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Acid mine drainage (AMD) is a worldwide environmental problem, characterized by low pH values and high concentrations of heavy metals. Heavy metal pollution of sediments caused by AMD has attracted widespread attention. However, research works on the leachability and distribution characteristics along with the ecological and health risks assessment of AMD-polluted sediment are limited. 15 sediments samples were collected from an AMD-polluted river, Shandi River, North China to analyze the leachability concentration, potential sources, and associated risk of eight metals, namely Ni, Cd, Cu, Zn, Fe2+, Fe3+, Pb, and Mn. Our results showed that Mn, Ni, Fe3+, and Fe2+ were the main leachate pollutants in the Shandi river. Certain levels of ecological risks existed in AMD-polluted stations and Ni was the common key metal that caused the high ecological risk factor in S1, S2, and S4. Cu, Ni, and Zn were the three metals that caused high or moderate risk to zebrafish. Mn and Fe were the main heavy metals that caused non-carcinogenic risks both for adults and children and Ni was another main heavy metal that caused non-carcinogenic risks for children. Ni and Cd can induce carcinogenic risks in these areas. Pearson's correlation and PCA results supported that these metals possibly originate from common AMD–polluted sources. The technology of "gravitational settling-neutralizing filter-aeration-coagulation-filtration" (GSNFACF) was an effective strategy to amend AMD and could be used for future cleaner production and environmental sustainability. These results suggested that the main contaminants in the sediments of the Shandi River should be preferentially treated by the government. [ABSTRACT FROM AUTHOR]

The combined cooling, heating and power (CCHP) system is an energy efficient system that the premium characteristic is the energy cascade utilization. However, there is a mismatch problem between system supply and building demands. This paper proposes a solar-assisted CCHP system with thermal storage so as to effectively reduce the waste of energy. The components including solar heat collector, internal combustion engine and heat storage tank are modeled based their thermodynamic performances. An office building in Beijing is selected as a feasibility case and the impact of solar energy and thermal storage on the thermodynamics performance of the CCHP system is analyzed in detail. The results shows that when this system operates following thermal load, the system energy efficiency and COP decrease with the increase of solar energy, while exergy efficiency appears a slight fluctuation. Additionally, the variations of adjustable cooling compared to the system without thermal storage are discussed. It is concluded that thermal storage involved in the solar-assisted CCHP system contributes to expand the variations of adjustable cooling evidently. [ABSTRACT FROM AUTHOR]

This study aims to present a thermodynamic performance analysis and to optimize the configurations of a hybrid combined cooling, heating and power (CCHP) system incorporating solar energy and natural gas. A basic natural gas CCHP system containing a power generation unit, a heat recovery system, an absorption cooling system and a storage tank is integrated with solar photovoltaic (PV) panels and/or a heat collector. Based on thermodynamic modeling, the thermodynamic performance, including energy and exergy efficiencies, under variable work conditions, such as electric load factor, solar irradiance and installation ratio, of the solar PV panels and heat collector is investigated and analyzed. The results of the energy supply side analysis indicate that the integration of solar PV into the CCHP system more efficiently improves the exergy efficiency, whereas the integration of a solar heat collector improves the energy efficiency. To match the building loads, the optimization method combined with the operation strategy is employed to optimize the system configurations to maximize the integrated benefits of energy and economic costs. The optimization results of demand–supply matching demonstrate that the integration of a solar heat collector achieves a better integrated performance than the solar PV integration in the specific case study. [ABSTRACT FROM AUTHOR]

Energy storage is an effective method to match the incompatibility of the ratio of heat to electricity between a combined cooling heating and power (CCHP) system and its users. This paper proposes an internal combustion engine CCHP system integrated with two types of thermal energy storage, which are accorded with energy levels of the waste heats of jacket hot water and exhausted gas after power generation. Correspondingly, two types of storage technologies including a hot water tank and a molten salt tank are introduced into the CCHP system. Then, the thermodynamic models are constructed, and two operation strategies are established to coordinate the operation of the thermal energy storage tanks. Through a case study, their performances are compared from three aspects: primary energy ratio, adjustable area of ratio of heating/cooling to electricity and application in different building loads. The results in summer work condition indicate that the CCHP system integrated with the jacket water storage tank achieves a primary energy ratio of 83.8% and a ratio of cooling to electricity of 2.24, which are both better than the integration of exhausted gas storage tank. These characteristics show that the CCHP system with thermal energy storage tank is more suitable to adopt the operation strategy in which the exhausted gas is adopted to drive the absorption chiller/heater, while the jacket water is used to store heat when the waste heat is larger than the heat demand. [ABSTRACT FROM AUTHOR]

The low-carbon economic operation of integrated energy systems (IES) cannot be separated from the carbon trading and green certificate trading market. Therefore, a low-carbon market mechanism and optimization method for IES is proposed. First, we establish a "green-carbon" offset mechanism to realize the conversion from tradable green certificate (TGC) to carbon quotas to offset system's carbon emissions. Second, considering the impact of market incentives and users' consumption behavior on IES, an energy management method of IES is put forward based on Stackelberg game. IES operators as leaders decide energy prices and trading strategies of carbon, TGC and multi-energy. Energy users as followers participate in the integrated demand response based on energy price. The game is solved by an improved adaptive catastrophic genetic algorithm and CPLEX solver. Finally, we take an industrial park in China as an example to analyze. The results show that the proposed method can significantly reduce the system's carbon emissions while improving the benefits for both IES and consumers. • A mechanism is proposed to offset system carbon emissions with green certificates. • An intelligent pricing and optimal method is proposed based on Stackelberg game. • Carbon capture and power-to-gas technology are used to reduce carbon emissions. • Key parameters sensitivity of the offset mechanism is analyzed for specific cases. [ABSTRACT FROM AUTHOR]