Combined Cooling, Heating And Power Research Articles

Experimental investigation of gamma Stirling refrigerator to convert thermal to cooling energy utilizing different gases

In recent years, combined cooling, heat, and power (CCHP) systems have attracted increasing attention worldwide. Owing to their advantages of high overall thermal efficiency, fuel flexibility, low noise and vibration, and low emissions, Stirling engines are promising candidates for micro-CCHP systems. The Stirling Cycle is one of the thermodynamic cycles that is close to the Carnot cycle in terms of theory, and these advantages cause to use of Stirling engines in wide industries. The main objective of this research is an experimental investigation of the Stirling Gamma engine for refrigeration. In this investigation, the effect of working fluid air and Helium, the operating pressure of the working fluid, and dynamo power on refrigeration generation have been investigated. Results show that using air fluid with a power of 520.8 Watts and operating pressure of 3 bar in 10 minutes could reach to the temperature of -23° Celsius and using Helium fluid with a power of 420 Watts and operating pressure of 6 bar and in 10 minutes could reach to temperature -21° Celsius. In the experimental implementation, it has been tried to reach lower than 10 % error results in various parts of the engine like insulation, leaking, belt lash, and measurement devices. Results show that increasing power supply, mean gas pressure, power supply turning on duration, and using fluids such as air and helium are effective in refrigeration. Also, by using helium instead of air, the amount of cooling output and engine output power decreases while engine efficiency increases.

Exergoeconomic analysis and multi-objective optimization of a CCHP system based on SOFC/GT and transcritical CO2 power/refrigeration cycles

A CCHP (Combined Cooling, Heating and Power) system based on SOFC/GT (Solid Oxide Fuel Cell/Gas Turbine) and transcritical CO2 power/refrigeration cycles is proposed to efficiently provide cooling, heating and power for users under the principle of energy cascade utilization. The energy, exergy and exergoeconomic analysis is conducted to assess the effects of key parameters on the system’s thermal-economic performance. The simulation results demonstrate that the cooling, heating and net electricity outputs could reach 48.37 kW, 240.65 kW and 250.95 kW with a trigeneration cost per unit exergy of 37.12$/GJ, while the power generation and exergetic efficiencies could reach 62.65% and 62.27%. The annualized capital cost, O&M cost and fuel cost are 131 549$, 90 532$ and 162 375$, respectively. The NPV and payback period of the CCHP system are 502 824$ and 12.5 years. The effects of SOFC pressure, air flowrate, refrigerant flowrate and CO2 flowrate of the transcritical CO2 power cycle on the CCHP system characteristics are discussed. Furthermore, exergoeconomic and multi-objective optimization methods are used to find the final optimum operation condition with best results. A solution set in Pareto frontier with each fitness value superior to that of the design condition is obtained after optimization. Through the decision-making process, the total energy output and the exergy efficiency increase by 35.58 kW and 0.20%, respectively, while the unit exergy cost of trigeneration rises by 0.21$/GJ.

Multi-objective distributionally robust optimization for hydrogen-involved total renewable energy CCHP planning under source-load uncertainties

Hydrogen is one type of clean renewable energy. By introducing hydrogen production, storage and conversion devices into the combined cooling, heating and power (CCHP) system to replace its fossil fuel components, the hydrogen-involved total renewable energy CCHP (H-RE-CCHP) system is formed, thus bringing an effective way to promote energy transition towards low carbon. However, the conflict between economy and environment, and interference of source-load uncertainties hinder the low-cost construction as well as economic, stable, and low-carbon operation of H-RE-CCHP. In view of this, this paper proposes a multi-objective distributionally robust optimization (DRO) model for H-RE-CCHP planning. Firstly, a moment-based ambiguity set is constructed to define the possible range for the joint distribution of solar irradiation and multiple loads. Secondly, considering the “worst-case” distribution within the ambiguity set, the economic and environmental objective functions are presented for minimizing system construction, maintenance and operation costs while reducing carbon emission. Furthermore, the sizing- and operation-related constraints are formulated according to such principles as maintaining multi-energy balance when the forecasting errors of uncertainties occur. Finally, by applying strong duality and augmented ε-constraint for model solving, Pareto optimal solution set is obtained, and from which final planning and operation scheme is selected according to decision preference and interactions between objectives. Simulations mainly verify: 1) due to considering multiple objectives, H-RE-CCHP planning and operation reach the reasonable trade-off between economy and environment, that is, carbon emission/economic cost can be reduced by 99.81 %/66.70 % comparing with single economic/environmental objective; 2) with applying DRO in resisting uncertainties, 100 % renewable energy accommodation is achieved while meeting stable H-RE-CCHP operation; etc. Accordingly, this paper provides an effective approach for renewable energy system planning, thus contributing to the low carbon development of economic society.

Guidance on Evaluating the Performance of Multigeneration Systems Based on Energetic and Exergetic Criteria

Abstract This paper presents an investigation of the performance indices employed in combined or multigeneration thermal systems. Specifically, the following thermal systems will be considered: (1) combined cooling and power (CCP) systems; (2) combined heating and power (CHP) systems; and (3) combined cooling, heating, and power (CCHP) systems. The investigation will highlight the main problems and limitations related to using these indices. We will propose a new procedure for evaluating the performance of CCP systems that can be generalized for use in other combined or multigeneration systems. Employing the subsystems forming any multigeneration system as a reference, the relative saving ratios of energy and exergy are calculated. These saving ratios are used as metrics for the goodness of multigeneration systems. We will also use them to calculate equivalent energetic and exergetic efficiencies of multigeneration systems. These equivalent efficiencies will be used as performance indicators of a multigeneration system as if it were producing only one of its products. The new procedure will be applied to three case studies in this paper. Results of this work indicate that the equivalent exergetic efficiency of power generation (ψP,eqv) is the most meaningful and accurate performance index for assessing the performance of multigeneration systems.

Thermodynamic performance comparison of SOFC-MGT-CCHP systems coupled with two different solar methane steam reforming processes

Multi-energy complementary distributed energy system integrated with renewable energy is at the forefront of energy sustainable development and is an important way to achieve energy conservation and emission reduction. A comparative analysis of solid oxide fuel cell (SOFC)-micro gas turbine (MGT)-combined cooling, heating and power (CCHP) systems coupled with two solar methane steam reforming processes is presented in terms of energy, exergy, environmental and economic performances in this paper. The first is to couple with the traditional solar methane steam reforming process. Then the produced hydrogen-rich syngas is directly sent into the SOFC anode to produce electricity. The second is to couple with the medium-temperature solar methane membrane separation and reforming process. The produced pure hydrogen enters the SOFC anode to generate electricity, and the remaining small amount of fuel gas enters the afterburner to increase the exhaust gas enthalpy. Both systems transfer the low-grade solar energy to high-grade hydrogen, and then orderly release energy in the systems. The research results show that the solar thermochemical efficiency, energy efficiency and exergy efficiency of the second system reach 52.20%, 77.97% and 57.29%, respectively, 19.05%, 7.51% and 3.63% higher than those of the first system, respectively. Exergy analysis results indicate that both the solar heat collection process and the SOFC electrochemical process have larger exergy destruction. The levelized cost of products of the first system is about 0.0735$/h that is lower than that of the second system. And these two new systems have less environmental impact, with specific CO2 emissions of 236.98 g/kWh and 249.89 g/kWh, respectively.

Analysis of performance and suitable users of CCHP systems with active thermal energy storage

Introducing a thermal energy storage (TES) unit in the combined cooling, heating, and power (CCHP) system can help alleviate the supply–demand energy mismatch and improve the system performance. However, the active regulation function of TES has not been fully exerted and the applicable user scenarios of the CCHP-TES system are not clear due to the limitations of case studies. In this work, based on the supply–demand energy matching principle, an improved design of active thermal energy storage is proposed to further develop the role of TES units. Meanwhile, to overcome the limitations of case studies and obtain the universal applicable user scenarios, dimensionless user load characteristic parameters are used to analyse the correlation between the user characteristics and the system performances. The system thermodynamic model and integrated design methodology are developed. The results indicate that the average energy-saving rates of the proposed active CCHP-TES system are higher than 14.63%, and the maximum differences compared with those of the conventional CCHP system and passive CCHP-TES system are 22.27 and 29.20 percentage points, respectively. Moreover, among the user load characteristic parameters, the cooling/heating-to-electricity ratio has the greatest impact on the performances of the proposed system, the duration time of the peak electricity load the next, and the peak-to-valley ratio of electricity load the least. In most cases, the larger the cooling/heating-to-electricity ratio and the duration time of the peak electricity load are and the smaller the peak-to-valley ratio of electricity load is, the better the system performance will be. Finally, the applicable user scenarios of the proposed system are given quantitatively and the system is applicable once the peak-to-valley ratio of electricity load is less than 2 and the cooling/heating-to-electricity ratio is greater than 0.5.

Hybrid multi-objective optimization and thermo-economic analysis of a multi-effect desalination unit integrated with a fuel cell-based trigeneration system

Due to fossil fuel depletion and global warming, biomass plays a significant role in supplying the required energy in the industrial and residential sectors. In order to develop clean and efficient conversion technology, an innovative combined cooling, heating and power (CCHP) system based on biomass is introduced in this paper. The proposed system comprises a gasification process, solid oxide fuel cell, gas turbine cycle, Rankine and organic Rankine cycles, absorption chiller, and multi-effect desalination unit simulated in ASPEN. In this system, a new configuration is proposed in order to regenerate the waste heat efficiently at every level of temperature and increase energy and exergy efficiencies. Also, thermodynamics, economic, and sensitivity analyses are performed in order to investigate the energy and exergy efficiencies, the overall cost of the system, and effective parameters. The novel optimization approach (RSM-GA-TOPSIS) is introduced by combining the response surface methodology, genetic algorithm, and Shannon entropy and TOPSIS in order to model and optimize the objective functions in DESIGN EXPERT and MATLAB software, respectively. The objectives of the optimization are maximizing energy and exergy efficiencies and minimizing the overall cost of the system. As a result, based on the initial conditions, the electricity production, overall energy and exergy efficiencies, overall cost of the system, and overall exergy destruction can be acquired at 25.235 MW, 76.69%, 57.07%, 6.1063 × 106 $, and 26.03 MW, respectively. After performing the optimization method, the optimum solution (point 3) is obtained through the TOPSIS approach. In terms of thermodynamics analysis, the electricity production, energy and exergy efficiencies are acquired at 31 MW, 88.15%, and 67.30%, which are increased by 22.85%, 14.94%, and 17.93%, respectively, compared with the initial conditions of the proposed system. In terms of economic analysis of the optimum solution, the annualized total cost, COE, and COTP can be obtained at 6.594 × 106 $, 7.3857 $/GJ, and 6.7624 $/GJ, respectively. By comparing this point to the initial conditions, although the annualized total cost at this point is increased by 7.99%, the COE and COTP are decreased by 12.1% and 10.4% due to a further increase in electricity production. Therefore, for producing energy with high efficiency and low COE, the system should be operated according to the working conditions of this point (point 3).

Sensitivity analysis of energy, exergy, and environmental models for a combined cooling, heating, and power system at different operating conditions of proton exchange membrane fuel cell

AbstractIn this research article, for recovering the waste heat of the proton exchange membrane (PEM) fuel cell, a combined cooling heating and power (CCHP) system with a new arrangement is proposed. The main system components are a PEM, an absorption chiller, an auxiliary boiler, and hydrogen and heat storage tanks. The electrochemical model of PEM is presented for evaluating the power and heat of the fuel cell. Also, energy and exergy efficiencies and fuel energy saving ratio of the CCHP system are evaluated by the steady‐state thermodynamic model, and for the first time, the impacts of critical operating parameters of PEM such as current density, operating pressure, and temperature on the annual carbon dioxide (CO2) emission reduction and annual CO2 tax reduction as well as fuel saving are studied. The results show that the proposed CCHP system's energy efficiency is evaluated at about 66%. With the increase in temperature of PEM, the exergy efficiency reaches 37%. In addition, using this system can reduce CO2 emissions by 191 ton per year. Also, this system can reduce the tax cost of carbon dioxide emissions by about $ 5700 per year.

Performance evaluation of proton exchange membrane fuel cell and air source heat pump system with energy storage for residential application

ABSTRACT This paper combines the advantages of air source heat pumps and proton exchange membrane fuel cells, and analyses the dynamic performance, environmental benefits, and economic benefits of combined cooling, heating, and power (CCHP) systems combined with energy storage systems applied to residential buildings. The fuel cell voltage and heat model, air source heat pump (ASHP) model, and energy storage system model are developed in MATLAB. The results show that the problem of thermoelectric asynchrony and excess energy wastage can be solved by using the heat-following strategy with a battery and the electric-following strategy with a water tank. With the heat-following strategy in winter, the total thermodynamic efficiency of the system is 1.265, the carbon emission reduction is 6208.6 g, and the initial cost, operation cost, and maintenance cost are 6007$, 11.99$, and 300.35$, respectively. The efficiency of the system with the winter electric-following strategy is 1.284, the emission reduction is 6781.4 g, and the initial cost, operation cost, and maintenance cost are 7202.9$, 11.88$, and 360.14$, respectively. In summer with the electric-following strategy, the thermodynamic efficiency of the system is 1.514; the carbon reduction is 8,033.6 g. The initial cost, operation cost, and maintenance cost are 7,208.3$, 14.84$, and 360.42$.

Energy Dispatch for CCHP System in Summer Based on Deep Reinforcement Learning

Combined cooling, heating, and power (CCHP) system is an effective solution to solve energy and environmental problems. However, due to the demand-side load uncertainty, load-prediction error, environmental change, and demand charge, the energy dispatch optimization of the CCHP system is definitely a tough challenge. In view of this, this paper proposes a dispatch method based on the deep reinforcement learning (DRL) algorithm, DoubleDQN, to generate an optimal dispatch strategy for the CCHP system in the summer. By integrating DRL, this method does not require any prediction information, and can adapt to the load uncertainty. The simulation result shows that compared with strategies based on benchmark policies and DQN, the proposed dispatch strategy not only well preserves the thermal comfort, but also reduces the total intra-month cost by 0.13~31.32%, of which the demand charge is reduced by 2.19~46.57%. In addition, this method is proven to have the potential to be applied in the real world by testing under extended scenarios.

A novel CCHP system based on a closed PEMEC-PEMFC loop with water self-supply

Targeting the shortcomings of oxygen waste and reactant supplement of electrolyzer, this paper proposes a novel combined cooling, heating and power (CCHP) system based on proton exchange membrane electrolysis cell (PEMEC) and H2/O2 proton exchange membrane fuel cell (PEMFC) with water self-supply. In this system, H2/O2 PEMFC adopts a dead-ended anode and cathode operation mode to achieve 100 % hydrogen and oxygen utilization and water recovery. For the application scenario of a household in Shanghai, China, the performance of the CCHP system in summer and winter is investigated. When the system gives priority to meeting the electric and cooling load, there will be insufficient heat at the initial stage of operation. The pre-operation model can realize the hourly matching of residential electric, heating and cooling loads. After one day of operation in summer and winter, there are 19.1 kWh and 45.5 kWh electricity surplus, 7.27 × 106 kJ and 1.97 × 106 kJ heat surplus, 1200 mol and 300 mol hydrogen surplus, respectively. Moreover, the estimated payback period for this system is 7.6 years, which will be significantly shortened with the decrease of the cost of photovoltaic panels and PEMEC.

A combined cooling, heating and power system with energy storage of waste heat to hydrogen

To improve the recovery of waste heat, a natural-gas based combined cooling, heating and power (CCHP) system with waste-heat to hydrogen as energy storage is proposed. In the novel system, the steam reforming of methanol (SRM) is applied in between the internal combustion engine (ICE) and absorption chiller, and integrated with a hydrogen tank and proton exchange membrane fuel cell (PEMFC) for energy storage. The mathematical model is developed to identify the thermodynamic performances of the system in three operation modes (normal, storage, supplemental) under design and off-design conditions, and multi-objective optimization is conducted to explore the optimal system performances. The results show that the overall exergy efficiencies of the three modes and reference system are 41.71 %, 46.34 %, 43.63 % and 40.51 % with given conditions, respectively. Except for ICE, the reactor accounts for 10.2% and 11.1 % exergy destruction ratio in M1 and M2 modes, while PEMFC accounts for 15% in M3 mode due to the chemical reactions. The parametric analysis demonstrates that increasing reaction temperature of SRM, methanol flow rate or working pressure of PEMFC can enhance the system exergy efficiencies for all modes. The optimal points determined by two decision methods are coincident and the energy and exergy efficiencies are 80.50 % and 43.00 %, which have increased by 0.36 % and 3.09 % than that under design conditions. The study constructs a promising scheme for realizing hydrogen storage by recovering the waste heat, and the results have verified the feasibility of the system and provided thermodynamic basis for further system configurations.

Strategic active and reactive power scheduling of integrated community energy systems in day-ahead distribution electricity market

The increasing penetration of distributed energy resources (DERs) enable integrated community energy systems (ICESs) as emerging techno-economic energy entities at the end-user side. In the deregulated electricity market, the ICESs can actively participate in the distribution electricity market (DEM) to provide active and reactive power dispatched by ICES operator (ICESO). In this context, a strategic active and reactive power scheduling model for ICESs in the day-ahead DEM is proposed in this paper. A novel trading mechanism designed for ICESO and distribution system operator (DSO)’s interaction toward both active and reactive power is represented in the day-ahead DEM, where distribution locational marginal prices (DLMPs) for both active and reactive power are introduced as the market settlements. Then, the trading process is formulated as a bi-level programming problem. The upper level describes the combined cooling, heating, and power (CCHP)-dominated ICESO’s strategic active and reactive power dispatch, in which the DLMPs for active and reactive power, internal flexibility services, and optimal dispatch for inverter-based distributed generators are considered. The lower level performs a DEM clearing for both active and reactive power. Further, Karush–Kuhn–Tucker (KKT) conditions, Big-M approach, and duality theory are used to convert the bi-level model from a Mathematical Programing with Equilibrium Constraints (MPEC) model to a single-level mixed-integer second-order cone programming (MISOCP) model for efficient calculation. Finally, case studies on modified IEEE 33-node and IEEE 123-node distribution systems are adopted to evaluate the performance of the proposed scheduling method. The results show that the proposed scheduling approach can contribute to the renewable energy share and energy efficiency, reduce CCHP-dominated ICESs’ operation costs by 38.13% and 13.21% compared to the case where ICESO only acts as a price-taking consumer, and 6.64% and 3.44% compared to the case where ICESO does not consider reactive power bids/offers, respectively.

Thermodynamic analysis of SOFC–CCHP system based on municipal sludge plasma gasification with carbon capture

To solve the environmental problems associated with municipal sludge incineration and landfilling, a combined cooling, heating, and power (CCHP) system integrating plasma gasification, solid oxide fuel cell (SOFC), gas turbine, supercritical carbon dioxide (S-CO2) cycle, and double-effect absorption refrigeration cycle (ARC) is proposed. Additionally, the CO2 generated in the system is captured to reduce the environmental impact. Energy, exergy, and sensitivity analyses of the developed system are conducted. Key parameters such as the SOFC temperature, SOFC pressure, and fuel utilization rate affecting the system performance are studied. The results show that net electrical efficiencies of the SOFC and the system are 41.96 % and 50.00 %, respectively. The exergy efficiency and comprehensive energy utilization rate of the system are 47.04 % and 87.59 %, respectively. The system can generate a power of 175.03 kW, cooling of 45.70 kW, and heating of 85.82 kW under the design conditions, accounting for 67.46 %, 21.23 %, and 11.31 % total energy output of system, respectively. The three main sources of exergy destruction of the system are the plasma gasification, SOFC, and supercritical CO2 cycle subsystems, accounting for 36.8 %, 12.2 %, and 10.7 % exergy destruction, respectively. The system performs the best when the SOFC temperature is 910 °C and the fuel utilization rate is between 0.85 and 0.90. The SOFC pressure has little effect on the system performance. In addition, the carbon capture rate of the system can reach 97.50 %. The CCHP system has high thermodynamic efficiency and hence can convert municipal sludge efficiently into clean energy; therefore, this study provides a new concept for resource treatment of urban sludge.

Optimal design of a novel hybrid renewable energy CCHP system considering long and short-term benefits

The combination of biomass and solar energy in the combined cooling heating and power (CCHP) system is conducive to reducing carbon dioxide emissions of the system. To improve the system's economic performance under the punishment of carbon tax, this paper optimizes the system from system design and operation strategies. A hybrid renewable energy CCHP system with shaft power distribution structure of an internal combustion engine (ICE) is proposed. By optimizing the shaft power distribution of ICE, the direct drive heat pump is realized, and the efficiency of the shaft power of ICE is improved. A double-layer optimization method considering the long and short-term benefits is proposed based on the system, fully improving the system economy in design and operation. The case study shows that the CCHP system reduces the annual cost by 40.37% and the CO2 emission by 88.93% compared with the separate production system. Compared with the non-shaft power distribution system, the maximum daily operation cost is saved by 557.11CNY. Compared with the hourly optimization method, the proposed optimization method based on total daily benefit reduces the annual cost by 7.73% and CO2 emission by 35.87%, and the utilization rate of the energy storage device is higher.

Advanced, extended and combined extended-advanced exergy analyses of a novel geothermal powered combined cooling, heating and power (CCHP) system

In this study, not only conventional and advanced exergies, but also advanced exergoeconomic, extended exergy and combined extended-advanced exergy analyses are firstly applied to the novel ejector-based CO2 transcritical Combined Cooling, Heating and Power (CCHP) system powered by geothermal energy. It is found that the evaporator and domestic water heater (DWH) components should be focused to increase system efficiency. For the vapor generator (VG), evaporator (EV) and DWH, avoidable exergy destruction rates are found as 26.334 kW, 0.323 kW and 8.288 kW, while their unavoidable exergy destruction rates are 11.206 kW, 0.276 kW and 1.410 kW, respectively. The extended avoidable exergy destruction rates are determined as 89.068 kW, 5.174 kW and 12.385 kW, while their unavoidable exergy destruction rates are 36.846 kW, 3.079 kW and 1.992 kW for the VG, EV and DWH, respectively. Improvement potential of VG, EV and DWH are endogenous, it means they should be focused on these components themselves. DWH is strongly connected to condenser which has important role on exergy destructions of it and condenser should be focused on improving DWH. According to mexogenous exergy destruction results, the condenser's exergy destruction is equal to −0.468, which means DWH's exergy destruction can be reduced.

Commercial building integrated energy system: sizing and energy-economic assessment

Abstract Integrated energy systems are one of the potential options for buildings that can reduce emission. In this research study, the energetic and economic performance of a micro-gas turbine combined heating and cooling plant coupled with a solar PV is analyzed for an office building in Iran. For each analysis, two different scenarios have been performed. System sizing parameters defined in a way that renewable to fossil fuel share is correlated to plant performance and economy. To model the studied system, a time-dependent method is used, which is the inherent characteristic of renewable energies. The renewable energies used here are solar heaters and solar panels. Contours of Net Present Value (NPV) are evaluated as a function of solar heating share and different economic parameters. In addition, optimal system sizing for a typical building is obtained and the results are provided. Effect of various major parameters shows that under the current condition and despite the supportive incentive for renewable energies, strategies and plans even without solar energy are not economically viable due to the high discount rates. In addition, results provide that, in reasonable and normal discount rate, fuel and grid electricity prices, governmental subsidization for conventional combined heat, and power (CHP) and combined cooling, heat, and power(CCHP) is not necessary, and only in this condition solar electricity selling price (i.e. governmental support program) is effective to increase renewable penetration. The results show that if the interest rate is less than 5%, the NPV becomes positive. Also, when the electricity price reaches $0.07/kWh or higher, the NPV becomes positive.

Economic dispatch of CAES in an integrated energy system with cooling, heating, and electricity supplies

AbstractFlexible combined cooling, heating, and power (CCHP) systems are effective in integrating wind sources. As an attractive, clean, and large‐scale energy storage technique, the advanced adiabatic compressed air energy storage (AA‐CAES) can store and generate both electricity and heating, and also provide cooling during expansion under certain conditions. Although AA‐CAES has immense potential in multi‐energy supply systems, CCHP dispatch with AA‐CAES and wind power generation (WPG) is yet to be systematically studied. In this study, the economic dispatch of an AA‐CAES system equipped with WPG is addressed. The AA‐CAES system is comprehensively modelled by considering its thermal characteristics, air‐temperature changes due to heating exchange, air storage constraint, and other factors, particularly the heat supply to the air for expansion, which is a key factor that influences the cooling supply. Subsequently, the cooling, heating, and power of the AA‐CAES system are dispatched to minimise the operating cost under different supply modes. In conclusion, the proposed method is demonstrated using an integrated energy system in an industrial park, and the operation cost of the AA‐CAES system is minimised. The numerical results demonstrate that the participation of AA‐CAES in CCHP dispatch can curtail WPG and reduce operation costs. The economics of the different supply modes of AA‐CAES are also discussed.

Optimal scheduling of combined cooling, heating, and power system-based microgrid coupled with carbon capture storage system

The paramount role of microgrids (MGs) in strengthening the energy network and supply of many users in more cost-effective, safe, and sustainable manner cannot be overlooked. Energy carriers' interdependence on each other, as well as the rapid rise of tri-generation technologies, provide several obstacles to ensuring the network's best performance. A combined-cooling heat and power (CCHP) system based on various renewable-based resources and MGs is capable of supplying electricity, thermal, and cooling loads, in which the operation of CHP-based MG (CBM) is heavily influenced by the interaction between these carriers. On this basis, this paper is proposed a comprehensive analysis of CBM operation, which is coupled with electrical and absorption chillers (ACs), energy storage, and renewable-based units like solar and wind power under a multi-objective optimization (MOO) technique. In addition, a Power-to-Gas (PtG) technology is utilized in the proposed system to enhance the overall operation, reduce CO2 emission, and to contribute to the cooling and heat supply in the presence of various uncertainties. The suggested MOO methodology evaluates the operation cost of the system as the first objective and the reduction of CO2 emission as the second objective. An epsilon-constrained approach and Pareto solution are considered to assess the methodology. As a result, this study examines the system's reliance on individual carriers as well as the interdependence of those carriers. The results reveal the effectiveness of the proposed model to reduce CO2 emission and operational costs.

Exergoeconomic, exergoenvironmental analysis and multi-objective optimization of a novel combined cooling, heating and power system for liquefied natural gas cold energy recovery

This paper designs and investigates a novel combined cooling, heating, and power (CCHP) system for effectively utilizing liquefied natural gas (LNG) cold energy and waste heat of exhaust gas based on thermodynamic, exergoeconomic and exergoenvironmental analysis. The effects of the mass flow rate of the ORC-I’s working fluid, turbine 1 inlet temperature, compressor and pump outlet pressure and the turbines’ isentropic efficiency on the system performance were investigated. In addition, the non-dominated sorting genetic algorithm II (NSGA-II) and the particle swarm optimization (PSO) were employed to optimize the CCHP system with multiple objectives, respectively, to find the optimal operating conditions of the system. The optimization results showed PSO was superior for the multi-objective optimization of this novel CCHP system compared to NSGA-II, showing the exergy efficiency, product unit cost and product unit environmental impact of 70.20%, 21.50 $/GJ and 57.91 mPts/GJ, respectively.