Efficiency Of Power Generation System Research Articles

Improving the Performance of Bimetallic Thermally Regenerative Ammonia Batteries

Greenhouse gas emissions produced during electricity generation can be reduced by increasing the energy efficiency of power generation systems. One approach to increase generation efficiency is by extracting additional electrical energy from low-grade waste heat (< 100 °C) using thermally regenerative redox flow batteries (TRABs). TRAB chemistries with the largest equilibrium potentials use two different active metals and are referred to as bimetallic TRABs (B-TRAB). In most designs, copper is the positive electrode and zinc is the negative electrode. Using thermal energy, ammonia is moved between battery electrolytes to favorably modify the cell potential of the two electrochemical steps within the cycle. A typical B-TRAB system has four steps to complete a full cycle: 1) high-voltage electrochemical discharge, 2) thermal ammonia separation, 3) low-voltage electrochemical charge, and 4) thermal ammonia separation. During step 1, copper is reduced at the positive electrode and zinc is oxidized at the negative electrode creating aqueous zinc-ammonia complexes. Next, ammonia is separated from the zinc complexes and introduced to the copper electrode electrolyte, thereby increasing the equilibrium potential of the negative electrode, and decreasing the potential of the positive electrode. This creates a smaller cell potential required for electrochemical charging during step 3. After charging, ammonia is thermally separated from the electrolyte and re-introduced to the zinc-containing electrolyte returning the system to step 1. Currently, B-TRAB designs use solid zinc and copper electrodes which lead to low coulombic efficiencies at the copper electrode. Here, we demonstrate how the B-TRAB system can be improved by the addition of ammonium bromide to the positive electrolyte stabilizing Cu(I) species and replacing copper deposition/dissolution reaction with the Cu(I, II) reaction on a carbon felt. As a result, the open circuit potential during charging can be as small as 0.8 V, and as large as 2 V for the discharge step. Polarization curves showed that peak power for the discharge cycle was 98 mW cm-2, a significant improvement over previous B-TRABs.

Hydrogen energy production, storage methods, and applications for power generation

Nowadays, the transformation of energy structure has become an important task for society. The advantages of hydrogen energy also meet the criteria of people's choice of energy. This paper introduces hydrogen production, storage methods, and their application for the power generation. In hydrogen production part, POM is the most satisfactory of four methanol to hydrogen methods as this reaction does not require any energy and can be more than 50% efficient. In terms of photolytic water technology, Ti- and Zr-based Photocatalysts, Ta- and Nb-Based Photocatalysts, Ga and Ge-Based Photocatalysts have been applied to increase the reaction rate, in addition, the device has the advantage of a small footprint, ease of operation and high measurement accuracy. In the microbial hydrogen production section, experiments have shown that hydrogen production is highest in a thermally shocked environment, and that genetic modification of the organisms at the molecular level can also increase hydrogen production. For the hydrogen power generation, the PEMFC is by far the most used experimental product for grid-connected power generation. In the future, researchers should focus on solving various existing problems and developing more economical and efficient hydrogen power generation systems to realize the large-scale use of clean energy. Meanwhile, this paper expects to find better solutions to solve existing problems.

Renewable Energy Technologies in the Global South: Sub-Saharan Africa Trends and Perspectives

Sub Saharan Africa (SSA) and other parts of the Global South are richly endowed with renewable energy resources (RERs) that are grossly untapped. The integration of these resources, such as hydro, wind, solar, and biomass will facilitate the desired net zero-CO2-emissions economy. If these RERs are adequately harnessed, the perennial power supply challenges in the region will be resolved, and the negative power supply narrative changed. Presently, a greater percentage of the population without access to electricity live in the Global South with SSA having the highest share. This inadequacy has been attributed to many factors, which include lack of connection to the national grid; lack of adequate technical capacities to design and manufacture efficient power generation and transmission components and systems; insufficient funds; unreliable, limited, and poor energy data. A comprehensive study of the renewable energy potential (REP) and technologies in the Global South is imperative to the management, regulation, and policies concerning energy, in this era of energy transition (ET). This study presents - a summary of REP of SSA; statistical analysis of the proposed and installed RE capacity across the region; and discussion on the pressing need for renewable energy integration (REI) to mitigate climate change. In addition, to develop RE schemes to facilitate greater access to clean, affordable, and adequate energy supply. Actualization of the integration of RERs into the national portfolio will promote CO2 reduction and improve the socio-economic benefits to the populace in both rural and urban areas of SSA and the Global South generally. Keywords— Renewable energy system; Net-zero-CO2 emissions, renewable energy in Global South; hydro; wind; solar; biomass

Ecological Consequences of Hydropower Development in Himachal Pradesh with Special Reference to Chamera Dam

Hydropower is an important renewable energy resource and one of the most efficient power generation systems on the planet. Despite all of the benefits of hydropower plants, there may be some drawbacks. However, its growth is accompanied by negative environmental consequences. Hydropower dams are still being constructed at a rapid pace in the developing world and are causing disturbances to river ecology, deforestation, loss of biodiversity, increased greenhouse gases emissions, as well as displacing thousands of people and affecting their food system, water sources, and agriculture. While environmentalists around the country reject massive projects with large reservoirs, locals in Himachal Pradesh consider modest projects as a scourge as well. The steady deterioration in environmental parameters in the hills has serious connotations for sustainable development, not only for the hill areas, but for the country as a whole. The goal of this research is to look at the environmental effects of hydropower and possible mitigating strategies. In short, our aim has been to study how damming has had ecological impacts on the dislocated people, to assess their reaction, receptivity, and outlook towards the projects. The interview method was adopted for collecting data. Survey has been conducted with the help of a well designed interview schedule.

Electrical Power Generation System: Optimal Design for Medium-Load Industries with High-Rated Generators

The demand for electrical power is rapidly increasing due to the rise of industries in developing countries. Power generation stations are having troubles to strike a balance between demand and generation. In this situation, it is urged that appropriate remedial action be taken. Rising power demand can be met by designing an efficient electric power generation system which will also help lowering the generation cost. It is shown that while high rated electric power generators are connected in parallel the value of neutral current is rising and the cooling temperature is also increased. Here, the goal of this experimental work is to present a new model for designing an efficient power production system for average-load (ranging up to 8000 Amp, 440 V) industries to minimize the demand on centralized interconnected grid. A scheme is proposed with four generators (2500 kVA, 2000 kVA, 2000 kVA and 1250 KVA) in parallel and enough cooling arrangement is provided with minimal cost. The coolant temperature is maintained 61 °C to 61.5 °C and at that time diesel temperature is not more than 38.5 °C. The amount of neutral-current is also optimized (up to 8.5 Amp.) which was more than 12 Amp. At the morning and afternoon, the neutral current is almost constant, but it is bit fluctuating between 7.5 Amp to 8.2 Amp at mid-day. The final outcome shows, the suggested system is efficiently stable with the change of load and generates optimal electricity.

Electrical Power Generation System: Optimal Design for Medium-Load Industries with High-Rated Generators

The demand for electrical power is rapidly increasing due to the rise of industries in developing countries. Power generation stations are having troubles to strike a balance between demand and generation. In this situation, it is urged that appropriate remedial action be taken. Rising power demand can be met by designing an efficient electric power generation system which will also help lowering the generation cost. It is shown that while high rated electric power generators are connected in parallel the value of neutral current is rising and the cooling temperature is also increased. Here, the goal of this experimental work is to present a new model for designing an efficient power production system for average-load (ranging up to 8000 Amp, 440 V) industries to minimize the demand on centralized interconnected grid. A scheme is proposed with four generators (2500 kVA, 2000 kVA, 2000 kVA and 1250 KVA) in parallel and enough cooling arrangement is provided with minimal cost. The coolant temperature is maintained 61 °C to 61.5 °C and at that time diesel temperature is not more than 38.5 °C. The amount of neutral-current is also optimized (up to 8.5 Amp.) which was more than 12 Amp. At the morning and afternoon, the neutral current is almost constant, but it is bit fluctuating between 7.5 Amp to 8.2 Amp at mid-day. The final outcome shows, the suggested system is efficiently stable with the change of load and generates optimal electricity.

Performance Characteristics of A Simulated Hybrid Solar-Photovoltaic-Thermoelectric System for Renewable and Direct Power Generation Applications

Advanced nonconventional renewable and alternative green energy technologies which are used for generation of electrical power have shown real promise and received renewed interest in recent years due to an increasing concern of environmental issues of greenhouse gas emissions, air pollution, and the limitations and conservation of natural energy resources. Solar-photovoltaic (PV) systems directly convert renewable solar energy into green electrical energy. However, their power production and efficiencies tend to decrease when operating at relatively higher temperatures. Therefore, reducing the temperature of PV modules using efficient cooling methods would improve their performances. Thermoelectric power generation (TEG) technology could be used to convert a portion of the waste-heat energy dissipated from PV systems, thus cooling them, and at the same time generates extra power. Hence, hybrid photovoltaic-thermoelectric power generation (HPV-TEG) systems integrate TEG modules with a PV module to form a more efficient power generation system. The main objective of this paper is to investigate the viability and performance characteristics of a hybrid HPV-TEG through detailed lab-simulated tests. Experimental results and in thermal images showed that the HPV-TEG system was able to generate more DC power than the solo PV system while operating at higher irradiance intensities and lower TEG’s inlet coolant temperature. At the irradiance of 615W/m2, the power generation from the hybrid HPV-TEG system increased by 4.1% compared to the solo PV system. The results also indicated that when the irradiance was increased to 750W/m2, the power generated from the hybrid system increased to approximately 8.6% higher than the power generated from the solo PV system at the same irradiance. The integration of the concentrators in the hybrid PV system increased the maximum power point by 23.3% compared to the hybrid PV system without concentrators.

Method for Predicting Thermoelectric Module Efficiency Using MATLAB/Simulink

Development new high-performance thermoelectric materials for more efficient power generation systems and eco-friendly refrigerating systems has been challenging. Over the past few decades, thermoelectric studies have been focused on increasing the thermoelectric properties of materials. However, for conventional applications, developing of thermoelectric devices or modules with lower cost and simpler fabrication processes is also important. Simulation models that can predict the thermoelectric efficiency of modules using the thermoelectric properties of materials are needed for this purpose. In this study, we developed a simple model for calculating the efficiency of thermoelectric modules using MATLAB/Simulink. In this model, the temperature difference between the hot source and heat sink was fixed to ensure the precise comparisons of thermoelectric efficiency. The electric resistivity and Seebeck coefficient of thermoelectric materials was used in order to predict the efficiency of the thermoelectric modules. Then, the efficiency of the thermoelectric modules was verified using measured values which had been reported in prior experimental works. In this study, the simulated values were higher than the real thermoelectric effiency values. To address this, the simulations should consider the thermal resistance or electric contact resistance between the thermoelectric materials and electrodes.

A novel design of power-cooling cogeneration system driven by solid oxide fuel cell waste heat in ocean-going vessels

Among many global energy and environmental problems, the ocean and air pollution caused by ocean-going vessels cannot be ignored. Cleaner and more efficient power generation systems should be used to replace traditional diesel generators on ships. To this problem, the combination of fuel cell and waste heat recovery technology can become a better choice. In this paper, a novel power-cooling cogeneration system is designed and analyzed, which is mainly composed of solid oxide fuel cell, preheating subsystem, homogeneous charge compression ignition engine and double-effect absorption refrigeration cycle. The study mainly includes mathematical modeling, reliability verification of each subsystem, numerical simulation and results analysis in energy, exergy and economics. The results show that the system thermal efficiency and exergy efficiency can reach 64.01% and 61.83%, respectively, which are 18.76% and 12.62% higher than those of simple cell. Compared with traditional combined system, the payback time of the proposed scheme is about 2.59 years, which not only proves that the cost can be recovered in a short time, but also shortened by about half. By improving energy efficiency and reducing costs, the proposed scheme can ensure the demand of electricity and cold energy in daily life of the crew, and provides a new choice for the marine auxiliary power generation equipment.

Development of High-Performance Anode-Supported Planar SOFC with Large Area by 4-Layer Co-Firing Process

Solid oxide fuel cell (SOFC) technology has attratced great attention because of higher efficiency, fuel flexibility and eco-friendly stationary power generation system. However, its commercialization is hindered due to the lack of durability and high cost. Herein, a facile and exceptionally reliable 4-layered anode supported SOFCs with a large area (12cm×12cm) was fabricated in a single step co-firing process at 1400 oC, in which tape-casted green films of NiO-YSZ, NiO-1CeScSZ, 1CeSxSZ, and GDC were laminated by isostatic press. The fabrication parameter such as viscosity of the slurries and mechanical strengths of the green films, etc. were optimized. As a result, finely porous anode layer, and highly dense 1CeScSZ electrolyte and GDC buffer layers on a robust porous anode-support were formed successfully. The LSC cathode was screen-printed on the GDC layer. The possibility of mass production of this process are verified through the fabrication of large area cells with an active area 100cm2. The single cell showed high power output of 38 W at total current 50A at 700°C and exhibits low degradation rate of 0.2% kh-1 at 25A for long-term test of 1000 hrs. This facile strategy is time-efficient, reproducible, cost-effective, and highly practical to produce SOFC system satisfying both high-performance and durability.

Development of High-Performance Anode-Supported Planar SOFC with Large Area by 4-Layer Co-Firing Process

Solid oxide fuel cell (SOFC) technology has attracted great attention because of higher efficiency, fuel flexibility, and eco-friendly stationary power generation system. However, its commercialization is hindered due to the lack of durability and high-cost. Herein, a facile and exceptionally reliable 4-layered anode supported SOFCs with a large area (12cm×12cm) was fabricated in a single step co-firing process at 1400°C, in which tape-casted green films of NiO-YSZ, NiO-1CeScSZ, 1CeScSZ, and GDC were laminated by isostatic press. The fabrication parameter, such as viscosity of the slurries and mechanical strengths of the green films, were optimized. As a result, finely porous anode layer, and highly dense 1CeScSZ electrolyte and GDC buffer layers on a robust porous anode-support, were formed successfully. The possibility of mass production is verified through the fabrication of large area cells with an active area 100 cm2. The single cell showed high-power output of 28 W at total current 50 A at 700°C and exhibits low degradation rate of 0.2%/kh at 25A for long-term test of 1000 hrs. This facile strategy is time-efficient, reproducible, cost-effective, and highly practical to produce SOFC system satisfying both high-performance and durability.

Numerical Comparison of Planar and Micro-Tubular Solid Oxide Fuel Cells

Solid oxide fuel cell (SOFC) is a highly efficient power generation system that can be designed in many different geometries including planar and tubular types of fuel cell. Although their operating performance is based on the same principles, parameters may be unique for each geometry. This study investigates numerically effects of cell configuration on performance by developing a finite element method (FEM) based SOFC models. The effects of configuration on the fuel cell are investigated in terms of voltage, the average cell current density, and the average cell power. These effects are illustrated with polarization and power curves by using COMSOL software. As the most convenient results of this study, although both types have their own advantages, it can be concluded that the performance of the SOFC increases with the planar geometry compared to micro-tubular type under the studied operating conditions.

System modification and thermal efficiency study on the semi-closed cycle of supercritical carbon dioxide

Supercritical carbon dioxide (sCO2) semi-closed cycle is an advanced, efficient, and economical power generation system that can meet the needs of low cost and efficient utilization of coal and low carbon emissions. The Advanced System for Process Engineering software (Aspen Plus) was used to simulate different sCO2 systems. In the simplified sCO2 closed cycle, multi-stage compression and inter-cooling of CO2 compressors together can increase the system efficiency by about 5%. The system thermal efficiency increases by 0.5% with every 10 bar increase of the combustion chamber pressure between 200 bar and 500 bar, and increases by 0.35% with every 10 °C increase of the combustion temperature between 800 °C and 1500 °C. In the typical sCO2 semi-closed cycle--Allam cycle, the gas temperature in the combustion chamber decreases with the increase of CO2 backflow, and it would decrease with increase of the excess O2 ratio. The system thermal efficiency could be improved by 3% by adding reheat and graded expansion, and by 2% with ASU coupling and CO2/O2 mixing. Adding heat exchangers and proper stream distribution can improve the system efficiency by up to 10%. When the combustion chamber temperature is 1300 °C, turbine inlet pressure is 300 bar, turbine outlet pressure is 30 bar, and the split ratio of CO2 is 5:95, the sCO2 semi-closed cycle with precompression, recompression or partial cooling reaches the highest thermal efficiency (~64%). Depending on the results of the system modification and sensitivity analysis, ideas can be provided for the improvement and demonstration of the system.

Operating scenario of 3GWth class FFHR power plant with bypass controlled supercritical CO2 gas turbine power generation system

Abstract In order to achieve high power generation efficiency, facility compactness, high safety, and high coexistence with fuel tritium in the 3 G Wth class FFHR(Force Free Helical Reactor) power plant, optimization, performance and operation scenario of the power generation system of the power plant model using the axial flow type uniaxial supercritical CO2 gas turbine power generation system were examined. As a result, the following conclusions were obtained. (1) The most efficient and compact axial flow uniaxial design supercritical CO2 gas turbine power generation system suitable for 3 G WthFFHR power plant has a maximum heat capacity of 1.5GWth×2, and the gas turbine conversion rate at that time was evaluated as 46.9 %(= 1,267MWe/2,700MWth). Therefore, split connection with two power generation systems is optimal for a 3 G Wth class FFHR power plant. Here, the operating speed of the turbo equipment was set to 3600 rpm in order to adapt this plant model to the power supply system in Japan. (2) Simultaneous supply of 818MWe/300 s electricity and 300MWth/30days heat is required at startup of the FFHR. (3) The in-house power during steady operation under the self-ignition condition was reduced to about 31.7MWe, and the amount of power generated at the transmission end was evaluated as 1,234MWe.

Design and simulation of current-fed dual-active full-bridge DC/DC converter control system applied to proton exchange membrane fuel cell

Proton exchange membrane fuel cells (PEMFC) have been increasingly applied in clean and efficient distributed power generation systems in recent years. However, the output characteristics of PEMFC are relatively soft due to the influence of multiple polarization overvoltage. With the increasement of current density, the output voltage shows to be a nonlinear downward trend. In addition, in order to ensure the lifetime of PEMFC, the output ripple current is often concerned. Considering above characteristics, in order to achieve efficient power transmission of the PEMFC system, this paper adopts the current-fed dual-active full-bridge (DAB) DC/DC converter topology, which can achieve soft switching of most switches. Furthermore, it can restrain the characteristics of the current ripple. Hence, the power transmission efficiency and current ripple requirements of PEMFC are fulfilled. Finally the current-fed DAB is designed and simulated through PSIM. The C-block is applied to simulate the PEMFC nonlinear power supply according to the actual PEMFC parameters. In order to achieve efficient constant power transmission of the nonlinear PEMFC, a novel power closed-loop control strategy is proposed.

Elucidation for prime power flow DelinPuent in wind energy system

Wind energy is a renewable energy source its generation rate is tends to be due to uncertainty. This issue (OPF) is considered to resolve by a replacement amalgam multi-destination synthetic physical optimisation (AMDSPO) algorithmic rule, which does not require any administration parameters contrasted with various meta-heuristic calculations. Synthetic physical optimisation (SPO), a modestly new population-based intelligence algorithm, indicates fine execution on change issues. Besides, this paper presents half breed assortment of animal trek optimisation (ATO) algorithmic govern to express the union normal for SPO. The proposed methodology effectiveness is tested on IEEE 30-bus, IEEE 118-bus and IEEE 300-bus check system. The results oriented in the proposed methodology are compared for its betterment from other techniques. Thus the proposed methodology resolves the OPF issue and gives efficient wind energy power generation system.

Steam gasification of chars of ash-free coals extracted using 1-methylnaphthalene and N-methyl-2-pyrrolidone

Coal that contains >70 wt% carbon is possibly an economical option as fuel for highly efficient power generation system such as catalytic coal gasification and direct carbon fuel cell, when mineral ashes in coal are removed. In this work, ash-free coals (AFs) are prepared via thermal extraction of carbonaceous components in parent raw coal (PA) and chars of AFs are made by pyrolysis at 300–900 °C. Then, those are characterized concerning the compositional change associated with the extraction and carbonization condition, based on the steam gasification behavior. The composition of AF chars changes depending on the polarity of the extraction solvent. Chars of AF extracted using a polar solvent (N-Methyl-2-Pyrrolidone) show much higher gasification rate than that using a non-polar solvent (1-methylnaphthalene). The addition of K2CO3 catalyst to the AF chars improves the conversion rate significantly, showing that AFs can be a feedstock of the catalytic coal gasification. The effect of the pyrolysis temperature on the reactivity varies between the AFs, implying the difference in the aromaticity and the chemical composition. The property of the AF chars that can be somewhat adjusted by the extraction and pyrolysis condition possibly provides a custom-made product for a particular application including a precursor of the functional carbon materials.

A quadruple power generation system for very high efficiency and its performance optimization using an artificial intelligence method

The demand for highly efficient power generation systems is ever escalating to reduce carbon dioxide emissions. This study proposes a novel quadruple power generation system, investigates its performance characteristics, and optimizes its efficiency using an artificial intelligence method based on the results of a thermodynamic simulation. The quadruple system integrates four power blocks consisting of a solid oxide fuel cell (SOFC), a molten carbonate fuel cell (MCFC), a gas turbine, and an organic Rankine cycle to achieve high efficiency. A parametric analysis of the main design parameters was conducted. An artificial intelligence method combining an artificial neural network and a genetic algorithm was devised to avoid the slow speed of the calculation for the thermodynamically optimal solution and used to find the optimized design parameters that produce the maximum efficiency. The results of the thermodynamic parametric analysis were used to train the artificial neural network. The results of the optimization method were verified through comparison with the results of thermodynamic analysis. A very high maximum efficiency of 78.1% was predicted. The performance of the optimized quadruple system was examined by comparing it with that of other hybrid power systems.

Conceptual design and optimization of power generation system for lead-based reactor

The lead-based reactor is one of the key nuclear energy systems for Generation-IV (Gen-IV) and Accelerator Driven Subcritical Systems (ADS). The Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences (INEST, CAS) has taken significant initiative for the design and development of the China Lead-based Reactor (CLEAR) series since 2011. The conventional power generation system has low performance and optimization of main parameter is a challenge when power generation system is connected with lead-based reactor. A new/modified conceptual design of an efficient power generation system with two reheaters has been proposed on the basis of a 400 MWth (thermal power) lead-based reactor with high performance. The analysis results show that the thermal efficiency was influenced by number of reheaters (with bleed-off steam at different positions). The thermal efficiency of Schematic-III (with two reheaters) was 44.3% and higher than Schematic-I and II (one reheater with bleed-off steam from the supply line of the first regenerator and main supply line, respectively). However, key parameters of the power generation system have been optimized to increase the overall performance of Schematic-III. The optimized temperature of feed water at the inlet of the reactor was 360 °C with a flow rate of 237 kg·s−1 and the outlet temperature of the reactor was 558 °C. The efficiency and net power of the plant increased with the part load.

Techno-Economic Analysis of Natural Gas-Based Polygeneration System of Electricity, Cooling, and Heating

Some remote and rurar areas in Indonesia have low electrification levels and this poses a undermines their economic development potential. In response to the aforementioned challenges, it is necessary to develop an integrated energy system that produces multi-utilities (polygeneration) in producing energy to meet local needs. The aim of this work is to investigate the technical and economic analysis on a polygeneration system of a gas-fired power plant to produce electricity and heating, and to be integrated with an LNG regasification system for the utilization of cold energy as well. This polygeneration system is located in Manokwari District, West Papua. The polygeneration system was simulated using Unisim Design R390.1 to evaluate the technical performances and its economic analysis was done by using cash flow method with several business schemes, financial and fiscal incentives. The results showed that technically the polygeneration system is able to increase the efficiency of power generation system of a stand-alone power plant, from 32.9% to 59.7%. Economically, the polygeneration system can reduce the electricity tariff of a stand-alone power system from 19.32 US cents/kWh to 12.31 USD cents /kWh.