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[Display omitted] • Sorting strategies based on source, physical and chemical properties were compared. • The gasification efficiency of sorted RMSW was 40.89% higher than that of unsorted. • The yield of syngas can be increased by 37.14% after waste sorting. • The emission of CO 2 can be reduced by 81 t·per year after waste sorting. • Elemental composition based sorting method benefited to efficient gasification. Gasification is a promising way to convert residual municipal solid waste (RMSW) to high-valued syngas. Waste sorting is helpful to alleviate the heterogeneity problem of waste on gasification. This paper aimed to search for an optimal sorting strategy and evaluate the influence of waste sorting on downstream gasification. A sorting strategy based on elemental composition was proposed and compared with common source and density based strategies. The results validated the enhancement of waste sorting on RMSW gasification, where the elemental composition based strategy showed optimal gasification. The yield of syngas, cold gas efficiency, the lower heating value of syngas and H 2 /CO were increased by 37.14 %, 38.95 %, 2.18 % and 8.81 %, respectively. It also showed a good effect on the improvement of air gasification compared with the literature, especially for H 2 /CO. This paper also discussed the economic and environmental potential of the elemental composition based sorting method. The waste sorting can help increase 29,250 RMB/year and reduce CO 2 emission by 81 t/year. This method has potential for industrial application. It is suggested that further fast elemental composition characterization technologies and intelligent sorting equipment can be developed. Limitations and future perspectives were discussed from gasification simulation models, more energy utilization technologies, the underlying logic of waste sorting and sustainability evaluation. It is hoped that this work can provide insightful fundamentals to their applications in RMSW sorting, thus benefiting resource recovery and circular economy. [ABSTRACT FROM AUTHOR]

• A new DPV-5G BS-ES communication and power mutual coupling system is developed. • A BSSCP model is proposed to minimize the number of 5G base station deployments. • The ISOM model is used to optimize the microgrid connection lines in 3D space. • Economically optimal simulation experiments are conducted for different PV systems. The emergence of ultra-dense 5G networks and a large number of connected devices will bring with them significant increases in energy consumption, operating costs, and CO 2 emissions. At the same time, the deployment of distributed photovoltaic (DPV) in megacities plays an important role in promoting the integration of "building-photovoltaic", adjusting the city's clean energy supply system, and building a green, and low-carbon smart city. The development of a new "DPV-5G Base Station-Energy Storage (DPV-5G BS-ES)" coupled DC microgrid system and its pre-deployment investment costs are fundamental factors to be considered when the problem of large-scale DPV and BS deployment in cities has to be addressed. There are almost no published papers on this issue in the literature, which only consider the problem of maximizing the deployment of 5G BS service coverage or only perform optimization analyses for the performance of microgrid systems without considering the economic optimality and low-carbon green issues in the construction of urban utilities. In order to solve the problem of 5G BS deployment and economic optimization of topology in the "DPV-5G BS-ES" coupled DC microgrid system, a novel deployment strategy is proposed in this paper. The strategy is divided into: (a) The Geographic Information System (GIS) for extracting and analyzing 3D data from all buildings in the area. (b) A GIS-based formulation of a mixed integer quadratic constrained planning model (BSSCP) under discrete fixed radius coverage constraints is used to delineate building clusters within the area and determine the optimal deployment location of 5G BS under each sub-cluster. (c) An Improved Self-Organizing Mapping (ISOM) model combines GIS and microgrid performance parameters to address the economically optimal connection of grid lines for DPV in 3D space. (d) Simulation experiments were conducted for the power output and profitability of eight different PV panels and tracking systems to calculate the economically optimal type of DPV generation hardware. The experimental results show that the BSSCP model proposed in this study reduced the 5G BS deployment cost input by up to 35.8974 % compared to that of the control experimental model. Meanwhile, the ISOM model obtained an average reduction of 52.3741 % in the cost of connecting cables for the optimized 25 DPV planning and DC microgrid topology. [ABSTRACT FROM AUTHOR]

• A CCHP system based on solar energy and thermochemical energy storage is proposed. • Increasing the share of solar energy used in combined cooling, heating and power (CCHP) systems. • The 4E analysis and parameter study of the system are carried out. • The SPECO method is done and provides direction for the optimization of the system. • The effects of the main parameters on the system performance were evaluated. The combination of calcium looping and concentrating solar power (CSP) is a promising energy conversion technology that can greatly increase the share of solar energy used in combined cooling, heating and power (CCHP) systems. This paper designs a CCHP system based on solar energy and thermochemical energy storage. The system runs all day through day and night modes. Under basic working conditions, the energy and exergy efficiencies of the system could reach 56.92 % and 35.94 %, respectively. The system is evaluated by multiple approaches including parametric sensitivity analysis and 4E (energy, exergy, economy and environment)) analyses. The results demonstrate that the system could produce 2618.09 MW of electricity, 305.56 MW of heat and 523.88 MW of cooling capacity per day, respectively. At the same time, the reductions of CO 2 emissions and fossil fuel consumption could reach 2222.76 tons and 696.41 m3 per day, respectively. Furthermore, the increasing mass flow of main turbine inlet could increase both the system efficiency and the exergy efficiency. Thus, it is beneficial to reduce the environmental impact but with the increasing investment cost. In the meanwhile, the exergoeconomic factor and exergoenvironment factor of the system were 55.65 % and 0.139, respectively. Besides, as the extraction flow rate of the intermediate pressure turbine increases, the energy efficiency increases but the exergy efficiency descends. This is unfavorable to reducing the environmental impact, yet it could decrease the investment cost of the system. These results reveal that the hybrid system has the characteristics of high efficiency and emission reduction in energy storage, power generation, heating and cooling, and has great development potential. [ABSTRACT FROM AUTHOR]

• We present a novel integration for reducing CO 2 emissions in blast furnaces. • It combines top gas recycling, oxy-fuel regime, power to gas and biomass pyrolysis. • The integration was modelled using the extended operating line methodology. • The best performance was found for pyrolysis at 700 °C. • The CO 2 emissions were reduced by 58% (9.8 MJ/kg CO2 energy consumption) The paper introduces a novel approach for mitigating CO 2 emissions in blast furnaces by integrating top gas recycling, an oxy-fuel regime, power to gas, and biomass pyrolysis. Various case studies were conducted, involving the adjustment of pyrolysis temperatures (300 °C, 500 °C, 700 °C, and 900 °C) and varying the quantity of blast furnace gas directed to methanation for carbon recycling. Pinus radiata, abundant and cost-effective in Chile and Spain, was chosen as the biomass source. The integration was modeled using the extended operating line methodology and evaluated through 12 key performance indicators, such as flame temperature, coke consumption, CO 2 emissions, and specific primary energy consumption per unit of CO 2 avoided. Optimal performance was observed with pyrolysis at 700 °C and no blast furnace gas recycled through methanation. This configuration achieved a 58 % reduction in CO 2 emissions, with an energy consumption of 9.8 MJ/kg CO2 , and obviated the need for geological storage. Comparing this innovative proposal with other oxygen blast furnace approaches from the literature revealed a 13 percentage point improvement in CO 2 reduction over the second-best alternative. Additionally, the required electrolysis capacity, influencing capital expenditure, was 57 % lower, and energy consumption was reduced by 44 %. [ABSTRACT FROM AUTHOR]

• Advanced climate-resilient energy retrofit technology reduces the use of non-renewable energy in the building sector. • Renewable District Heating as an optimal technology in deep energy renovation strategies. • Sustainable cities and buildings are feasible by Centralised District Heating system powered by biomass. • Key Performance Indicators (KPIs), to achieve nZEB performances established in the European legislations. This paper presents the implementation of a biomass-fuelled District Heating System (DHS), as a part of a deep energy renovation exercise to achieve a climate-resilient campus with minimum carbon dioxide emissions. The case study is carried out for the University of Valladolid, an average-sized university in Spain, with a continental weather climate. Prior to renovation, the different building blocks had a wide-ranging level of fossil fuel consumption for space heating and domestic hot water ranging between 60 and 430 kWh/m2·year. The application of this centralised heating system allows to achieve the minimum threshold for near zero-energy buildings (nZEB) of 100–120 kWh/m2, in accordance with the Spanish Standards. These values correspond to the maximum European indicators for offices in continental weather conditions. Results of this comprehensive study show that 15 out of the 19 buildings reached the nZEB target, due to the proposed strategy. The overall carbon dioxide emissions have dropped by 92.69% as compared to the original fossil-fuel powered boiler, thus bringing carbon dioxide emissions down to 1.57 kgCO 2 /m2·y. Therefore, it is shown that deep energy renovation strategies through renewable energy DHS have the potential of achieving nZEB for universities in continental weather conditions. [ABSTRACT FROM AUTHOR]

For an extensive decarbonization of district multi-energy systems, efforts are needed that go beyond today's cogeneration of heat and power in district multi-energy systems. The multitude of existing technical possibilities are confronted with a large variety of existing multi-energy system configurations. The variety impedes the development of universal decarbonization pathways. In order to tackle the decarbonization challenge in existing and distinct districts, this paper calculates a wide range of urban district configurations in an extensive co-simulation based on domain specific submodels. A district multi-energy system comprising a district heating network, a power grid, and cogeneration is simulated for two locations in Germany with locally captured weather data, and for a whole year with variable parameters to configure a power-to-heat operation, building insolation/refurbishment, rooftop photovoltaic orientation, future energy demand scenarios, and district sizes with a temporal resolution of 60 s, in total 3840 variants. The interdependencies and synergies between the electrical low-voltage distribution grid and the district heating network are analysed in terms of efficiency and compliance with network restrictions. Thus, important sector-specific simulations of the heat and the electricity sector are combined in a holistic district multi-energy system co-simulation. The clearly most important impact on emission reduction and fuel consumption is a low heat demand, which can be achieved through thermal refurbishment of buildings. Up to 46 % reduction in CO 2 emissions are possible using the surplus electricity from photovoltaics for power-to-heat in combination with central heat storage in the district's combined heat and power plant. Domestic hot water heated by district heating network in combination with power-to-heat conversion distributed in the district reduces the load on the distribution power grid. Even though the investigated measures already improve the sustainability significantly, providing the energy needed for the production of synthetic fuels remains the crucial challenge on the further path towards net-zero. • Cross-sectoral simulation of a district multi-energy system in 3840 configurations. • Impact quantification for different structural conditions and construction measures. • Calculation of the remaining effort to reach net-zero using synthetic fuels. [ABSTRACT FROM AUTHOR]

An oxycombustion spark-ignition engine coupled to an O 2 production cycle based on a mixed electronic-ionic ceramic-type membrane is studied in this paper. The exhaust gases drive oxygen production through a heat exchanger network and a set of turbochargers. Initially, a study at medium speed is carried out to determine the influence of the oxygen concentration and the engine compression ratio on the system performance. A 16.3 % of fuel consumption reduction is reached when 30 % of O 2 mass fraction and an engine compression ratio of 20 are implemented when compared with conventional engine operation. Then, a full load study in a wide range of engine speeds is performed, where a maximum fuel consumption reduction of 21 % is obtained at high speed (5000 rpm) comparing with conventional engine operation. The study shows the whole cycle has demonstrated promising performance parameters at different working conditions (O 2 mass fraction, compression ratio, engine load and speed). • A spark-ignition oxycombustion engine with onboard O 2 production has been modeled. • The membrane-based O 2 production is powered by waste heat from the exhaust gases. • Different O 2 concentrations and compression ratios have been compared. • Up to 21% lower fuel consumption than conventional combustion have been achieved. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel system for production and storage of H 2 with net-zero carbon emissions is developed. • High-temperature fuel cells and biogas upgrading unit are efficiently integrated. • Waste heat of the fuel cells is recovered in the Cu-Cl unit for hydrogen production. • Integrated process can generate 108 kmol/h liquid hydrogen and 18.88 MW power. • A hybrid method of the GA and artificial intelligence tools is applied for optimization. Global energy consumption has been exponentially increasing, leading to the depletion of conventional energy sources and a considerable increase in greenhouse gas emissions. The exploitation of sustainable energy sources and the development of innovative methods for mitigation of CO 2 emissions is necessary. Hydrogen (H 2) as a versatile and green fuel can be produced and stored in liquid form using sustainable energy sources through innovative methods. In this paper, a novel optimal hybrid structure is proposed for hydrogen production and storage with net-zero CO 2 emissions. A high-temperature fuel cell is utilized to reduce CO 2 emissions and supply the heat and power needed to produce and liquefy hydrogen. The hybrid configuration employs an electro-thermochemical unit for hydrogen production, molten carbonate fuel cells, a hydrogen liquefaction process, and a biogas upgrading by water scrubbing. A robust combination of meta-heuristic algorithms and artificial intelligence is developed to optimize the investment return period and energy/exergy efficiencies. The fuzzy Bellman-Zadeh, LINMAP, and TOPSIS techniques are also used to make decisions in multi-objective optimization. This innovative configuration generates 108 kmol/h liquid hydrogen, 18.88 MW power, 54 kmol/h oxygen, and 3258 kmol/h hot water. Pinch, sensitivity, exergy, and economic assessments are implemented to evaluate the performance of the hybrid structure. The thermal and exergy efficiencies of the proposed configuration are obtained to be 78.21 % and 64.83 %, respectively. The greatest portions of destructed exergy are resulted from the fuel cells-gas turbine hybrid system (63.63 %), electro-thermochemical unit (25.96 %), and biogas upgrading technology (6.23 %). The returns period on investment, the prime price of electricity, and the net benefit are computed as 4.854 years, 0.0420 US$/kWh, and 15.73 million US$/years, respectively, based on the energy potentials of Newfoundland and Labrador, Canada. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study conducts an innovative comparative analysis of energy indicators. • Primary energy rate and primary energy saving rate have same optimization effect. • Annual average comprehensive energy utilization efficiency cannot be lonely used. • Larger value of primary energy rate means reduction of carbon dioxide emissions. Combined cooling, heating and power system is an effective technology for energy conservation and environmental protection, especially for buildings with multiple demands on electricity, cooling and heating load. Various energy indicators have been proposed for evaluating and optimizing the energy efficiency of combined cooling, heating and power systems, but previous studies have not yet clarified how to use them in a reasonable way that takes their specific merits into account. This paper aims to identify the underlying effects of three common energy indicators, including the primary energy rate, primary energy saving rate, and annual average comprehensive energy utilization efficiency, based on the optimized performance of combined cooling, heating and power systems with different typical configurations. This paper proposes three combined cooling, heating and power system configurations for an office building in Kunming to conduct a comparative analysis of three energy indicators. Two common operation strategy (the following thermal load and following electricity load) and the genetic algorithm are selected to performed single-objective optimization with energy indicator as target. The economic and environmental analysis is also carried out to show the impact of energy indicators on other indicators. The results show that, the indicators primary energy rate and primary energy saving rate have the same optimization effect of energy consumption when the system configuration and operation strategy are identical, as the difference between the primary energy rate values is not more than 1%, and the difference between the primary energy saving rate values is not more than 0.5%. The advantage of primary energy rate is that the difference between the primary energy rate values of combined cooling, heating and power systems and reference system could show whether carbon dioxide emissions are reduced, and the advantage of primary energy saving rate is that its value directly indicates whether the system achieves energy-saving or not. Furthermore, the annual average comprehensive energy utilization rate is not suitable for the single-objective optimization of combined cooling, heating and power systems. This study distinguishes the differences between indicators and the conclusions are of general significance which could provide valuable guidance for designers to select optimal energy indicators applying to the optimization design of combined cooling, heating and power systems. [ABSTRACT FROM AUTHOR]

• Urban waterfronts are more suitable for conversion into positive energy districts than residential or more compact urban areas. • A methodology for planning positive energy districts in waterfronts is proposed. • Strategic scenario planning can assist urban planners to choose between scenarios toward positive energy districts in urban waterfronts. • The methodology is validated with a case study in Valencia, Spain. • Scenarios show a common path for a positive energy district in the case study. Cities consume two-thirds of the energy supply, and 70% of carbon dioxide equivalent emissions come from urban environments. Positive Energy Districts are innovative tools to achieve energy and climate neutrality in cities. Positive Energy Districts are regions or neighbourhoods with a positive annual energy balance, obtained mainly through energy efficiency and energy generation from renewables. Urban Waterfronts are extended areas close to the sea, which makes them suitable for several types of production with renewables, therefore seeming to be a suitable location to develop Positive Energy Districts. This paper proposes a method that combines strategic planning for project management and the procedure for energy audits to design the optimal district configuration. The study presents and analyses the case of La Marina de València, a district in a Mediterranean city. Three strategic scenarios, both technically feasible and with a positive energy balance, are presented. All the alternatives include PV and switching to light-emitting diode in lighting. The different strategies presented together with a sensitivity analysis facilitate the decision-making process in energy planning and establish a common pathway to achieve Positive Energy Districts in Urban Water Fronts. The results suggest that urban waterfronts are uniquely suited to achieve a positive annual energy balance, thus emerging as a crucial springboard to provide traction to the positive energy districts policy agenda. [ABSTRACT FROM AUTHOR]

• A comparison between energy communities modelled as aggregation of prosumers. • A multi-objective optimization of the design and operation of energy communities. • Demand Side Management as a powerful tool for improving the energy community design. • Reduction in the cost of energy and CO 2 emissions of 14% and 24%, respectively. • Community demand management enhances the exploitation of renewable energy sources. This paper focuses on three different configurations of energy communities (ECs) modelled as aggregations of local prosumers of renewable electric and thermal energy. The goal consists in improving the economic performance of the ECs while contributing to address the issue of climate change and fulfilling the existing energy demands or demands modified with smart strategies. Accordingly, type and size of the energy conversion and storage units of the prosumers included into ECs (design) and their operation are optimized with a bi-objective approach, considering investment and operation costs, and greenhouse gas emissions, both direct due to fuel burning, and indirect due to life cycle, as objectives to minimize. Moreover, two strategies of demand side management (DSM) are considered: a price-based demand response program applied downstream of the design optimization, and a new DSM model, which adapts the electricity demand to the renewable energy sources locally available, applied upstream of the design optimization. It results that the proposed DSM can ensure a better balancing between generation and demand profiles, thereby decreasing the stress on the electricity grid. Globally, ECs can reduce their energy expenditure of 14% and the overall CO 2 -equivalent emissions of 24% compared to the reference case of the simple consumers. [ABSTRACT FROM AUTHOR]

• A novel adjustable dual receiver for dish-Stirling cogeneration system is proposed. • A new accurate formula to calculate the focal spot diameter is proposed. • Control strategy of generation and heating switching based on irradiance is built. • Technical and economic indicators of the cogeneration system are evaluated. • Comprehensive energy efficiency can be increased by 55.83%. With the increasing global demand for carbon emission reduction, solar energy has received great attention worldwide, with solar dish Stirling system as a representative technology. However, some shortcomings of the conventional design limit its commercial application. In this paper, a novel solar dish Stirling cogeneration system (SDSCS) with adjustable dual receiver is proposed. A control strategy for switching between power generation and heat production modes is established, which is based on direct normal irradiance (DNI). In order to verify the system performance, three regions with significant differences in DNI levels in Tianjin, Yinchuan, and Lhasa were selected for comparison of technical and economic indicators. The results show that, compared with the conventional system that can only generate electricity, the SDSCS can achieve a significantly higher proportion of system running time in three regions at 14.66%, 24.53%, and 34.32%, respectively. The comprehensive energy efficiency shows the same trend at 55.83%, 53.91%, and 41.03%. In addition, the load satisfaction rate calculated by the day of the three regions is 43.05%, 81.46%, and 94.04%, respectively. In terms of levelized energy cost, the value of using SDSCS is 6.77 CNY/(kW·h), 3.37 CNY/(kW·h), and 1.94 CNY/(kW·h), lower than conventional system except for Tianjin. [ABSTRACT FROM AUTHOR]