Clean Power Generation System Research Articles

National and local labor impacts of coal phase-out scenarios in Chile

Phasing out coal-fired power plants is one of the most urgent steps needed to achieve the 1.5- or 2-degree target in the Paris Agreement. Many developed and developing countries have announced their plans to phase out coal from their electricity sectors. Managing the social and economic impacts of this energy transition is key to achieving political and social acceptability and pursuing environmental and social development hand in hand. As one of the leading countries committed to decarbonization in Latin America, Chile has launched a plan to phase out coal by 2050. To analyze the impacts of phasing out coal in Chile on jobs and value added, we combined an Input-Output analysis with ad-hoc labor surveys. We analyzed four contrasting electricity production scenarios that the Chilean government used to frame the policy debate: the current Long-Term Energy Plan (a baseline), and three scenarios that phase out coal-based generation by 2030 or 2050. Our findings show that coal phase-out will contribute to net job creation on the national level, adding 23–26 thousand jobs by 2030. In addition, value-added in the power generation sector will also grow by 1.7 billion dollars above today's levels as a result of the coal phase-out. These overall positive numbers mask a gross job destruction of 4.4 thousand jobs in coal power plants, concentrated in a few communities. In the most affected community, 7.1% of the population works in a coal power plant. Negative impacts in coal-reliant communities require special attention to ensure a just transition towards a clean power generation system. The results of this study highlight the need for strategic policy development that supports a smooth transition to a low-carbon economy, taking into account the associated national and local impacts. Our study also contributes to the literature about the evaluation framework of coal phase-out projects around the world, improving the understanding of their associated impacts beyond the case study country.

Review on Greenhouse Gases Emission in the Association of Southeast Asian Nations (ASEAN) Countries

The Association of the Southeast Asian Nations (ASEAN) region is a critical contributor to global development from an environmental perspective. This study has reviewed carbon emissions from energy generation, influence factors from the population, economic growth and renewable energy, emission and energy intensity projection, spatial distribution characteristics, and decarbonization strategy. This work utilizes a comparison methodology between ASEAN countries in the emission intensity and energy intensity in the future projection of electricity conditions in 2030 or 2040, as well as opportunities for reducing greenhouse gas (GHG) emissions as determined by the national policies of each government. The results show that Indonesia, Vietnam, Thailand, and Malaysia produce 79.7% of the electricity in the ASEAN region. As a developing country, Indonesia has the largest population and gross domestic product (GDP) but has the highest predicted emission intensity, of 0.97 CO2e/MWh, in 2030. Vietnam is predicted to have an emission intensity of about 3.56t-CO2e/cap and 0.747t-CO2e/GDP in 2030. Vietnam is expected to increase in energy intensity to 1241 MWh/GDP, while Brunei Darussalam has a high energy intensity of 11.35 MWh/cap. However, the capacity of solar power plants (more than 11 GW) and wind-power plants (2384 MW) have generally increased in ASEAN from 2015 to 2019, indicating the positive development of renewable energy source (RES) use. The national policies strongly influence the estimated GHG emission in ASEAN by aggressively replacing fossil fuels with RESs. Support, via government policies, can reduce the cost of electricity generation from RESs is needed to increase and enhance the installment of clean power generation systems. In future work, the research needs to consider the intermittent characteristics of variable RES in power system operation.

Life cycle assessment of power generation systems in Spain: Exploring a broader view from a consequential perspective

Developing new clean power generation systems is a research priority for the energy sector, and selection should be based on environmental performance over the entire lifetime. Consequential Life Cycle Assessment evaluates the consequences of this selection and provides environmental data to support decision-making. This research uses a consequential approach to assess the environmental impacts of two medium power generation systems. The selected environmental impact assessment methods are IPCC 2013 GWP 100y and ReCiPe 2016. Moreover, the work describes a methodology for finding the marginal mix technologies for electricity and cooling energy production depending on the time horizon. The positive environmental consequences associated with short-term marginal energy mixes (electricity and cooling) progressively disappear when the marginal energy mix varies throughout time. The environmental results strongly depend on the marginal mix of technologies and evidence the necessity to develop methodologies and standards to improve the robustness of environmental assessments. A new line of discussion is opened concerning the temporal variation of environmental impacts of an energy production system, which could also be considered in Attributional Life Cycle Assessments.

Renewable Energy Potential Estimation Using Climatic-Weather-Forecasting Machine Learning Algorithms

The major challenge facing renewable energy systems in Nigeria is the lack of appropriate, affordable, and available meteorological stations that can accurately provide present and future trends in weather data and solar PV performance. It is crucial to find a solution to this because information on present and future solar PV performance is important to renewable energy investors so that they can assess the potential of renewable energy systems in various locations across the country. Although Nigerian weather provides favorable weather conditions for clean power generation, there is little penetration of renewable energy systems in the region, since over 95% of the power is fossil-fuel-generated. This is because there has been no detailed report showing the potential of clean power generation systems due to the dysfunctional meteorological stations in the country. This paper sought to fill this knowledge gap by providing a machine-learning-inspired forecasting of environmental weather parameters that can be used by manufacturing companies in evaluating the profitability of siting renewable energy systems in the region. Crucial weather parameters such as daily air temperature, relative humidity, atmospheric pressure, wind speed, and rainfall were obtained from NASA for a period of 19 years (viz. 2004–2022), resulting in the collection of 6664 high-resolution data points. These data were used to build diverse regressive neural networks with varying hyperparameters to find the best network arrangement. In summary, a low mean-squared error of 7 × 10−3 and high regression correlations of 96% were obtained during the training.

Business model and planning approach for hydrogen energy systems at three application scenarios

Green hydrogen is used as fuel or raw material in power systems, transportation, and industry, which is expected to curb carbon emissions at the root. First, a unified energy system consisting of clean power generation systems, hydrogen energy systems (HESs), and transmission systems was proposed, and the characteristics of hydrogen load in different fields are analyzed. Possible business models for HESs in industry and transportation are then presented, cost and benefit functions for stakeholders of HES were created, and a business model with multi-party participation was modeled as a multi-objective optimization model. In a power system, the business model of combining two operating modes for hydrogen storage was proposed at the power generation side as well. Finally, three HESs were designed for a chemical plant with a hydrogen demand of 1000 Nm3/h, a hydrogen refueling station with a daily hydrogen load of 600 kg, and a 100% clean power generation system, respectively. The results of the case study show that one or more feasible business models (i.e., all stakeholders are profitable) can be found in both industrial and transportation by the HES planning approach proposed, while the internal rate of return of HES installed on the generation side is less than 5% due to high investment cost at this stage and low utilization rate; nonetheless, the profitable strategies are shown by 3D graphics.

Power Generation Characteristics of PEFCs Using Heteropolyacids As Anode Redox Mediators

Polymer electrolyte fuel cells (PEFCs) have attracted much attention as clean power generation systems. PEFCs have been employed for residential cogeneration systems, fuel cell vehicles and spaceships due to short startup/shutdown times, small size, and low weight, compared to high– temperature FCs. Because precious metals such as Pt are utilized for electrocatalysts in order to obtain high power generation efficiency, high cost of the system is one of the issues in the spread period. In addition, hydrogen fuel has problems in safety and transportation.Therefore, in recent years, PEFC using heteropolyacid (HPA) as a mediator has been reported for the solution of these problems [1]. In this system, reduced HPA is supplied to the anode, and is converted to oxidized HPA over the electrode via the following reaction. [H nXM V nM VI 12–n O40] z – → [XM VI 12O40] z – + ne– + nH+ (1) where X = Si, P and M = W, Mo, V On the other hand, oxygen is reduced to produce water on the cathode, as in the case of general PEFCs. This PEFC system can be continuously operated by reducing the oxidized HPA and supplying it to the anode again. Electrochemical methods and addition of reducing agents can be considered for reducing oxidized HPA [2]. However, more effective reduction methods have been needed to achieve high performance and long-term operation.In this study, various metal pieces were utilized for the reduction of oxidized HPA in order to establish an effective method. The effect of metal pieces on the power generation performance and long-term operation of PEFC was evaluated. H3PW12O40·28H2O (PW12) and H2SO4 were added to ultrapure water to prepare an oxidized PW12 solution (0.01 M PW12–0.5 M H2SO4). This solution was subjected to a constant current electrolysis (1.00 mA cm–2) or an addition of metal pieces (Al, Ni, Fe, Co) to obtain the reduced PW12. A membrane–electrode assembly was prepared using Nafion® membrane as an electrolyte, carbon black as an anode, and Pt/C as a cathode. The operating temperature was 80 ºC, and O2 (relative humidity: 100%) was supplied to the cathode. The reduced PW12 solution bubbled with Ar gas was supplied to the anode by a liquid feed pump. Current–voltage (I–V) measurements and galvanostatic operation tests (5.00 mA cm–2) were performed using this single cell. As a result, the addition of Co pieces achieved the high reduction degree of HPA and the superior cell characteristics. The suppression of the side reactions such as hydrogen generation and the increase of the output power were necessary for the improvement of PEFC system using HPA as the anode redox mediator.[1] R. Singh, A. A. Shah, A. Potter, B. Clarkson, A. Creeth, C. Downs, F. C. Walsh, J. Power Sources, 201 (2012) 159–163.[2] S. Nakada, E. Morikawa, T. Okanishi, H. Muroyama, T. Matsui, Y. Hirao, K. Eguchi, of 82th Meeting of Electrochem. Soc. Jpn., 3B09 (2015).

Development of 3-Dimensionally Ordered Microporous Polyimide Based Composite Membranes Apply on Non-Humidified Intermediate Temperature Fuel Cells

Polymer electrolyte fuel cells (PEFC) have been used as clean power generation systems for households and vehicles because of their high energy conversion efficiency and low emissions. Perfluorosulfonic acid (PFSA) polymers have been used as electrolyte membranes in PEFCs due to their high proton conductivity, excellent chemical stability and superior durability. However, the membranes require water which limits the operating temperature to be below 100 °C leading to a complex system of water management and low effective utilization of heat. So new kinds of electrolyte membranes which can be operated under non-humidified intermediate temperature (120- 200 °C) are required. To achieve this kind of fuel cell, we focused on a mixed electrolyte based on phosphoric acid (PA) and sulfonic acid group containing ionic liquids (ILs) in our previous studies1. The PA_IL mixed electrolyte not only showed higher thermal stabilities, but also higher electrochemical activities and higher durability of Pt catalyst comparing with pure PA or pure IL. In this study, in order to realize a composite membrane for fuel cell, 3-dimensionally ordered microporous polyimide (3-DOM PI) which has the properties of high porosity, uniform pore structure and high thermal stability was developed as a backbone for composite electrolyte membrane. Polyamic acid (20 wt.%, JFE chemical Co.) was mixed with silica particles (100 nm, 300 nm and 900 nm in diameters, respectively) to making a slurry. The slurry was applicate on a glass board. Then the slurry membrane was drying for polymerization at 320 °C. At last, the silica was removed by HF aqueous solution (10 wt.%) etching for 12 hours. The 3-DOM PI was washed by distilled water then drying at room temperature for 2 days. The composite membrane was composed by PA_IL mixed electrolyte and 3-DOM PI under vacuum condition for 10 min at 100 °C. Figure 1 showed the image of 3-DOM PI. From the SEM analysis, it was confirmed that the different uniform pore sizes of 3-DOM PI were successfully fabricated. The composite membranes were evaluated by the thermogravimetric analysis, the ionic conductivities analysis and the fuel cell polarization test under the non-humidified intermediate temperature. The hydrogen crossover was also evaluated by changing the pore size and thickness of composite membranes. The optimized pore size (nanoscale) and thickness (microscale) of composite membranes were discussed to be 100 nm and 25±3 μm, respectively. The maximum current density and power density at 180 °C are 1.8 A cm -2 and 450 mW cm -2, respectively. The durability of the composite membranes was observed for more than 280 h with a constant current. From the result in Fig. 2 a), the stability of MEA was not only confirmed by the stable OCV, maximum current density and the stability of cathode Pt catalyst from TEM analysis (Fig. 2 b) and c)). In this study, the PA_IL/3-DOM PI composite membrane for Non-humidified IT-FC was developed. Acknowledgement This research was partly supported by “Platform for Technology and Industry” of Tokyo Metropolitan Government. References Yu, S. Kikuchi, H.P. Peediyakkal, H. Munakata, K. Kanamura. ACS Appl. Mater. & Interfaces2019, 11, 14, 13761-13767 Figure 1

Diethylmethylammonium Trifluoromethanesulfonate/Phosphoric Acid Mixture As Electrolyte for Non-Humidified Intermediate Temperature Fuel Cells

Polymer electrolyte fuel cells (PEFCs) have received more and more attention due to their high energy conversion efficiency and low emissions. Moreover, PEFCs have been used in wide range of applications, such as clean power generation systems for households and vehicles. Perfluorosulfonic acid (PFSA) polymers, such as Dupont’s Nafion®1have been used as electrolyte membranes in PEFCs for decades due to their high proton conductivity, excellent chemical stability and superior durability. However, the membranes require water to retain high proton conductivity, which limits the operating temperature to be below 100 °C, and needs a large humidification system. In order to realize more compact PEFC systems, new electrolytes applicable to intermediate temperature (IT), above 150 ºC, without humidification are needed. Under these conditions, phosphoric acid fuel cell (PAFC) has been applied, but the dehydration condensation of phosphoric acid (PA) still remains as a big problem to diminish its stable operation. Ionic liquids (ILs) have unique properties such as high ionic conductivity, high thermal stability, wide electrochemical potential window and non-volatility. Thus, they have been focused as candidate electrolytes for intermediate temperature fuel cells. In this study, we aimed to achieve the non-humidified intermediate temperature fuel cell by using 3-dimensionally ordered macroporous polyimide (3 DOM PI)/diethylmethylammonium trifluoromethanesulfonate (Dema-TfO)/phosphoric acid (PA) composite membrane. Dema-TfO was synthesized by direct neutralization of the N,N-diethylmethylamine and trifluoromethanesulfonic acid with 1 : 1 molar ratio followed by vacuum drying at 100 °C for 48 h, as a protic IL to prepare the composite membrane. Dema-TfO was added with different ratios of PA. 3 DOM PI was fabricated by using previous method2. 3 DOM PI/Dema-TfO/PA composite electrolyte membrane was then prepared by immersion of 3 DOM PI into the mixture of Dema-TfO and PA under vacuum at 100 °C. Figure 1 showed TG curves for the Dema-TfO/PA mixture. For comparison, the TG curves of Dema-TfO and PA were also provided. It was confirmed that Dema-TfO was thermally stable to 230 ℃. At 180 ℃, which is a target temperature of FC operation, the weight loss ratio of PA was as high as 6%. However, when the mixture was considered, 50 wt% PA in mixture, the loss weight ratio was same with the value of Dema-TfO which was less than 1.5%. Also the detection of 3 DOM PI/Dema-TfO/PA composite membrane showed thermally stable at 180 ℃. The thermally stable property indicated that interaction of mixture suppressed PA dehydration. The mechanism of interaction was explained by FT-IR and NMR analysis. From FT-IR results, the [P(OH)2] antisymmetric stretching in PA and the SO2 symmetric stretching in Dema-TfO showed peak shift when the two functional groups were in the Dema-TfO/PA mixture. On the other hand, in H1 NMR analysis of Dema-TfO/PA mixture, both of the weakened O-H bond in PA and enhanced N-H bond in Dema-TfO compared with pure PA and Dema-TfO could be explained by the interactions existing between phosphate groups and sulfonic groups from TfO-which were the same explanation with the FT-IR results. The proton ionic conductivities and proton transport number of Dema-TfO/PA mixture were measured, too. The oxidation reduction electrochemical polarization performances of Dema-TfO/PA mixture will be presented at the conference. According to our results, the Dema-TfO/PA mixture as electrolyte is one of the possible electrolytes to achieve the non-humidified intermediate temperature fuel cell. Acknowledgement This research was supported by “Platform for Technology and Industry” of Tokyo Metropolitan Government. References R. L. Coalson, W. G. Grot, US Patent 3, 1972, 684-747H. Munakata, D. Yamamoto, K. Kanamura, Journal of Power Sources 2008, 178, 596–602 Figure 1

On a clean power generation system with the co-gasification of biomass and coal in a quadruple fluidized bed gasifier

A clean power generation system was built based on the steam co-gasification of biomass and coal in a quadruple fluidized bed gasifier. The chemical looping with oxygen uncoupling technology was used to supply oxygen for the calciner. The solid oxide fuel cell and the steam turbine were combined to generate power. The calcium looping and mineral carbonation were used for CO2 capture and sequestration. The aim of this work was to study the characteristics of this system. The effects of key operation parameters on the system total energy efficiency (ŋten), total exergy efficiency (ŋtex) and carbon sequestration rate (Rcs) were detected. The energy and exergy balance calculations were implemented and the corresponding Sankey and Grassmann diagrams were drawn. It was found that the maximum energy and exergy losses occurred in the steam turbine. The system ŋten and ŋtex could be ∼50% and ∼47%, and Rcs could be over unit.

Preparation of Electrolyte Membrane Composite Composed of Ionic Liquid and Porous Polyimide for Non-Humidified Intermediate-Temperature Fuel Cell

Introduction Polymer electrolyte fuel cells (PEFCs) have been used as clean power generation systems for houses and cars because of their high energy conversion efficiency and low emissions. Presently, perfluorosulfonic acid membranes such as Nafion® have been used as electrolyte membranes in PEFCs because of their excellent chemical stability, high ionic conductivity and good mechanical strength. However, this kind of membranes requires water to have high proton conductivity, which limits the operating temperature of PEFCs to be below 100 °C and makes the system very large. For example, this system needs a humidifier. To realize more compact PEFC systems with higher energy conversion efficiency, new electrolytes applicable to intermediate temperatures, above 180 ºC, without humidification are needed. Ionic liquid (ILs) have unique properties such as non-volatility, high thermal stability, wide electrochemical potential window and high ionic conductivity. Therefore, they have been focused as candidate electrolytes for intermediate temperature fuel cells. In this study, we prepared and tested a composite membrane composed of a porous polyimide (PI) matrix with three-dimensionally ordered macroporous (3DOM) structure and a protic IL as a new electrolyte membrane to realize intermediate temperature fuel cells. Experimental Diethylmethylamine-trifluoromethanesulfonic acid (dema-TfO) was synthesized by direct neutralization of the N,N-diethylmethylamine and trifluoromethanesulfonic acid in a 1 : 1 molar ratio followed by vacuum drying at 100 °C for 48 h, as a protic IL to prepare the composite membrane. Poly(dimethylaminoethyl methacrylate) (PDMEMA) was added to dema-TfO in concentration of 50 g L-1 and stirred at 150 ºC. After dissolving PDMEMA in dema-TfO, the solution was cooled to room temperature and N,N,N’,N’-tetra(trifluoromethanesulfonyl)- dodecane-1,12-diamine was added to the solution in concentration of 50 g L-1 to prepare a precursor solution of dema-TfO-gel. 3DOM PI / dema-TfO-gel composite electrolyte membrane was then prepared by immersion of 3DOM PI into the precursor solution under vacuum at room temperature, followed by heating at 80 °C for gelation. Results and discussion The ionic conductivities of 3DOM PI / dema-TfO-gel composite electrolyte membrane, Nafion® and dema-TfO were investigated in a temperature range from 80 to 150 °C under non-humidified condition. Figure 1 shows the Arrhenius plots for three electrolytes. 3DOM PI / dema-TfO-gel composite electrolyte membrane showed three orders of magnitude higher ion conductivity than that of Nafion®. The activation energies of those electrolytes were estimated to be 16.1 kJ mol-1, 17.0 kJ mol-1 and 18.3 kJ mol-1, respectively. The similar activation energies for dema-TfO and 3DOM PI / dema-TfO-gel composite electrolyte membrane indicate that the ionic conduction mechanism of dema-TfO is maintaind in the composite electrolyte membrane. Figure 2 shows I-V and I-W curves of fuel cells using 3DOM PI / dema-TfO-gel composite and Nafion® membranes at 100 ºC under non-humidified condition. The open circuit voltage and maximum power density of fuel cell using the composite electrolyte membrane and Nafion® membrane were 0.658 V, 22.7 mW cm-2 and 0.592 V, 13.7 mW cm-2, respectively. The fuel cell using 3DOM PI / dema-TfO-gel composite electrolyte membrane showed about 1.7 times higher maximum power density than that of the fuel cell using Nafion® membrane. From this result, it can be said that 3DOM PI / dema-TfO-gel composite electrolyte membrane has advantage for fuel cell operation at intermediate temperature under non-humidified conditions. Figure 1

Double-stage chemical looping combustion combined with sorption enhanced natural gas steam reforming process for hydrogen and power cogeneration: Thermodynamic investigation

Chemical looping combustion (CLC) is a high efficiency and clean power generation system. With the principle of energy cascade utilization and methodology of system integration, a cogeneration system for hydrogen and power from natural gas was proposed by thermally coupling high-pressure (HP) and low-pressure (LP) double-stage CLC and sorption-enhanced steam reforming unit. The effects of operating parameters on the different performances indicators (including product gas concentration, H2 yield, and CH4 conversion) were investigated. The proposed novel process and a benchmark cogeneration process (i.e., natural gas CLC combustion unit along with sorption-enhanced steam reforming process) were both evaluated and compared from a thermodynamic point of view.Results show that increasing the FuelHP/C and FuelLP/C ratio (i.e., natural gas as fuel for HP-/LP-CLC divided by the feed molar flow for reformer ratio) leads significantly in improving the H2 yield and CH4 conversion. The addition of Ca-based sorbent and steam in reformer also has positive impacts on system performances. Under the conditions of FuelHP/C=0.42 and FuelLP/C=0.70, the novel process has a H2 concentration of 92%, H2 yield of 3.64, and CH4 conversion of 75%, while for the benchmark process, the H2 concentration is 89%, H2 yield is 3.55, and has a CH4 conversion of 69%. In addition, the optimized process minimizes exergy destruction and increases exergy efficiency over 6% when compared to the base-case system.

Investment planning and strategic management of sustainable systems for clean power generation: An ε-constraint based multi objective modelling approach

Biomass based energy production has been considered as a part of the solution to energy crisis, which is mainly caused by diminishing fossil fuel resources and environmental pollution from traditional fossil fuel based energy production systems. Therefore, it is important to design sustainable and effective systems for biomass based energy production to provide competitive advantage on fossil fuel resourced systems. This study develops a novel optimization model to aid investment planning and strategic management of biomass based clean power generation systems. The model integrates the location, capacity and technology decisions to find the optimal combination of bioenergy production systems to meet electricity demand of particular regions and accounts for multiple biomass types and power technologies. The modelling approach and data analysis are presented to outline the important characteristics of the problem for minimization of the supply chain cost and minimization of the greenhouse gas (GHG) emissions simultaneously. To handle the multi objective problem efficiently, an integrated approach based on fuzzy decision making and ε-constraint method is proposed and used, considering both sustainability aspects and uncertainties in the system parameters. The viability of the proposed approach is explored on a case study of İzmir region in Turkey. Different supply chain configuration alternatives are provided for the case study region considering various weights for objective functions representing relative importance of each objective. Corresponding supply chain performance measures in terms of total cost and GHG emissions are proposed and discussed for each configuration alternative. Further enviro-economic analyses denote that discounted investment cost and GHG emissions associated with energy production activities receive the biggest shares in the total cost and in the total GHG emissions, respectively. The government and private investors can employ the model and solution algorithm to design the most cost effective and environment friendly supply chain, to monitor the economic and environmental performance of the current biomass based supply chains and identify policies to support a viable, profitable and eco-friendly energy industry.

Vanadium-promoted Pt/CeO2 catalyst for water–gas shift reaction

Water–gas shift reaction has found new purpose and challenges due to its application in clean power generation systems based on fuel cells. It has been shown that the catalysts performance is dependent on both the metal phase and the nature of the support. In this contribution the modification of Pt/CeO2 catalyst with vanadium was exploited. Spectroscopic techniques revealed that distinct dispersed VOx species were generated onto the catalysts by using different vanadium loadings. The reduction of the catalysts and CO adsorption were monitored by infrared spectroscopy. It was found that the formation/decomposition of surface carbonates is affected by vanadium. Generation of multicoordinated carbonates is inhibited due to the decrease of the exposed cerium surface cations. The catalytic activity increased up to a vanadium surface density of 6 V atoms/nm2. Improvement in water–gas shift reaction kinetics is associated with the VOCe bonds.