Multi-generation System Research Articles

Performance prediction and optimization of a hybrid renewable-energy-based multigeneration system using machine learning

This paper proposes an innovative multi-generation hybrid renewable energy system (HRES). The proposed HRES is optimized using the recently developed equilibrium optimizer algorithm and the efficacy of this algorithm is investigated by comparing the optimized sizing with results obtained from more traditional optimization algorithms, i.e., gray wolf optimizer, lightning search algorithm, and artificial bee colony. The results indicate that using the equilibrium optimizer algorithm outperforms conventional optimization algorithms in minimizing the levelized cost of electricity to $0.83 per kWh. This proves applicability of this modern optimization algorithm in improving HRES, which is a novelty of this research. Moreover, machine learning is implemented to predict the exergy efficiency of the proposed HRES, which provides insight into the performance and sustainability of the system. A thermodynamic database is established to train the machine learning model using secondary data. Using the multi-layer perceptron class, the exergy efficiency of the system is predicted; the trained model is able to deliver a prediction with an R-Squared value of 0.98. Thus, the appropriateness of machine learning algorithms in predicting the performance of HRES is verified. This research will, therefore, pave the way towards expanding real-world application of HRES's. This study provides insights into the optimization and economic and environmental benefits of hybrid renewable energy systems and inform policymakers on how to incentivize their implementation. As the study is performed for a specific location, exploring the feasibility of implementing the proposed system in other locations is recommended for future research.

Emergy analysis of applying a multi-generation system for building based on renewable energies for various weather conditions

Emergy analysis of applying a multi-generation system for building based on renewable energies for various weather conditions

Thermodynamic and exergoeconomic analysis of a combined cooling, desalination and power system for low-grade waste heat utilization

As a form of sustainable energy, low-grade waste heat has considerable amount to be recovered, but the energy utilization efficiency is still low. In this paper, a novel multi-generation system is proposed to utilize the low-grade waste heat efficiently and meet the needs for cooling, freshwater and power simultaneously, by integrating vapor compression refrigeration (VCR), humidification and dehumidification (HDH) desalination with transcritical organic Rankine cycle (TORC). Thermodynamic and exergoeconomic performances of the multi-generation system with five working fluids are evaluated. Parametric studies are conducted to identify the key operating parameters. Results show that the highest exergy efficiency ηex and the lowest average unit cost of products (AUCP) can be obtained by using R161, while the highest coefficient of performance (COPtot) belongs to R143a. The proportion of the vapor generator in the total exergy destruction is the largest, followed by the condenser. Higher net power output and freshwater production can be achieved by raising the vapor generation temperature and the ratio of mass flow rates of working fluid, and the corresponding ηex and AUCP are also improved. There is an optimal pressure for the lowest AUCP and the highest net power output and ηex. Performance comparison with systems from the literature is conducted as well.

Thermodynamic analysis of integrated ammonia fuel cells system for maritime application

This paper presents a novel multigeneration system that utilizes ammonia as the primary fuel for marine vessel applications. The system integrates and thermodynamically investigates various components, including solid oxide fuel cells (SOFC), gas turbines (GT), proton exchange membrane fuel cells (PEMFC), organic Rankine cycle (ORC), steam Rankine cycle (SRC), Kalina cycle (KC), and waste heat boiler (WHB). The primary objective of the integration strategy is to recover waste heat from the SOFC and harness the power generated by the PEMFC, resulting in improved thermal efficiency, reduced vessel startup time, and enhanced environmental sustainability. Mathematical models have been developed to facilitate the examination of the system’s thermodynamic performance. Comprehensive thermodynamic modeling employing energy and exergy analysis methods is employed to evaluate the effectiveness of both the proposed system and its subsystem. Moreover, the exergy destruction of all system components and integrated subsystems is quantified to provide a comprehensive understanding of their impact. The projected system exhibits an energy efficiency of 60.69% and an exergy efficiency of 57.50%. The waste heat recovery combined systems generate 1634.46 kW, accounting for 30.07% of the total power output of the integrated SOFC system. The performance of the system was analyzed through parametric studies, where different values of current density, distribution ratio (β) (from 0.1–0.4), and δ parameter (from 0–0.5) were examined. The findings revealed that increasing the current density led to a decrease in energy and exergy efficiency, despite an overall rise in the power output of the cogeneration system. Moreover, the waste heat boiler is capable of providing 1081 kg/h of superheated steam at 162 °C and 405 kPa to fulfill the heating requirements of marine lubricating oil, devices, and accommodation for seafarers on board the ship.

A multi-generation system based on geothermal driven: energy, exergy, economic and exergoenvironmental (4E) analysis for combined power, freshwater, hydrogen, oxygen, and heating production

A multi-generation system based on geothermal driven: energy, exergy, economic and exergoenvironmental (4E) analysis for combined power, freshwater, hydrogen, oxygen, and heating production

A solar based integrated gasification system for municipal plastic wastes to produce multiple useful outputs for environmental protection

A unique, solar based waste to energy type multigenerational system was developed and analyzed for producing ammonia, electricity and providing heating. Thermodynamic modeling and assessment studies were performed using energy and exergy analysis methods, and the performance of the developed system was evaluated through both energy and exergy efficiencies. In addition to this, the effect of varying operating conditions on the sub-systems' performance was investigated. In the present integrated system, a solar tower was used as a renewable energy-driven unit for producing steam. The plastics based municipal solid wastes were utilized as a gasification feedstock for the production of syngas, and the steam produced by the solar tower unit was utilized as gasification agent. A CO2 capture system was deployed where the solar tower was integrated to the gasification system for decreasing CO2 emissions of the system. Some parametric studies were performed to investigate how to improve the overall and subsystem energy and exergy efficiencies. The Rankine and Brayton cycles were also used for providing heat and electricity to the community.

Thermodynamic and economic analysis of a novel multi-generation system integrating solid oxide electrolysis cell and compressed air energy storage with SOFC-GT

Traditional gas-fired power plants are characterized by low efficiency and challenges in peak regulation. Even with the incorporation of compressed air energy storage, they still exhibit deficiencies in flexibility during peak load regulation. In this paper, we propose a novel hybrid power system based on gas-fired power plants, capable of producing electricity, heat, and hydrogen, while achieving flexible peak load regulation. The system is comprehensively evaluated using energy analysis, exergy analysis, and economic analysis. Results show that the total energy efficiency and exergy efficiency of this hybrid power system perform well, surpassing existing research on fuel cell-gas turbine systems. Among the subsystems, the fuel cell contributes the most to the total energy output of the hybrid system but also incurs the highest exergy losses, while the relative exergy losses of the water electrolysis and compressed air energy storage systems are relatively small. The configuration of dual energy storage systems enhances the flexibility in peak load regulation. Additionally, the proposed hybrid system exhibits low carbon emissions of 0.08 to 0.12 t/GJ. Considering factors such as discount rate, the initial investment cost can be recovered in 5.81 years, and the calculated net present value is 492,275.82 k$. Thus, the proposed scheme also possesses certain advantages in terms of economic feasibility.

Optimal design of a multi-generation system based on solar and geothermal energy integrated with multi-effect distillatory

In this study, an optimal system is designed to meet the needs of fresh water, heating, cooling and electricity. Four modes were simulated in MATLAB to provide the requirements of a hotel. The combined cooling, heating and power (CCHP) with multi-effect distillation through thermal vapor compression (MED-TVC) was used as the base mode. Geothermal wells (Geo) were employed to convert the renewable energy of the earth into heat and electricity. Also, the flat plate collectors (FPC), photovoltaic panels (PV) were utilized to gain the sun's radiant energy and convert it into heat and electricity. An organic Rankine cycle (ORC) has been used to convert the obtained geothermal energy into electricity. The genetic algorithm has been used for optimal design. In the case of base, base + Solar, base + Geo and base + Solar + Geo 21, 24, 24, 27 design parameters were considered respectively. The total annual cost (TAC), in which the effects of pollution were included, was considered as the objective function in the optimal design. As the innovation of this work, the use of geothermal and solar energy with desalination process combined with CCHP was mentioned, which was not done in previous works. For a case study, the annual needs of a hotel in Bandar Abbas, Hormozgan province, Iran were considered and the TAC obtained results for base, base + Solar, base + Geo and base + Solar + Geo modes were 1.2789×106$/year, 1.0950×106$/year, 5.8048×105$/year and 5.1436×105$/year , respectively. It was found that in the mode of using solar energy, geothermal energy and solar and geothermal energy, the objective function was improved 14.38%, 54.61% and 59.78%, respectively, comparing to the base mode.

Multi-variable investigation of an innovative multigeneration process based on geothermal energy and Allam power unit for yielding electric power, cooling, heating, and liquid CO2 with zero CO2 footprint

Multigeneration systems which use the produced carbon dioxide (CO2) are an appropriate solution for current global challenges in the energy sector, i.e., input fuel supply and environmental crisis. These techniques bring a situation for environmental protection in addition to sustainable production. This idea has been enriched in the current work using a clean and renewable energy source (geothermal energy) combined with an Allam power unit. Hence, this study presents a novel environmentally friendly multigeneration framework for the first time, where in addition to using a clean energy source, the produced CO2 is utilized as well. The components of this system include an Allam power unit, a geothermal power plant, a unit for producing cooling water, a geofluid Rankine cycle, a transcritical CO2 Rankine cycle, and a unit for generating power and heat. Electricity, heating, cooling, and liquid CO2 are other goods. The Aspen HYSYS program is used to model this system as it is studied from an exergy, energy, environmental, and economic perspective. The findings show that the suggested system's overall exergy and energy efficiencies are 50.33% and 53.41%, respectively. In addition, the Allam power unit is the most important irreversibility source, contributing to 37% of total exergy destruction. The levelized cost of energy is computed at 0.031 $/kWh. In addition, since this study uses an advanced design approach, its CO2 emission is zero. Thus, compared to earlier investigations, the suggested approach has been successful in enhancing the thermodynamic, economic, and environmental conclusions.

Development and assessment of an integrated underground gasification system for cleaner outputs

In this study, an underground coal gasification-based integrated multigenerational system is developed to generate multiple useful outputs, including electricity, heating, cooling, hydrogen, ethanol and sulfuric acid, for achieving cleaner applications and meeting the community needs. An application of this conceptually developed system is considered for a community as identified in Kutahya, Turkey. The proposed system is developed, modelled, and analyzed using thermodynamic-based, sensitive modeling tools and software packages. The effects of operating conditions such as oxygen, steam, as well as lignite feed rate, reference temperature, and gasifier temperature are investigated to evaluate the performance of the integrated underground coal gasification system. This research further aims to analyze the influence of varying system parameters and operational conditions on ethanol and hydrogen generation and increase energetic and exergetic efficiencies while reducing harmful product gas emissions. In this regard, many parametric studies of the underground coal-powered multigeneration system are conducted. According to the results, the integrated underground lignite gasification combined system's overall system energetic and exergetic efficiencies are found to be 68.8% and 66.56%, respectively.

Multi-variable assessment/optimization of a new two-source multigeneration system integrated with a solid oxide fuel cell

The integration of renewable energies can improve the thermodynamic performance and increase the popularity and commercialization of the energy production system. Moreover, the exploitation of renewables in the form of cascade energy systems with multigeneration goals has been able to overcome many restrictions and penalties. Meantime, fuel cells are efficient, carbon-free, and promising energy conversion technologies can act as a storage system and improve the sustainability of the energy system. In this article, a new two-source multigeneration system (TS/MGS) based on a biomass fuel and a geothermal source is introduced and evaluated. The upstream process of the considered system is based on a municipal solid waste (MSW)-gasification process-fueled solid oxide fuel cell (SOFC) stack. Besides, the downstream process is comprised of a geothermal source based on a triple-flash cycle, an ejection-based refrigeration process, a water electrolysis cycle, and a domestic water heater unit. The offered TS/MGS is capable of generating electricity, cooling load, heating load, and hydrogen fuel. Converting MSW to energy, in addition to producing efficient energy, can help waste management in urban communities. The operation of the offered TS/MGS was comprehensively investigated from thermodynamic, cost and environmental standpoints. Moreover, the optimal behavior of the TS/MGS is compared under two different decision-making approaches (based on a tri-objective optimization algorithm). Under the considered design parameters, the considered TS/MGS can provide about 3.92 MW of electric power, 2.19 MW of cooling load, ∼ 1.55 MW of heating load, and 0.1 g/s of hydrogen fuel to the consumer (at a thermal efficiency of 33.5% and an exergy efficiency of 61%). The values of total unit cost of products and levelized total carbon dioxide emissions were 0.0211 $/kWh and 0.21 kg/kWh. Under the TOPSIS decision-making approach, relatively more optimal exergoeconomic and environmental outcomes can be achieved compared to the LINMAP decision-making approach. However, the thermodynamic behavior under the LINMAP decision-making approach is more optimal than the TOPSIS decision-making approach.

Modeling and multi-objective optimization of a solar-boosted gas turbine cycle for green hydrogen production and potable water production

Global warming has caused lots of problems in recent years. Renewable energy can be a solution to this problem. In this research, a multigeneration system is modeled including a concentrated solar plan, Brayton cycle, Rankine cycle, organic Rankine cycle, absorption chiller, single-stage flash desalination, humidification, and dehumidification desalination, and PEM electrolyzer to produce power, cooling load, desalinated water, and hydrogen. The system is modeled in EES software. The results show that the system's overall energy and exergy efficiency is 46.6 % and 43.11 %, respectively. The total power production is 7533 kW after modeling the system in EES, by using a neural network, the data was transferred to MATLAB software. In MATLAB, multi-objective optimization was performed using the genetic algorithm to maximize exergy efficiency and minimize the cost rate. The optimized results show that the overall energy and exergy efficiencies are 46.1 % and 42.1 %, respectively. The total power production is 7628 kW.

Dynamic simulation of a triple-mode multi-generation system assisted by heat recovery and solar energy storage modules: Techno-economic optimization using machine learning approaches

Intelligent design and operation optimization allow energy systems to take advantage of the flexibility that multi-generation provides. This study proposes a basic solar-driven system integrated with thermal energy storage for round-the-clock energy harvesting. A modified configuration is then designed incorporating innovative multi-heat recovery approaches to increase the capacity and product diversity of the basic system. The modified system is able to cover vital urban utilities such as electricity, fresh water, cooling, and hydrogen throughout the day. To overcome the time-consuming procedure of dynamic techno-economic simulation as well as the limitation of commercial engineering equation solvers for tri-objective optimization, a deep learning approach is developed to reduce the computational complexity and improve the analysis accuracy. In this regard, the trained neural networks play an intermediary role in coupling the developed code with the MATLAB optimization toolbox. A comparison between the modified and conventional configurations indicates that implementing the multi-heat recovery approach results in a 29% increase in power generation while only increasing the overall system cost by 1.97%. From an economic perspective, the Sankey diagram depicts that the storage unit with a cost rate of 12.25 $/h accounts for 6.77% of the plant's cost rate, which enables the system to operate continuously. According to the sensitivity analysis and contour plots, the number of collectors significantly affects the total cost rate and fresh water production capacity while it has no tangible effect on the exergy efficiency.

Energetic, exergetic, exergoeconomic, environmental and sustainability analyses of a solar, geothermal and biomass based novel multi-generation system for production of power, hydrogen, heating, cooling and fresh water

The present study proposes and investigates a novel solar, geothermal and biomass based multi-generation system producing multiple outputs to generate power, hydrogen, heating, cooling, and fresh water. Parabolic trough solar collectors, a two stages Rankine cycle, two organic Rankine cycles, two absorption cooling systems, a gas turbine system, a once-through (OT) multi stage flash (MSF) desalination unit, a geothermal unit, a heat pump, an electrolyser and a thermal energy storage are used as sub-systems. The novelty of the system is to focus on novel sub-system design pattern for the proposed multi-generation system by using multiple energy inputs as there is a gap about those studies in the literature. The overall system performance is evaluated from energetic, exergetic, exergo-economic, environmental (4E) and sustainability points of view by using the EES software package. The total installed power and hydrogen mass flow rates are 7.76 MW and 3.52 kg/h, respectively. The energy and exergy efficiency values of the overall system are found to be 65.55% and 27.09%. Fresh water flow rate is calculated to be 6.16 kg/s with 10 stages. The overall unit product cost is determined to be 21,79 $/GJ and the overall social ecologic factor is calculated to be 1.37.

Performance assessment of a novel solar heliostat and digester-based multigeneration system with hydrogen production

Renewable energy sources have the potential to mitigate environmental risks by replacing fossil fuels. The aim of this study is firstly to consider the use of renewable energy sources to develop a new multigeneration system for meeting the energy demands of residential communities; secondly to analyze the presently developed system using mass, energy, entropy and exergy balance equations; and finally to assess the system's performance in terms of energy and exergy efficiencies. The system uniquely employs an ammonia-water-based triple-effect absorption system with other systems, such as an organic Rankine cycle, a Brayton cycle, and a steam turbine Rankine cycle. The Engineering Equation Solver (EES) software package is used to determine the thermodynamic properties and perform the aforementioned thermodynamic analyses through the constructed codes. The results of this study show that the steam Rankine, Brayton and organic Rankine cycles have energy efficiencies of 35.90%, 19.50%, and 11.49%, respectively, while the exergy analysis reveals that the steam Rankine, Brayton and organic Rankine cycles achieve the corresponding exergy efficiencies of 74.30%, 31.68%, and 23.23%, respectively. Additionally, the energetic and exergetic coefficients of performance (COPs) of the absorption cooling system are determined to be 1.60 and 0.32, respectively.

Multiobjective optimization and performance assessment of a PEM fuel cell-based energy system for multiple products

In this article, the optimal design of a novel multi-generation system for the production of electricity, cooling, heat and freshwater is discussed. In this system, a Proton exchange membrane fuel cell (PEM FC) is used to generate electricity, and the heat produced by it is absorbed by the Ejector Refrigeration Cycle (ERC) and used to provide cooling and heating capacity. A reverse osmosis (RO) desalination system is also used to supply freshwater. The esign variables in this research are operating temperature and pressure and current density of FC, as well as the operating pressure of the HRVG, evaporator, and condenser of the ERC system. In order to optimize the considered system, the exergy efficiency and total cost rate (TCR) of the system are considered as optimization objective functions. To this end, the genetic algorithm (GA) is used and the Pareto front is extracted. Also, three refrigerants R134a, R600 and R123 areused as ERC system refrigerant and their performance are evaluated. Finally, the optimal design point is selected. At the mentioned point, the exergy efficiency is 70.2% and the TCR of the system is 1.78 S/h.

Performance investigation of a solar/biomass based multi-generation system in pig farm

Intensive pig farm usually needs a large amount of energy, renewable energy supply system contributes to reducing the reliance of fossil fuel. In this study, load prediction of piggery considering different breeding characteristics and climate condition are carried out. An innovative solar/biomass hybrid multi-generation system combined with biomass combustor, ice thermal energy storage, absorption chiller, evacuated flat plate collector, photovoltaic panel and thermal energy storage is proposed. The operation strategy of following cooling demand is designed for proposed system, which considers the feature of high cooling load of piggery. The influences of key parameters on thermodynamic, economy and environment performances are investigated, thermodynamic operation performances of multi-generation system on different typical days are analyzed. Moreover, non-dominated sorted genetic algorithm is used for tri-objective optimization to obtain the optimal operating parameters and performances. Under the optimal condition, exergy and energy efficiency of integrated system are 19.05% and 53.59%, respectively. Compared with separation system, CO2 emission reduction ratio and dynamic investment payback period of multi-generation system are 70.39% and 5.12 years, respectively. In summary, this study offers a novel way for multiple energy coupling poly-generation system in intensive pig farm so as to obtain optimal performance in operation and scheduling.

4E and risk assessment of a novel integrated biomass driven polygeneration system based on integrated sCO2-ORC-AD-SOFC-SOEC-PEMFC-PEMEC

This study presents an innovative multi-generation system that produces valuable products such as power, fresh water, hydrogen, and oxygen by burning two different fuels in a biomass burner. Fresh water production in this system is done with the help of an adsorption desolation unit. The evaluations on this system have been done considering two types of biomass fuel from the four perspectives: energy, exergy, exergoeconomic, and exergoenvironmental analysis. In this study, the possible risks of the system have been evaluated using the numerical risk method and process stream index. In addition, by simulating the risks in the system with the help of PHAST software, a more accurate assessment of risk and accident modeling has been done. Furthermore, the integrated system is optimized with seven different optimization algorithms in two modes of four and five objectives. The results show that the polygeneration efficiency for municipal solid waste is 51.84% and for olive pits is 41.05%. The development of the exergoeconomic indicates that the total cost rate of the entire system for municipal solid waste and olive pits equals 0.181 US$/s and 0.156 US$/s, respectively. In evaluating the environmental effects of this system, the total ecological impact rate for municipal solid waste and olive pits equal 128.50 Pts/h and 119.70 Pts/h, respectively. The results obtained from the system risk assessment using the process stream index method show that the stream entering the turbine of one of the proposed organic Rankine cycles (stream 80) is the most dangerous stream among other steams. Also, the results obtained from the numerical risk analysis of the system show that the system will have a lower risk in the case of using municipal solid waste than in the case of using olive pits. Also, this system has been optimized with the help of seven different algorithms in two modes of four and five objectives. The objective functions used in this evaluation are polygeneration efficiency, total cost rate, total environmental impact rate, Levelized cost of electricity, and total risk. The optimization results show that the widespread use of two algorithms, multiobjective particle swarm optimization and Thompson sampling efficient multiobjective optimization, can create a higher percentage of improvement in the objective functions in both four and five objective modes.

Energy and environmental analyses of a sustainable multi-generation municipal solid waste-to-energy integrated system for hydrogen production

Municipal solid waste (MSW) management is a global challenge, and its efficient treatment is critical to reducing environmental pollution and greenhouse gas emissions. MSW-to-energy systems have emerged as a promising solution for sustainable waste management. Hydrogen production from MSW offers several benefits, including reducing reliance on fossil fuels, mitigating climate change, and promoting circular economy principles. The main aim of this study is to design and model an innovative integrated energy system to convert an MSW stream to hydrogen in a multi-generation system. In this regard, a gas turbine cycle, a proton exchange membrane, and a supercritical carbon dioxide Brayton cycle are integrated and produce hydrogen, power, oxygen, heated air, and heated water. Energy and environmental analyses are implemented on the system and its performance is multi-objectively optimized using the Taguchi technique and the signal to noise analysis. The contributions of the input variables on the system performance are evaluated using the analysis of variance. Municipal solid waste of 1.75 kg/min, inlet turbine temperature of 850 °C, and pressure ratio of 10 are recognized as the optimum conditions. The system produces 472 kW of power, 57.7 g/min of hydrogen, 458 g/min of oxygen, 480 m3/min of heated air, and 12.2 L/min of heated water in the optimum state. The system presents the efficiency of 79.3% and emits 8.32 g/kW.min of carbon dioxide.

Comparison of two newly suggested power, refrigeration, and hydrogen production, for moving towards sustainability schemes using improved solar-powered evolutionary algorithm optimization

In the third millennium, developing countries will confront significant environmental problems such as ozone depletion, global warming, the shortage of fossil resources, and greenhouse gas emissions. This research looked at a multigenerational system that can generate clean hydrogen, fresh water, electricity, heat, and cooling. The system's components include Rankine and Brayton cycles, an Organic Rankine Cycle (ORC), flash desalination, an Alkaline electrolyzer, and a solar heliostat. The proposed process has been compared for two different start-up modes with a combustion chamber and solar heliostat to compare renewable and fossil fuel sources. This research evaluated various characteristics, including turbine pressure, system efficiency, solar radiation, and isentropic efficiency. The energy and exergy efficiency of the proposed system were obtained at around 78.93% and 47.56%, respectively. Exergy study revealed that heat exchangers and alkaline electrolyzers had the greatest exergy destruction rates, at 78.93% and 47.56%, respectively. The suggested system produces 0.04663 kg/s of hydrogen. Results indicate that at the best operational conditions, the exergetic efficiency, power, and hydrogen generation of 56%, 6000 kW, and 1.28 kg/s is reached, respectively. Also, With a 15% improvement in the Brayton cycle's isentropic efficacy, the quantity of hydrogen produced increases from 0.040 kg/s to 0.0520 kg/s.