Power Production System Research Articles

Exergy and Exergoeconomic Analyses of a Combined Power Producing System including a Proton Exchange Membrane Fuel Cell and an Organic Rankine Cycle

Comprehensive exergy and exergoeconomic assessments are reported for a proposed power producing system, in which an organic Rankine cycle is employed to utilize the waste heat from the fuel cell stack. A complete mathematical model is presented for simulating the system performance while considering water management in the fuel cell. The simulation is performed for individual components of the fuel cell system, e.g., the compressor and humidifiers. A parametric study is conducted to evaluate the effects on the system’s thermodynamic and economic performance of parameters, such as the fuel cell operating pressure, current density, and turbine back pressure. The results show that an increase in the fuel cell operating pressure leads to a higher exergy efficiency and exergoeconomic factor for the overall system. In addition, it is observed that the overall exergy efficiency is 4.16% higher than the corresponding value that is obtained for the standalone fuel cell for the same value of fuel cell operating pressure. Furthermore, the results indicate that the compressor and condenser exhibit the worst exergoeconomic performance and that the exergoeconomic factor, the capital cost rate and the exergy destruction cost rate for the overall system are 40.8%, 27.21 $/h, and 39.49 $/h, respectively.

Energetic and exergetic analyses of a combined system consisting of a high-temperature polymer electrolyte membrane fuel cell and a thermoelectric generator with Thomson effect

A combined system model consisting of a high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC), a regenerator and a thermoelectric generator (TEG) is proposed, where the TEG is applied to harness the generated waste heat in the HT-PEMFC for extra electricity production. The TEG considers not only the Seebeck effect and Peltier effect but also the Thomson effect. The mathematical expressions of power output, energy efficiency, exergy destruction rate and exergy efficiency for the proposed system are derived. The energetic and exergetic performance characteristics for the whole system are revealed. The optimum operating ranges for some key performance parameters of the combined system are determined using the maximum power density as the objective function. The combined system maximum power density and its corresponding energy efficiency and exergy efficiency allow 19.1%, 12.4% and 12.6% higher than that of a stand-alone HT-PEMFC, while the exergy destruction rate density is only increased by 8.6%. The system performances are compared between the TEG with and without the Thomson effect. Moreover, the impacts of comprehensive parameters on the system performance characteristics are discussed. The obtained results are helpful in developing and designing such an actual combined system for efficient and clean power production.

Development of an integrated wind and PV system for ammonia and power production for a sustainable community

This paper proposes a new renewable energy based integrated system for sustainable communities. The proposed system is conceptually developed, modeled, simulated and analyzed using four software packages, including Engineering Equation Solver (EES), Eureqa, SAM and Aspen Plus. The proposed bi-generation system consists of wind turbines, PV units, electrolyzer, and an ammonia synthesis system. The main inputs to the system are nitrogen, water, solar irradiance, and wind. The freshwater is used as the feedstock for the electrolyzers for hydrogen production. The hydrogen produced by the system is then used as feedstock for the multistage ammonia synthesis system. The maximum overall energy and exergy efficiencies of the system are obtained as follows 75.8% and 73.6% at a wind speed of 8 m/s and a solar irradiance of 0 W/m2. However, at maximum power output from the solar field, the maximum exergy and energy efficiencies of the overall system are found to be 18.8% and 19.1%, respectively. The total exergy destruction at peak power and ammonia production is found to be 21.1 GW.

Systems analysis, design, and optimization of geothermal energy systems for power production and polygeneration: State-of-the-art and future challenges

Geothermal energy has significant potential to reduce fossil fuel consumptions and environmental impacts. To improve energy conversion efficiency of geothermal energy systems, numerous systems designs have been proposed and their optimization sought. At this point, it is worth reviewing current developed geothermal energy systems because understanding configurations and principles of basic and state-of-the-art technologies is important for developing advanced energy systems. A comprehensive review of the geothermal energy systems is carried out from the perspective of systems analysis, design, and optimization. Results illustrate that limited sets of parameters have been considered in most studies on design and optimization, though these studies provide great insight into specific designs. However, all influential factors have to be fully considered for practical applications. This study identifies and organizes influential factors for geothermal energy systems. In addition, critical analyses of studies on systems design and optimization are performed to determine limitations of current studies. As polygeneration systems produce various energy products (electricity, heat, and/or cooling), it might play key roles to maximize utilization of geothermal energy. Especially, polygeneration systems with binary technology, which can effectively produce electricity from moderate temperature geothermal resources, have significant potentials to enhance the overall performance. In this regard, the energy production strategy and technology selection are of significant importance to meet electric, heating, and cooling loads efficiently. To fill the knowledge gaps and to maximize geothermal energy utilization, this review proposes state-of-the-art multi-scale modeling and optimization framework.

A Novel Hybrid Evolutionary Data-Intelligence Algorithm for Irrigation and Power Production Management: Application to Multi-Purpose Reservoir Systems

Multi-purpose advanced systems are considered a complex problem in water resource management, and the use of data-intelligence methodologies in operating such systems provides major advantages for decision-makers. The current research is devoted to the implementation of hybrid novel meta-heuristic algorithms (e.g., the bat algorithm (BA) and particle swarm optimization (PSO) algorithm) to formulate multi-purpose systems for power production and irrigation supply. The proposed hybrid modelling method was applied for the multi-purpose reservoir system of Bhadra Dam, which is located in the state of Karnataka, India. The average monthly demand for irrigation is 142.14 (106 m3), and the amount of released water based on the new hybrid algorithm (NHA) is 141.25 (106 m3). Compared with the shark algorithm (SA), BA, weed algorithm (WA), PSO algorithm, and genetic algorithm (GA), the NHA decreased the computation time by 28%, 36%, 39%, 82%, and 88%, respectively, which represents an excellent enhancement result. The amount of released water based on the proposed hybrid method attains a more reliable index for the volumetric percentage and provides a more effective operation rule for supplying the irrigation demand. Additionally, the average demand for power production is 18.90 (106 kwh), whereas the NHA produces 18.09 (106 kwh) of power. Power production utilizing the NHA’s operation rule achieved a sufficient magnitude relative to that of stand-alone models, such as the BA, PSO, WA, SA, and GA. The excellent proficiency of the developed intelligence expert system is the result of the hybrid structure of the BA and PSO algorithm and the substitution of weaker solutions in each algorithm with better solutions from other algorithms. The main advantage of the proposed NHA is its ability to increase the diversity of solutions and hence avoid the worst possible solutions obtained using BA, that is, preventing a decrease in local optima. In addition, the NHA enhances the convergence rate obtained using the PSO algorithm. Hence, the proposed NHA as an intelligence model could contribute to providing reliable solutions for complex multi-purpose reservoir systems to optimize the operation rule for similar reservoir systems worldwide.

Two objective optimization for a new molten carbonate fuel cell based power producing system

A new molten carbonate fuel cell based combined cycle is proposed and analysed in detail from the viewpoints of exergoeconomics. The system utilizes methane as a fuel and makes use of liquid natural gas cooling effect as a heat sink. The system performance is simulated using the conservations of mass and energy as well as the exergy and cost balances. By considering different organic fluids for each stage of the cascade organic Rankine cycle, it is observed that the best performance is achieved with using toluene and n-pentane for the top and bottom organic Rankine cycles, respectively. It is observed that the highest and second highest exergy destructions occur in the after burner and fuel cell, respectively. Parametric studies are performed to specify the decision parameters prior to optimization process. Performance optimization is accomplished in order to minimize the sum of product cost (SUPC), case A; and to maximize the exergy efficiency, case C. The results show that the highest exergy efficiency is obtained as 67.96% and the lowest produced power unit cost is calculated as $32.09/GJ. Performing a multi objective optimization for the system resulted in an exergy efficiency of 66.56% and a SUPC of $33.57/GJ, case B.

Edge-Node-Aware Adaptive Data Processing Framework for Smart Grid

Smart grid is an autonomous power generation and production system, that includes various energy management sub-systems such as energy efficient resources, smart appliances, renewable energy resources and smart meters. It is a sensory-based power network that adopts digital technology to supply electricity to consumers and industries. Recently, it is observed that the grid infrastructure is rapidly transforming network topology towards green and eco-friendly computing. For this, edge-computing environment is being adopted to inter-connect distributed IoT nodes in peer-to-peer sequential order. With this approach, the grid ideally cope to green computing issues than traditional infrastructure, however, it faces certain data processing problems such as differentiating IoT and non-IoT data segments, storing data chunk with end of file (EOF) assurance, management of replica data segments and systematic analytics of edge node datasets. This produces operational latency at edges as well as onto segment reservoir and results delay in exchanging data segments at smart grid. This paper presents an Edge-node-aware framework that empowers nodes to intelligently process IoT and counterpart data segments, a portable plugin to identify EOF data chunk, reliable replica management system and hassle-free dataset analytics. The simulation results show that the proposed framework effectively manage data segments and store into smart grid reservoir.

A unique permeate gap membrane distillation system for combined fresh water and power production

The low-energy consumption process appears as one of the most dominant priority for sustainable fresh water production in recent years. Membrane distillation (MD) can be adapted effectively for water desalination due to lower operating temperature and ability to integrate to low grade waste heat. In this work, the feasibility of combined water and power production (CWP) is investigated by a unique permeate gap (PGMD) module. The permeate gap hydraulic pressure is controlled by connecting the permeate outlet to a sealed pressurized tank. Furthermore, the effect of permeate hydraulic pressure on the permeate flux and power density are explored experimentally. The maximum hydraulic pressure within this setup by polyvinylidene difluoride (PVDF) membrane was around 2 bar. It is demonstrated that under 80 °C and 15 °C of the fluid bulk temperatures in the inlet of hot and cold sides, respectively an optimum permeates hydraulic pressure of 1.1 bar, 12.5 kg/m2 h of permeate flux, 0.4 W/m2 of power density and 0.03 kWh/m3 of specific energy production (SEP) are achievable. This capacity of power generation has been accompanied by around 50% permeate flux reduction. The achieved results propose the system potential to produce higher SEP rate, via implementation of the advanced hydrophobic membranes with the higher-pressure resistance feature.

Comparative Analysis on Economic Viability of Independent Power Producing System in Nigeria

The aim of this research is to compare the economic benefits of various types of power generating technologies such as gas turbines, wind turbines and solar energy that is suitable for power producing plants in Nigeria. The study conducts economic assessment by developing a data-intensive spread-sheet-based model. The model estimates the unit cost of electricity generated by a 10MW capacity solar photovoltaic system (PV), Wind turbine and Gas Turbine. Comparison based on investment cost and capacity charge indicated that the levelized cost of electricity (LCOEsolar) by solar PV was found to be $0.05188 per kWh with a net present value of (-$3,520,003), (LCOEwind), by Wind turbine was found to be $0.0732per kWh or with a net present cost of (-$24,486,076), while (LCOEgas) by Gas turbine was found to be $0.07214 per kWh or with a net present value of ($11,813,136). Results obtained with reference to LCOE showed that solar PV has the lowest cost of power generation, followed by gas turbine, and then wind turbine. Consequently, comparison based on decision for economic and preferable energy to invest in as well as the annual return the investment is projected to generate indicated that the internal rate of return (IRR) for both solar PV and wind turbine was found to be negative with a simple payback period of 14 and 35 years respectively, while internal rate of return (IRR) for gas turbine was found to be 18.67% with 5 years payback period. Hence, result obtained with reference to IRR and SPBP showed that gas turbine is the most economic and preferable energy generating technology to invest in since it is projected to generate 18.67% annual return from the investment in a minimum of 5 years period as compared to solar PV and wind turbine. Although natural gas-based power generation has lower upfront costs but it is vulnerable to volatile fuel prices, whereas electricity generation from renewables has higher upfront costs but provides electricity at costs that are highly predictable.

Comparative Analysis on Economic Viability of Independent Power Producing System in Nigeria

The aim of this research is to compare the economic benefits of various types of power generating technologies such as gas turbines, wind turbines and solar energy that is suitable for power producing plants in Nigeria. The study conducts economic assessment by developing a data-intensive spread-sheet-based model. The model estimates the unit cost of electricity generated by a 10MW capacity solar photovoltaic system (PV), Wind turbine and Gas Turbine. Comparison based on investment cost and capacity charge indicated that the levelized cost of electricity (LCOEsolar) by solar PV was found to be $0.05188 per kWh with a net present value of (-$3,520,003), (LCOEwind), by Wind turbine was found to be $0.0732per kWh or with a net present cost of (-$24,486,076), while (LCOEgas) by Gas turbine was found to be $10.07214 per kWh or with a net present value of ($11,813,136). Results obtained with reference to LCOE showed that solar PV has the lowest cost of power generation, followed by gas turbine, and then wind turbine. Consequently, comparison based on decision for economic and preferable energy to invest in as well as the annual return the investment is projected to generate indicated that the internal rate of return (IRR) for both solar PV and wind turbine was found to be negative with a simple payback period of 14 and 35 years respectively, while internal rate of return (IRR) for gas turbine was found to be 18.67% with 5 years payback period. Hence, result obtained with reference to IRR and SPBP showed that gas turbine is the most economic and preferable energy generating technology to invest in since it is projected to generate 18.67% annual return from the investment in a minimum of 5 years period as compared to solar PV and wind turbine. Although natural gas-based power generation has lower upfront costs but it is vulnerable to volatile fuel prices, whereas electricity generation from renewables has higher upfront costs but provides electricity at costs that are highly predictable.

SWOT ANALYSIS OF ENERGY POLICY 2013 OF PAKISTAN

Pakistan is going through the worst energy crisis over a decade. The hide and seek of electricity have threatened lives in all sectors of Pakistan. To cope up with this issue, the National Power Policy 2013 of Pakistan was formulated. The main problems faced by the national energy sector are supply-demand gap, highly expensive generation of electricity from sustainable energy recourses, incompetent power production, transmission and distribution system, power and transmission losses, lack of production of electricity from renewable energy recourses, and misuse of electricity and electricity theft. The Strengths, Weaknesses, Opportunities, and Threats (SWOT) of the policy are discussed in this paper. The SWOT analysis of national power policy 2013 gives a better solution to the government regarding current and future energy needs. This paper presents the formulated actions such as comprehensive energy strategy; up-gradation of existing transmission and distribution systems; development of indigenous resources and energy mix systems; productions at low price electricity by low price fuels; electricity generation from renewable energy recourses; structural change in industry; subsidies to private sectors generation and compliance with environmental standard. This further enlightens the adoption of institutional and human capacity building by the energy sector for the betterment of the country.

Comparison of the solid oxide fuel cell system for micro CHP using natural gas with a system using a mixture of natural gas and hydrogen

Solid oxide fuel cell systems for combined heat and power production (SOFC μCHP) fueled by natural gas are attractive because of their high electrical and total efficiency even at small scale. The development of a hydrogen economy will increase the availability of distributed hydrogen as a pure gas. Alternatively, hydrogen may be blended with natural gas in the grid. This study investigates the performance of SOFC μCHP systems, while using a fuel varying from pure hydrogen to pure methane via mixtures of hydrogen and methane called Hythane. Flowsheet models of external as well as internal reforming fuel cell systems were developed in Cycle-Tempo simulation software. Results show that both the external as well as the internal reforming system can operated on all fuel gas compositions varying from pure hydrogen to pure methane, thus allowing for a transition towards a hydrogen economy via the mixing of hydrogen into the natural gas grid. Although the natural gas based systems have a higher electrical efficiency, the introduction of hydrogen into the gas leads to a higher total efficiency of the combined heat and power system. The addition of hydrogen into the fuel minimizes the problems of thermal stress and thermal shock associated with the use of methane in internal reforming fuel cell systems. The internal reforming system showed a higher performance compared to the external reforming system for all Hythane gas mixtures in terms of not only electrical efficiency but also in terms of thermal and total efficiency.

Control algorithms development for manufacturing and economic systems activity

The present study explores the efficiency of the manufacturing and economic entities and aims to improve the controlling mechanisms. Detailed analysis is proven to be required for the occurring manufacturing and economic processes in fuel and energy complex since the manufacturing ramp-up will inevitably entail environmental deterioration. A control algorithm for the activity of a regional manufacturing and economic entity of Samara oblast power grid was developed. This control algorithm allowed to perform an integrated analysis of the entity functioning, to study the internal and external connections between the resources, to design the control systems for the entity functioning, to forecast the development scenarios and suggest alternative options for the power grid activity. The developed control systems for the processes within the thermal power production and related systems contain adaptive capital investment share control systems. They differ from the known systems in the part of ensuring the sustainable decrease of the negative environmental impact while increasing the overall efficiency of thermal energy production in the regional power grid.

Techno‐Economic Analysis of a Coal Staged Conversion Polygeneration System for Power and Chemicals Production

AbstractSteady‐state process simulation and techno‐economic analysis of a pyrolysis‐based coal staged conversion polygeneration (CSCP) plant, integrated with wastewater biochemical treatment after phenol‐ammonia recovery, are studied using Aspen Plus software. Appropriate models for the proposed system are set up in detail. Furthermore, by optimization of a methanation unit, a conventional supercritical circulating fluidized bed (SCCFB) power plant with the same capacity is chosen for comparison. Simulation results reveal that system energy and exergy efficiency of the CSCP system can reach much higher values than those of a conventional SCCFB power plant. In conclusion, a CSCP plant will have practical and economic advantages in the near future.

Economic framework for net power density and levelized cost of electricity in pressure-retarded osmosis

Economic analysis is necessary to ascertain the practical viability of a pressure-retarded osmosis (PRO) system for power production, but high complexity and the lack of large scale data has limited such work. In this study, a simple yet powerful economic framework is developed to relate the lower bound of levelized cost of electricity (LCOE) to net power density. A set of simplifying assumptions are used to develop an inverse linear relationship between net power density and LCOE. While net power density can be inferred based on experimentally measured power density, LCOE can be used to judge the economic viability of the PRO system. The minimum required net power density for PRO system to achieve an LCOE of $0.074/kWh (the capacity-weighted average LCOE of solar PV in the U.S.) is found to be 56.4 W/m2. Using this framework, we revisit the commonly cited power density of 5 W/m2 to conclude that it is not economically viable because net power density would be even lower. Finally, we demonstrate that fundamental difference exists between power density and net power density, and as a result we recommend using net power density as a performance metric for PRO system.

Methodology of system dynamic approach for solar energy integration in district heating

District heating (DH) systems are in a great opportunity to increase renewable energy share in both, the heating and cooling sectors. All the possibilities for centralized heat productions allow the integration of multiple energy sources, including renewables such as biomass, heat pumps and solar energy. Nevertheless, DH system is a complex system with several aspects, which needs to be consider when planning different development scenarios. Therefore, research analyzes installation of PV and heat pump system for heat and power production in DH system by system dynamic approach. The system dynamic model was developed in order to forecast competitiveness of solar technology with other technical solutions.The heat tariff is used as a main indicator to evaluate the economic aspects of different energy source integration into the system. The heat tariff for solar power technology is predicted to become competitive with conventional technologies in 2025. The total capacity of the proposed solar system will reach 300 MW at the end of the simulation period in 2040.

Social cognitive optimization with tent map for combined heat and power economic dispatch

Combined heat and power economic dispatch (CHPED) problem is a sophisticated constrained nonlinear optimization problem in a heat and power production system for assigning heat and power production to minimize the production costs. To address this challenging problem, a novel social cognitive optimization algorithm with tent map (TSCO) is presented for solving the CHPED problem. To handle the equality constraints in heat and power balance constraints, adaptive constraints relaxing rule is adopted in constraint processing. The novelty of our work lies in the introduction of a new powerful TSCO algorithm to solve the CHPED issue. The effectiveness and superiority of the presented algorithm is validated by conducting 2 typical CHPED cases. The numerical results show that the proposed approach has better convergence speed and solution quality than all other existing state-of-the-art algorithms.

Power and methanol production from biomass combined with solar and wind energy: analysis and comparison

This study addresses the techno-economic analysis and comparison of systems for power and methanol production from biomass combined with solar and wind energy, from both technical and economic perspectives. Three different systems, based on Integrated Gasification Combined-Cycle (IGCC), Oxy-fuel combustion, and syngas gasification, were evaluated. The hydrogen required for methanol production comes from water electrolysis driven by solar and wind energy. In addition, the effect of location was discussed.

Assessment of linear solar concentrating technologies for Greek climate

The objective of this work is to compare and to evaluate the performance parabolic trough solar collector (PTC) and the linear Fresnel solar reflector (LFR) for the climate conditions of Athens, Greece. These collectors are examined under the same operating conditions and they are evaluated energetically, exergetically and financially. The analysis is conducted for all the year period using twelve typical days, one for every month. Performance curves for the solar systems are taken from the literature in order to estimate the collector performance for different operating temperature levels, solar irradiation level and solar angles. According to the final results, the mean yearly incident angle modifier for the PTC is about 83.73%, while for the LFR is 58.66%, at the examined climate conditions. It has been found that the mean yearly thermal efficiency at 350 °C is 52.25% for the PTC and 35.39% for the LFR, while the mean yearly electrical efficiency of the equivalent power production system is 16.11% with the PTC and 10.92% with the LFR. The simple payback period for process heat production was found close to 3–4 years, while for power production close to 8–9 years. Moreover, it is proved that the specific cost of the LFR has to be lower than 185 €/m2 in order to be a more attractive choice financially compared to the PTC.

Thermodynamic and economic analyses and optimization of a multi-generation system composed by a compressed air storage, solar dish collector, micro gas turbine, organic Rankine cycle, and desalination system

In this work, a hybrid system composed of a compressed air energy storage, a micro gas turbine, an organic Rankine cycle, a solar dish collector, and a multi effect distillation is presented as a combined power, heat, and fresh water production system. Energy and exergy analyses are applied to investigate thermodynamic performance of the system. The results show that the system consumes 278 kWh electricity and produces about 3.7 ton hot water during charging mode. Also, the system is capable of generating up to 523 kWh electrical energy and 2.5 ton potable water during the discharge period. The charge and the discharge period are 6.52 and 4 h respectively. Exergy analyses reveals that solar dish collector and combustion chamber are the major contributors for exergy destruction. Parametric analysis is employed to investigate the key parameters which have the major influence on the system performance. These parameters include cavern minimum and maximum pressures, gas turbine inlet temperature, dish collector aperture diameter, steam turbine inlet pressure, and desalinator feed water temperature. Optimization results show that round trip efficiency can rise from 65.2% to 70.35%, using upper limits of cavern minimum and maximum pressures. Besides, rising inlet temperature of gas turbine and restricting air cavern maximum and minimum pressures to their lower limits results in a 19.18% exergy efficiency improvement. Finally, economic analysis is performed to evaluate main cost and income sources of the system. As multi objective optimization shows, devising conditions that lead to produce more electrical energy improves system economic performance considerably.