Conventional Coal Power Plants Research Articles

Comparative assessment of the environmental impact of nuclear power plant technology using life cycle assessment approach: A review

Nuclear power plants (NPP) are being considered as an alternative energy that could reducing greenhouse gas emissions. However, there are various challenges that need to be addressed regarding the variation of current nuclear technology such as environmental impact issues. To ensure the sustainability and effectiveness of nuclear power plants technology, a Life Cycle Assessment (LCA) approach can be used to study the environmental impacts of the nuclear power plant. LCA is a method for evaluating the environmental impact of a product or process from start to finish. By conducting a preliminary LCA study of each Nuclear Power Plant technologies, the environmental impacts of the stages of construction, operation, and management of radioactive waste can be understood. This study can also help compare the environmental impacts of nuclear power plants with other energy technologies. This preliminary study will review the environmental impact from pressurized water reactor, boiling water reactor, molten salt reactor, and compare with conventional coal power plant to provide compact summary of the technology. The results of the LCA study can help identify areas that require more attention in the development of nuclear power plants in Indonesia.

Scheduling optimization of a wind power-containing power system considering the integrated and flexible carbon capture power plant and P2G equipment under demand response and reward and punishment ladder-type carbon trading

At present, coal-fired thermal power still dominates in China, and as the environmental pollution problem worsens, it is critical to find the optimal combination of coal and new energy to reduce CO2 emissions and promote new energy consumption. Based on this, this paper considers a reward and punishment ladder-type carbon trading mechanism, firstly, unit transformation of the conventional coal power plant (CPP) on the power side, forming the integrated and flexible carbon capture power plant (IFCCPP), and constructing a coupling model of the IFCCPP with power to gas (P2G) equipment and wind farms(WFs), forming an IFCCPP-P2G-WF system; secondly, introducing a price demand response mechanism on the load side, and establishing a two-stage scheduling model for the IFCCPP-P2G-WF system, with the first stage model aiming at the minimum sum of squared load fluctuations and the second stage model aiming at the minimum operation cost. Finally, the effectiveness of the scheduling model proposed in this paper is validated by comparing and analyzing the scheduling results under eight scenarios. When compared to other models, the proposed model significantly increases wind power consumption, reduces carbon emissions, and lowers operation cost, all of which have advantages.

Parametric investigation of combustion process optimization for Gas Turbines at SJ Putrajaya

Gas Turbine (GT) power plants have been represented as essential assets of energy units because of their numerous advantages compared to conventional coal power plants. However, their low thermal efficiency may make the continuous baseload operations a lossmaking alternative and threaten to continue. This fact is raising the importance of performing thermodynamic investigation according to the current operations’ conditions. This paper aims to conduct a thermodynamic investigation for two Siemens V94.2 gas turbine (GT) units based on current operations’ conditions. The reason for selecting these units is because they are operating at a much lower thermal efficiency than the designed thermal efficiency, and due to the age factor, the GTs are not suitable for major retrofitting due to poor return on investments. A numerical model is designed to simulate the overall thermodynamic process in the gas turbine using MATLAB SIMULINK.The obtained numerical results are validated by comparing them with the operational data collected from the stations. The thermal efficiency is increased by 30%, with a maximum output power equal to 140MW. The power output had decreased by 0.2% when the ambient temperature was increased by about 6.0 oC. A graphical optimization, where various conditions are plotted as graphs, is also carried out to achieve the maximum thermal efficiency and power output. Finally, a number of recommendations are made to address decreased thermal efficiency and output power.

An Integrated Comparative Assessment of Coal-Based Carbon Capture and Storage (CCS) Vis-à-Vis Renewable Energies in India’s Low Carbon Electricity Transition Scenarios

Roadmaps for India’s energy future foresee that coal power will continue to play a considerable role until the middle of the 21st century. Among other options, carbon capture and storage (CCS) is being considered as a potential technology for decarbonising the power sector. Consequently, it is important to quantify the relative benefits and trade-offs of coal-CCS in comparison to its competing renewable power sources from multiple sustainability perspectives. In this paper, we assess coal-CCS pathways in India up to 2050 and compare coal-CCS with conventional coal, solar PV and wind power sources through an integrated assessment approach coupled with a nexus perspective (energy-cost-climate-water nexus). Our levelized costs assessment reveals that coal-CCS is expensive and significant cost reductions would be needed for CCS to compete in the Indian power market. In addition, although carbon pricing could make coal-CCS competitive in relation to conventional coal power plants, it cannot influence the lack of competitiveness of coal-CCS with respect to renewables. From a climate perspective, CCS can significantly reduce the life cycle GHG emissions of conventional coal power plants, but renewables are better positioned than coal-CCS if the goal is ambitious climate change mitigation. Our water footprint assessment reveals that coal-CCS consumes an enormous volume of water resources in comparison to conventional coal and, in particular, to renewables. To conclude, our findings highlight that coal-CCS not only suffers from typical new technology development related challenges—such as a lack of technical potential assessments and necessary support infrastructure, and high costs—but also from severe resource constraints (especially water) in an era of global warming and the competition from outperforming renewable power sources. Our study, therefore, adds a considerable level of techno-economic and environmental nexus specificity to the current debate about coal-based large-scale CCS and the low carbon energy transition in emerging and developing economies in the Global South.

Process simulation and comprehensive evaluation of a system of coal power plant coupled with waste incineration

The technology of coal power plant coupled with waste incineration is considered as a promising technology for fossil fuel conservation and waste disposal. In this paper, a system of coal power plant coupled with waste incineration is simulated by Aspen Plus software, and a conventional coal power plant is also simulated for comparison. Comprehensive evaluation including thermodynamic, economic and environmental impact performances are analysed and compared. Evaluation results indicate that the thermodynamic performance and environmental impact of the system of coal power plant coupled with waste incineration are worse, but the economic performance of the system is obviously better than the coal power plant. When the replacement ratio of waste is 20%, the energy and exergy efficiencies of the system are 38.54% and 37.27%, the internal rate of return and discounted payback period of the system are 21.83% and 9.14 years, and the environmental cost of the system is $3597.73 h-1. Therefore, the technology of coal power plant coupled with waste incineration has technical feasibility and economic advantages, and the environmental impacts need to be considered in the application of the technology.

Electrochemical study of composite materials for coal-based direct carbon fuel cell

The efficient conversion of solid carbon fuels into energy by reducing the emission of harmful gases is important for clean environment. In this regards, direct carbon fuel cell (DCFC) is a system that converts solid carbon directly into electrical energy with high thermodynamic efficiency (100%), system efficiency of 80% and half emission of gases compared to conventional coal power plants. This can generate electricity from any carbonaceous fuel such as charcoal, carbon black, carbon fiber, graphite, lignite, bituminous coal and waste materials. In this paper, ternary carbonate-samarium doped ceria (LNK-SDC) electrolyte has been synthesized via co-precipitation technique, while LiNiCuZnFeO (LNCZFO) electrode has been prepared using solid state reaction method. Due to significant ionic conductivity of electrolyte LNK-SDC, it is used in DCFC. Three types of solid carbon (lignite, bituminous, sub-bituminous) are used as fuel to generate power. The X-ray diffraction confirmed the cubic crystalline structure of samarium doped ceria, whereas XRD pattern of LNCZFO showed its composite structure.The proximate and ultimate coal analysis showed that fuel (carbon) with higher carbon content and lower ash content was promising fuel for DCFC. The measured ionic conductivity of LNK-SDC is 0.0998 Scm−1 and electronic conductivity of LNCZFO is 10.1 Scm−1 at 700 °C, respectively. A maximum power density of 58 mWcm−2 is obtained using sub-bituminous fuel.

The Role of Hydropower in Climate Change Mitigation and Adaptation: A Review

Abstract Hydropower is a clean, renewable, and environmentally friendly source of energy. It produces 3930 (TW.h).a −1 , and yields 16% of the world’s generated electricity and about 78% of renewable electricity generation (in 2015). Hydropower and climate change show a double relationship. On the one hand, as an important renewable energy resource, hydropower contributes significantly to the avoidance of greenhouse gas (GHG) emissions and to the mitigation of global warming. On the other hand, climate change is likely to alter river discharge, impacting water availability and hydropower generation. Hydropower contributes significantly to the reduction of GHG emissions and to energy supply security. Compared with conventional coal power plants, hydropower prevents the emission of about 3 GT CO 2 per year, which represents about 9% of global annual CO 2 emissions. Hydropower projects may also have an enabling role beyond the electricity sector, as a financing instrument for multipurpose reservoirs and as an adaptive measure regarding the impacts of climate change on water resources, because regulated basins with large reservoir capacities are more resilient to water resource changes, less vulnerable to climate change, and act as a storage buffer against climate change. At the global level, the overall impact of climate change on existing hydropower generation may be expected to be small, or even slightly positive. However, there is the possibility of substantial variations across regions and even within countries. In conclusion, the general verdict on hydropower is that it is a cheap and mature technology that contributes significantly to climate change mitigation, and could play an important role in the climate change adaptation of water resource availability. However, careful attention is necessary to mitigate the substantial environmental and social costs. Roughly more than a terawatt of capacity could be added in upcoming decades.

Surface Characterization of Candidate Materials for High Temperature Power Plants

Introduction The decreasing supply of fossil fuel sources, coupled with the increasing concentration of green house gases has placed enormous pressure to maximize the efficiency of power generation (1). Increasing the outlet temperature of these power plants will result in an increase in Carnot efficiency (2). To increase their efficiency, coal fired power plants currently use both supercritical water (SCW) and ultrasupercritical water (USCW) with the most advanced designs allowing for a decrease of 58000 kg/hr in the coal fed to produce the same power as a conventional coal power plant (1). By employing a supercritical fluid as the coolant in nuclear reactors, the plant efficiency can be increased to 45%, compared to traditional reactors which currently operate at ~33% (3, 4). Experimental Experiments were conducted using the supercritical water loop (SCWL) facility at UNR. This unique facility allows for accelerated corrosion testing and mechanical behavior studies to be conducted. The primary loop environment that was used for these experiments contained deionized water held at a pressure of 27 MPa and temperatures ranging from room temperature up to 600°C. Materials studied include; austenitic steels (stainless steel 304 and Nitronic 50), and nickel based alloys (Inconel 625 and 718). Surface chemistry of the oxide layer was studied using, X-ray diffraction, X-ray photoelectron and Raman spectroscopies. Results Raman spectra for SS316 and I625 exposed to 600°C supercritical water is displayed in Figure 1. It can be observed that the oxide composition varies. Based on the Raman shift it can be observed that the largest features correspond to NiFe2O4 and Fe3O4, which formed on the surfaces of I625 and SS316 respectively (5-7). Further, the corrosion behavior of the candidate materials will be discussed with respect to surface chemistry. Figure 1: Raman spectra for alloys I625 and SS316 exposed to 600°C supercritical water. Acknowledgements: This study was supported by the Department of Energy (DOE) under contracts DE-NE0000454 and DE-NE0008236 and Nuclear Regulatory Commission (NRC) under awards NRC-38-10-949 and NRC-HQ-11-G-38-0039. D.R. is supported under a Fellowship program funded by NRC. Mr. Kenny Osborne and Ms. Nancy Hebron-Isreal serve as the program managers for the DOE and NRC awards, respectively.

Accelerated Corrosion of Candidate Materials for High Temperature Power Plants

Introduction The decreasing supply of fossil fuel sources, coupled with the increasing concentration of green house gases has made it necessary to maximize the efficiency of power generation (1). Increasing the outlet temperature of these power plants will result in an increase in efficiency (2). To increase their efficiency, coal fired power plants currently use both supercritical water (SCW) and ultrasupercritical water (USCW) with the most advanced designs allowing for a decrease of 58000 kg/hr in the coal fed to produce the same power as a conventional coal power plant (1, 3). By employing high temperature fluid, including supercritical water, the plant efficiency can be increased to 45%, compared to traditional reactors which currently operate at ~33% (4, 5). Experimental Experiments were conducted in the recently established supercritical water loop (SCWL) facility at UNR. This unique facility allows accelerated corrosion testing and mechanical behavior studies to be conducted simultaneously. The primary loop environment that was used for these experiments contained deionized water held at a pressure of 27 MPa and temperatures ranging from room temperature up to 600°C. A secondary high pressure pump was used to supply an electrolyte containing 1 g/L of boric acid at a flow rate of 1.5mL/min with a chlorinated silver wire used as a reference electrode. Materials studied include; austenitic steels (Nitronic 50 stainless steels 304 and 316), nickel based alloys (Inconel 625 and 718) and a high carbon steel (A285 class C). Although A285 will not come into contact with the working fluid it will be studied due to the low amount of alloying elements when compared to the austenitic and nickel based alloys. A Gamry PCI4 potentiostat was used for polarization of these samples. The oxide layer that was formed was characterized to determine the corrosion characteristics in this environment. Surface chemistry of the oxide layer was studied using X-ray photoelectron, Raman, and infrared spectroscopies. The corrosion products in the electrolyte were analyzed using inductively coupled plasma atomic emission. Results The corrosion behavior of the high carbon steel A285 class C samples were studied using potentiodynamic polarization at temperatures ranging from 20°C to 600°C. The results indicate that the corrosion potential becomes more noble with increasing temperature while the corrosion current exhibited no such trend. Tests conducted at 600oC indicate the possibility of the formation of protective oxide layer. Surface chemistry of the films formed on the samples was found to vary based on the test conditions. Acknowledgements: This study was supported by the Department of Energy, NEUP under Contract DE-NE0000454 and Nuclear Regulatory Commission (NRC) under award NRC-HQ-11-G-38-0039. D.R. is supported under NRC Fellowship award NRC-38-10-949.

Environmental and Economic Performances of Different Technologies for Power Generation from Rice Husks

This work compares the environmental impacts and economic performances of different technologies for rice husk-fuelled Combined Heat and Power (CHP) generation, in Thailand. A modified integrated model for efficient biomass and bioenergy network optimisation was used based on a previous work by Cucek et al. (2012). This model accounts for the evaluation of environmental footprints and economic performance within the framework of a Life Cycle Assessment (LCA). Rice husk is considered to be one of the main sources of biomass waste in Thailand. More recently, the Thai government has promoted the use of biomass for energy purposes as a substitute for fossil fuel consumption, and to reduce the environmental impacts caused by using fossil fuels. Consequently, rice husk is being widely used for electricity generation on a commercial scale. This contribution assesses the environmental and economic profiles of different technologies for rice husk-fuelled CHP by employing a wider spectrum of technological options, including combustion, gasification, and pyrolysis systems. The indicators analysed are the key environmental footprints associated with biomass and fossil energy sources: carbon, nitrogen, and water footprints, and are supplemented by the costs. The results show that the best option from amongst the analysed options is pyrolysis, and the use of oil as a substitute for coal in the conventional coal power plants. The aggregated single measurement of sustainability regarding different technological options, the Sustainable Environmental Performance Indicator - SEPI (De Benedetto and Klemes, 2009), was calculated, having the advantage that the subjective weighting of environmental footprints is unrequired. The results obtained from this work can be exploited by decision makers for selecting appropriate systems in terms of environmental and economic performances.

An experimental and numerical study of the gap effect on wind load on heliostat

The main handicap of the concentrating solar power technology is still the higher cost compared with the conventional coal power plant. Heliostat arrays cause about 40% of the costs of central receiver power plants. The cost reduction of heliostats is of crucial importance to central receiver power plants. The reduction of wind load on heliostats will decrease the structural requirement for heliostats, and then cut the cost of heliostats. In this paper, different gap sizes (0–40mm) between the facets of the heliostats were studied experimentally and numerically. Both of the results showed that the wind load increases slightly with the increase of gap size (0–40mm). The result of the numerical simulation shows the flow pattern through the gap resembles a jet flow which does not affect the static pressure on the windward surface but does decrease the static pressure on the leeward surface of the facets. Consequently it increases the total drag force on the heliostat. However, the absolute increment of the wind load is very small compared with the overall wind load on the heliostat structure. It is not necessary to take account of the gap size effects on the wind load during the design process of heliostat.

Thermoeconomic analysis of a novel zero-CO 2-emission high-efficiency power cycle using LNG coldness

This paper presents a thermoeconomic analysis aimed at the optimization of a novel zero-CO 2 and other emissions and high-efficiency power and refrigeration cogeneration system, COOLCEP-S (Patent pending), which uses the liquefied natural gas (LNG) coldness during its revaporization. It was predicted that at the turbine inlet temperature ( TIT) of 900 °C, the energy efficiency of the COOLCEP-S system reaches 59%. The thermoeconomic analysis determines the specific cost, the cost of electricity, the system payback period and the total net revenue. The optimization started by performing a thermodynamic sensitivity analysis, which has shown that for a fixed TIT and pressure ratio, the pinch point temperature difference in the recuperator, Δ T p1, and that in the condenser, Δ T p2 are the most significant unconstrained variables to have a significant effect on the thermal performance of novel cycle. The payback period of this novel cycle (with fixed net power output of 20 MW and plant life of 40 years) was ∼5.9 years at most, and would be reduced to ∼3.1 years at most when there is a market for the refrigeration byproduct. The capital investment cost of the economically optimized plant is estimated to be about 1000 $/kWe, and the cost of electricity is estimated to be 0.34–0.37 CNY/kWh (∼0.04 $/kWh). These values are much lower than those of conventional coal power plants being installed at this time in China, which, in contrast to COOLCEP-S, do produce CO 2 emissions at that.

Integrated gasification combined cycle (IGCC) process simulation and optimization

The integrated gasification combined cycle (IGCC) is an electrical power generation system which offers efficient generation from coal with lower effect on the environment than conventional coal power plants. However, further improvement of its efficiency and thereby lowering emissions are important tasks to achieve a more sustainable energy production. In this paper, a process simulation tool is proposed for simulation of IGCC. This tool is used to improve IGCC's efficiency and the environmental performance through an analysis of the operating conditions, together with process integration studies. Pinch analysis principles and process integration insights are then employed to make topological changes to the flowsheet to improve the energy efficiency and minimize the operation costs. Process data of the Texaco gasifier and the associated plants (coal preparation, air separation unit, gas cleaning, sulfur recovery, gas turbine, steam turbine and the heat recovery steam generator) are considered as a base case, and simulated using Aspen Plus ®. The results of parameter analysis and heat integration studies indicate that thermal efficiency of 45% can be reached, while a significant decrease in CO 2 and SO x emissions is observed. The CO 2 and SO x emission levels reached are 698 kg/MWh and 0.15 kg/MWh, respectively. Application of pinch analysis determines energy targets, and also identifies potential modifications for further improvement to overall energy efficiency. Benefits of energy integration and steam production possibilities can further be quantified. Overall benefits can be translated to minimum operation costs and atmospheric emissions.

The comparison study on the operating condition of gasification power plant with various feedstocks

Gasification technology, which converts fossil fuels into either combustible gas or synthesis gas (syngas) for subsequent utilization, offers the potential of both clean power and chemicals. Especially, IGCC is recognized as next power generation technology which can replace conventional coal power plants in the near future. It produces not only power but also chemical energy sources such as H2, DME and other chemicals with simultaneous reduction of CO2. This study is focused on the determination of operating conditions for a 300 MW scale IGCC plant with various feedstocks through ASPEN plus simulator. The input materials of gasification are chosen as 4 representative cases of pulverized dry coal (Illinois#6), coal water slurry, bunker-C and naphtha. The gasifier model reflects on the reactivity among the components of syngas in the gasification process through the comparison of syngas composition from a real gasifier. For evaluating the performance of a gasification plant from developed models, simulation results were compared with a real commercial plant through approximation of relative error between real operating data and simulation results. The results were then checked for operating characteristics of each unit process such as gasification, ash removal, acid gas (CO2, H2S) removal and power islands. To evaluate the performance of the developed model, evaluated parameters are chosen as cold gas efficiency and carbon conversion for the gasifier, power output and efficiency of combined cycle. According to simulation results, pulverized dry coal which has 40.93% of plant net efficiency has relatively superiority over the other cases such as 33.45% of coal water slurry, 35.43% of bunker-C and 30.81% of naphtha for generating power in the range of equivalent 300 MW.

Particle size effect on the filtration drag of fly ash from a coal power plant

In order to investigate the filtration properties of fly ash from a conventional coal power plant, the filtration drag across the dust cake over an absolute fiber- glass filter element was measured. A fluidized bed column was utilized to obtain a well characterized particle stream. The cake resistance coefficient was analyzed by the equation proposed by Endo et al. (1998) in order to observe the effect of particle size and polydispersity. The filtration drag was measured for three kinds of particle stream having the geometric mean particle size of 3.15, 6.07, and 7.83 μm and the geometric standard deviation less than 1.44 in the practical operation conditions for the field applications of face velocity of 0.03- 0.06 m/s and area dust load up to 0.2 kg/m 2 . A dust cake of smaller particle size showed larger pressure drop even though the porosity was higher and presented high compressibility according to the face velocity. The particle polydispersity was also a dominant factor affecting the compressibility of the dust cake.