International Journal of Green Energy

Journal Information
ISSN / EISSN : 1543-5075 / 1543-5083
Published by: Informa UK Limited (10.1080)
Total articles ≅ 1,628
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Latest articles in this journal

, François Balavoine, Daniel Roger
International Journal of Green Energy pp 1-11;

The environmental impacts of four French scenarios of electricity production systems are compared. They propose a variable part of nuclear which is essentially replaced by wind and solar energy. The paper proposes a comparison of these scenarios based on a Life Cycle Assessments. The systems with a large part of intermittent wind and solar sources need a higher installed power. In addition, for the same installed power, renewable energies require more building materials than nuclear ones. Therefore, the environmental impacts of infrastructures increase with the part of renewable energy. During the use phase, the environmental impacts of fossil fuels, especially coal, are significant. Consequently, the best systems must use the least fossil fuels and need the lower installed power. Finally, if we exclude the risk of nuclear disaster and if we consider that nuclear wastes are well managed, the electricity production systems that achieve the lowest environmental impacts, with the same availability for the electricity to end users, are those that have a large part of nuclear power.
Tiancheng Cui, , Huijuan Yan, Yunlu Zhang,
International Journal of Green Energy pp 1-13;

Hydrogen production using solid oxide electrolysis cells (SOECs) is a highly efficient and low-carbon pathway to generate high purity hydrogen. However, high working temperatures may result in high thermal stress due to a mismatch in the coefficient of thermal expansion (CTE) between components with a nonuniform temperature distribution. Serious stress concentration may lead to structural failure of the SOEC stack. Hence, this work investigated the thermal stress of SOECs through a three-dimensional planar SOEC unit model. A stress analysis method was proposed via a multi-physics coupling model of SOECs using Comsol Multiphysics software. The impacts of voltage, flow direction, water mole fraction, and operating pressure on the thermal stress were evaluated. Numerical results show that the highest maximum principal stress is located in the electrolyte in the SOEC unit. Raising the water mole fraction and the CTE of the electrolyte could reduce the thermal stress if the voltage is below the thermoneutral voltage.
Yichao Ma, , Yi Wang,
International Journal of Green Energy pp 1-9;

A two-stage biodiesel production directly from wet microalgae (Chlorella vulgaris) assisted by radio frequency (RF) heating was optimized in this study with the response surface methodology (RSM) applied to both two steps. In order to apply RSM to the two stages rather than to a one-step reaction, a three-variable, five-level central composite design (CCD) was employed to evaluate the effects of three key parameters, i.e. HCl to MeOH ratio (v/v), MeOH volume, and RF heating time. Two regression equations (one regression equation for each stage) were obtained, and two sets of optimized production conditions with a slight difference were also determined. The best predicted FAME yield of 93.1% was obtained at a HCl to MeOH ratio of 4.27 (v/v), a MeOH volume of 28.5 mL, and a RF heating time of 19.2 min. Although the second stage of conversion increased the FAME yield from 82.9% to 93.1%, this process would cause additional consumption of time, solvent, and energy. Verification experiments were carried out at the optimized point and resulted in a yield of 92.7 ± 0.1%, which validated the reliability of the prediction model. All processing steps, including cell destruction, esterification, and transesterification, were carried out at temperatures below 100°C and atmospheric pressure. Therefore, no pressure-proof nor high-temperature apparatus was required. The procedure shows great potential for industrial application because of its high FAME yield, simple operation, low chemical consumption, and short processing time. The principles of the procedure can also be applied to other microalgae with high lipid contents.
Xiangfu Qin, Junwen Cao, Ga Geng, Yifeng Li, Yun Zheng, Wenqiang Zhang,
International Journal of Green Energy pp 1-10;

Solid oxide fuel cell (SOFC) is a clean and efficient energy conversion device, which possesses great application prospects in automobiles. In this review, we not only introduce the simple SOFC system configuration, but also mention two ways to improve its efficiency: anode tail gas recycle (ATGR) and reasonable heat recovery. Moreover, we highlight that the use of SOFC-based hybrid power system (such as SOFC-ICE and SOFC-PEMFC) can further improve the efficiency and feasibility. In addition, the applications of SOFC system as auxiliary power unit (APU) for the heavy truck and as a range extender for electric vehicle are introduced. Despite these broad application prospects, several existing technical challenges, including the long start-up time and energy management issues, are also discussed. Facing these challenges, future research directions are proposed to improve the technical maturity of SOFC system for automobiles.
International Journal of Green Energy pp 1-16;

In this study, some of the commonly used daily global solar radiation decomposition models are improved by considering ambient temperature, relative humidity, and air pressure to estimate hourly global solar irradiance from measured daily global solar radiation in Eskişehir, Turkey. Accordingly, the identified functions of the considered parameters are integrated into the selected daily global solar radiation decomposition models. The accuracy of the improved models is evaluated based on the measured monthly average hourly global solar irradiance values. In addition, the monthly average power values provided by the original and improved models are compared with the measured power output values. The results indicate that the improved models have significantly higher performance in the accuracy of both global solar radiation estimation and power output forecasting in a specific time interval. Therefore, the proposed methodology can be used to improve any global solar radiation decomposition model based on locally measured data for different regions.
Yansong Luo, , Jie Sun, Baichen Liu
International Journal of Green Energy pp 1-12;

Interdigitated flow field and serpentine flow field are widely adopted in redox flow batteries, but their superiority cannot be determined independently of the operating conditions, electrode properties, and electrolyte properties. Matching the flow field to the operating conditions can effectively improve the efficiency of flow cells. To this end, the present study proposes a model-based optimization method to promote the system energy efficiency of flow cells by combining the interdigitated and serpentine flow channels and considering the heterogeneous distribution of reactants. The fluid dynamic model, electrochemical model, and genetic algorithm are integrated into an optimization framework in the present study to obtain the novel interdigitated-serpentine flow field. Simulative results show that compared to the interdigitated or serpentine flow field, the optimized interdigitated-serpentine flow field yields increments in the system energy efficiency ranging from 2% to 20% under varying operation conditions.
Akhil Ailaboina,
International Journal of Green Energy pp 1-16;

Methanol and ethanol are considered as potential candidates for alternative fuels in spark-ignited engines and flex-fuel vehicles. Alcoholic fuels have higher latent heat of vaporization ( hfg), lower boiling-point temperature and higher-octane numbers help the engine run under higher compression ratios, resulting in better efficiency and fuel economy. A numerical study is carried out to understand the spray-breakup and vaporization characteristics of binary blended fuel and ternary fuel blend compared to single-component fuel for gasoline direct injection (GDI) system. Multiple simulations were carried out by substituting individual fuel properties of isooctane with those of ethanol to understand the relative importance and effect of fuel properties on spray characteristics. The spray characteristics of pure isooctane fuel and their blends with ethanol and methanol are studied and compared, and the charge cooling effects for alcoholic fuels have been observed. The Spray G operating condition has been taken from the Engine Combustion Network (ECN) for this study. The simulated data for isooctane has been validated with the experimental data from the ECN, and a similar model setup has been used for pure and blended fuel sprays. The discrete-phase modeling (DPM) approach is carried out, and the Unsteady Reynolds-Averaged Navier–Stokes (URANS) RNG (Renormalization) k-ε turbulence model is considered in understanding the spray characterization. The blended methanol fuels have higher penetration lengths compared with ethanol ones. The penetration of the blended fuels (binary and ternary) is slightly lower than the isooctane. The ternary blends showed spray characteristics similar to those of E85, and it indicates that the ternary blended fuel has the potential to be used as a drop-in fuel for a GDI-based flex-fuel vehicle.
International Journal of Green Energy pp 1-9;

In this study, the design parameters of Open Slotted Axial Flux Permanent Magnet (OSAFPM) Generator for wind turbines are presented using Genetic Algorithms (GA), an optimization algorithm based on natural selection and genetic mechanisms. Electromagnetic analysis of Open Slotted Axial Flux Permanent Magnet generator has been performed by using parameters optimized with Genetic Algorithms. The ANSYS Maxwell program, which uses the finite element method (FEM), has been used for electromagnetic analysis. Compared to ANSYS Maxwell, it is observed that the genetic algorithm significantly reduces the computational time required for design optimization. However, initial design and optimization with Genetic Algorithms have resulted by 8.94% increase in power densities. In addition, 12.71%, 38.62%, 62.02%, and 56.39% improvements have been obtained for air gap magnetic flux density, flux linkage, induced voltage, and current waveforms, respectively. This suggests that optimization with a Genetic algorithm improves the Open Slotted Axial Flux Permanent Magnet generator parameters.
Mingzhang Pan, Pengfei Hu, Ran Gao,
International Journal of Green Energy pp 1-15;

Proton-exchange membrane fuel cells (PEMFCs), as potential energy converters with broad application prospects, have low durability owing to several factors that make it difficult to quantify the degradation of PEMFC components. The accurate prediction of the remaining useful life (RUL) can help users understand the degradation status of PEMFCs and adopt reasonable maintenance strategies to improve durability. This paper proposes an RUL prediction framework based on a temporal convolutional network (TCN). First, an equivalent circuit model of the PEMFC is established, and complex nonlinear least squares regression is used to fit the model to estimate the polarization resistance. Then, the prediction framework and joint degradation indicator of the TCN are constructed to predict the RUL. The TCN is compared with four models: linear regression, Holt–Winters, seasonal autoregressive integrated moving average, and Prophet. The results show that the TCN performs significantly better in terms of all the predictive metrics, including the root-mean-squared error which is at least 13.43% lower than those of the four models. The RUL prediction accuracy of the TCN is at least 7.76% higher than that of the four models. Except at 800 h, the average RUL accuracy of TCN is 92.20%. This confirms that the TCN (double variables) can accurately predict the RUL of PEMFCs.
Bingnan Wang, Shan Jiang,
International Journal of Green Energy pp 1-12;

Photovoltaic systems are sensitive to weather conditions in terms of fluctuation, intermittentness and randomness, which could be affected drastically by the factors such as fast variation from sunlight conditions, environment temperature, cloud shadings under outdoor environmental conditions. The performance of photovoltaic systems could pose greater impact on the security and stability to the power grid especially under extreme irradiance condition. This paper established a mathematical analysis model for photovoltaic system under over-irradiation (OI) condition (>1000 W/m2) combined with the experimental data of a 5.605 kWp monocrystal silicon modules system from 2019 to 2020 in arid climate. The result evaluated the data in aspects of amplitude, frequency, velocity and duration of the performance of the system along with the weather data. The results show that the yield of the system under OI status accounts for 15.09% of the total energy generation, the maximum operating current exceeded the short-circuit current by 26.8% with average duration reaches 272 seconds. Finally, the four typical OI days were chosen from the date and demonstrated that the fuses of the string and inverters in the system would undertake an over-rated status over 12,050 seconds, which raised a challenge to the response time of the inverter and the MPPT algorithm as well as the fuses reliability.
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