Geothermal Power Systems Research Articles

Heat energy utilization of a double-flash geothermal source efficiently for heating/electricity supply through particle swarm optimization method

The principal aim of this article is to optimize the thermal and electrical efficiency of a geothermal combined heat and power system through metaheuristic particle swarm optimization (PSO) method. The objective of this research is to conduct a thorough analysis of the incorporation of metaheuristic PSO technique, with a specific emphasis on the potential advantages and obstacles associated with the utilization of metaheuristic approaches in improving the effectiveness of geothermal energy systems. The utilization of a double-flash geothermal system in conjunction with a transcritical carbon dioxide Rankine cycle is utilized for the co-generation of electricity and thermal energy. The research utilized a PSO method to enhance power generation, heating capacity, and overall system efficiency. The PSO algorithm was employed to determine the optimum operational parameters for a pressure level of 820 kPa and a pressure ratio of 1.59, leading to the maximization of power output to 2591.4 kW The PSO algorithm effectively identified the optimal operational parameters as a pressure of 820 kPa and a pressure ratio of 1.59, resulting in the achievement of a peak power output of 2591.4 kW. The methodology has determined that a pressure of 916.4 kPa and a pressure ratio of 1.5 represent the optimal parameters for achieving a maximum heating capacity of 12329.1 kW.

Artificial intelligence application for assessment/optimization of a cost-efficient energy system: Double-flash geothermal scheme tailored combined heat/power plant

Utilizing the capabilities of artificial intelligence can lead to the development of energy systems and power supply chain that are more efficient, sustainable, and resilient. The integration of machine learning techniques within these systems provides substantial benefits and is essential for enhancing overall performance. As the global community confronts challenges like climate change and rising energy demands, machine learning will play an increasingly vital role in defining the future of energy systems. This research examines how effective regression-based machine learning techniques are for analyzing and optimizing the performance of a geothermal combined heat and power system. It focuses on creating both linear and quadratic models to assess electricity generation, heat production, and the efficiency of the entire system. The evaluation of these models is performed through residual analysis and R-squared statistics. Results indicate that quadratic models surpass linear ones, with linear model achieving an R-squared value of 88.56 % for power generation, while the quadratic model reaches an impressive R-squared level of 99.88 %. Furthermore, the study demonstrates that quadratic machine learning models hold significant promise for optimizing system performance, shown by desirability metrics exceeding 0.99. This research highlights the importance of regression-based machine learning methods in analyzing and improving geothermal combined heat and power systems.

Optimization of Organic Rankine Cycle for Hot Dry Rock Power System: A Stackelberg Game Approach

Due to its simple structure and stable operation, the Organic Rankine Cycle (ORC) has gained significant attention as a primary solution for low-grade thermal power generation. However, the economic challenges associated with development difficulties in hot dry rock (HDR) geothermal power systems have necessitated a better balance between performance and cost effectiveness within ORC systems. This paper establishes a game pattern of the Organic Rankine Cycle with performance as the master layer and economy as the slave layer, based on the Stackelberg game theory. The optimal working fluid for the ORC is identified as R600. At the R600 mass flow rate of 50 kg/s, the net system cycle work is 4186 kW, the generation efficiency is 14.52%, and the levelized cost of energy is 0.0176 USD/kWh. The research establishes an optimization method for the Organic Rankine Cycle based on the Stackelberg game framework, where the network of the system is the primary optimization objective, and the heat transfer areas of the evaporator and condenser serve as the secondary optimization objective. An iterative solving method is utilized to achieve equilibrium between the performance and economy of the ORC system. The proposed method is validated through a case study utilizing hot dry rock data from Qinghai Gonghe, allowing for a thorough analysis of the working fluid and system parameters. The findings indicate that the proposed approach effectively balances ORC performance with economic considerations, thereby enhancing the overall revenue of the HDR power system.

Solar cells combined with geothermal or wind power systems reduces climate and environmental impact

This research investigates the environmental sustainability of three integrated power cycles: combined geothermal-wind, combined solar-geothermal, and combined solar-wind. Here, a promising solar technology, the perovskite solar cell, is considered and analysed in conjunction with another renewable-based cycle, evaluating 17 scenarios focusing on improving the efficiency and lifespan. Among the base cases, combined solar-wind had the lowest ozone depletion impact, while combined geothermal-wind had the lowest freshwater ecotoxicity and marine ecotoxicity impacts. The study shows that extending the perovskite solar cell lifespan from 3 to 15 years reduces CO2 emissions by 28% for the combined solar-geothermal and 56% for the combined solar-wind scenario. The most sustainable cases in ozone depletion, marine ecotoxicity, freshwater ecotoxicity, and climate change impacts are combined solar-wind, combined solar-geothermal, and combined geothermal-wind, respectively, among all evaluated scenarios. This research suggests investing in the best mix of integrated power cycles using established and emerging renewable technologies for maximum environmental sustainability.

Advanced exergo-economic and exergo-environmental analyses of a geothermal sourced power system with the modified productive structure analysis method (MOPSA)

Advanced exergo-economic and exergo-environmental analyses of a geothermal sourced power system with the modified productive structure analysis method (MOPSA)

Development and modeling of power, hydrogen and freshwater production based on a novel double-flash geothermal power plant

In this article, a novel geothermal energy-assisted multigeneration plant is proposed and analyzed from the thermodynamic, economic, and environmental perspectives. In the design of the geothermal power system, a transcritical Rankine cycle, which employs CO2 as the working fluid (tCO2-RC), a Kalina cycle (KC), a hydrogen generation sub-plant, and a desalination unit are considered. The reverse osmosis (RO) desalination process is used for freshwater production, while the proton exchanger membrane (PEM) electrolyzer is utilized for hydrogen generation. In addition, parametric analyses are conducted to ascertain the impacts of the temperature of the geothermal source, mass flow rate, and flash chamber pressure on system performance. According to the results, the plant's overall energetic and exergetic efficiencies are determined to be 8.6 % and 34.9 %, respectively where the net power production is calculated as 3317.94 kW, and the system's total irreversibility is found to be 5852.88 kW. Furthermore, the hourly H2, O2, and freshwater generation amounts are 8.5 kg, 49.1 kg, and 9.3 m3, respectively. Finally, the levelized energy cost (LEC) and sustainability index of the system are found to be 0.128 USD/kWh and 0.215.

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.

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

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.

Comprehensive energy, exergy, and economic analyses of a geothermal and flue gas-based dual-source power, hydrogen, and freshwater trigeneration system

Designing a ploy-generation system to produce various products is an effective method to improve the common power plant’s performance. Hence, the current investigation proposes a green poly-generation system driven by geothermal and flue gas. The proposed scheme consists of an organic Rankine cycle, proton exchange membrane electrolyzer, saline water desalination unit, and Allam cycle to produce power, hydrogen, and freshwater. The produced oxygen in the electrolyzer feeds the Allam cycle to perform an oxyfuel process to achieve zero CO2 emission. Per the 4E analysis, the system produces 27,720 kW net power, 931 kmol/h hydrogen, and 616.7 kmol/h freshwater. In this way, the energy and exergy efficiencies are obtained at about 16.87% and 51.65%. The total exergy destruction rate is estimated at about 78,926 kW, in which the organic Rankine cycle and its vapor generator have the highest portions among the different parts and equipment by about 69% and 18.87%. The sensitivity analysis indicates that by the CO2 recycle ratio of 60%, the highest energy and exergy efficiencies reach 19.3% and 54.33%. Furthermore, the unit cost of hydrogen and electricity productions are 0.07$/kWh and 7.24 $/GJ, which is a considerable reduction compared to similar methods.

Analysis and Research on the Development of Geothermal Energy and Future Development Trend

Scientists and engineers from all over the world have acknowledged the significance of employing environmentally friendly energy to replace fossil fuels in manufacturing as global warming has gotten worse over the past century. Geothermal energy, which is a form of subsurface energy that is stored as heat and gas, is one of many sustainable energy sources. There are currently three popular exploitation techniques. The Xero-thermal power system is appropriate for regions with shallow heat sources and mild temperature gradients since it generates energy from low-temperature geothermal resources. Flash geothermal power systems are appropriate for locations with hot fluids. Binary cycle generation system employs a secondary working fluid with a boiling point that is lower than water, allowing for power generation from lower temperature geothermal resources, thereby expanding the potential for geothermal energy production. The study then largely focuses on the key elements, such as resource availability, technological hurdles, and market conditions, that can influence the utilization of geothermal energy. Researchers and engineers can more clearly comprehend the benefits and constraints in various resource environments by closely evaluating these elements. While the government should urge the people to pay greater attention to the exploitation and deployment of renewable energy, engineers could improve drilling techniques. The current situation of harnessing and exploiting geothermal energy highlights the necessity for ongoing research and development to fully realize geothermal energy's potential. This essay contributes to the larger conversation on renewable energy and offers insightful information about the significance of geothermal energy.

Withdrawn: Flow field analysis of a turbo expander based on organic rankine cycle for geothermal power system simulation

AbstractWithdrawal: Zixuan Guo, Chao Zhao, Wenguang Jia, Flow field analysis of a turbo expander based on Organic Rankine Cycle for Geothermal Power System Simulation, published in Energy Science & Engineering, DOI 10.1002/ese3.1454. The above article, published online on 01 April 2023 in Wiley Online Library (wileyonlinelibrary.com), has been withdrawn by agreement between the journal Editor in Chief, Yun Hang Hu, and Society of Chemical Industry and John Wiley & Sons Ltd. The withdrawal has been agreed following no response from the author to requests to sign the Journal's publishing license.

Improved efficiency in an integrated geothermal power system including fresh water unit: Exergoeconomic analysis and dual-objective optimization

The single-flash geothermal cycle (SFGC) is not without its limitations, featuring drawbacks like diminished efficiency, restricted power generation capacity, and the incapability to yield multiple outputs concurrently. Furthermore, the SFGC requires a substantial water supply, potentially leading to adverse environmental consequences. In a concerted effort to enhance overall performance and facilitate the concurrent production of multiple valuable products, this study introduces a multigeneration system (MGS). By integrating additional subsystems into the SFGC framework, including a branched GAX cycle enabled by a thermoelectric generator (TEG), a domestic water heater (DWH), and a reverse osmosis unit, the objective is to surmount these limitations effectively. A thermodynamic and exergoeconomic analysis of the system is conducted and a bi-objective optimization is employed to minimize system cost and maximize exergy efficiency. The parametric study reveals that when degassing ranges are in the range of 0.2–0.37, the system product cost varies from $27.07/MWh to $28.44/MWh. In the optimized scenario there is a decrease of 67.7% in cooling provided by the system. This leads to an increase of 3.5% in generated electricity and a 3% increase in water purification compared to the base scenario. Through optimization the exergy efficiency of the system improves from 61.84% to 62.90% while the multigeneration gain output ratio (MGOR) decreases from 1.40 to 1.38.

Computational analysis of natural convection with water based nanofluid in a square cavity with partially active side walls: Applications to thermal storage

Heat transport induced by buoyancy caused natural convection inside a segmented or selectively heated enclosure has grown in importance over the decades due to its significance in many fields in industrial implementations such as heat source cooling, food sterilizers, crystal growth, geothermal power systems, solar thermal collectors, melting and recrystallization procedures, microelectronic and nuclear industries, biomedical, and so forth. The novelty of current modern analysis is to scrutinize the natural convection of Titanium Oxide-water nanofluid in the cavity with partially active walls simulated by the finite element (FEM) method. The fluid flow and the thermal transportation within the enclosure are scrutinized. Two cases are carried out in this novel study, heat sink with constant temperature Tc consists in case 1 from the left and right partially active cavity walls and isothermal heat source having temperature Th correspondingly, whereTh>Tc. While upper and lower walls with inactive portions of the left and right walls are kept insulated. In case 2 the left and right walls of the cavity are heated while a partially active bottom wall is cold with other inactive parts insulated by the cavity walls. The finite element method is applied to tackle the governing equations. The Significance of Rayleigh number (100⩽Re⩽1e6) and volume fractions of nanopowders (0.01⩽ϕ⩽0.06) against fluid flow and heat transfer is demonstrated through streamlines and isotherms. From the results it is concluded that velocity amount is increased with escalating the values of Rayleigh number. The thermal results are enhanced with Rayleigh number. Furthermore the heat transfer is rised with volume fraction of nanoparticles. Additionally, from the analysis reveals that local Nusselt number is enhanced with Rayleigh number and nanoparticle volume fraction.

Modelling reinjection of two-phase non-condensable gases and water in geothermal wells

Steam production from high enthalpy geothermal systems is frequently accompanied by the emission of non-condensable gases (NCGs), initially dissolved in the liquid phase or mixed in the vapour phase at depth in the reservoir. Capturing and reinjecting geothermal gases (CO2, CH4, NH3, H2S, H2, …) together with condensed steam leads to a significant improvement of the environmental profile of geothermal power systems and helps with reservoir recharge and pressure support. Nowadays, there are several ongoing projects targeting the minimalization of the environmental impact of geothermal exploitation through reinjection of the NCGs. For low NCG content, the gases can be fully dissolved into the condensed water and reinjected. However, for a high concentration of NCGs, the dissolution is only partial, and a two-phase mixture needs to be reinjected to achieve this goal. We present here the numerical results for the reinjection process in two different geothermal sites and for two different injection scenarios, focusing on the case of two-phase (liquid–gas) flows. Three commercial software (UniSim®, PIPESIM, and OLGA) and one in-house developed code (GWellFM) were used, and their results were compared. The injection should always take place inside a liquid column in the well to avoid degassing and accumulation of the NCGs. When targeting high pressure reservoirs or when injecting high ratios of water to NCGs flow rates, mixing of the two phases should take place on the surface. Whereas for low pressure reservoirs or for high gas contents mixing must occur deep in the well through one or several mixing points to ensure either complete dissolution of the gas or the downward flow of a two-phase mixture with minimum compression on the surface. The uncertainties of two-phase downward flows and water/NCGs mixtures characterisations introduce additional complexities in the modelling of the reinjection process.

Power from Geothermal Resources as a Co-product of the Oil and Gas Industry: A Review.

The increase in the global demand for energy and fossil fuel dependency is hindering efforts to reduce greenhouse gas (GHG) emissions. Geothermal resources supplement this increase in energy demand with reduced emissions because of their availability, base-load production profile, and climatic independence. Despite these advantages, the development of geothermal energy is limited because of different reasons such as subsurface exploration risk and high upfront capital cost for drilling and facility construction. However, similarities in infrastructure and operations between the oil and gas industry and the geothermal industry can optimize expense and development when exploiting geothermal resources. Thus, in this review, we present recent advances and applications of geothermal power systems in the oil and gas industry starting from the fundamentals and basic principles of geothermal energy and the organic Rankine cycle (ORC). These applications include the use of geothermal resources via abandoned wells, active wells, and paired thermal enhanced oil recovery processes with injection for fluid heating and energy production. Abandoned wells are alternatives that reduce costs in geothermal energy-use projects. The use of geothermal resources via active wells allows the valorization of a resource, such as the production of water, which is considered a byproduct of production activities in an oilfield. The use of thermally enhanced oil recovery processes enhances the energy conditions of fluids produced in the field, improving geothermal systems with fluids at higher temperatures. Finally, an overview is presented of the challenges and opportunities of geothermal energy in the oil industry where the requirement to improve the usage of technologies, such as the ORCs, with the working fluids used in the cycles, is highlighted. Furthermore, the importance of environmental studies and use of novel tools, such as nanotechnology, to improve the efficiency of geothermal energy usage is highlighted.

Modelling and control strategy of a distributed small‐scale low‐temperature geothermal power generation system

At present, commercial geothermal power stations are mainly high-temperature and medium-temperature geothermal energy, while the large number of low-temperature geothermal energy resources are rarely used for power generation applications. This paper proposes a new model for energy conversion in low-temperature geothermal power systems. The basic structure and working principle of this new model are analysed, in detail, a low-temperature geothermal model and a Stirling engine model for geothermal energy conversion are established, and the control strategies on the rotor and stator sides of the Stirling-driven doubly-fed generator are discussed. Finally, the simulation analysis is carried out, and its results show that the thermal conversion efficiency of Stirling’s engine can reach 38%, the output AC voltage of the power generation system reaches the set value 50Hz, 190V, and the DC bus voltage is constant at 300V, which verified the validity of the proposed power generation model and related control strategies. This system expands the range of available heat sources in geothermal power generation, makes geothermal power generation more flexible in terms of site selection, power generation capacity and control, and provides a new idea for geothermal power generation structure.

On Site Monitoring During Nearby Drilling Operations Toward a Geothermal Power System Installation

On Site Monitoring During Nearby Drilling Operations Toward a Geothermal Power System Installation

New Horizons for Geothermal Energy

Abstract The geothermal heat resource is not limited the way fuel or iron or other materials are. But the low efficiency of geothermal power systems is unsatisfying and contributes to often-poor economics. To improve efficiency, engineers could look for a different thermodynamic cycle in the power plant. And, the economics can be improved by developing a facility whereby geothermal heat and electricity is the by-product of a process to produce lithium.

Using [formula omitted]-Plume geothermal (CPG) energy technologies to support wind and solar power in renewable-heavy electricity systems

CO2-Plume Geothermal (CPG) technologies are geothermal power systems that use geologically stored CO2 as the subsurface heat extraction fluid to generate renewable energy. CPG technologies can support variable wind and solar energy technologies by providing dispatchable power, while Flexible CPG (CPG-F) facilities can provide dispatchable power, energy storage, or both simultaneously. We present the first study investigating how CPG power plants and CPG-F facilities may operate as part of a renewable-heavy electricity system by integrating plant-level power plant models with systems-level optimization models. We use North Dakota, USA as a case study to demonstrate the potential of CPG to expand the geothermal resource base to locations not typically considered for geothermal power. We find that optimal system capacity for a solar-wind-CPG model can be up to 20 times greater than peak-demand. CPG-F facilities can reduce this modeled system capacity to just over 2 times peak demand by providing energy storage over both seasonal and short-term timescales. The operational flexibility of CPG-F facilities is further leveraged to bypass the ambient air temperature constraint of CPG power plants by storing energy at critical temperatures. Across all scenarios, a tax on CO2 emissions, on the order of hundreds of dollars per tonne, is required to financially justify using renewable energy over natural-gas power plants. Our findings suggest that CPG and CPG-F technologies may play a valuable role in future renewable-heavy electricity systems, and we propose a few recommendations to further study its integration potential.