Payback Period Of System Research Articles

Simultaneous sizing and scheduling optimization for farmhouse PV-battery systems with a multi-structured power system model

Increasing the proportion of photovoltaic (PV) power in energy supplies is effective in decarbonizing energy use in buildings. Optimization model analysis is essential for the design and operation of PV-battery systems. The optimization models developed in previous studies are mainly suitable for one specific scenario, and there is a lack of research on the suitability of different types of PV-battery systems applying in various scenarios. This study proposes a multi-structured power system optimization model for various rural PV-battery systems, compares the optimal sizing and performance of three commonly used PV-battery systems, and quantifies the impacts of system capacity on system performance. The optimization model was constructed using the improved simulated annealing algorithm with the self-consumption rate and economy as the objective functions, while the system node power balance was the constraint. The sensitivity analysis shows that increasing the PV capacity will reduce the PV self-consumption rate and payback period of the system while increasing the battery capacity will increase the PV self-consumption rate and payback period of the system. For every 1 kW·h increase in battery capacity, the payback period of the system increases by 0.5 years. The spatial optimization model simulates the operation strategies of typical farm houses in different climate zones in China, and obtains payback periods for rural PV-battery systems in different regions of China. This study provides a theoretical basis for capacity sizing for rural PV-battery systems. The payback period of farmhouse PV systems in Gansu, Ningxia, Qinghai, Tibet, and Yunnan regions is <7 years, while the payback period of farmhouse PV systems in Guangdong, Guangxi, Jiangsu, Zhejiang, and Chongqing regions is higher than 10 years.

Techno-economic evaluation and multi-objective optimization of a cogeneration system integrating solid oxide fuel cell with steam Rankine and supercritical carbon dioxide Brayton cycles

Developing highly efficient thermodynamic cycles is of great importance in the area of distributed energy system, there are still many non-negligible problems on feasibility assessment and performance evaluation in the application of some emerging technologies, especially involving the fuel cells and carbon dioxide power cycles. This study proposes a distributed heat and power cogeneration system composed of a solid oxide fuel cell, a gas turbine, a steam Rankine cycle, a supercritical carbon dioxide Brayton cycle, and a heat exchanger. The system mathematical model is constructed, and the investigation on system energy, exergy, economic, environmental, and techno-economic performance is performed to demonstrate the technology’s feasibility and applicability. The simulation results indicate that the system can provide 367.03 kW of power and 58.02 kW of heating at the design point, and the overall electrical, exergetic, and energy efficiencies are 68.38 %, 72.41 %, and 79.19 %. The total cost rate of system is achieved to be 11.62 $/h with the system carbon dioxide emission and payback period being 0.2829 kg/kWh and 10.87 year. It can be concluded from the sensitivity analysis that the increases of the compressor pressure ratio, fuel flow rate, and SOFC inlet temperature contribute to improving the system electrical efficiency, while the carbon dioxide emission and the payback period can be reduced. Finally, multi-objective optimization of the cogeneration system is further performed to provide a strategy of performance improvement for system designers and decision makers. The optimization result indicates that though the system carbon emission is increased by 0.25 %, the system payback period and levelized cost of energy are obtained to be 9.88 year and 0.2836 kg/kWh, which are decreased by 9.11 % and 1.47 % compared to the design point.

Application of heat pump assisted solar evacuated tube water heater operated within passive solar house in severe cold region

Replace coal with solar energy to low-cost heating in severe cold regions can improve indoor air quality, but indoor thermal comfort is not fully guaranteed. Therefore, a dual-source heat pump (DSHP) assisted solar evacuated tube water heater heating system was used in a house with sunspace to meet the heating stable and cleaning. TRNSYS model verified by experiment was used to research performance and economy of system. Results found the higher ambient temperature and solar radiation, the more heat from sunspace, solar assisted heat pump (SAHP) and solar water heater, conversely, the longer heating time of air-source heat pump (ASHP). During heating season, solar fraction of heating was 51.6 %, solar heat collection efficiency was 46.0 %, EER was 3.35, COP were 2.81 (ASHP) and 3.65 (SAHP). Heating time proportion of ASHP, SAHP and solar water heating were 15.0 %, 40.3 %, 44.7 %, ASHP heating was accounting for 22 % and 50 % in November and January. The system, sunspace supplied 16707.1, 2307.6 kW h of heat for room, solar effective heat collection was 10107.0 kW h, power consumption was 5164.7 kW h, CO2 emission reduction was 14232.4 kg. The dynamic payback period of system was 6.78 years, as will be shortened with support of clean energy heating policy.

Enhancing the productivity of pyramid solar still utilizing repurposed finishing pads as cost-effective porous material

The primary objective of the current research is to augment the potable water yield of the solar still (SS). This objective is achieved by integrating a used brushed refinishing pad (BRP) as a porous material (PM) in the absorber basin. This integration maximizes the wet surface area due to the pad's porous nature, thereby enhancing photothermal absorption, which is the process where a material absorbs light and converts it into heat. An experimental investigation was conducted to analyze the effect of porous materials in a rectangular pyramid solar still (RPSS) regarding potable water yield and feasibility. The results were compared with those of the conventional solar still (CSS), revealing a noteworthy enhancement in the production of potable water with RPSS-PM, showing a 47.7 % increase on day one and a 48.1 % increase on the second day with a mere 10 % rise in basin water temperatures. The energy efficiency of RPSS-PM improved significantly by about 9 % on both days compared to CSS. From an economic perspective, this system's payback period (PBP) was 5.2 months, compared to 6.1 months for the CSS. Furthermore, the cost per liter (CPL) of potable water produced by the RPSS-PM was 16.6 % lower than that of the CSS. This innovative approach holds great potential for effectively addressing challenges related to water scarcity.

Integrating insulated concrete form (ICF) with solar-driven reverse osmosis desalination for building integrated energy storage in cold climates

This research addresses the pressing global challenges of clean energy and water supplies, emphasizing the need for sustainable solutions for the building sector. The study integrates Reverse Osmosis (RO) systems with building energy systems, incorporating Solar Thermal Collectors (STC)/Photovoltaic Thermal (PVT), water-to-water heat pumps, and an Insulated Concrete Form (ICF) based building foundation wall thermal energy storage. It explores the effectiveness of four configurations—STC-ICF, STC-ICF-RO, PVT-ICF, and PVT-ICF-RO—using sensitivity analysis on collector area (25 % and 50 % increase) and weather data from four Canadian cities: Winnipeg, Toronto, Halifax, and Vancouver and two non-Canadian cities: Helsinki, Finland and Bergen, Norway. Key outcomes highlight the benefits of integrated RO scenarios, such as reduced ICF wall temperature, diminished unwanted heat in the cooling season, reduced RO pump consumption, and enhanced solar energy production. The STC-ICF-RO and PVT-ICF-RO systems achieved energy savings of 653 kWh and 131 kWh, respectively, compared to their non-integrated RO counterparts. Both systems also contributed to lowering CO2 production levels. The STC-ICF-RO system's payback period is 2 years, affirming its economic viability. Compared to the base system without ICF and RO integration, the STC-ICF-RO and PVT-ICF-RO configurations reduced energy consumption by 20 % and 32 %, respectively. The sensitivity analysis suggests potential system improvements under specific conditions, primarily when implemented in communities of buildings.

Performance enhancement by integrating concentrated inclined solar still for jaggery production

While unrefined sugar/jaggery consumption has various health benefits, unsustainable and inefficient production processes can negatively impact the environment and health. This study proposes a novel, sustainable approach to jaggery production using solar energy. The primary concentration is done in a VARS system, followed by the secondary concentration in a solar still field at low temperatures to maintain jaggery quality. The study presents experimental observations from the developed inclined solar still with external reflectors to preheat and concentrate the juice. In the absence of sun, the solar still field functions as an evaporation-condensation unit under auxiliary heating. By connecting several solar stills in series, the energy requirements from the PTC field can be reduced. The system is capable of producing a by product of distilled water, amounting to 169.78 kg/day, under varying solar radiation in April at Chennai, India. The overall energy efficiency of the system is 48.31 % under solar load, and 63.05 % under auxiliary heating. The system also leads to enhancement in CO2 mitigations, amounting to around 3134.7 tons of CO2 from dry bagasse combustion. Due to the added revenue from distilled water production, the system's payback period is reduced to as low as 4.89 years, depending on product selling price.

Performance Optimization and Techno-Economic Analysis of an Organic Rankine Cycle Powered by Solar Energy

Abstract To improve the performance of traditional solar power generation systems, a new solar organic Rankine cycle system that can generate electricity and heat is proposed. The system incorporates the separation-flash process, regenerator, and ejector to enhance its efficiency. The optimization of the working fluid, pinch point temperature difference, evaporator outlet dryness, flash dryness, and entrainment ratio is conducted to achieve optimal performance. Aiming at maximum exergy efficiency and minimum levelized energy cost, the operating parameters are further optimized using a multi-objective optimization algorithm. R245fa is the optimal working fluid for the system, offering maximum net output power and thermal efficiency. The optimal performance can be achieved when the pinch point temperature difference is 1 K, evaporator outlet dryness is 0.6, flash dryness is 0.44, and entrainment ratio is 0.29. Moreover, the photovoltaic subsystem can further increase the net output power and thermal efficiency by 15.52% and 15.45%, achieving a maximum net output power and thermal efficiency of 33.95 kW and 10.61%. Additionally, when the solar hot water temperature is 100 °C, pinch point temperature difference is 1.8 K, evaporator outlet dryness is 0.6, flash dryness is 0.65, and entrainment ratio is 0.16, the system can achieve the optimal state of both performance and economy, exhibiting an optimal exergy efficiency and levelized energy cost of 64.1% and 0.294 $/kWh, respectively. Finally, the payback period of system is 3.43 years, indicating the potential for significant economic benefits.

Industrial Park low-carbon energy system planning framework: Heat pump based energy conjugation between industry and buildings

The accelerating urbanization, rapid industrial development, and excessive consumption of fossil fuels pose survival challenges such as energy depletion and environmental degradation for humanity. In the context of industrial park development, constructing a low-carbon energy system, increasing the proportion of renewable energy, enhancing energy-level matching, and utilizing heat pumps for deep waste heat recovery are effective approaches to reduce fossil energy consumption and alleviate environmental pressures. Addressing issues such as diverse thermal flows in industrial sites, complex electricity-heat-cooling energy demands, and unclear industrial-building energy coupling mechanisms, this paper proposes a two-stage planning framework, comprising the following five steps: (1) constructing a waste heat utilization system centered around heat pumps, (2) establishing a mechanism for matching heat sources, equipment, and thermal sinks, (3) establishing an energy conversion model and energy quality quantification system, (4) optimizing waste heat utilization path allocation, and (5) conducting a system energy flow analysis. Case studies demonstrate that the proposed system achieves optimized matching of multiple heat sources and sinks in industrial and building scenarios through thermal integration, meeting diverse energy demands in the park, including electricity, cooling, and multi-grade heat. After coupling with traditional steam pipeline networks, the annual total cost and annual steam power consumption decrease by 33% and 39% respectively, with a waste heat contribution rate of up to 26% and a renewable energy penetration rate of up to 25%, and a waste heat recovery system payback period of 6 years. By establishing an energy quality quantification system and conducting multi-objective optimization considering losses and economic costs, this paper provides Pareto frontier solutions, offering references for engineering proposals. The proposed networked waste heat recovery system is characterized by low energy consumption and high economic efficiency, effectively integrating the energy characteristics of industrial parks and demonstrating engineering applicability.

Thermoeconomic analysis of a novel configuration of a biomass‐powered organic Rankine cycle for residential application with consideration the effect of battery energy storage

AbstractIn this article, the energy, exergy, and economic analysis of an organic Rankine cycle (ORC) system powered by biogas to provide electricity, heating, and cooling loads for a residential building in Munich city is investigated. Two methods have been proposed to meet the heating and cooling needs of the residential building. In the first method, heating and cooling needs are provided by a heat pump and mechanical refrigeration (System I), and in the second method, these needs are provided by a radiator and absorption refrigeration cycle (System II). In both modes of this system, the effects of battery energy storage (BES) have been analyzed for peak shaving. The working method of this research is that the residential building's electricity, heating, and cooling needs are calculated by Homer and Carrier software, respectively. Engineering equation solver software models the main local power generation system. A new method has been proposed to select the required number of units to meet the needs of the building with and without BES. The results showed that for System I with and without BES, 3 and 1 ORC units with a nominal power of 2 kW can meet all the needs of the building, respectively. In contrast, for System II, the number of 1 unit with 2 kW and 1 unit with 1 kW is needed to meet the energy needs of a residential building with and without BES. It can be concluded that heating and cooling the building with a radiator and absorption chiller cycle is more cost‐effective. The energy and exergy efficiency of ORC is reported as 11.3% and 65.7%, respectively, and the highest exergy destruction rate is related to the heater and boiler. From the economic point of view, the payback period of System II compared with System I is reduced from 18.4 to 5.66 years without using BES. With the use of BES, the payback period is reduced to 5.3 and 5.66 years, respectively. The lowest and highest electricity prices belong to System I with and without BES, which are 3.11 and 0.36 US$/kWh, respectively.

Energy, exergy, economic, and environmental (4E) analysis of SAHP water heaters in very cold climatic conditions

Solar-assisted heat pumps (SAHPs) are emerging as promising solutions for space/water heating. Compared to conventional air-source heat pumps (ASHPs), SAHPs show superior thermal performance in cold climates where outdoor air temperatures are below freezing most of the heating season. However, given the inherent variability of solar energy, SAHPs have poor thermal performance to meet the load requirements during periods of weak solar radiation. To enhance the reliability of SAHPs, an air-source evaporator can be integrated with a SAHP, forming a dual SAHP – ASHP system with better performance. In this research, the energy, exergy, environmental, and economic performance of a dual-source solar/air source heat pump, which provides hot water for a typical Canadian household, is investigated. The performance of the system is compared with a solar-assisted direct-expansion heat pump (DX-SAHP), an ASHP, and conventional gas/electric water heaters. A thoroughly validated mathematical model based on heat transfer and thermodynamics fundamentals is developed and implemented in MATLAB® coupled with the CoolProp® library, which gives the refrigerant's properties. Results highlight the superior performance of the dual-source heat pump, particularly in the summer, where it surpasses the DX-SAHP. Among the examined heat pump configurations, the dual-source heat pump demonstrates the lowest annual power consumption. The system attains the maximum monthly average COP of 3.94 and achieves a minimum of 2.4 during the severe winter season in Calgary, Alberta. Compared to a conventional ASHP, the energy consumption of the system was reduced by 25%. The second-law analysis shows that the ASHP obtains the highest monthly average exergy efficiencies, followed by the DX-SAHP and the dual-source heat pump. Furthermore, results show that the solar/air source heat pump water heater can reduce CO2 emissions by 1450 kg/year, while the system's payback period is 19 years.

On the issue of neutralizing carbon dioxide at processing coal in boilers of thermal power plants

The aim of the work is to predict 100% decarbonization of power plant's flue gases; to recover carbon from CO2 in in-situ mode; to extract valuable metals from ash; and to process ash and converter slag into stone casting. The novelty of the work is the development of a system for the integrated processing of coal in a smelter reactor by using high-temperature off gases in a boiler; carbon splitting according to the formula CO2 + 2Zn = 2ZnO + C, with the return of “C" to the system; sublimation of Zn from ZnO using a highly efficient counter-impacting jet method. Experiments carried out in a smelter have shown, the degree of reduction of germanium and zinc from slags ∼70%. The specific energy consumption is 2–3 times lower than in an acting analog. In a pessimistic scenario, the net profit of the system will be sufficient to purchase the missing electricity for the distillation unit: for the 60% carbonization of CO2, at the cost of electricity from wind turbines $46.3/MWh; in order to fully decarbonize CO2 - $31.8/MWh. The system's payback period will not exceed 6–8 years, with the expected net profit of $21,660,860/y.

Integration of biomass gasification and O2/H2 separation membranes for H2 production/separation with inherent CO2 capture: Techno-economic evaluation and artificial neural network based multi-objective optimization

This study delves into the thermodynamic and techno-economic intricacies of a cutting-edge hydrogen production system driven by biomass gasification. The quest for zero emissions propels our innovative integration of an oxygen transport membrane and a hydrogen separation membrane, strategically optimized through artificial intelligence. By situating the oxygen transport membrane near the gasifier, efficient heat transfer and oxygen production synergistically enhance the molar fraction of hydrogen in the syngas. Subsequent utilization of the hydrogen separation membrane, coupled with water gas shift reactors, not only facilitates hydrogen separation and purification but also achieves inherent carbon dioxide capture and storage. This novel membrane-based approach obviates the need for a conventional carbon capture system. Before optimization, our system exhibited a generation rate of approximately 10.29 tons of H2 per day. The levelized cost of production stands at $2.78 per kilogram of hydrogen, with power consumption estimated at 2.99 kWh/kg-H2. The calculated payback period is 9.96 years, considering a sales cost of $3.50 per kg-H2. Multi objective optimization reveals promising prospects, with a potential 26% reduction in power consumption in one scenario. An alternative scenario indicates a remarkable 20% decrease in the system's payback period, accompanied by an 8% dip in the levelized cost of H2. These findings underscore the economic and energy benefits of our membrane-integrated hydrogen production system.

Thermodynamic and exergo-economic analyses and multi-objective optimization of an innovative and efficient geothermal-assisted power and hydrogen cogeneration system

This paper presents an efficient integration of a flash-binary geothermal system with a double-pressure Kalina cycle and a proton exchange membrane electrolyzer unit. The main objective is to generate power and hydrogen simultaneously. A comprehensive thermodynamic analysis is conducted, encompassing mass, energy, and exergy assessments, along with an exergo-economic approach, to thoroughly evaluate system performance. The operation of the system is examined under varying conditions, and trends in the assessment indexes are predicted accordingly. The designed system achieves notable results, producing 1018 kW of net power and 0.1119 kg/h of hydrogen. The thermal and exergetic efficiencies are found to be 14.34 % and 45.59 %, respectively, based on the thermodynamic approach. From an economic perspective, the payback period is estimated to be 2.51 years, while the sum unit cost of products is calculated at 8.94 $/GJ. Furthermore, a detailed exergy analysis highlights that the Kalina cycle's condenser contributes the most to exergy destruction, accounting for approximately 129.6 kW. Through a parametric study, it is revealed that the pressure of the production well significantly influences the performance indicators, and the price of electricity sold has a substantial impact on the system's payback period and net present value. Moreover, the application of a multi-objective optimization strategy leads to the identification of the system's optimal state through an exergo-economic assessment. This optimization yields an exergy efficiency of around 49.75 % and a sum unit cost of products of 8.56 $/GJ.

An investigation and multi-criteria optimization of an innovative compressed air energy storage

Compressed air energy storage, a well-known technique for energy storage purposes on a large scale, has recently attracted substantial interest due to the development and long-term viability of smart grids. The current research focus on the design and thorough examination of a compressed air energy storage system utilizing a constant pressure tank. Various aspects, including energy, exergy, economic, and exergoeconomic factors, have been extensively investigated in this study. The goal of the referenced design is to maximize the utilization of air's energy stored in the tank, minimize exergy destruction, enhance production capacity and energy storage density, optimize system performance, and recover waste heat efficiently. Additionally, through the utilization of artificial neural networks and genetic algorithms, this study provides an analysis of optimal operational conditions, taking into account both thermodynamic and economic performance considerations. The referenced system, which stores 209 MWh of excess power from the grid as compressed air and heat throughout off-peak times and utilizes it to produce 137 MWh of electrical power during peak demand periods, demonstrates remarkable performance compared to the conventional storage methods. The findings indicate that the total electrical efficiency, round trip efficiency, and exergy round trip efficiency of the referenced system are equal to 65.63 %, 68.28 %, and 66.01 %, respectively. The total cost of the products of the system is 21.15 $/GJ, while exhibiting a value of 190.4 $/MWh for its levelized cost of electricity. The system's payback period is approximately 5.11 years, and the ultimate profit amounts to around $40 million.

Feasibility study of rooftop solar photovoltaic system for 33/11 kV primary substation at Al Suwairah

&lt;span&gt;This article presents an overview of the technical and financial feasibility analysis of integrating a photovoltaic (PV) source with the conventional power system to supply the auxiliary load at the Al Suwairah 33/11 kV primary substation (PSS) in Suhar, Sultanate of Oman. This study estimates the required electrical energy for the primary substation's auxiliary load. A method is implemented to utilize the available area in the primary substation for determining the solar photovoltaic system's capacity. PVSyst software is employed to determine the ideal system capacity. The proposed solar PV system's payback period and overall annual savings have been evaluated using a series of simulated analyses. The proposed PV can inject 172.5 MWh/year with an average performance ratio of 0.826. The economic evaluation by the photovoltaic system (PVSyst) considering the present auxiliary load at the Al Suwarah PSS has suggested a total payback period of 8.9 years which is quite feasible. The cost of power generated by the proposed system is 49.2% less than the cost of power supplied from the utility service provider.&lt;/span&gt;

Triple-objective MPSO of zeotropic-fluid solar ejector cycle integrated with cold storage tank based on techno-economic criteria

The current study objective is to optimize the integration of a solar ejector cycle with cold storage by applying a multi-objective modified particle swarm optimization technique. Various collector and working fluid's effects are evaluated on dynamic system behavior, which zeotropic fluid and parabolic trough collector have been the most effective choices. Hot and cold storage tanks are applied to overcome the instability of solar energy and ensure sustainable access to produced cold. Design parameter's optimum values are estimated through sensitivity analysis and genetic algorithm optimization which are decreased up to 70% compared to initial guesses. An artificial neural network is employed to train exergo-economic-environmental data which fed into the multi-objective modified particle swarm optimization algorithm. With using of cold storage tank, the system's coefficient of performance is enhanced up to three times compared to the ejector cycle at optimum design variable. By employing of parabolic trough collector, the system has its maximum coefficient of performance and exergy efficiency, as well as the minimum size of the ejector cycle and cold storage tank. The parabolic trough collector, air handling unit, and cold storage tank waste over 80% of the overall system's exergy. The payback period of system is estimated about 3.5 years.

Design and analysis of an innovative biomass-powered cogeneration system based on organic flash and supercritical carbon dioxide cycles

Technological advancements play a significant role in increasing energy demand. As societies progress, new technologies emerge, and they often require additional energy resources to operate. Therefore, it is important to design an efficient power system that can achieve higher performance. Additionally, considering the environmental aspect of the designed system is another crucial criterion for power system design. The current investigation proposes a renewable-based co-generation system for the production of power and heating load. The proposed system consists of several subsystems, including a municipal solid waste-driven gas turbine cycle, a supercritical CO2 cycle, and a high-temperature organic flash cycle. The system's performance is analyzed using energy, exergy, economic, and environmental approaches. Double-objective and triple-objective optimizations are applied to determine the optimum state of the system. The results indicate that the system can produce a net power of 8.21 MW and a heating load of 5.81 MW. This translates to energy and exergy efficiencies of 75.8 % and 41.21 % respectively, with a levelized CO2 emission of 0.518 t/kWh at the base-case. Furthermore, the system's payback period is estimated to be approximately 1.97 years, resulting in a net profit of 10.7 M$. In the parametric study, it was found that the gas turbine's inlet temperature has a significant impact on the system's performance indexes. Ultimately, the system achieves an exergy efficiency of 43.18 % and a levelized CO2 emission of 0.457 t/kWh at the optimum state. In conclusion, the proposed renewable-based co-generation system offers a promising solution for achieving higher performance, environmental sustainability, and economic viability in the design of efficient power systems. In conclusion, the proposed renewable-based co-generation system offers a promising solution for achieving higher performance, environmental sustainability, and economic viability in the design of efficient power systems.

Exergoeconomic and exergoenvironmental analysis and optimization of an integrated double-flash-binary geothermal system and dual-pressure ORC using zeotropic mixtures; multi-objective optimization

The current study focuses on proposing a double-flash geothermal system with a dual-pressure organic Rankine cycle that utilizes zeotropic mixtures. This system aims to harness the geothermal energy efficiently and sustainably. The performance of the system is evaluated using the exergy, exergoeconomic, and exergoenvironmental approaches, taking into account the utilization of different mass fractions of the R123/R142b mixture. The results of the analysis indicate that the designed system is capable of producing a net power output of 6336.04 kW with an exergetic efficiency of 66.70%. The payback period of the system is estimated to be 3.48 years, indicating its economic viability. Moreover, the electricity sale price has a substantial impact on the system's payback period and revenue, surpassing the influence of the geofluid purchase cost. Through the application of triple-objective optimization scenarios, the best optimum state of the system is determined to achieve a 66.96% exergetic efficiency, 3017.82 mPts/h exergoenvironmental impacts, and a payback period of 3.38 years. Furthermore, this state yields a revenue of 11.1 M$. Overall, the study highlights the potential of the proposed double-flash geothermal system with a dual-pressure organic Rankine cycle utilizing zeotropic mixtures for sustainable power generation.

Recurrent machine learning based optimization of an enhanced fuel cell in an efficient energy system: Proposal, and techno-environmental analysis

Real hybrid energy systems based on developing fuel cell (FC) technology are promising in addressing energy and environmental problems. Before looking at the research investigations, the earlier review studies are briefly examined to spot any gaps in the literature. In the present study, a novel scheme of fuel cells is introduced with higher efficiency and compatibility. The exhaust gases are then introduced to the transcritical carbon dioxide cycle for the production of more power and to extract heat from the intercoolers. The system is analyzed from the multiple objective functions aspect, and the net present value method is occupied for determining the system's payback period. The important design conditions are then put to the test to seek their effect on the overall system. The genetic algorithm is applied for the sake of optimization, and the efficiency is maximized while minimization of environmental impact and the cost of the system. The results indicate that maximum ηII and minimum of LCOP and ζ at the ideal point which equals to 73.8%, 0.24 $/MWh and 0.07 kg/kWh, can be reached correspondingly. Also, by changing the selling price of electricity from 0.19 $/kWh to 0.22 $/kWh, the net present value and the payback period reach 1329000 $ and 6.24 years, respectively.

Thermodynamic, economic and environmental investigations of a novel solar heat enhancing compressed air energy storage hybrid system and its energy release strategies

In this paper, a novel solar heat enhancing compressed air energy storage hybrid system is proposed, which mainly consist of three subsections: wind power sub-system, compressed air energy storage sub-system, and solar heat enhancing sub-system. The hybrid system driven by the excess electricity of wind power sub-system storages compressed air in an air storage tank and reserves compression heat with thermal storage medium from cylinder liner heat exchangers and inter-stage heat exchangers, and improves the thermal storage medium to a higher temperature by solar heat enhancing sub-system for a greater power output of the system. Three energy release strategies of the systems are proposed. And the thermodynamic performance of three release strategies is compared. The results show that Strategy 2 has a largest energy storage efficiency and energy storage density, which is 56.52%, 19.8 MJ/m3, respectively. In addition, energy, economic and environmental analyses are conducted. The payback period of system is 3.5 years. Compared with systems which are not combined with solar energy, the energy conversion efficiency of the system designed in this paper enhances by 25%, and the carbon emission reduces approximately by 42%. The payback period of system is also reduced. The influence of important parameters on system performance is explored using parametric analysis. The system can achieve a maximum energy storage efficiency when wind speed is 11 m/s. Meanwhile, energy storage efficiency and energy storage density all improve with the increase in environment pressure and solar irradiance, whereas these characteristics show divergent trends as the ambient temperature changes.