Energy nexus最新文献

Economic utilization of waste in the generation of value-added products is the primary prerequisite of a circular economy. Agro-waste is one waste that is enormous on one hand and is rich in nutrients and bioproducts on the other hand. Microbial fermentation is an easy technology that can work following the nature of the waste substrate. Development of such a process is very much possible however it faces the initial challenge of diversity in substrates, microorganisms, enzymes, and bioproducts. It would be thus ideal to make an axis of one waste to one value-added product and then optimize around this axis. Here we explore the potential of a widely industrially used enzyme α-amylase as one terminal of the axis. The other axis would be starch-rich agro-waste like cereal waste. The connection between these two axis terminals would be an α-amylase producing microorganism. A lot of products e.g. nutraceuticals, biofuels, other enzymes, fertilizers, nanoparticles, etc. are possible around this axis. This review explores the suitability of α-amylase to serve as such an axis. We discuss the agro-waste that has the potential for α-amylase production, the industrial applicability of α-amylase, microorganisms known and bioengineered to produce α-amylase, and the optimization of this production process.

Thermal networks, part of heat-and-power multi-energy microgrids, may face capacity issues, generation and distribution ones, either due to the increase in the requested demand or capacity underused, which is sized for peak hours. Under-capacity issues may be addressed with generation and pipeline capacity expansion, resulting in considerable capital costs and extra maintenance costs. In the case of over-capacity, better usage of the existing assets may bring further revenues and increase the multi-energy microgrid’s overall energy efficiency. In the electricity sector, it is being considered the interconnection of microgrids via the distribution system network, since microgrids can operate in both islanded and network-connected modes. In this work, in a similar fashion, we propose the interconnection of adjacent thermal networks enabling direct heat trading among them to increase the micro-grids’ supply flexibility, help meeting demand peaks, and reduce operational costs. Examples of integrated heat-and-power microgrids that could benefit from thermal interconnections are industrial parks, university campuses, hospitals, and even residential complexes with a shared heat generator.

This paper presents a market model for the optimal heat transfer between thermally interconnected heat-and-power microgrids. The resulting model is a convex quadratic programming model that enables the derivation of heat transfer prices that guarantee a competitive equilibrium. Furthermore, we performed numerical tests to explore the impact of connection topology, thermal power transfer capacity, and interconnection efficiency on transferred energy and prices.

The air conditioning and refrigeration applications use a significant portion of the electrical energy. This research analyses a performance of refrigeration system, which comprises on different configurations of solar based organic Rankine cycle (ORC) and vapor compression refrigeration (VCR) cycles requiring low evaporation temperatures. In this research, the dry natural hydrocarbons such as n-Decane, n-Dodecane and Toluene have been chosen to serve as the working fluids in ORC. Whereas in VCR cycle natural hydrocarbons such as Ethane, Propane, isobutane, isopentane and isohexane have been used because traditional working fluids have a negative environmental impact due to high values of ozone depletion and global warming potential. The simulated results showed that the facility can be operated efficiently with the use solar thermal energy resources within the temperature range 90 to 315ºC and decreasing the need for conventional fossil fuel resources. It was also revealed that the highest efficiency was achieved by n-Dodecane in regenerative ORC, which is 35.34 % at the evaporation temperature of 315ºC and the highest overall coefficient of performance ($\text{CO}{P}_{\text{overall}})$ in regenerative ORCCRS facility was achieved by n-Dodecane in ORC and isopentane in refrigeration cycle which is 1.017 while in case of Simple ORC–VCR facility the highest $\text{CO}{P}_{\text{overall}}$ was achieved by Toluene in ORC and isopentane in refrigeration cycle, which is 0.7174 at the evaporation temperature 315ºC.

Among the transition metals copper is one of the cheapest earth- abandoned elements which can enhance electrocatalytic activity. The Cu-based catalysts are superior for catalytic performance and stability in alkaline media for oxygen evolution reaction (OER) and exhibit high activity in acidic media for hydrogen evolution reaction (HER).Synthesized CuSe nanoparticle is found as the most efficient bifunctional electrocatalyst among the synthesized Cu chalcogenides for water splitting reaction. Electrocatalytic performance for water oxidation was investigated in alkaline solution1(M) KOH for OER and 0.5 (M) H₂SO₄ for HER. To achieve 10 mA/cm², it was observed an over potential (mV) of 343 for OER and 126 for HER, which are much smaller than these of CuS (385,320) and CuO (410, 345) studied. In this article, we have elucidated some essential criteria need to be specified to evaluate the water splitting performance including onset potential, overpotential, Tafel slope, turnover frequency (TOF), and stability of the copper chalcogenide nanoparticles.

The Wastewater Treatment Plant (WWTP) uses a dewatering machine to separate sludge from water. The resulting sludge is used as raw material for Refuse Derived Fuel (RDF), while the separated water is treated in the subsequent WWTP unit. However, the sludge from the WWTP is currently only processed into briquettes as per policy and then disposed of in landfills. Our investigation centers on the effects of carbonization temperature on sludge characteristics in a dewatering unit. Initial analysis revealed that 1-day-old sludge possesses a high moisture content (87.72 %) and a low calorific value (3.44 MJ/kg). Carbonization at 300 °C significantly enhanced the sludge's calorific value to 12,504 MJ/kg, reduced its moisture content to 60.72 %, and increased its carbon percentage to 22.76 %, indicating a direct correlation between carbonization temperature and both energy recovery and carbon content. Comparative analysis showed sludge carbonized at lower temperatures (200 °C and 100 °C) yielded lower carbon percentages (22.23 % and 21.66 %, respectively) and energy values, underscoring the efficiency of higher temperature carbonization in optimizing energy recovery.. This research contributes to developing sustainable organic waste recycling practices and supports achieving Sustainable Development Goals 11 and 12 targets. This research promotes sustainable development by improving sludge utilization from WWTPs as a raw material for energy production rather than being directly disposed of in landfills. This study provides insight into the potential for energy recovery from organic waste, technology, and policy's role in achieving a circular economy.

Renewable energy systems, such as solar power, are becoming increasingly important worldwide due to the limited supply of non-renewable energy sources. Solar power stands out as a practical choice for electricity generation because it's simple to set up and costs less than other renewable options. Solar-based on-grid or grid-tied systems are more effective compared to other PV grid systems due to their more reasonable installation system, favorable maintenance, and less complex system. This study was designed with a solar-based grid-tied system. This study evaluates the performance and economic viability of a 15 MW on-grid photovoltaic (PV) system in Bakalia Char, Chittagong, Bangladesh, and will propose this study for the Bangladesh Power Development Board (BPDB). Developing a clean energy system in Bangladesh is the main purpose of this study. This system performed efficiently, with an 84.03 % performance ratio, produced energy of 21,510.186 MWh/year and proved economically attractive with a 4.5-year payback period, a competitive electricity cost of 0.024 USD/kWh, and a 389 % return on investment(ROI%). Using software like PVsyst and SketchUp ensures precise system design and optimal module placement. Also, use a better PV panel system whose efficiency is higher than that of another PV panel system designed for a similar project. This system boosts local electricity production and aligns with sustainable energy goals. Its success is a valuable model for future solar projects in similar regions facing energy challenges. The system also shows significant environmental benefits, with a projected reduction of approximately 252,168.5 tons of CO₂ emissions over its operational lifespan.

The most crucial industries for growth, particularly in developing countries, are agriculture, tourism, and the fertilizer industry. These businesses are also linked to environmental deterioration. The current study uses empirical research to inspect the links between carbon dioxide (CO₂) secretions and Gross Domestic Product (GDP) progression, government expenditure, tourism, fertilizer usage, renewable and non-renewable energies, and agricultural production. Information commencing from six South Asian nations is used to produce the findings between 1991 and 2019. Following the establishment of stationary and cointegration, a static analysis using a Fixed Effect and Random Effect Model and a dynamic analysis using a One Step Difference and System GMM (Generalized Method of Moments) are performed. This article employs Mean Group (MG) and Augmented Mean Group (AMG) approaches to increase robustness, while multicollinearity, heteroscedasticity, autocorrelation, and Cross-Sectional Dependency (CSD) are used for post-estimation. According to the study, the selected South Asian region's agricultural, fertilizer use, non-renewable energy use, tourism, GDP growth, and government spending all result in a rise in CO₂ emissions, while using clean energy reduces those emissions and is crucial to reducing those emissions. The study offers some policy ramifications concerning green farming and tourism.

Wastewater treatment plants are essential in improving life quality by degrading organic matter, reducing contamination, and therefore greatly impacting human activities. The role of these critical treatment units can be further promoted by integrating new biological processes that currently are still under experimental scale. The co-digestion of sewage sludge and food waste has been proposed as an efficient way to increase plant treatment capacity and energy recovery. The assessment of hydrogen production along with food waste co-digestion is carried out in the present manuscript. Assessing several parameters is necessary to implement a new biological process in an operating plant, and quantifying its effects on the plant's overall performance is crucial. The implications associated with the extra equipment needed to handle additional waste material were evaluated. Results indicated that a conventional unit may treat a 10 % addition of food waste (expressed as VS) without experiencing severe modifications in process parameters, thus obtaining 16 % extra energy. However, the increase in food waste by over 10 % translates into substantial plant modifications requiring the installation of digesters with higher volumes and handling an additional amount of sludge. Another relevant factor is the lower energetic content of biogas when mixed with hydrogen. The increase in food waste until 50 % VS in the mixture reduced the biogas lower heating value to 15.5 MJ/m³. Future research will deal with an economic analysis of the approach and the effect on engine performance when dealing with a fuel mixture with different combustion properties.

Pakistan has faced a persistent energy deficit over the past few decades, with energy-intensive industries occupying a substantial share of energy consumption. Despite the potential for energy efficiency improvements within the industrial sector, numerous barriers hinder progress. This study identifies the barriers and drivers of energy efficiency practices specifically within the steel and iron industries of the economic hub of Pakistan. Through a questionnaire-based approach and follow-up interviews, responses were gathered from 32 executives and professionals within the steel sector, representing eight firms. Reliability analysis was conducted to ensure the robustness of the data. The analysis reveals that limited awareness and inadequate managerial commitment are significant barriers to energy efficiency initiatives. Moreover, ineffective policies and a lack of government implementation plans contribute to diminishing demand for energy-efficient technologies. However, there is a growing interest among respondents in reducing energy consumption to enhance cost-effectiveness. Key drivers such as long-term economic benefits, improved working conditions, and cost savings emerge as crucial factors motivating the adoption of energy-efficient practices. Positively, some companies have already initiated energy-saving measures, including the adoption of advanced technologies and renewable energy sources. These findings highlight the urgent need for collaborative efforts to overcome barriers and promote sustainability in steel and iron sector of Pakistan.

This study focuses on investigating the performance dynamics of high-temperature Proton Exchange Membrane fuel cells, with an emphasis on critical design parameters. Utilizing a comprehensive mathematical model, the research explores concentration profiles, current density profiles, and polarization curves within a three-dimensional, isothermal, steady-state PEM fuel cell.

The model incorporates the intricate processes of gas transport in anode and cathode channels, diffusion in catalyst layers, and the transport of water and hydronium ions in both the polymer electrolyte and catalyst layers. Additionally, it accounts for electrical current transport in the solid phase. Simulations conducted with Comsol Multiphysics 6.1 demonstrate a robust alignment between model results and experimental polarization data obtained at 180 °C. Optimal conditions for performance are outlined, specifying an inlet hydrogen gas velocity of 0.12 m/s and an inlet air velocity of 1.2 m/s, with consideration for a proton conductivity of 9.825 S/m.

In a parallel investigation, numerical analysis assesses the sustainability of Serpentine Flow-Field PEM fuel cells, using critical parameters. The model applied in this research considers gas, water, and electrical current transport across various layers of the fuel cell, with a crucial focus on optimizing the membrane electrode assembly's design. The finite element method and ANSYS Fluent are employed for model solution.

This study contributes significantly to the understanding of HT-PEM fuel cell dynamics, providing insights into the interdependencies of design parameters and their impact on system performance. The study emphasizes the pivotal roles of air and hydrogen inlet velocities in shaping fuel cell performance, elucidating the intricate dynamics dictating reactant distributions within diverse cell components.