Multi-generation System Research Articles

Comprehensive Exergoeconomic Analysis and Optimization of a Novel Zero-Carbon-Emission Multi-Generation System based on Carbon Dioxide Cycle

Comprehensive Exergoeconomic Analysis and Optimization of a Novel Zero-Carbon-Emission Multi-Generation System based on Carbon Dioxide Cycle

Thermodynamic feasibility evaluation of an innovative multigeneration system using biogas dry reforming integrated with a CCHP-desalination process

This work investigates a new method for developing systems that use a creative heat integration process that provides heating, cooling, fresh water and power. Specifically, the suggested framework operates by syngas obtained through the dry reforming process of biogas. Environmental considerations and decrease in thermodynamic irreversibility are main features of suggested system. The energy, exergy-related, environmental, and thermoeconomic properties of the suggested system are evaluated after it has been simulated using the Aspen HYSYS software. Results indicate 99,775.5 kW of net power, 10,880 kW of cooling power, and 141,800 kW of heating power. Also, the multigeneration scenario exhibits energy and exergy efficiencies of 58.06 % and 36.0 %, respectively. From the exergetic point of view, total exergy destruction rate is found at 493479 kW. The results of the environmental assessment show that the structure emits 0.27 kg of carbon dioxide per kWh while it is operating in the multigeneration mode. This value is contrasted with a reduction of 34.15 % in heat generation and a decrease of 69.11 % in power generation modes. According to the economic study, when the system functions under multigeneration conditions, the total equipment cost and the levelized cost of products are obtained at 59,536,233 $ and 0.029 $/kWh.

Assessment of a sustainable multigeneration system integrating supercritical CO2 Brayton cycle and LNG regasification: Thermodynamic and exergoeconomic evaluation

This study proposes a cost-effective multigeneration system that integrates a supercritical carbon dioxide (sCO2) power cycle with a liquefied natural gas (LNG) regasification process. The system aims to deliver electricity, cooling, heating, and hydrogen simultaneously. Utilizing the temperature difference between the sCO2 cycle and the LNG thermal sink, an ammonia-water-based absorption refrigeration cycle (ARC) recovers waste heat from the sCO2 power cycle, producing cooling. The elevated ammonia concentration at the ARC's condenser outlet is leveraged by a heat pump system for heating production. Concurrently, cold energy from LNG is used to recover latent heat from the condenser and heat rejected from the sCO2 power cycle, providing inputs for additional electrical power through an NG turbine. The system incorporates a PEM electrolyzer (PEME) for hydrogen production. A comprehensive examination, including energy, exergy, and exergoeconomic analyses, evaluates system performance. A sensitivity analysis illustrates the impacts of key parameters. In the baseline scenario, the system achieves energy and exergy efficiencies of 62.79% and 54.89%, with a low product unit cost of 11.35 ($/GJ). The system demonstrates substantial net power output (259.184 MW), cooling capacity (88.938 MW), heating capacity (2.839 MW), and hydrogen production (391.68 kg/h). This robust performance, coupled with cost-effectiveness, positions the proposed system as a versatile and impactful solution for sustainable and environmentally friendly energy applications.

Performance evaluation and optimization of a multigeneration hybrid system for power, hydrogen, cooling, and freshwater production from renewable sources

Designing a hybrid system emerges as a highly efficient strategy for augmenting the performance of renewable-based power plants, owing to their adaptability in integrating diverse subsystems. In this study, a new multigeneration system is introduced, showcasing its capability to concurrently generate power, hydrogen, cooling, and freshwater through a synergy of methanol-steam reforming, modified absorption refrigeration cycles, humidification-dehumidification, and multi-effect desalination. The operational foundation of the system is rooted in the harmonious integration of solar and geothermal energy sources. To comprehensively evaluate the proposed system's performance, a combination of exergy and economic analyses is employed. This research studies the impacts of varying key parameters on the system's operation. Notably, the water-to-methanol ratio is identified as the most influential variable affecting reformer performance, underscoring the pivotal role of reforming pressure. The estimated total fixed cost of the system stands at $4.039 million, with a calculated payback period of 6 years and a net present value of $3.454 million. Furthermore, in its optimized state, the system achieves an impressive exergy efficiency of 49.80 % and a unit product cost of $32.38/GJ. These findings unequivocally validate the feasibility and economic viability of the proposed hybrid renewable-based power generation system. In conclusion, the amalgamation of solar and geothermal energy, coupled with meticulous parameter optimization, substantiates the potential of this innovative system to serve as a sustainable and economically viable solution for power generation.

Thermodynamic performance evaluation of a novel solar-assisted multi-generation system driven by ammonia-fueled SOFC with anode outlet gas recirculation

The cracking of ammonia to produce hydrogen and nitrogen at high temperatures, without carbon dioxide emissions, has great potential for future energy development. Hence, a novel solar-assisted multi-generation system driven by ammonia-fueled SOFC with anode outlet gas recirculation is proposed and the thermodynamic models are constructed. Under the design conditions, the exergy efficiency, and primary energy saving rate of the novel system in summer are 47.83%, and 51.36%, respectively, while in winter, they are 50.52%, and 52.01%, respectively. Meanwhile, the thermodynamic performances of the new system and two reference systems are compared, in which the reference system 1 isn't coupled with a solar collector, and SOFC adopts an anode outlet gas recirculation layout, the reference system 2 has neither coupled solar collector nor anode outlet gas recirculation arrangement for SOFC. The results demonstrate that the anode outlet gas recirculation layout and coupling solar collectors in SOFC help to reduce the fuel consumption of the system. Moreover, the subsystem's exergy flow diagrams under the design condition reveal the exergy destruction of the components. And the impacts of key factors including SOFC operating temperature, fuel utilization rate, direct normal irradiance, and hydrogen recovery factor are analyzed.

Integrated renewable-based multi-generation system with environmental and economic optimization

Utilizing renewable reservoirs as a primary source of energy in power systems significantly mitigates environmental concerns. This approach, coupled with the integration of various subsystems, yields multiple products, thereby enhancing economic benefits. This paper introduces an innovative multi-generation system based on a gasifier-fed solid oxide fuel cell. In this system, waste heat recovery is achieved through a bespoke transcritical CO2 cycle, combined with a Kalina cycle and an organic Rankine cycle subsystem. Additionally, a proton membrane electrolyzer is employed to supply a reactor for ammonia production. A comprehensive analysis of this configuration is performed, employing thermodynamic, economic, and environmental assessment methodologies. Moreover, two multi-objective optimization strategies are implemented to determine the system's optimal operating conditions. The results demonstrate that the proposed system generates a net power output of 293.1 kW, provides cooling of 40.8 kW, produces hydrogen at a rate of 2.689 kg/h, and ammonia at a rate of 15.14 kg/h. The environmental and economic impacts of these products are quantified as an exergoenvironmental impact rate of 111.89 Pt/h and a cost rate of 11.77 $/h, resulting in an exergy efficiency of 27.59%. Furthermore, the system's financial feasibility is evident from its payback period of approximately 3.42 years and a net present value of 1.64 M$. The study also identifies that variations in the fuel cell's current density significantly influence the system's exergy performance and environmental footprint.

Zero energy building optimization for a residential complex with a new optimized cogeneration system for electricity, cooling, heating and freshwater production

In this research, a multi-generation system was proposed to meet the energy consumption of a 120-unit zero-energy residential complex with 100 m2 and 2 bedrooms in Sydney, Australia. To meet the heating and cooling demand of the residential complex, a compression chiller was used, and electrical energy was provided using the system's production power. The main goal of this research is to define a zero-energy building by providing the energy consumption of a residential complex with a solar system. Building Energy Optimization (BEopt) Software has been used for the process of simulating the residential complex and extracting the required load of the residential complex. The design of the load supply system of the residential complex was done using EES thermodynamic software. In this research, a large number of inputs have been used in different scenarios to optimize the residential complex, and the tool used in this research by all the modes introduced as inputs turns the problem into a multi-objective optimization problem. The results of the investigation of the residential complex showed that the amount of electricity consumption, heating, and cooling of the residential complex during the year is 36728, 133123, and 17,902 kWh, respectively. Also, by optimizing the energy consumption of the residential complex, it is possible to reduce CO2 emissions and prevent the increase in environmental pollution. The optimal results showed that the system in its most optimal state can reach an exergy efficiency of 25.18 % and a system cost rate of 46.6 $/h. The performance of the system in the city of Sydney showed that the system can produce 166,164 kWh of electricity, 467,945 kWh of heating, and 183,370 kWh of cooling in one year. Comparing the results of residential complex consumption load and system production showed that the proposed system can easily provide the residential complex consumption load throughout the year.

Energetic/exergetic study of Kalina and refrigeration bottoming cycles on different solar‐driven organic Rankine cycles

AbstractCombination of different power cycle scenarios is of prime importance in achieving maximum energy utilization from solar‐driven multigeneration systems. To fulfill such objective, the present article proposes a novel energy distribution system, leveraging a combination of direct‐fed organic Rankine cycle (ORC) and a bottom‐cycled arrangement of Kalina cycle system (KCS) and double‐effect absorption refrigeration cycle (DEARC) within a parabolic trough solar collector powered trigeneration system. The study explores three different ORC configurations: simple ORC; ORC equipped with internal heat exchanger (ORC‐IHE) and regenerative ORC (RORC). It is shown that although higher efficiencies are achievable from a larger portion of PTSC energy absorbed by the ORC, the ORC energy absorption is limited by ORC evaporator temperature differences, and there is unused energy that can be recovered by the KCS, based on the proposed energy system. The results indicate that the addition of bottoming KCS leads to a considerable increase in the exergy efficiency of ORC, ORC‐IHE and RORC‐based systems by 11.7%, 30.7% and 32.6%, respectively. The impact of different ORC configurations, key ORC parameters and various organic working fluids on the energetic/exergetic efficiencies is also examined to find the optimal configuration. In terms of overall energetic/exergetic efficiencies, the highest performance belongs to ORC (78.4%/30.4%) while the lowest energetic and exergetic efficiencies belong to ORC‐IHE and RORC, respectively (56.3% and 25.65%). On the basis of a comparative study with the available literature, these values are higher than what is already reported for similar solar‐driven multigeneration systems. Appropriate thermal match and lower exergy destruction in the KCS, and bottoming cycle arrangement of the DEARC are the main reasons for such enhanced performance. This research not only contributes valuable insights into efficient solar‐driven systems but also sets a new benchmark for performance metrics in the existing literature.

Evaluation & optimization of solar-fossil-fuel-based multi-generation system with energy storage

The integrated solar energy hybrid system combines decentralized, energy-efficient approaches to various energy production methods, offering benefits such as improved efficiency, emissions reduction, cost-effectiveness, sustainability and reliability. Thus, in this study, the optimal design of a solar-fossil-fuel-based combined cooling, heating, power and freshwater generation system is presented. The main prime movers for generating power and heat concurrently are considered gas engines, diesel engines, gas turbines, and solid oxide fuel cell. The suggested system configuration contains a prime mover, two chillers, auxiliary boiler, desalination unit, parabolic trough collectors, photovoltaic panels, proton exchange membrane electrolyzer, thermal and cooling storage tanks. The genetic algorithm is considered as the optimization method for determining the lowest total annual cost. Various decision parameters are considered in this assessment, including the prime mover's capacity and operating under 12 partial loads, the number of prime movers, mass flow rate of the solar parabolic trough collectors, the electric cooling ratio, operation of 16 partial loads for chillers (with each chiller accommodating 8 partial loads), capacity of the auxiliary boiler, thermal and cooling energy storage tank capacities, number of photovoltaic panels, and the isentropic efficiency of the high pressure pump. The total annual cost comprises economic, energy, and environmental factors. Notably, the current system permits the purchase or sale of electricity to the grid. The optimal results disclosed a reduction of 27.08 %, 13.83 %, and a 23.80 % in the total annual cost of the system including the gas engine compared to the system with solid oxide fuel cell, diesel engine, and gas turbine, respectively. Furthermore, the system with solid oxide fuel cell showed fuel energy savings ratios of 48.6 %, 38.26 %, and 24.46 %, respectively, compared to the system including gas turbine, gas engine, and diesel engine. Additionally, in comparison to systems with solid oxide fuel cell, diesel engine, and gas turbine, the exergy efficiency of the system with gas engine is higher approximately 40.31 %, 3.04 %, and 92.50 %, respectively. The optimum total annual cost and exergy efficiency were determined to be 1.6708 ×106 $/year and 42.08 %, respectively, for the system utilizing the gas engine. Eventually, the comparison and analysis of optimal results from energy, exergy, economic and environmental perspectives were presented.

Application of PCM in a Zero-Energy Building and Using a CCHP System Based on Geothermal Energy in Canada and the UAE

In this research, the optimization of energy consumption of zero-energy buildings using PCMs in the two study cities of Vancouver and Dubai and its energy supply with a multi-generation geothermal system is discussed. PCMs used in the walls and roofs of designed buildings are of two types, namely PCM (solid) and PCM (liquid). By optimizing the energy consumption of the residential complex in two study cities, it is finally possible to choose the best mode in optimal conditions to reduce energy consumption in the residential complex, reduce the costs of the residential complex, and reduce the environmental pollution. The results showed that the amount of electricity consumption, heating, and cooling of the residential complex during the year in the city of Vancouver is 8493.55, 7899.1, and 1083.97 kWh, respectively, and in the city of Dubai, the values are 9572.1, 8.99, and 18,845.44 kW, respectively. Also, by optimizing the energy consumption of residential complexes in Vancouver and Dubai, it is possible to reduce CO2 emissions by 2129.7 and 2773.2 kg/year, respectively. The electricity consumption of the residential complex in Dubai is 11.26% and the carbon dioxide emission is 23.20% more. In the end, a multi-generation system is proposed to meet the energy consumption of a six-unit zero-energy residential complex with 120 m2 and two bedrooms in Vancouver, Canada. By setting up the study system in the city of Vancouver, 237,364.6 kWh of electricity, 425,959.4 kWh of heating, and 304,732.8 kWh of electricity can be produced in one year. According to the investigation, the geothermal system can easily provide the energy consumption required by residential buildings.

Solar-driven multi-generation system: Thermoeconomic and environmental optimization for power, cooling, and liquefied hydrogen production

This study explores the utilization of solar energy to power an integrated energy system that includes power, cooling, and liquefied hydrogen production. The proposed system undergoes a thorough evaluation from three essential perspectives: thermodynamics, economics, and environmental. Additionally, a sensitivity analysis is conducted to gain insights into the operational dynamics. Furthermore, an optimization process is implemented to attain the optimal sate. The findings reveal a net power production of 13.45 MW, a cooling production rate of 3.41 MW, and a liquefied hydrogen production rate of 27.3 kg/h. These production rates are associated with cost and exergoenvironmental impact rates of 1280.9 $/h and 122.04 Pt/h, respectively, resulting in a payback period of 6.04 years at the baseline. An increase in the electrolyzer input power from 5 % to 15 % of the total power production enhances the liquefied hydrogen production from 14.84 to 41.2 kg/h. However, this increment leads to a reduction in exergy efficiency from 9.27 % to 8.78 % due to a decrement in net power. The optimal state yields net power and liquefied hydrogen rates of 14.03 MW and 33.53 kg/h, respectively. This state results in an increased products cost rate of 1301.85 $/h but reduces the payback period to 5.77 years.

4E comparison and optimization of natural gas or solar-powered combined gas turbine cycle and inverse Brayton cycle in hydrogen and freshwater multi-generation systems

Replacing fossil fuel-based systems with renewable energy resources is a method to enhance the performance of the layout and reduce environmental pollution. The gas turbine cycle (GTC) is one of the main sources of consuming natural gas (NG) in a combustion chamber (CC). In the present study, the theoretical performance of a 500 kW CC-based gas turbine cycle is improved by replacing the NG CC with a solar power tower (SPT) and converting it into a multi-generation system. The waste heat recovery of GTC is done by a hot water unit and an inverse Brayton cycle (IBC), and then the energy of the heat rejection stage of IBC and the exhausted gas of the system is recovered by a thermoelectric generator (TEG) and an absorption chiller. Afterwards, the produced power of IBC and TEG is fed to a proton exchange membrane electrolyzer and a reverse osmosis desalination unit for hydrogen and potable water outputs. 4E optimization shows that the exergy efficiencies of the CC-based system (Configuration 1) and the SPT-based system (Configuration 2) are equal to 37.2% and 9.12%, respectively. However, the economic performance of Configuration 2 is better. In this case, the total cost rate and unit cost of multi-generation in Configuration 2 are 142.1 $/h and 15.14 $/GJ in comparison with 145.5 $/h and 31.58 $/GJ for Configuration 1. In addition, the fossil fuel consumption and emissions of Configuration 2 are zero, while the fuel and environmental cost rate make up 54.76% of the total cost rate of Configuration 1.

A fuel gas waste heat recovery-based multigeneration plant integrated with a LNG cold energy process, a water desalination unit, and a CO2 separation process

Development of the multigeneration plants based on the simultaneous production of water and energy can solve many of the current problems of these two major fields. In addition, the integration of fossil power plants with waste heat recovery processes in order to prevent the release of pollutants in the environment can simultaneously cover the environmental and thermodynamic improvements. Besides, the addition of a carbon dioxide (CO2) capturing cycles with such plants is a key issue towards a sustainable environment. Accordingly, a novel waste heat recovery-based multigeneration plant integrated with a carbon dioxide separation/liquefaction cycle is proposed and investigated under multi-variable assessments (energy/exergy, financial, and environmental). The offered multigeneration system is able to generate various beneficial outputs (electricity, liquefied CO2 (L-CO2), natural gas (NG), and freshwater). In the offered system, the liquified natural gas (LNG) cold energy is used to carry out condensation processes, which is a relatively new idea. Based on the results, the outputs rates of net power, NG, L-CO2, and water were determined to be approximately 42.72 MW and 18.01E+03, 612 and 3.56E+03 kmol/h, respectively. Moreover, the multigeneration plant was efficient about 32.08% and 87.72%, respectively, in terms of energy and exergy. Economic estimates indicated that the unit product costs of electricity and liquefied carbon dioxide production, respectively, were around 0.0466 USD per kWh and 0.0728 USD per kg-CO2. Finally, the total released CO2 was about 0.034 kg per kWh. According to a comprehensive comparison, the offered multigeneration plant can provide superior environmental, thermodynamic, and economic performances compared to similar plants. Moreover, there was no need to purchase electricity from the grid.

An innovative process design and multi-criteria study/optimization of a biomass digestion-supercritical carbon dioxide scenario toward boosting a geothermal-driven cogeneration system for power and heat

In the pursuit of enhancing both sustainability and energy density in low-temperature, renewable energy-based cycles, the integration of high-temperature renewable streams is considered a key objective in multigenerational scenarios that focus on renewable energy. This integration is recognized for its ability to reduce irreversibility and facilitate the development of eco-friendly designs. Consequently, the development, analysis, and optimization of an innovative multigenerational system, which utilizes a combination of biomass feedstock and geothermal energy resources, are the aims of this study. In this system, the performance of a geothermal-driven subsystem is significantly enhanced by a biomass-fueled subsystem, contributing to a more efficient overall system. This enhancement involves the integration of biomass digestion with a supercritical CO2 process. The energetic flue gas generated in this process is then utilized to enhance the enthalpy level of geothermal water through a dual-flash process. This process includes an advanced Kalina cycle, enabling combined cooling, heating, and power generation. The feasibility of this structure is examined through a comprehensive analysis that encompasses thermodynamic and economic considerations. The performance optimization is targeted using the Multi-Objective Grey Wolf Optimization technique, and within this framework, two multi-criteria optimization scenarios are defined based on power and heat output, exergy efficiency, and the system's profitability. Furthermore, a detailed sensitivity analysis is conducted, where the impact of variations in five key decision parameters is evaluated. It is indicated by the results that 500.8 kW of power, 900.2 kW of heating, and 4.931 kW of cooling can be provided by the system, which also achieves an exergetic efficiency of 23.08 % and a payback period of 6.87 years.

A low-carbon multigeneration system based on a solar collector unit, a bio waste gasification process and a water harvesting unit

Abstract In this study, we introduce and examine a novel multigeneration cycle powered by low-carbon bio-waste and integrated with a solar thermal component. This system is designed to convert sewage sludge into a variety of useful products. The cycle utilizes anaerobic digestion and gasification to produce biogas and syngas. Additionally, it incorporates processes for generating water and hydrogen energy, utilizing the atmospheric water harvesting unit and water/gas shift reaction, sequentially. The system employs a Rankine cycle, a Brayton cycle and two organic Rankine cycles (ORCs) for electricity generation. A significant portion of the heat and electricity in this proposed project is sourced from a waste heat recovery system. This innovative project not only presents a new structure and configuration for product generation but also addresses energy, water and environmental challenges concurrently. The energy system’s performance has been thoroughly assessed in terms of thermodynamics, environmental impact and economic feasibility. The proposed plant is capable of producing an estimated 17 920 kW of electric power, 3207.6 kg/h of hydrogen energy and 5.14 × 10−3 L/s of freshwater. Under these design conditions, the energy and exergy efficiencies of the system were determined to be 35.76% and 40.49%, respectively. Additionally, the exergy sustainability factor, the levelized total emitted carbon dioxide and the unit cost of total products were characterized to be 52.28%, 0.2145 kg per kWh and 0.05219 $ per kWh, respectively.

Comprehensive analysis and optimization of a low-carbon multi-generation system driven by municipal solid waste and solar thermal energy integrated with a microbial fuel cell

Abstract In this article, a novel multi-generation plant is addressed and assessed from the energy, exergy, exergoenvironmental and exergoeconomic points of view. The multi-generation plant is composed of two main units: one unit for energy production and another unit for carbon capture and methanol synthesis. Biomass fuel, solar energy and seawater are the main nutrients in the plant. Steam, Brayton, organic Rankine and Kalina cycles have been employed to generate electricity. A linear Fresnel collector-driven solar farm is considered as an auxiliary heat source. In addition, an integrated desalination unit based on a multi-effect desalination unit, a microbial fuel cell and a reverse osmosis unit has been installed in the multi-generation plant. The proposed structure for the offered multi-generation plant is designed under a new configuration and layout that had not been reported in the publications. From the outcomes, the multi-generation plant can produce 69.6 MW of net electricity, 0.53 kg/s of methanol, 0.81 kg/s of oxygen gas, 73.8 kg/s of fresh water and ~0.015 kg/s of hydrogen gas. Under such performance, the offered multi-generation plant can be 51.72 and 27.5% efficient from the points of view of energy and exergy, respectively. Further, the total cost rate and environmental impact of the plant are ~3378 US$/h and 294.1 mPts/s, respectively. A comparative analysis is developed to exhibit the superiority of the planned multi-generation plant. A five-objective optimization is also developed to achieve the optimum design data and outcomes of the plant.

A comprehensive analysis and multi-objective optimization of a sustainable production system based on renewable energies

The adoption and promotion of clean and sustainable energy sources bring about significant benefits to the environment, economy, and society, both in the present and for future generations. This study introduces a pioneering solar-wind biomass multi-generation system, aimed at facilitating the sustainable production of electricity, fresh water, hydrogen, and heating. This system provides a comprehensive evaluation of the influence of environmental conditions and design factors on system efficiency, taking into account the crucial aspects of energy, exergy, economy, and environment (4E). Additionally, a meticulous sensitivity analysis is conducted to identify and prioritize key decision variables that exert the most significant impact on the overall system. Ultimately, the multi-objective optimization is conducted by taking into account various priorities in four distinct scenarios. This approach enables the simultaneous or individual optimization of the system's useful objective functions in relation to the total cost rate. Subsequently, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method is employed to determine the ideal point that best fulfills the optimization criteria. By employing TOPSIS, this study aims to provide a robust and systematic decision-making framework for scenario selection in various domains. By evaluating the optimal points across various scenarios, the first scenario yields the most favorable outcomes in terms of the system's useful outputs. These include an exergy efficiency of 19.63 %, hydrogen production of 11.07 kg/h, fresh water production of 34.16 kg/s, and a total cost rate amounting to 213.80 $/h. Additionally, a considerable decrease of 22.65 % in the total cost rate is noted at the optimal point.

A new system for hydrogen and methane production with post-combustion amine-based carbon capturing option for better sustainability

In the present paper, a novel integrated multigeneration system is developed to produce hydrogen and methane simultaneously driven by a renewable energy source. Besides, this system captures carbon dioxide from a coal power plant through an amine-based absorber and stripper. Also, solar energy is set to provide the heat required for the system. The generated power is used for different purposes from the coupled Brayton-Rankine combined cycle. There are two methods of iron-based chemical looping with four reactors and steam methane reforming, which are integrated into the system to produce hydrogen and store it at the same time. After gaining enough heat and electricity from mixing and heating the CO2 and H2, the methane is then produced, stored or used for different purposes during the system. This system primarily utilizes solar energy to produce the required heat of the system which is suitable for sunny locations. The governing and balance equations are employed to determine the energy and exergy efficiencies, methane and hydrogen production rates and carbon capture percentage as 48 %, 32 %, 0.0048 kg/s and 0.004 kg/s and 80 % carbon capturing.

Dynamic response characteristics and economic analyses of two solar-assisted multi-generation systems

Efficient use of solar energy can alleviate the depletion of fossil energy and global warming. In this paper, two solar-aided combined cooling, heating and power systems are proposed and dynamically modeled. The main difference between the two systems is whether the solar energy is stored. A rotor speed-temperature-fuel control system is established, which is suitable for both systems. A control system for solar heat collection process is developed. Energy, exergy and techno-economic analyses are carried out to evaluate the thermodynamic and economic performances. The dynamic responses under direct normal irradiation perturbation and load perturbation are also investigated. The result shows that compared with the system without energy storage, the system with energy storage has higher primary energy utilization rate, exergy efficiency and fuel saving rate, but the economic performance is poorer. The rotor speed-temperature-fuel control system can guarantee a short equilibrium time and a small overshoot for power generation process. When electrical load disturbance occurs, the stabilization times of the output power, cooling energy supply and thermal energy supply are 30 s, 675 s and 770 s, respectively. Under the regulation of the solar heat collection control system, the maximum overshoot of the outlet thermal oil temperature of the parabolic trough solar collector is 2.6 % with a stabilization time of 83 s when the direct normal irradiation step disturbance occurs.

Sustainable development and multi-aspect analysis of a novel polygeneration system using biogas upgrading and LNG regasification processes, producing power, heating, fresh water and liquid CO2

Considering biogas upgrading to feed energy systems and its significant impact on the biogas energy density, a novel polygeneration system utilizing biogas from landfill waste is designed, simulated, and studied in this paper. The primary innovation is to design a biogas upgrading technology for a novel multigeneration system using a thermal matching approach. This system is capable of simultaneously generating power, providing heating, producing fresh water, and extracting liquid carbon dioxide in an environmentally sustainable manner, thus resulting in reduced environmental impacts. For this purpose, a cryogenic separation system based on liquefied natural gas cold utilization is employed for biogas upgrading and biomethane separation. The proposed process also consists of a Kalina cycle, an organic Rankine cycle, a multi-effect desalination technology, and a heating provider unit. This system is simulated within the Aspen HYSYS software and is undergone a comprehensive analysis from the viewpoints of energy, exergy, environmental, and economic. The results indicate that the proposed structure achieves energy and exergy efficiencies of 80.91% and 43.76%, respectively. Environmental assessment reveals that the emission intensity is 90.43% lower in polygeneration mode compared to power generation mode, and the system’s net emission is equal to 23,041.51 kg/h. The economic evaluation demonstrates that the total unit cost of products is minimized in polygeneration operation (1.84 $/GJ), while it is highest in power generation condition (7.564 $/GJ). The investigations show that when a system is modified from a single generation to polygeneration, all thermodynamic, economic, and environmental indicators face an improvement.