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To raise the power supply reliability of microgrids in remote areas, it's necessary to establish a multi-energy system to improve energy efficiency. However, the uncertainties in load fluctuation and renewable energy will hinder the implementation of planning schemes, resulting in scheduling plans mismatching the actual demand, and ultimately failing to ensure the economic operation of microgrids. Therefore, the two-stage robust optimal scheduling framework that combines energy recovery, demand response, and forecast is proposed for scheduling in microgrids. Uncertainties and economic costs are fully considered in the framework to make the planning scheme for microgrids more in line with the actual project. Simulation consequences indicate that the BP neural network could efficiently forecast the load with an error within 5%. Additionally, considering thermodynamics and economy, 0.3 is the optimal split ratio for recompression supercritical CO 2 Brayton cycle to recover waste heat from the gas turbine. Finally, Case 4 with energy recovery and demand response is economically optimal, with an annual operating cost of $1.71 million lower than the original Case 1 and a total annual cost 13.92% lower than Case 1. By comparing different cases, it is proved that the proposed Case 4 optimization framework has advantages for scheduling in microgrids. [Display omitted] [ABSTRACT FROM AUTHOR]

Improving energy efficiency and reducing CO 2 emissions are main objectives of energy saving and emission reduction. However, residential buildings' daily operation not only consumes enormous energy, but emits relatively elevated CO 2 , which runs counter to energy saving and emission reduction. Consequently, it's urgent to acquire a more environmentally-friendly and efficient system for residential buildings. To solve this problem, a novel trigeneration system based on solid oxide fuel cell is proposed, integrating cooling, heating, electricity supply, and energy storage. Firstly, the system's mathematical model is established and the influence of key parameters on the system's performance is analyzed. Then, the genetic algorithm is utilized to optimize parameters of waste heat recovery system. Finally, the novel system is applied to satisfy energy demands of residential buildings, and five energy supply options are proposed to compare with the original option in terms of economy and environment. Numerical results show that among the five options, Option 3 has the best economy, with a payback period of 5.54 years and the total cost is 65.33% lower than the original option. Option 4 is more advantageous in reducing CO 2 emissions, and its total CO 2 emission in 15 years is 57.42% less than the original option. [Display omitted] • A novel system with cooling, heating, power supply and stored energy is designed. • Working parameters of energy recovery system are optimized by genetic algorithm. • Five supply options are proposed for residential buildings' energy needs. • CO 2 emissions are reduced by up to 57.42 % within 15 years in the proposed option. [ABSTRACT FROM AUTHOR]

With the significant increase in social electricity consumption, the volatility and uncertainty of the electricity load have a significant influence on the operation of the coal-fired power plant. To address this issue, a novel compressed air energy storage system integrated into a coal-fired power plant is proposed to realize that excess electricity is stored at off-peak time and discharged to the customers at peak time to increase the profit. The double parameters regulation method is adopted to broaden the operating ranges of the compressor and expander. Additionally, the relationship between charging and discharging cycles and the system performance is obtained by analyzing the dynamic characteristics of the packed bed. The simulation results indicate that the operating ranges of the compressor and expander are increased to 63.1–121.6 MW and 12.3–53.7 MW, respectively. Furthermore, the round-trip efficiency and total heat storage capacity of the packed bed gradually stabilized at 54.3% and 650 MWh as the number of cycles increased. The economic analysis shows that the levelized cost of electricity and dynamic payback period of the system are 92.35 USD/MWh and 8.4 years. Finally, compared with previous literature by fuzzy evaluation, the proposed system obtains the optimal membership degree of 0.99. [Display omitted] • Compressed air energy storage coupled with coal-fired power plant is proposed. • Flexible purchasing-selling electricity strategy is used to maximize economy. • Operating range of compressor and expander is widen by novel regulation method. • Some of energy storage systems are evaluated by fuzzy evaluation. [ABSTRACT FROM AUTHOR]

Coal-fired power plants (CFPPs) not only bear the burden of peak shaving, but the mission of energy saving. However, the increasing peak-valley difference leads to the difficulties of peak shaving and the energy waste caused by the ineffective utilization of waste heat, which undoubtedly becomes a new problem for CFPPs. So, a new integrated system combining flexible energy storage and waste heat recovery in the CFPP is presented. The scheme consists of a double-effect absorption heat pump (D-AHP) with an integrated thermal electricity storage system (IT-ESS). Waste heat from flue gas is recovered by D-AHP, while IT-ESS is responsible for peak shaving. Firstly, comprehensive satisfaction is used for demand-side management. Subsequently, D-AHP is utilized to recover waste heat to meet the users' heating demand. Finally, steam is extracted during off-peak time to store energy for IT-ESS, while energy is released for peak shaving during peak time. Throughout the process, the proportional-integral-differential is applied to control the airflow into the IT-ESS. Numerical results indicate that the maximum peak-valley difference is decreased by 55.3 MW after the optimization of comprehensive satisfaction, and the response time for the airflow to reach the target value is only about 10% of one period with the PID control strategy. Besides, the scheme successfully satisfies the electricity demand and heating demand in isolated microgrids, and the round-trip efficiency of IT-ESS is 23.11%. Lastly, the daily revenue of the system is 1.40 million dollars and the payback period is 3.16 years. [Display omitted] • A new design of flexible energy storage combined with waste heat recovery is proposed. • Peak-valley difference of load is reduced after applying comprehensive satisfaction. • The integrated thermal electricity storage system is applied for peak shaving. [ABSTRACT FROM AUTHOR]

To ensure the sustainable development of the economy and society, energy-saving and emission reduction is an inevitable choice to solve resource scarcity and control environmental pollution, while coal-fired power plants are an important industry to implement this strategy. A novel design combining organic Rankine cycle with electron beam flue gas treatment is proposed to reduce pollutant emissions and recover flue gas waste heat of 600 MW power plant. The flue gas flows through the organic Rankine cycle to recover waste heat, then enters the electron beam irradiation device for desulfurization-denitrification, and eventually generates by-products of ammonium sulfate and ammonium nitrate that could be applied in agriculture. The particle swarm optimization algorithm is employed to improve the thermodynamic, economic and environmental performance, then the most suitable scheme is selected by combining TOPSIS and the entropy weight method. The optimization results indicate that the integrated system could produce equivalent electric quantity of 22.58 MW, and the payback period is 4.91 years. Meanwhile, ammonium sulfate and nitrate with production of 3544 kg/h and 6165 kg/h are obtained. Compared with the referenced power plant, the thermal efficiency of the improved scheme increases by 1.26% and the standard coal consumption rate decreases by 2.72%. [Display omitted] • A new integration of waste heat reuse and desulfurization-denitrification is proposed. • The reaction mechanism and thermodynamic model of EBFGT are studied. • TOPSIS and EWM are combined to screen the multi-objective functions optimized by PSO. • The feasibility of system is discussed from thermodynamics, economy and environment. [ABSTRACT FROM AUTHOR]

Converting waste biomass to fuel and coupling it with solid oxide fuel cell to generate electricity cheaply and efficiently is what researchers are pursuing to achieve carbon neutrality. Therefore, a novel scheme of biosyngas-fueled solid oxide fuel cell power generation integrated with carbon capture is proposed in this paper, fully converting woody biomass into syngas. Based on the mathematical modelling, this system is evaluated by multiple evaluation criterion, including thermodynamic, economic and environmental perspectives. The correctness and accuracy of the proposed model are validated against the published literature. The studies on the key operating parameters show that increasing the gasifying temperature can markedly improve the quality of syngas, while the improvement of steam to biomass ratio is not evident, and the conversion ratio of water gas shift reactor is crucial for carbon capture. Moreover, low current density and high fuel utilization ratio are preferable to the high-efficiency power generation of solid oxide fuel cell. After multi-objective optimization, the CO 2 emission ratio and energy efficiency achieve 0.285 t/MWh (is the lowest among various schemes) and 52%, which proves that the proposed scheme is a highly-efficient and eco-friendly power generation system. [ABSTRACT FROM AUTHOR]

Energy storage system is an important component of the microgrid for peak shaving, and vanadium redox flow battery is suitable for small-scale microgrid owing to its high flexibility, fast response and long service time. Therefore, a microgrid based on vanadium redox flow battery is studied for rural applications in this paper, in which biomass gasification and solid oxide fuel cell are integrated as power generation units to provide stable electricity. A predictive control method is presented to improve the efficiency of flow battery and the economic feasibility of this system is evaluated. The mathematical model is validated with the experimental data of published literature. The results indicate that controlling the electrolyte flow rate according to the current and the state of battery can reduce the energy loss of flow battery. The optimal electrolyte flow rate is determined by predictive control method, which can significantly improve the performance of flow battery compared with previous method. The overall efficiency of battery for peak shaving is achieved by 84% and the pay back period of this microgrid system is 7.33 year. [Display omitted] • A stable and high-efficiency power generation system is proposed for microgrid. • Predictive control method is presented to improve the efficiency of flow battery. • The efficiency of flow battery in a complete charge-discharge cycle is 84%. • The payback time of this microgrid is 7.33 year based on time sharing tariffs. [ABSTRACT FROM AUTHOR]

To reduce fossil resource consumption and air pollution, the effective utilization of furnace's redundant heat during peak shaving period, carbon dioxide emission reduction and flue gas waste heat recovery are three significant issues for energy saving and emission reduction of coal-fired power plants. However, these three aspects are considered separately in the past. In this study, an innovative design is proposed, in which the high and medium-grade heat during peak-off period is used for methane reforming reaction heating, while the low-grade waste heat of flue gas is used as the heat source for carbon capture process. The captured CO 2 is employed as feedstock of methane dry reforming reaction to produce syngas. Meanwhile, sulfuric acid is recovered from flue gas in a special heat exchanger. Results show that this design can reduce by 445132.2 tonne of CO 2 every year while the max output rate of syngas's high heating value and mass are 17,777 GJ/d and 601.7 t/d (with H 2 /CO = 0.618). Meanwhile, it can recover H 2 SO 4 of 14,649 t/yr. This design not only recovers the heat energy of coal-fired power plants, but also realizes the capture and utilization of CO 2 , which deeply embodies the concepts of energy conservation and environmental protection. [Display omitted] • High and middle-grade excess heat of CFPP in peak-off time is used to produce syngas. • The captured CO 2 is utilized as feedstock of dry reforming of methane reaction. • A cogeneration of sulfuric acid and syngas is realized. [ABSTRACT FROM AUTHOR]

Although the prosperous shipping industry promotes economic globalization, it causes the environmental issues like air pollution and ecological destruction, due to the emission of harmful substances. Accordingly, many waste heat recovery technologies of ships have been developed and improved, among which the supercritical Brayton cycle has attracted wide attention due to its high energy conversion efficiency. Taking an actual diesel engine as the research object, this study presents four waste heat utilization schemes by combining different supercritical carbon dioxide cycles with a double effect absorption refrigeration system. The indicators of each scheme are calculated from three perspectives of thermodynamics, economy and environment, and the overall evaluation of all schemes is carried out through the analytical hierarchy process. The addition of the refrigeration system to the recuperation supercritical carbon dioxide cycle is considered to be the optimal combination. Parameter study indicates that output power, thermal and exergy efficiency increase with the turbine inlet pressure and temperature. The maximum of these thermodynamic indexes are 5987 kW, 27.35% and 56%, respectively. Furthermore, to lower temperature of high pressure generator is conducive to improving the refrigeration performance and to raise the temperature of low pressure generator also has a similar effect. Before optimization, the capital payback period and product exergoenvironmental impact of the combined system are 6.845 years and 63.023 mPts/s. After operating the optimization program, both of them become 5.81 years and 54.94 mPts/s, which are reduced by 15.12% and 12.83%, respectively. [Display omitted] • Four electricity-cooling cogeneration systems for waste heat recovery are proposed. • Energy, economy and exergoenvironment analysis of combined system are conducted. • Selection of optimal scheme is completed through analytical hierarchy process. • Multi-objective particle swarm optimization is used to improve the performance. [ABSTRACT FROM AUTHOR]

To advance sustainable development and emission reduction efforts within the maritime industry, a novel combined cooling, heating, power, and storage (CCHPS) system is proposed. This system comprises a cogeneration system (ORC + ARC) and a thermal energy storage (TES) system. Initially, optimal working fluids are selected for the ORC and TES discharge systems. Subsequently, an analysis is conducted regarding the correlation between sensitivity parameters and system performance. Then, the cogeneration system's optimum design parameters are determined utilizing the multi-objective grey wolf optimization (MOGWO) algorithm. Finally, the TES system is analyzed and matched with the diesel generators to meet the ship's electricity demand. The CCHPS system achieves optimal thermal efficiency, payback period, annual CO 2 emission reduction, and annual fuel savings of 30.07%, 6.22 years, 8910.49 tons, and 2791.74 kL, respectively. In contrast to the TES-absent system, the CCHPS system exhibits a 12.88% increase in thermal efficiency, along with a 25.48% improvement in annual fuel savings and annual CO 2 emission reduction. [Display omitted] [ABSTRACT FROM AUTHOR]

In spite of the fact that the solar power tower system is considered as one of the most valuable power generation facilities, it still faces challenges such as insufficient utilization of the solar salt temperature range and the dependence on high solar radiation intensity. To address this issue, an integrated recompression Brayton cycle and trans -critical regenerative organic Rankine cycle in parallel layout is proposed. The comparison with other literature shows that the specific work of the integrated system (147.8 kW/kg) outperforms the partial cooling Brayton cycle (130.1 kW/kg) under the same solar salt temperature range. In order to forecast future electricity generation and serve as a reference for plant operation, a power prediction strategy using neural networks is developed. Findings indicate that the integrated system can increase power production and maximize solar salt temperature utilization by adjusting the physical constraint strategy based on the changing temperature interval. Its equivalent work and thermal efficiency reach 12.7 MW and 38.36%, respectively, and it can recover the cost in 8 years. These results suggest that the proposed integrated system is a promising solution to enhance the performance of solar power tower systems with significant economic benefits. [Display omitted] • A two-stage power cycle to fully utilize SPT solar salt temperature range is offered. • Proposed system increases power production by adopting physical constraints. • The power cycle adopts low GWP and zero ODP working fluid. • The total specific work of the combined system surpasses the partial cooling cycle. • A BI-LSTM-based power generation prediction strategy of the system is developed. [ABSTRACT FROM AUTHOR]

Waste heat recovery technology of ships is meaningful for the enhancement of system efficiency and protection of environment. Compared with conventional diesel engines, the natural gas engines have the advantage of low emission, and its exhaust gas with quite high temperature is very suitable for utilization as the heat source of cascade waste heat system. This study integrates an over-expansion transcritical CO 2 cycle with a double effect absorption refrigeration cycle to recover the heat energy from a natural gas engine. At the same time, a post-processing unit is proposed to remove the nitrogen oxide of flue gas. The research results indicate that the higher engine load contributes to improving the equivalent output work and economy of the combined cycle while the post-processing unit can further reduce the payback time under the given conditions. In terms of the parameters analyses, the turbine outlet pressure of transcritical cycle has an optimal value of 2.25 MPa, which can make the output work to reach the maximum value of 305.0 kW, and the performance improvement of refrigeration cycle can be achieved by decreasing the temperature of high pressure generator or increasing the temperature of low pressure generator. After multi-objective optimization, the residual equivalent output work, payback period and amount of NOx reduction of the total system are 150.77 kW, 4.20 years and 8.16 g/kWh, respectively. In addition, the Energy Efficiency Existing Ship Index is further reduced to 8.21 gCO 2 /ton·nm with the aid of the proposed system. [Display omitted] • A joint system is used to recover energy and remove nitrogen oxide simultaneously. • The produced hydrogen is used to achieve the emission removal and ammonia synthesis. • Payback period of system is reduced to 4.2 years by multi-objective optimization. • Energy Efficiency Existing Ship Index is reduced by 11.9% with the proposed system. [ABSTRACT FROM AUTHOR]

Energy shortage, greenhouse effect and environmental pollution are the three major crises faced by mankind. How to solve these three problems effectively has become the focus of all countries. Therefore, this paper proposes an innovative LNG cold energy utilization method that can simultaneously alleviate these three problems. This method includes an improved structure of the organic Rankine cycle, CO 2 capture cycle and supercritical CO 2 extraction of wastewater. In addition, automated machine learning based on data-driven approach is effectively used for modeling the wastewater extraction. Then, after verifying the accuracy of the proposed model, some parameters have great influence on the system performance. For instance, the temperature of supercritical CO 2 and working fluid water affect the local exergy efficiency and their regression coefficients are −0.29%/°C and 0.13%/°C, respectively. These parameters in wastewater extraction process are studied. Finally, under the optimization of genetic algorithm, the maximum wastewater treatment can reach 62.7 t/h increasing by 14.0%, and the LNG cold energy generation can reach 110.1 kWh/tLNG with an increase of 28.9%, while the exergy efficiency of the system is 50.4% increasing by 24.1%. Thus, organic Rankine cycle power generation, carbon capture and wastewater treatment play the roles of energy saving, emission reduction and environmental protection. At the same time, the results are compared with those of other scholars to verify the superiority of the proposed scheme. [Display omitted] • LNG cold energy reuse covering electricity, CO 2 capture and extraction is proposed. • Automated machine learning approach is used to build wastewater extraction model. • Reasonable arrangement of regenerative heat exchanger enhances system performance. • The maximum wastewater treatment reaches 62.7 ton/h utilizing genetic algorithm. [ABSTRACT FROM AUTHOR]

Under the severe situation of low energy efficiency and strict emission standards, waste heat recovery, is considered to be a feasible technology, to achieve fuel economic in automobile industry. Among them, supercritical CO 2 Brayton cycle has become one of the most promising technology owing to its high efficiency and compactness. Besides, the exhaust temperature and flow of automobile engine change dramatically in practice, resulting in a negative impact on the thermodynamic performance of the power cycle. Therefore, this paper develops a dynamic model of waste heat recovery system, carries out operating parameters analysis, transient response characteristics research and performance optimization, and finally proposes an improved method to adjust turbine inlet temperature to obtain higher output power. The change trend displays that the influence of turbine inlet pressure on thermodynamic performance is opposite to the dynamic response characteristics, and similar results also occur under engine start-up conditions. The numerical results indicate that the optimized output power and electric production cost reach 2.97 kW and 0.38 USD/kW·h, compared with the previous method, an improvement of 3.48% and 5.00% are achieved, respectively, reflecting the significance of energy conservation and emission reduction. [Display omitted] • A dynamic model for a recuperator supercritical CO 2 Brayton cycle is proposed. • Transient response characteristics in different operating conditions are considered. • To propose a new method to adjust turbine inlet temperature for higher output work. • Optimization gets improvements of 3.48% and 5.00% in output and economic performance. [ABSTRACT FROM AUTHOR]