Geoelectric Research Articles

Assessing the Environmental Sustainability of Deep Geothermal Heat Plants

The energy sector is responsible for a large share of climate-damaging emissions. Regarding the decarbonization of the energy sector, deep geothermal energy is considered to have high potential, particularly in the area of heat supply. In order to gauge the extent to which heat use from deep geothermal energy can make a positive contribution to climate protection, deep geothermal systems should be appraised using an environmental sustainability assessment. Although electricity generation from deep geothermal power plants has been evaluated in many ways in the literature with respect to its sustainability, no such sustainability evaluations of pure geothermal heat plants have been conducted so far. In order to close this research gap, this study presents a systematic approach that makes it possible to apply suitable sustainability criteria across the individual life stages of deep geothermal heat plants based on life-cycle assessment (LCA) guidelines. To demonstrate the effectiveness of the systematic approach presented here, a planned geothermal heat plant in the Upper Rhine Valley, Germany, serves as an example. Based on the estimated plant parameters and the predicted total heat yield, it was possible to determine, for example, the “energy returned on energy invested” (EROI) of the plant, which was approximately 34, and the specific CO2 emissions, which were approximately 5.6 g/kWhth.

Evaluation and Prioritization of Power-Generating Systems Using a Life Cycle Assessment and a Multicriteria Decision-Making Approach

Millions of people in Asia and sub-Saharan Africa still lack access to power, which emphasizes the need for sustainable and clean energy solutions. This study attempts to address this issue by integrating a life cycle assessment (LCA) and a multicriteria decision-making (MCDM) analysis to determine the preferred energy technology for electrification. This research focuses on the environmental implications and long-term viability of various energy system options. The LCA evaluates midpoint characterization containing 18 environmental impact categories; the COPRAS and ARAS methods of MCDM analysis are then used to rank the energy alternatives based on their environmental performance. This study’s key finding is that the gas-powered power plant is the most preferred energy system alternative, while the geothermal power plant is the least preferred. This midpoint characterization study provides in-depth insights into how various stages contribute to major environmental impact categories like global warming, ozone depletion, and ecotoxicity. By considering environmental impacts and sustainability requirements, informed decisions may be made to encourage clean and cost-effective power generation, thereby contributing to climate change mitigation and supporting economic growth and human development. Future research may include analysis from cradle-to-grave compared to cradle-to-gate.

Environmental Impact Assessment of Nesjavellir Geothermal Power Plant for Heat and Electricity Production

This work is focused on presenting the main results and discussions concerning the environmental benefits of reducing the non-condensable gases emitted from the Nesjavellir geothermal power plant. The primary objective of this study is to conduct a life cycle evaluation to analyse the overall environmental benefit effects of producing 1 kWh of electricity and 1 kWh of thermal energy in the geothermal power plant at Nesjavellir, which is located in Iceland. The assessment is performed both before and after implementing an abatement system designed to reduce CO2 and H2S gases. The production of geothermal energy is increasing every year and, therefore, it is crucial to identify and quantify the key environmental factors of producing this type of energy and improvements for the future energy transition of the energy generation sector. Firstly, the results show that the environmental impact of electricity production is higher compared to heat production. More in detail, the emissions due to the nature of the geothermal fluid and the construction phase represent the most relevant environmental load for both electricity and heat production for nearly all the 18 environmental impact indicators studied. Furthermore, considering the abatement system for the non-condensable gas emissions, reductions of 78% and 60% in global warming potential is achieved for a production of 1 kWh of electricity and 1 kWh of thermal energy. In terms of external environmental costs, the implementation of an abatement system results in a reduction exceeding 95% for both electricity and thermal energy production per kilowatt-hour. The outcomes obtained from both the baseline scenario and the application of the abatement system undeniably prove that the latter results in a substantial decrease in the overall environmental impacts linked to the generation of 1 kWh of electricity and 1 kWh of heat, encompassing a notable reduction in external environmental costs (externalities).

Stability scrutinization and model development for mixed convective non-Newtonian hybrid nanomaterial flow in thermal system over a vertical shrinking surface

The development of a better extremely high-efficiency coolant classified as nanofluid for numerous engineering and industrial technologies has been made possible by recent advancements in nanotechnology. In this work, we investigate the impression of an irregular heat generation or heat absorption on the improvement of heat transfer of Williamson hybrid nanoparticles composed of water-based Ag and MgO over a porous surface that is shrinking and stretching. The assisting and opposing flows are also provoked. The non-linear model based on differential equations is derived and numerically handled via a bvp4c process based on some reasonable assumptions. In an appropriate region of mixed convection, mass transpiration velocity, and shrinking surface characteristics, two dissimilar branch outcomes are discovered with the change of the influential parameters. In addition, the analysis of the temporal stability to moderate disruptions is executed on these multiple solutions. It is also discovered that whereas the lower solution is unstable with negative lowest eigenvalues, the upper solution is stable and essentially realistic. In addition, the friction factor and the rate of heat transfer rose by nearly 0.129% and 0.039% for the upper branch solution for superior nanoparticle volume fraction, respectively, and decreases by nearly 0.101% and 0.044% for the lower branch solution. Moreover, the outlines of temperature escalates due to the heat source and decelerates due to the heat sink. Finally, the present fallouts are assessed with the prior findings in a specific case to demonstrate the correctness of the existing technique. This study has a wide range of intriguing applications like heating and cooling systems, geothermal energy plants, aerodynamics, and the manufacture of gate disc valves, etc.

Renewable electricity capacity planning with uncertainty at multiple scales

We formulate and compare optimization models of investment in renewable generation using a suite of social planning models that compute optimal generation capacity investments for a hydro-dominated electricity system where inflow uncertainty results in a risk of energy shortage. The models optimize the expected cost of capacity expansion and operation allowing for investments in hydro, geothermal, solar, wind, and thermal plant, as well as battery storage for smoothing load profiles. A novel feature is the integration of uncertain seasonal hydroelectric energy supply and short-term variability in renewable supply in a two-stage stochastic programming framework. The models are applied to data from the New Zealand electricity system and used to estimate the costs of moving to a 100% renewable electricity system by 2035. We also explore the outcomes obtained when applying different forms of CO2 constraint that limit respectively non-renewable capacity, non-renewable generation, and CO2 emissions on average, almost surely, or in a chance-constrained setting, and show how our models can be used to investigate the merits of a proposed pumped-hydro scheme in New Zealand’s South Island.

Petrographic features and carbon structural evolution of a series of high-temperature treated anthracites

Clean energies such as solar, wind, and geothermal power have developed rapidly in recent years and they will probably become the dominant energy source in the future. Thus, coal utilization will have to shift from traditional combustion for energy to coal being a source for raw carbon materials. In this paper, anthracite from the Jinzhushan mine located in central Hunan, China, was treated up to 2900 °C to examine its chemical, petrographic, and carbon structural evolution. Carbon content increased rapidly from 90.2 to 98.8% (daf basis) when treated up to 1700 °C; beyond this temperature the carbon content increased gradually to 100% (daf) at 2900 °C. Altered macerals (vitrinite and inertinite) with an amorphous carbon structure were prevalent in samples treated to ≤1500 °C. Graphitized components were identified in the anthracite heated to ≥1700 °C, as confirmed by micro-Raman spectroscopy and HRTEM. Based on D1 band FWHM versus R1 plots, the carbon structural evolution of anthracite between room temperature and 1700 °C was classified as carbonization, whereas the graphitization process occurred between 1700 and 2900 °C. The nanometric polyaromatic rings retained short-range order during carbonization; the condensed aromatic rings remained randomly oriented at the submicron scale. During graphitization, the aligned structural units were able to undergo condensation reactions and de-wrinkle with temperature increase, leading to a marked increase in crystallite parameters La and Lc. Most vitrinite and inertinite in the anthracite transformed into graphitic components in samples treated to 2600 and 2900 °C, and La showed a significant increase whereas Lc only showed a slight increase between 2600 and 2900 °C. This study will provide insights for optimizing temperature control strategies during preparation of anthracite-based carbon materials in the future.

The economic feasibility approach of the development of geothermal power plant 2 x 20 MW

The development of a geothermal power plant project can be implemented if the project is feasible and can provide benefits from the economic side. In this study, the economic feasibility calculation for the development of a 2 x 20 MW power plant project was carried out based on economic indicators such as Net Present Value (NPV), Internal Rate of Return (IRR) and Pay Out Time (POT). The discounted cash flow method is used in determining the economic feasibility. The calculation results obtained for this power plant development project is not feasible because the NPV is US$ -31,336 million, IRR is 7.11% and POT is 0 year. Due to the uneconomical results obtained, a sensitivity analysis was carried out on the tariff price, drilling costs, and Engineering, Procurement, Construction, and Commissioning (EPCC) costs. With electricity tariffs regulated based on Presidential Regulation Number 112 of 2022, it is found that the resulting taxes in the area are not economical and there is needed for tariff adjustments, namely at a minimum price of 15 cents/kWh and 18 cents/kWh so that the project is economical. However, this price could not be realized because the price far exceeded the highest benchmark price set. Meanwhile, with these uneconomical and unfeasible results, a scenario of a loan was carried out to get better results with an NPV is US$ 528,000, IRR is 10.46% and POT is 28 years. Therefore, with a loan scenario, the project can be obtained as feasible.

Combined frequency and voltage control of two-area multi-source interconnected microgrids via the 2DOF-TIDμ controller

The focus of this study is the utilization of a new two degree of freedom fractional controller, namely the two degree of freedom tilt-integral-derivative controller with fractional derivative (2DOF-TIDμ) and filter, optimized by the coot algorithm, for voltage and frequency regulation in two interconnected microgrids comprising of various sustainable and renewable sources. Both microgrids comprise of a biomass combined heat and power, biodiesel generator, micro-hydro turbine generator and biogas turbine generator along with a battery and superconducting energy storage system. In addition, the first microgrid includes a geothermal power plant, whereas the second microgrid a wind power plant. Furthermore, a power system stabilizer and a unified power flow controller are included in the system. The study aims to present an appropriate controller for the frequency and voltage control of interconnected microgrids which could be isolated communities and/or farms. The controller is compared with the 2DOF-PID and 2DOF-TID controllers, in various scenarios. The scenarios include various simultaneous step load perturbations in both microgrids, penetration of renewable energy sources in one or both areas and injection of noise in the control channels. The results indicate that the 2DOF-TIDμ controller has better transient response and is more effective at suppressing deviations than the other controllers.

Low-carbon lithium extraction makes deep geothermal plants cost-competitive in future energy systems

Low-carbon lithium extraction makes deep geothermal plants cost-competitive in future energy systems

Application of COOT algorithm optimized PID plus D2 controller for combined control of frequency and voltage considering renewable energy sources

This article presents the combined frequency and voltage regulation of two area interconnected power systems. In addition to conventional generations, renewable energy sources such as wind plants, solar PV plants, and geothermal power plants are considered. The COOT algorithm optimized PID + D2 controller is presented for the first time and its performance found superior to commonly employed PI and PID controllers. The individual and combined effects of the boiler dynamics (BD) non-linearity and superconducting magnetic energy storage (SMES) systems are presented. Studies confirmed that the BD non-linearity jeopardizes, and the presence of SMES suppresses the system dynamics oscillations. The COOT based PID + D2 controller performs well even for the higher magnitudes of perturbations over the PID controller. Sensitivity analysis confirms the toughness of PID + D2 controller parameter values for widely varied time constants of the geothermal plant. The COOT algorithm optimized PID + D2 controller outperforms the PID controller in arbitrary load pattern perturbation. The COOT algorithm shows better convergence and figure of demerit characteristics compared with particle swarm optimization and firefly algorithms. The obtained simulation results are also tested successfully through OPAL-RT OP4500 RT-LAB-RCP/HIL system for their real-time validation.

Development of the methodology of energy and environmental safety of Ukraine based on own geothermics

The article presents an idea of the project that defines the development of a geothermal power plant methodology based on a single isolated well. It is planned to develop a technical and economic rationale and geological and geophysical aspects of the development of geothermal energy and to obtain data on deposits of geothermal water in the deep.
 Extraction of heat from hot rocks at the pits is to be carried out using a special energy carrier, construction of the operating column, and circulation mode.
 To create a model in the project, a well is needed with a depth of 4,702 m, temperature at the bottom of 130 °С, an unperforated casing string with a diameter of 245 mm to a depth of 4,500 m, and no formation fluids.
 The transfer and transformation of the energy carrier by the working body into electric and hydrogen energy is maintained by ORC (Organic Rankine Cycle).
 The development of the methodology includes two stages:
 The first stage of the project involves legal preparation at the local and state levels for the use of the land plot and technical means of the drilled well and obtaining licenses and permits for the implementation of the project. It is planned to develop a technical and economic feasibility study for the construction of a geothermal electric station that will generate electricity and hydrogen energy for consumers.
 The second stage of the project involves the technical preparation of the well for its use as part of a geothermal power station. Remediation of the well to a depth of 4,500 m is foreseen, as well as the implementation of industrial geophysical studies of the technical condition of the unperforated casing string; conducting preliminary geothermal studies on the stability and thermal productivity of hot rocks.
 The authors intend to use results in the oil-and-gas industry, which has deep wells that have completed their purpose for hydrocarbon extraction, as well as in the nuclear, metallurgical, chemical, and many other fields.

IOT-Based Hydrogen Sulfide Monitoring at PT. Pertamina Geothermal Energy on Lumut Balai Area

Geothermal Power Plants produce electricity energy from geothermal sources found in geothermal wells. Inside the geothermal well there is H2S content which is a toxic gas that can cause death to humans when human exposed the H2S content for 500-700 ppm within 30-60 minutes. Based on several literacies, in this research, H2S sensor type MQ-136 was used to monitoring H2S content in the geothermal environment. The Internet of Things system is used to read data parameters as a tool to display PPM values on the LCD of the transmitter and receiver device, as well as Adafruit IO website for reading parameter sensor data.. To transmit data from the transmitter to the receiver, Lora Ra-01 AI Thinker is used. The focus of this research is to be able to remotely monitor H2S content through the Adafruit IO website, the highest data was read is 0.54 ppm and the lowest at 0 ppm. This equipment will give "BHY" signal on the LCD display on the transmitter and from the Adafruit IO website it will send a notification "hazard of high ppm H2S" to mobile phones who installed IFTTT application if the H2S concentration was read for 10 ppm or higher, so that workers avoid being exposed to high concentrations of H2S when they want to monitor the parameters in the Geothermal well area.

Environmental benefits for a geothermal power plant with CO2 reinjection: case study of the Kizildere 3 U1 geothermal power plant

Geothermal power plants (GPP) with high non condensable gases (NCG) content geothermal fluid have shown to be environmental impacting relating to their energy production, which could be critical if no corrective actions are achieved. The GPP of Kizildere 3 U1, located in Türkiye (Denizli), in where the geothermal fluid contains high percentage of CO2, 99% of the NCG fraction, which represents the 3% of the geothermal fluid mass, is taken as a relevant case study to implement a new innovation consisting of NCG reinjection to reduce the amount of NCGs released to the atmosphere. In order to calculate the present environmental impacts which the plant is causing (baseline); and the potential reduction of environmental impacts which can be achieved with the innovation (reinjection), a life cycle assessment (LCA) calculation were developed. Primary data were collected for all the relevant stages of the energy conversion cycle and complemented where necessary with secondary data from other geothermal power plants studies. The main results of the baseline environmental assessment show that the construction phase is the most impacting phase due to the materials used in the power plant building construction, electrical generation equipment and distributed machinery and infrastructures; the effects in the operation phase are dominated by the geothermal fluid composition. In this sense, the application of CO2 reinjection at the Turkish site into the reservoir will prevent the emission of 1,700 tons·year−1 in the pilot site and 10% of the total emissions released along the life span of the GPP.

Proposal and comprehensive study of an integrated polygeneration process relying on landfill gas, renewable hydrogen, and binary geothermal cycle

Landfill gas (LFG) is an accessible, inexpensive, and carbon-rich source, and due to its methane content, it can also be used as a fuel. In this paper, a novel polygeneration structure is presented that uses LFG as the input fuel as well as geothermal energy to produce valuable products, including electricity, methanol, freshwater, heating, and cooling. The configuration is made of biogas combustion unit, binary geothermal power plant, cooling water production unit, Kalina power cycle, desalination unit, water electrolysis unit, and methanol synthesis and purification unit. The methanol synthesis unit is modified using a scrubbing column, resulting in recovery of methanol without loss. Aspen HYSYS application is used to model this procedure, and it is examined from a 4E (energy, exergy, economic, and environmental) standpoint. The findings show that a total of55.46% of energyand 77.29% of exergy efficienciesare reached. From the environmental standpoint, it is found that the proposed structure has negative emissions, and its carbon dioxide (CO2) footprint is equal to −0.161 kgCO2/kgprod. In addition, the total CO2 emission of 46,780 kg/h is calculated. Concerning the economic aspect, the cost rate of produced methanol, heating, cooling, and freshwater are found at 0.268 $/kgMeOH, 1.01 $/kgLPS, 0.26 $/kgCW, and 0.7 $/kgFW, respectively. Besides, it is concluded that the methanol production cost rate of this model is comparatively lower than the methods such as power-to-methanol and coke oven gas-to-methanol.

Phytoremediation Technology for Heavy Metal Removal from the Environment

Anthropogenic activities, industrialization, and urbanization have contributed extensively to the enhanced pollution levels in theenvironment. Along with soil and water pollution, air pollution is also escalating and contamination with heavy metals (HMs) isdangerous for the environment since it has negative impacts on people, animals, plants, and the ecosystem. HMs derive their origin from natural and anthropogenic sources. Commercial activities like processing of metals, mining, automobiles, geothermal energy plants, manufacturing industries, tanning, dyeing and plating are the sources of HM contamination. The non biodegradable, permanent inorganic chemical components recognized as HMs are typically harmful at small doses even in humans. HM toxicity leads to carcinogenic effects, developmental and reproductive damage, cardiovascular ailments, haematological, respiratory and nervous system disorders, inflammation and gastrointestinal troubles etc. The absorption and accretion of these metals cause oxidative stress and molecular damage, cytotoxic and mutagenic effects, growth reduction and physiological disorder in plants. Therefore considering their toxic effects, various mechanical as well as physio-chemical technologies are employed for metal removal from the air, water and soil but these techniques have their own limitations and environmental consequences. Hence, phytoremediation is considered an innovative, potentially promising technology employing majorly green plants. The various phytoremediation techniques involve phytoextraction, phytostabilization, phytodegradation, phytotransformation, phytovolitization, and rhizofiltration. Employing these techniques, plants can remove contaminants through a variety of processes, including adsorption, absorption, transport and translocation, hyper-accumulation, transformation, and mineralization. While phytoremediation of air pollutants is still an emerging technology, assimilation properties of plants to convert a toxicant into non-toxic forms have been used extensively for phytoremediation of air. Plants like Morus alba and Eucalyptus globulus can efficiently remove metallic pollutants from air. Moreover, aquatic macrophytes like Eichhornia crassipes,Spirodela polyrhiza, Pistia stratiotes, Azolla, Lemna minor, and Salvinia herzogii are potentially used for cleanup of the HMs in water, while Brassica juncea, Thlaspi caerulescens, Jatropha curcas, Pteris vittata, Vetiveria zizanioides, Gentiana pennelliana, Ambrossia artemisifolia etc. display tremendous well known phytoremediation activity in soil. Phytoremediation is an innovative, aesthetically pleasing, nonintrusive, sustainable and cost-effective technology. Furthermore, due to the disadvantages like high maintenance cost, extensive labor requirement and risks involved in existing conventional technologies associated with pollution abatement, phytoremediation technique can act as a potential, cost-effective and efficient method for water, soil as well as air pollution control.

A compact production plant model for green hydrogen production from medium temperature geothermal resources: A case study of the Van Lake-Zilan location

Considering the abundance of renewable energy potential in Turkey, green hydrogen derived from renewable sources holds great promise as a fuel. This paper presents a model for obtaining green hydrogen from medium-temperature geothermal sources. In this model, the Zilan location in the Van province of Turkey was identified as a suitable site for electricity and hydrogen production from low or medium-temperature geothermal sources due to its significant geothermal and water resource potential. In this regard, the installed capacity of the Organic Rankine Cycle (ORC) geothermal power plant is determined by using Monte Carlo Simulation based on the characteristics of the geothermal well at this location, and subsequently, the hydrogen production performance has been evaluated by analyzing the water of Lake Van. According to the analysis results, Lake Van was found to be efficient for hydrogen production. Hydrogen production from Lake Van water was subsequently simulated using the electrolysis method with this ORC geothermal power plant. According to the findings of this model, the hourly hydrogen production potential at this location using a 1.4 MW ORC plant, based on 2022 data, was estimated to be 18.6 kg, which is projected to increase to 28 kg based on 2050 estimated data. In addition, the techno-economic analysis of this compact green hydrogen production process was conducted in the study. The production cost of 1 kg of hydrogen was calculated to be €4.91 in 2022, while it is expected to be €1.21 in 2050. These results indicate that ORC technology will become competitive in hydrogen production in the upcoming years.

Failure analysis of corroded heat exchanger CuNi tubes from a geothermal plant

This study examined the premature failure of cupronickel (CuNi10Fe) tubes in a shell-and-tube heat exchanger after five months of service. An investigation to identify the root cause of the tube burst was carried out using macroscopic and microscopic inspection, chemical analysis, and mechanical analysis. The optical microscopy (OM) and scanning electron microscopy (SEM) evaluation revealed crack propagation characterized by pits and inclusions at the tube surface. This was due to the diffusion of hydrogen ions into the material from the hydrogen sulfide (H2S) rich geothermal environment. Furthermore, high tensile residual stresses of 172 MPa were recorded in the failed tube, leading to stress cracking in hydrogen-containing material. Additionally, the high sulfide content in corroded water and condensate samples suggests that the leading cause of tube rupture was through hydrogen embrittlement and sulfide stress cracking mechanism in the presence of hydrogen sulfide. Therefore, the use of laser cladding to protect tubes using functionally graded materials is recommended to mitigate degradation in aggressive environments, through careful material selection and additional water treatment to eliminate the contaminants.

Geothermal energy prospect for decarbonization, EWF nexus and energy poverty mitigation in East Africa; the role of hydrogen production

The affordability and availability of water and energy have a huge impact on food production. Research has shown that there exists a direct and indirect link between power production and clean water generation. Hence the inclusion/importance given to the energy-water-food (EWF) nexus in the United Nations' sustainable development goals. Acknowledging the importance of decarbonization to the global future, there exists a gap in literature on the development of models that can enhance the EWF nexus, reduce energy poverty, and achieve 100% renewable energy in the electricity sector. Therefore, the technical and economic prospect of geothermal energy for bridging the aforementioned gaps in existing works of literature is presented in this study. The energy poverty/wealthy status of a country has been confirmed to have a significant impact on economic development, as economic development is largely reflected in the food-water availability. Ditto, this study is focused on the interconnectivity of the EWF nexus while incorporating global decarbonization targets. Geothermal energy is of the utmost significance in East Africa due to its abundant potential and distinctive geological features. Located in the Great Rift Valley, the region has an abundance of geothermal reservoirs, making it an ideal location for geothermal power generation. This study is novel as a comprehensive assessment framework for energy poverty is developed and innovative models utilizing primarily the geothermal resource in the East African region to mitigate this problem are proposed and analyzed. The role of hydrogen generation from critical excess electricity production is also analyzed. The East Africa region is considered the case study for implementing the models developed. A central renewable energy grid is proposed/modelled to meet the energy demand for seven East African countries namely; Ethiopia, Tanzania, Uganda, Djibouti, Comoros, Eritrea, and Rwanda. This study considers 2030, 2040, and 2050 as the timestamp for the implementation of the proposed models. The hybrid mix of the biomass power plant, solar photovoltaic (PV), pumped hydro storage system and onshore wind power is considered to furthermore show the potency of renewable energy resources in this region. Results showed that the use of geothermal energy to meet energy demands in the case study will mitigate energy poverty and enhance the region's EWF.

Advanced monitoring of geothermal Organic Rankine Cycles

Geothermal Organic Rankine Cycle (ORC) power plants have tremendous worldwide potential for the utilization of low- and medium-temperature geothermal resources. However, monitoring of such a system is associated with special challenges for plant operators since the generated electrical power fluctuates strongly, which is caused by mainly two reasons: Firstly, due to the changing condensation conditions caused by air-cooled condensers, and secondly, due to the formation of scaling and fouling. Therefore, the process parameters of a geothermal ORC plant are highly variable, both in terms of diurnal and seasonal fluctuations. Considering the currently applied control software in commercial ORC plants, these fluctuations result in challenges regarding a reliable identification of potential degradation processes within the ORC process.This paper presents a novel analytical and data-based methodology for advanced monitoring of the main components of a two-staged subcritical geothermal ORC system in Southern Germany. These components are the heat exchanger, turbine and air-cooled condenser. For this purpose, operational data from more than three years were preprocessed and evaluated.For the shell-and-tube evaporator, this work applies an equation-based simulation model for the calculation of the thermal resistance due to scaling and fouling. For the turbine and condenser, polynomial functions of various degrees and different objective functions for the numerical computation of regression coefficients are examined. Regression models for three years of operation of the investigated geothermal plant were computed and compared with each other.The results indicate that there are no significant negative changes in the operational performance of most ORC main components during the investigated time period. However, negative operational changes are detected over a three-year period for one turbine of the ORC system. The detailed evaluation of the turbine data reveal a decrease of the normalized isentropic efficiency by 10%, which is significantly higher than the calculated RMSE of the developed correlations, thus indicating a clear performance reduction of the turbine. The developed advanced monitoring methodology allows the operator detailed and accurate assessment of the ORC components conditions, which can not be provided by the software solutions of the commercial ORC manufacturer. Furthermore, the presented methodology can also be applied to other thermal cycle systems with similar components, such as the Kalina Cycle.Finally, a user-friendly software application, developed with the MATLAB® App Designer, is presented. The developed software tool facilitates operators to easily and precisely monitor the operation of the main components of a geothermal ORC plant.

Improvement of Geothermal Power Plants by Utilizing Hydrogen Steam Superheating: A Review

The rapid growth of geothermal power plants is due to their great potential and environmentally friendly energy source. In its development, hydrogen is used as energy storage for several intermittent renewable energy sources. Hydrogen Steam Superheating utilizing hydrogen products can pressure steam as additional fuel to operate steam turbines. The electrolysis method with high-temperature water fluid produces more hydrogen content and is more efficient than ambient temperature water; therefore, it is suitable for producing superheating hydrogen steam by electrolysis using geothermal power plants. A combined cycle (flash & binary) geothermal power plant with additional hydrogen steam superheating can increase the power 8 - 9 MW using the mixed working fluid R-31-10 and RC-318 in a binary cycle power plant and improve the thermal efficiency of flash cycles by up to 12.3%. Thus, the application of adding hydrogen steam superheating is a method that can be utilized to increase the power capacity of geothermal power plants, replacing the current conventional method of drilling to open steam production wells.