Silica scaling has a high silica (SiO2) content so it has the potential to be used as a value-added material, namely nanosilica. One method to obtain nanosilica is alkali fusion. This research aims to obtain nanosilica from silica scaling waste from PLTP Dieng using the alkali fusion method as well as knowing the characteristics of the nanosilica produced. The alkali fusion process is carried out using NaOH as an alkali source. Then mixing silica scaling powder and NaOH at varying temperatures of 600°C, 650°C and 700°C to produce nanosilica. The resulting nanosilica was then characterized to confirm the success of the synthesis process in producing nanosilica particles. The characterization carried out included x-ray diffraction (XRD) to characterize crystallinity, Fourier transform infrared (FTIR) to characterize functional groups, transmission electron microscope (TEM) and particle size analyzer (PSA) to determine particle size. The results of this research showed that amorphous nanosilica was successfully synthesized from silica scaling using the NaOH alkali fusion method. It was found from the results of TEM and PSA characterization that the smallest particle size was produced at a fusion temperature of 650°C. Furthermore, FTIR data also confirms the existence of functional groups at wave numbers identical to silica.