•Current patent review on CO2 utilization technologies for CCUS application using Derwent Innovation platform.•Emerging hybrid technologies concepts with disruptive potential was found and potential ...future study proposed.•Health, safety and environmental impact due to CO2 utilization technologies implementation.
There is rising concern on the increasing trend of global warming due to anthropogenic CO₂ emission which steers progress of carbon capture and storage (CCS) projects worldwide. However, due to high cost and uncertainties in long term geological storage, there is a growing inclination to include utilization, which re-use the CO2, hence carbon capture utilization and storage (CCUS). Additionally, it is expected to generate income to offset the initial costs. This study methodically review patents on CO₂ utilization technologies for CCUS application published between year 1980–2017. It was conducted using the Derwent Innovation patent database and more than 3000 number of patents was identified. The patents identified are in the field of enhanced oil recovery (EOR) and enhanced coal-bed methane (ECBM), chemical and fuel, mineral carbonation, biological algae cultivation and enhanced geothermal system (EGS). Over 60% of these patents were published since the last 10 years, and a sharp increase in patents were seen in the last 5 years (∼38%). The top major patent types are patents granted in the United States (US), China (CN) and Canada (CA) which makes of 3/5 of the overall patent type found. Recent patents published include enhancements to the state-of-the-art technologies and hybrid concepts such as in photo-bioreactor in algae cultivation, chemical reaction and EGS. From this study, it was found that further research for the best CO₂ utilization method which fulfil the need of an economic, safe, non-location dependent and environmentally friendly whilst efficiently mitigate the worldwide global warming issue is much needed.
As per the recommendations of the American Association of Physicists in Medicine Task Group 43, Monte Carlo (MC) investigators should reproduce previously published dose distributions whenever new ...features of the code are explored. The purpose of the present study is to benchmark the TG-43 dosimetric parameters calculated using the new MC user-code egs_brachy of EGSnrc code system for three different radionuclides
Ir,
Yb, and
I which represent high-, intermediate-, and low-energy sources, respectively.
Brachytherapy sources investigated in this study are high-dose rate (HDR)
Ir VariSource (Model VS2000),
Yb HDR (Model 4140), and
I -low-dose-rate (LDR) (Model OcuProsta). The TG-43 dosimetric parameters such as air-kerma strength,
, dose rate constant, Λ, radial dose function, g(r) and anisotropy function,
θ
and two-dimensional (2D) absorbed dose rate data (along-away table) are calculated in a cylindrical water phantom of mass density 0.998 g/cm
using the MC code egs_brachy. Dimensions of phantom considered for
Ir VS2000 and
Yb sources are 80 cm diameter ×80 cm height, whereas for
I OcuProsta source, 30 cm diameter ×30 cm height cylindrical water phantom is considered for MC calculations.
The dosimetric parameters calculated using egs_brachy are compared against the values published in the literature. The calculated values of dose rate constants from this study agree with the published values within statistical uncertainties for all investigated sources. Good agreement is found between the egs_brachy calculated radial dose functions, g(r), anisotropy functions, and 2D dose rate data with the published values (within 2%) for the same phantom dimensions. For
Ir VS2000 source, difference of about 28% is observed in g(r) value at 18 cm from the source which is due to differences in the phantom dimensions.
The study validates TG-43 dose parameters calculated using egs_brachy for
Ir,
Yb, and
I brachytherapy sources with the values published in the literature.
The increasing demand for clean energy with minimum environmental impact motivates development of geothermal energy. Simulating a geothermal reservoir is complex and time consuming, mainly because of ...the systems spatial and temporal non-isothermal nature and the enormous size of the domain/reservoir. Simulations become even more complex when representing Enhanced Geothermal Systems (EGS), where wells in a hot, low permeability reservoir are interconnected by hydraulic fracturing to provide pathways for injection of cold water, in situ heating, and consequent production of hot water. In this study, various issues related to simulation of enhanced geothermal systems are investigated and practical solutions are proposed. A comprehensive study was conducted to show the effect of different grid systems on predictions of the transient temperature of the produced water. It is shown that the performance of an EGS is affected by the transmissivity (product of permeability and width of the fracture) of the fracture more so than by the values of permeability and width of the fracture considered individually. A simplified model (downscaled model) reduces the simulation times significantly (by 1.5–14.5 times) without compromising the accuracy of the results. In the proposed model, only two simulations - capturing small portions of the top and bottom of a reservoir with two active hydraulic fractures is used to evaluate performance of the entire reservoir. The proposed model is proved to be robust when exposed to different scenarios created by varying the inclination of the wells with respect to horizontal, spacing of the hydraulic factures, and spacing between the injection and producing wells. Value of R2 close to unity (0.96–1.0) and smaller value of MAPE (Mean Absolute Percentage Error), less than 3% in comparison to the entire reservoir simulations, indicate the utility of proposed model.
•Challenges faced in simulating and upscaling of EGS are investigated.•Grid sensitivity of simulation models is studied and optimized.•The effects of fracture permeability and width are analyzed.•A simplified model is proposed to represent the entire reservoir by simulating small sections.•The proposed model works efficiently and reduces simulation time by 1.5–14 times.
Enhancing the heat transfer efficiency between working fluids and hot dry rocks (HDRs) in fracture reservoirs is important. In this paper, we present the seepage and convective heat transfer ...experiment to investigate the behavior of distilled water in the artificial rock samples. The reproducibility of the experimental studies can be achieved based on Barton's JRC profiles and advanced 3D printing technology. The roughness of two rock samples is 10–12 &18–20 and 18–20 &10–12 respectively. The effects of roughness and confining pressure on seepage characteristics were analyzed. The variation of rock temperature with time under initial temperature and flow rate was obtained. And the effects of roughness on heat transfer performance for two specimens were evaluated. The results indicated that large roughness in the direction perpendicular to flow would decrease seepage capacity and the confining pressure had great influence on seepage. And higher flow rate would extract more heat in fractured reservoir. Furthermore, the outlet temperature was almost linear with the original rock temperatures. Finally, the large roughness in the direction perpendicular to flow would strengthen heat transfer and large roughness in the direction parallel to flow would reduce effective heat transfer area.
•The repeatable rock samples with rough fracture are manufactured by 3D printing technology based on JRC profile.•The variations of rock external wall temperature with time under initial temperature and flow rate are obtained.•The effects of roughness on seepage and convective heat transfer are analyzed quantitatively.
•Quantifying structural uncertainties requires a vast variety of time-consuming numerical simulations.•Machine learning methods can save the computation time up to several orders of magnitude.•A ...machine learning algorithm can be robust enough to predict time series based on the structural information of the geological model.
Including uncertainty is essential for accurate decision-making in underground applications. We propose a novel approach to consider structural uncertainty in two enhanced geothermal systems (EGSs) using machine learning (ML) models. The results of numerical simulations show that a small change in the structural model can cause a significant variation in the tracer breakthrough curves (BTCs). To develop a more robust method for including structural uncertainty, we train three different ML models: decision tree regression (DTR), random forest regression (RFR), and gradient boosting regression (GBR). DTR and RFR predict the entire BTC at once, but they are susceptible to overfitting and underfitting. In contrast, GBR predicts each time step of the BTC as a separate target variable, considering the possible correlation between consecutive time steps. This approach is implemented using a chain of regression models. The chain model achieves an acceptable increase in RMSE from train to test data, confirming its ability to capture both the general trend and small-scale heterogeneities of the BTCs. Additionally, using the ML model instead of the numerical solver reduces the computational time by six orders of magnitude. This time efficiency allows us to calculate BTCs for 2′000 different reservoir models, enabling a more comprehensive structural uncertainty quantification for EGS cases. The chain model is particularly promising, as it is robust to overfitting and underfitting and can generate BTCs for a large number of structural models efficiently.
A conceptual Enhanced Geothermal System (EGS) with triplet horizontal well layout is proposed, in which the injection well is flanked by two production wells. The injection well is completed with ...perforated casing, followed by multistage fracturing with casing packers. Two production wells are drilled through the stimulation zone induced by multistage fracturing and completed openhole to maximize contact with the reservoir. Based on a fully coupled hydrothermal (HT) model accounting for local thermal non-equilibrium (LTNE), sensitivity analysis and optimization for EGS design parameters are conducted. Simulation results show that increasing circulation rate only facilitates the heat extraction rate before thermal breakthrough, but cannot improve the heat extraction performance at the end of EGS operation. Compared with the fracture aperture, the increase in the stimulation zone permeability is more conducive to reducing the injection pressure and increasing the cumulative output thermal power. Insufficient or excessive fracturing stages are detrimental to economic heat extraction. It is found that more uniform flow into each perforation can achieve better thermal sweep efficiency and prevent local thermal breakthrough. The stimulation zone has an optimal reservoir permeability to match the fracture aperture. The optimum number of fracturing segments for a specified wellbore length is obtained. The preferable zone for the production well is between the fracture front and the outermost periphery of the stimulation zone.
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•A novel EGS model for horizontal wells with multistage fractures is designed.•An EGS hydrothermal simulation method considering local thermal non-equilibrium is developed.•Sensitivity analysis of potential factors to heat extraction performance is performed.•Optimization results for key design parameters are presented.
Operational optimization is the key to maximize the heat extraction efficiency of Enhanced Geothermal Systems (EGS). Injection/production flowrate is one of the operational parameters that can be ...easily manipulated to produce desired amount of energy. In this study, the effect of different flow schemes on the rate of heat production is analyzed over a period of 30 years. Seven flow schemes (four continuous functions namely constant flow, linear flow, exponential flow, mirror exponential flow, and three step functions with step sizes of six months, three years and ten years) developed on the basis of mathematical functions were examined. A doublet EGS model with a single fracture was simulated using a commercial thermal reservoir simulator. The reservoir and well data were obtained from the FORGE (Frontier Observatory for Research in Geothermal Energy) site at Milford Utah. The results were analyzed on the basis of their temperature decline curves for the produced water and the total amount of heat extracted over the entire period. The exponential flow scheme is the optimum case considering the rise in energy demand over the next 30 years. The amount of heat extracted per unit volume of water decreases with increase in total water volume circulated.
•A doublet well system based on data from the FORGE site near Milford, Utah, USA is studied.•Seven different injection schemes are explored to optimize the heat recovery from EGS.•Exponential flow is the optimized water injection scheme in maximizing heat recovery in 30 years.•This study is useful for development and sustainable operation of geothermal power plant.
In the present study, activated carbon (AC) was prepared from Eucalyptus globulus seed (EGS) by a simple hydrothermal method followed by chemical activation using potassium hydroxide as the ...activating agent under different carbonization temperatures. X-ray diffraction and Raman spectroscopic analysis confirmed the amorphous and turbostratic disordered nature of the carbon. FT-IR analysis of the activated carbon samples shows the presence of N and O functional groups. Brunauer-Emmett-Teller (BET) specific surface area analysis of EGS derived activated carbon at 900 °C showed the highest specific surface area of 2388.38 m2g−1 and exhibited a specific capacitance of 150 Fg−1. The appearance of small and large graphitic pores with random orientation and approximately 88.3 wt% of carbon and 11.7 wt% of oxygen were confirmed by SEM/EDX analyses. Further to understand the electrocatalytic nature of the synthesizing carbon, the material was tested as an electrode for supercapacitors. The electrochemical performance was demonstrated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance (EIS) studies. The electrochemical properties of EGS derived activated carbon demonstrate its potential application as high-performance and low-cost supercapacitor electrode material to fabricate energy storage devices.
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•Eucalyptus globulus seed-derived carbon exhibited a specific surface area of 2388.38 m2g−1.•Exhibited a specific capacitance of 150 F g−1 comparable with other biomass derived carbon•An economically feasible electrode material for supercapacitor application
This paper presents a coupled Wellbore-Reservoir-Organic Rankine Cycle (ORC) power plant model for sustainable and efficient use of multiple-fractures Enhanced Geothermal System with simulations ...conducted over 40 years of operation time. A multi-objective optimization of the ORC under off-design conditions was conducted using constrained NSGA-II technique considering specific investment cost, energy and exergy efficiencies as objective functions. Twenty working fluids were considered to select the best one based on the turbine inlet superheated vapor condition, the lowest specific investment cost, the best energy and exergy efficiencies. Optimal operations conditions were determined for each working fluid considering turbine inlet temperature, turbine inlet pressure, condenser temperature, refrigerant mass flow rate, and length, tubes number, inner diameter and outer diameter of evaporator and condenser, isentropic turbine efficiency, isentropic pump efficiency as decision variables. The results show that the working fluids have a significant effect on the reinjection geofluid temperature and slight effect on the production temperature. The best performing working fluid was R1233zd(E) providing an energy efficiency of 19.2–19.32% and the exergy efficiency found is between 56.4% and 58.44% over the 40 years of production in off-design conditions and optimal operation conditions. The energy efficiency and the exergy efficiency decrease with increasing condenser temperature.
•A new wellbores-reservoir-ORC model is performed for efficient energy management.•Multi-objective optimization of geothermal ORC under off-design conditions.•Energy and exergy efficiencies and economic performance were optimized with NSGA-II.•R1233zd(E), a hydrofluoroolefin refrigerant was the best performing working fluid.•New combination of operation parameters to avoid droplets formation in the turbine.
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