Hasil untuk "Energy industries. Energy policy. Fuel trade"

Margaret S. Wooldridge, Jenna Stolzman, Ashray Mohit et al.

Flares are critical for the safe destruction of waste gases and must operate effectively over a broad range of conditions. Even at low gas flow rates, the flames created by flares are highly turbulent and exhibit significant transient behavior, yet few studies report time-resolved emission data. This work presents spatially- and temporally-resolved experimental and computational results for gas-phase emissions from a utility-pipe flare (7.62 cm diameter) under varying crosswind speeds. Emissions measurements are presented for high and low combustion efficiency (CE) using natural gas and a propane and natural gas blend. The experiments considered flow rates of 98 liters per minute (LPM) for natural gas with crosswind speeds of 0.3 m/s (CE = 100 % ± 0.03 %) and 10 m/s (CE = 80.2 % ± 2.46 %). The propane and natural gas blend experiments were conducted at a flow rate of 490 LPM and crosswind speeds of 8.8 m/s (CE = 94.3 % ± 2.71 %) and 16 m/s (CE = 88.0 % ± 2.71 %). Large-eddy simulations (LES) of methane at 830 LPM with crosswind speeds of 3 to 12 m/s yielded CE values from 99.45 % to 95.89 %. Both experiments and LES demonstrate that severe thermal and species gradients persist well downstream of the primary combustion zone. LES further reveals that local CE can deviate significantly from global CE, underscoring potential limitations of emissions measurement approaches. The findings provide a benchmark data set for flare emissions under crosswind conditions and highlight the need to refine existing analytical methods while guiding the development of next-generation measurement strategies.

Gunindra Krishna Mahanta, Nilay Bhatt, Bitan Ghosal et al.

\textit{PeVatrons} are the extreme galactic accelerators capable of producing PeV particles. Recent observation of Large High Altitude Air Shower Observatory have detected UHE photons ($\geq$ 100 TeV) from 43 galactic sources. Detection of UHE photons demands the presence of at least PeV particles in the acceleration site. Although the exact nature of most of the sources are still unknown, a large fraction of these sources have spatial association with pulsar wind nebula. In this work we investigate the acceleration mechanism in pulsar wind nebula by following a magnetohydrodynamics approach. Current study relates the MHD flow solution in immediate downstream with the particle spectrum and spectral energy distribution of photons. Our study shows that MHD description in the PWN environment reduces the parameter space and most of the parameters can be constrained in terms of a single parameter, \textit{the magnetization parameter} $σ$ only. Considering the effect of $σ$, we show that in low $σ$ environment pulsar wind nebula can produce PeV particles. We have also investigate the role of turbulence in the nebular region in acceleration of particle to PeV energy. Current study shows that both low $σ$ environment and turbulence environment is favorable for acceleration of particles up to PeV energy. We have also tested our model in two different LHAASO detected PeVatron 1LHAASO J1848-000u and 1LHAASO J1929+1846u.

Federica Cappelli, Giovanni Carnazza

Yiqun Wu, Shibing Zhang

Abstract With the rapid development of the digital economy, energy consumption patterns are transforming. However, problems remain, such as low energy efficiency and heavy dependence on traditional energy. By addressing data privacy compliance, enhancing model generalization, expanding to practical cases like the BRI, integrating system dynamics concepts, grounding machine learning techniques in theory, linking numerical results to theory, and highlighting research novelty through comparisons, we have provided a robust and insightful analysis. With the development of the digital economy, the transformation of energy consumption patterns is accelerating. In terms of improving energy consumption efficiency, energy consumption per unit of GDP decreased by 0.74%. Technological innovation and the widespread application of digital tools have significantly improved energy efficiency. In international trade, the proportion of exports of high energy-consuming products decreased from 44.7 to 35.67%. In comparison, the proportion of exports of new energy technology products increased from 35.8 to 40.0%. The trade volume of high-tech products accounted for 91.0%, showing that international trade is gradually transforming in a green, low-carbon, and high-value-added direction.

Zhifei Yi

Abstract On the basis of reviewing relevant literature research, this paper uses the LDA clustering model to conduct a clustering analysis on the news corpus of China’s A-share market. Three environmental risk factors, namely “climate”, “carbon emissions”, and “ecology”, are extracted and their impact on stock excess returns is empirically tested. The results showed that environmental risk factors could better explain the returns of long-short portfolios based on environmental ratings, while traditional Fama–French five-factors and momentum factors could not explain this portfolio return. This paper further proposes a weighted investment portfolio strategy based on environmental risk factors. Compared with the equally weighted portfolio, the long-short portfolio constructed using this strategy demonstrates a stronger upward trend and lower volatility during the sample period from 2009 to 2024, effectively avoiding the impact of the 2015 A-share market crash. At the individual stock level, the Fama–MacBeth regression results showed that all three environmental risk factors had significant predictive power for future returns.

Mohamad Javad Mohamadi, Mohammad Tolou Askari, Mahmoud Samiei Moghaddam et al.

Abstract This paper presents a two-stage optimization framework for long-term energy management in microgrids, aiming to efficiently integrate various energy sources, storage systems, and consumption elements while addressing uncertainties in load demand and renewable generation. The framework consists of an offline optimization stage and an online optimization stage, each with distinct roles to balance long-term planning and real-time adaptability. In the offline stage, a robust two-stage mixed-integer linear programming (MILP) model is used to set annual targets for the state of charge (SoC) of energy storage systems. This stage applies a min-max-min approach to optimize for worst-case scenarios, establishing a cost-effective and reliable baseline plan that reduces dependency on conventional power sources and minimizes load deficits. The online stage, on the other hand, employs a new online convex optimization model that dynamically adjusts energy storage and dispatch decisions based on real-time data, allowing the microgrid to respond flexibly to fluctuations in demand and renewable generation. Simulation results using the Elia and North China datasets demonstrate the effectiveness of this two-stage approach. Offline optimization achieved up to 25% cost savings and reduced unmet demand by up to 99%, providing a stable foundation for efficient energy management. The online optimization stage further improved system responsiveness, minimizing reliance on backup generators and enhancing load reliability. This combined framework offers a comprehensive solution for optimizing microgrid performance, balancing predictive planning with real-time adaptability in complex, variable energy environments.

J. Martinez, Jaime Marti-Herrero, S. Villacis et al.

The objective of this study is to analyze the CO2 emissions and economic impacts of the implementation of the National Efficient Cooking Program (NECP) in Ecuador, which aims to migrate the population from Liquefied Petroleum Gas (LPG)-based stoves to electric induction stoves. This program is rooted in the current effort to change Ecuador's energy balance, with hydroelectric power expected to generate 83.61% of national electricity by 2022, ending the need for subsidized LPG. For this analysis, the 2014 baseline situation has been compared with two future scenarios for 2022: a business-as-usual scenario and an NECP-success scenario. This study demonstrates the viability of migration from imported fossil fuels to locally-produced renewable energy as the basis for an efficient cooking facility. The new policies scenario would save US$ 1.162 billion in annual government expenditure on cooking subsidies, and reducing CO2 emissions associated to energy for cooking in 1.8 tCO2/y.

Frans Öhrström, Joakim Oscarsson, Zeeshan Afzal et al.

Battery energy storage systems are an important part of modern power systems as a solution to maintain grid balance. However, such systems are often remotely managed using cloud-based control systems. This exposes them to cyberattacks that could result in catastrophic consequences for the electrical grid and the connected infrastructure. This paper takes a step towards advancing understanding of these systems and investigates the effects of cyberattacks targeting them. We propose a reference model for an electrical grid cloud-controlled load-balancing system connected to remote battery energy storage systems. The reference model is evaluated from a cybersecurity perspective by implementing and simulating various cyberattacks. The results reveal the system's attack surface and demonstrate the impact of cyberattacks that can criticaly threaten the security and stability of the electrical grid.

Swaraj Pratim Sarmah. Pranjal Sarmah, Umananda Dev Goswami

We explore the effects of Bumblebee gravity on the propagation of ultra-high energy cosmic rays (UHECRs) using astrophysical sources modelled in the Unger-Farrar-Anchordoqui (UFA) framework (2015), which includes star formation rate (SFR), gamma-ray bursts (GRBs), and active galactic nuclei (AGN). We compute the density enhancement factor for various source separations distances ($d_\text{s}$s) up to 100 Mpc within the Bumblebee gravity scenario. Additionally, we calculate the CRs flux and their suppression, goodness-of-fit values obtained from comparisons with observational data from the Pierre Auger Observatory (PAO) and the Telescope Array experiment data for the flux and the Levenberg-Marquardt algorithm for suppression. The anisotropy in the CRs arrival directions is examined, with corresponding goodness-of-fit values obtained from the PAO surface detector data (SD 750 and SD 1500). Finally, we present skymaps of flux and anisotropy under different model assumptions, providing insights into the observational signatures of UHECRs in Bumblebee gravity. We show that Bumblebee gravity stands as a viable cosmological model for explaining key observational features of UHECRs, including spectrum, composition and anisotropy. Our results show that increasing the Bumblebee gravity parameter $l$ enhances the density factor $ξ$, particularly at low energies, highlighting Lorentz violation's impact on CRs' propagation. Larger $d_\text{s}$ values amplify deviations from the $Λ$CDM model, with AGN sources dominating at high energies and GRB/SFR sources at lower energies. The skymaps indicate the structured flux patterns at large $d_\text{s}$ and structured anisotropies at higher energies.

Etienne Bienvenu Akono, Vatis Christian Kemezang

Abstract This study examines the short- and long-term impacts of various factors on the volatility and price of electricity in Cameroon, including hydroelectric power generation, economic growth, energy demand, and exchange rates from 2000 to 2019. The study uses an autoregressive distributed lag model. The study found that increasing hydroelectric power generation has both positive and negative impacts on electricity prices in the short and long term. While increasing the share of hydropower in overall energy production results in increased variation of electricity costs in the short term, it leads to significant price reductions in the long run. The study also found that economic growth has a considerable positive impact on the variation of power prices, while energy demand has a negative but insignificant effect on price volatility in the short term. Further, the study indicates that measures, such as encouraging SME engagement in renewable energy production, could improve the participation of local enterprises in the power industry and reduce the volatility of electricity prices. On the other hand, the study suggests that exchange rates could have a negative impact on electricity prices in the short term, but depreciation of the local currency could lower fuel costs and improve the availability of power. Overall, the study provides insights that can inform policymakers, energy regulators, and investors in making decisions that contribute to the efficient and sustainable development of Cameroon's electricity market. The study also highlights the need to prioritize power generation to stimulate economic growth and private investment while promoting renewable energy production.

Sebastian Valencia, Andres Mendiburu, Luis Bravo et al.

This study explores in depth rotating detonation engines (RDEs) fueled by premixed stoichiometric hydrogen/air mixtures through two-dimensional numerical simulations including a detailed chemical kinetic mechanism. To model the spatial reactant non-uniformities observed in practical RDE combustors, the referred simulations incorporate different numbers of discrete inlet nozzles. The primary focus here is to analyze the influence of reactant non-uniformities on detonation combustion dynamics in RDEs. By systematically varying the number of reactant injection nozzles (from 15 to 240), while maintaining a constant total injection area, the study delves into how this variation influences the behavior of rotating detonation waves (RDWs) and the associated overall flow field structure. The numerical results obtained here reveal significant effects of the number of inlets employed on both RDE stability (self-sustaining detonation wave) and performance. RDE configurations with a lower number of inlets exhibit a detonation front with chaotic behavior (pressure oscillations) due to an increased amount of unburned gas ahead of the detonation wave. This chaotic behavior can lead to the flame extinguishing or decreasing in intensity, ultimately diminishing the engine's overall performance. Conversely, RDE configurations with a higher number of inlets feature smoother detonation propagations without chaotic transients, leading to more stable and reliable performance metrics. This study uses high-fidelity numerical techniques such as adaptive mesh refinement (AMR) and the PeleC compressible reacting flow solver. This comprehensive approach enables a thorough evaluation of critical RDE characteristics including detonation velocity, fuel mass flow rate, impulse, thrust, and reverse pressure waves under varying reactant injection conditions. The insights derived from the numerical simulations carried out here enhance the understanding of the fundamental processes governing the performance of RDE concepts.

Siwei Li, Liang Yue, Xiangyu Kong et al.

This article introduces the concept of load aggregation, which involves a comprehensive analysis of loads to acquire their external characteristics for the purpose of modeling and analyzing power systems. The online identification method is a computer-involved approach for data collection, processing, and system identification, commonly used for adaptive control and prediction. This paper proposes a method for dynamically aggregating large-scale adjustable loads to support high proportions of new energy integration, aiming to study the aggregation characteristics of regional large-scale adjustable loads using online identification techniques and feature extraction methods. The experiment selected 300 central air conditioners as the research subject and analyzed their regulation characteristics, economic efficiency, and comfort. The experimental results show that as the adjustment time of the air conditioner increases from 5 minutes to 35 minutes, the stable adjustment quantity during the adjustment period decreases from 28.46 to 3.57, indicating that air conditioning loads can be controlled over a long period and have better adjustment effects in the short term. Overall, the experimental results of this paper demonstrate that analyzing the aggregation characteristics of regional large-scale adjustable loads using online identification techniques and feature extraction algorithms is effective.

Wai-Yu Ashley Lam, Hong Zhao, Bo Zhang et al.

With the increasing demand for electric vehicles, further development of Li+ batteries require more comprehensive studies and advanced techniques to analyze various battery material and mechanisms. Determining the concentration of Li+ and electric potential inside batteries can effectively reveal and predict the electrochemical performance, understanding the charge/discharge processes and failure mechanisms. Recently, in situ observation of Li+ movement have been reported by utilizing optical microscopy, neutron imaging (NI), neutron depth profiling (NDP), and transmission electron microscopy (TEM)-based electron energy-loss spectroscopy (EELS). These extensive works suggest their broad potential applications, including revealing the spatial distribution of Li+, mapping electrode elements, and indicating degradation mechanisms. Moreover, direct visualization of potential changes through TEM-based electron holography (EH) and Kelvin probe force microscopy (KPFM) can discover and validate more valuable information. This perspective paper summarizes the current development of advanced in situ techniques for observing Li+ and potential distribution inside batteries for the first time. Additionally, we address the key challenges faced by these techniques along with their possible solutions. The aim of this paper is to provide a comprehensive discussion of in situ methods for analyzing reaction mechanisms, optimizing electrochemical performance, and potentially supporting the further development of battery simulation.

Rajesh Tanna, Vivek Mohan, Gopalakrishnan Ennappadam Ananthanarayanan et al.

Abstract In this article, the stability of a synchronous motor generator pair (SMGP) used for improving the inertia of grid‐connected renewable energy systems is investigated. The useful operational regime for different sets of system parameters is identified, such as electromagnetic torque, damping co‐efficient, and inertia by employing bifurcation analysis to detect stability boundaries. For the first time, the existence of bi‐stable regimes for the SMGP with non‐linear stability analysis is revealed. The authors' analysis unravels the possibility of the system getting transited to unsafe operation even when the system is in the linearly stable region. The existence of the bistable regime indicates the possibility of the system becoming unstable even when the eigenvalues are in the left half plane. The authors also identify globally stable and globally unstable regimes in the parameter space. The safe operating range of inertia and damping co‐efficient values helps in the design of a suitable MGP set that is robust to frequency deviations, even with a low inertia source. With the recommended values of electromagnetic torque, the authors' analysis provides a safe operational regime for power generation from renewable energy sources.

Aloys Ekoe A. Akata

Photovoltaic energy has the potential to become one of the major energy sources used in the households in the tropical region of Africa, where the solar radiation intensity is abundant and almost constant over the year. Solar photovoltaic systems present many advantages when they are integrated in the building structure envelope and have a significant influence on the indoor air temperature of dwelling buildings due to the thermal resistance modification. In this paper, a simplified model of the photovoltaic system integrated on the roof of a residential building according to the building construction customs and materials has been designed and modeled. The heat transfer is studied in several situations: with and without a Building Integrated Photovoltaic (BIPV) system and for a building with and without false ceiling. The BIPV system installed over an effective area of 35 m2 increases the building indoor air temperature of approximately 5 °C which is corrected by the heat insulation optimization of the false ceiling made up with building local materials. The final indoor air temperature obtained is in good agreement with the ASHRAE standards and can, therefore, be applied to tropical regions.

Dongwei Zhao, Vladimir Dvorkin, Stefanos Delikaraoglou et al.

Accommodating the uncertain and variable renewable energy sources (VRES) in electricity markets requires sophisticated and scalable tools to achieve market efficiency. To account for the uncertain imbalance costs in the real-time market while remaining compatible with the existing sequential market-clearing structure, our work adopts an uncertainty-informed adjustment toward the VRES contract quantity scheduled in the day-ahead market. This mechanism requires solving a bilevel problem, which is computationally challenging for practical large-scale systems. To improve the scalability, we propose a technique based on strong duality and McCormick envelopes, which relaxes the original problem to linear programming. We conduct numerical studies on both IEEE 118-bus and 1814-bus NYISO systems. Results show that the proposed relaxation can achieve good performance in accuracy (0.7%-gap in the system cost wrt. the least-cost stochastic clearing benchmark) and scalability (solving the NYISO system in minutes). Furthermore, the benefit of this bilevel VRES-quantity adjustment is more significant under higher penetration levels of VRES (e.g., 70%), under which the system cost can be reduced substantially compared to a myopic day-ahead offer strategy of VRES.

Souvik Banerjee, Ulf Danielsson, Suvendu Giri

In this paper we clear up misconceptions concerning the dark bubble model as a realization of dark energy in string theory. In particular we point out important differences with Randall-Sundrum, and explain why gravity neither is, nor need to be, localized on the dark bubble.

Parvathy Sobha, Nita R Patne

Energy consumption and energy ananlytics has gained increased focus and consideration in industrial applications especially process lines to upgrade their performance and efficiency in the competitive world. A competent analytics method will be highly advantageous to provide the correct direction of energy saving for an industry. Energy analytics method was introduced into energy consumption time analysis model and is developed in this paper. Energy consumption of a camplate production plant was analysed as a case study. The result shows that energy utilization is dependent on the time of operation of the equipments in the plant. Energy sparing obtained via technical innovation in unit process maybe misplaced due to the expanding time of operation within the plant. Energy loss and the distribution of energy loss in the camplate production plant were analysed and the probable energy saving methods were identified from the results.

Bertrand Rioux, Rami Shabaneh, Steven Griffiths

Angela Tritto

This paper contributes to the debate on the sustainability of the Belt and Road Initiative (BRI) by analyzing Chinese investments in Indonesia's coal power sector. Insofar, scholarship on the BRI examined the role of Chinese companies “going out,” neglecting host countries' agency in shaping this initiative. This study analyses this important yet often overlooked dimension through the lens of local stakeholders. Fifteen in-depth interviews provide key insights into themes that are explored using a novel database. Results show a sharp increase in the Chinese-led financing, construction, and investments in Indonesia's coal power plants. While large State-owned enterprises spearheaded this increase, the BRI is also generating an impetus of private investments in new “instrumental” coal power plants that serve industrial parks, owned by non-energy companies. After the Paris Agreement, only Chinese, Japanese, and Malaysian institutions continued to finance coal power plants in Indonesia. However, unlike other foreign investors, Chinese companies are bringing mostly subcritical (low-end) technology, and their operations have been associated with the use of illegal labour. Overall, results show how China's export of industrial capacity and financing through the BRI is met by Indonesia's developmental attitude towards using coal and foreign investments to prioritize its economy growth over environmental and social sustainability.