Abstract

By reducing total travel time and travel distance, taxi ride-sharing is of great significance to decrease urban carbon emissions sourced from ground transport. Efficiency of taxi ride-sharing at metropolitan-wide scale can be challenged by heavy computation in matching multiple ride demands in. In this paper, a fast matching strategy based on time and distance constraints is proposed to filter candidates. Experiment shows that the strategy can reduce the times of candidate matching and improve the searching efficiency. An empirical analysis of potential taxi ride-sharing in two periods of a day (9:00-10:00,21:00-22:00) based on taxi GPS trajectory data in Qingdao shows that when tolerance time of delay time is 5 min, 35% of the total trips can be shared. Total travel time of all trips can be saved by nearly 222 hours and the total travel distance can be reduced by nearly 9200 km. CO, NOx, PM2.5 and fuel consumption can be saved about 6348g, 515g, 10g and 515.2kg during each period, respectively. Our study provides a positive evidence for potential emissions reduction by taxi ride-sharing, so as to support better understanding on low-carbon urban transport service.

Abstract

Environmental protection and technological innovation activities are key issues affecting urban sustainable development and value growth. using the data of 272 prefecture-level cities, this paper applying two-stage OLS to investigates how air pollution influences China’s technological innovation and its influential channels and, on the basis of the spatial effect of the spread of PM2.5 concentrations. The results of research indicate: the rise in air pollution significantly inhibits technological innovation level of regions as a whole. When considering the spatial effect of the spread of PM2.5 concentrations, due to the positive spillover effect of innovation activities, the spread of air pollution has negative impacts on the technological innovation activities of the surrounding cities. Human capital and labor cost are important channels through which air pollution influences China’s technological innovation. The implementation of carbon trading pilot policy can effectively reduce air pollution, thereby increasing technological innovation in China.

Abstract

In order to stimulate clean energy consumption, the Chinese government issued a guarantee mechanism for the accommodation of renewable energy in May 2019. It stipulated the minimum accommodation responsibilities of the total amount of renewable energy power and non-hydropower in each province. However, China’s electricity consumption and renewable energy resources are unevenly distributed. This will cause the mismatch problem between accommodation capacity and responsibility. So, each province has different levels of pressure to fulfill its responsibilities. We establish a renewable energy accommodation assessment model, which aims to propose a reasonable renewable energy optimal dispatch strategy to make full use of resources and complete the accommodation goal. First, we use support vector regression to predict power demand, and then establish a linear programming model to simulate renewable energy dispatch. Finally, an assessment index is constructed to estimate the level of pressure for each province to fulfill the accommodation responsibilities. The results show the flow of renewable energy across China in 2022. 347.7 and 86.4 TWh of hydropower and non-hydropower will be dispatched nationwide. Among them, 11 provinces face huge completion pressure.

Abstract

Residential thermostatically controlled loads are considered as an important demand response resource. Evaluating their response potential before demand response will help to improve the response effect. Based on the above situation, driven by smart meter data of residents, the electricity consumption mode of residential users is explored. A response potential evaluation model is proposed. Firstly, the residential load is clustered. And the basic curves of thermostatically controlled loads are given. Secondly, in demand response, a demand-side management scheme is proposed through quantitative optimization of user satisfaction. At the same time, the demand response potential is evaluated. Finally, the load data of households are selected for simulation to verify the validity of the evaluation model.

Abstract

Due to the requirements of clean development and economic transition, China’s natural gas consumption has grown rapidly over the years. However, the price of natural gas in China has been regulated by the government for a long time. Cross-subsidy and price inversion have distorted price mechanism, and are not conducive to the development of the natural gas market. In June 2013, nationwide price reform was implemented in the non-residential sector. To explore the effect of the reform on price distortion, this paper uses monthly data from 27 key cities to estimate the scale and rate of natural gas price subsidy from 2008 to 2017. The results show that the natural gas subsidy is still severe, and there are differences between sectors. The time interval in the implementation of the policy provides a quasi-natural experiment for studying the reform. The difference-in-difference-in-difference estimations prove that the natural gas pricing reform has significantly cut down the subsidy rate in the non-residential sector, and an effective terminal pricing mechanism has been conducted.

Abstract

Smart home, with the Internet of Things as the core, will substantially change the time scale of residents’ electricity consumption, increase the flexibility of power load, and provide more opportunity for demand response and related services, but also bring huge uncertainties. Focus on the transferable function of smart home working time, we are committed to exploring the possible changes of smart home participating in demand response. Here, we establish the smart-home integrated management model with goals of minimizing the electricity cost and peak-valley difference, and provide an optimization scheme that integrates smart home into demand response. Furthermore, the peak shaving potential of smart home participating in demand response and its impacts on power supply and grid investment are evaluated. Our results show that the time-of-use policy can reduce the peak-valley difference between -29.2% and -23.9%, and cut electricity cost by up to 9.5%, which is conducive to encouraging smart home to participate in demand response. The shift of working time in smart home may increase power consumption and increase residential electricity costs by 4.8%-11.5%. In the unconstrained dispatch mode, driven by smart home participation in demand response, it is expected to reduce the peak load of the power grid by 141 to 149 million kilowatts, and reduce power supply and power grid investment by 1.13-1.19 trillion yuan.

Abstract

In this paper, the loss of silicon carbide (SiC) MOSFETs based electric vehicle (EV) traction systems are investigated comprehensively. The loss of SiC MOSFETs are analyzed and modeled based on the commutation process in the inverter. The analysis model includes parasitic inductance, parasitic capacitance nonlinearity, transconductance nonlinearity, body diode reverse recovery, and parasitic capacitance charging and discharging. The simulation results confirm the losses models of SiC MOSFETs.

Abstract

The high heat flux on the PV cells can lead to the decrease of electricity efficiency. To tackle with the high temperature problems in PV cells microchannel is attracting increasing attentions recently due to its much higher heat flux. In this paper, the characteristics of flow boiling pressure drop and heat transfer of deionized water flow boiling in a microchannel with hydraulic diameter of 400 μm had been experimentally investigated. To further understand the effect of variation of solar radiation on cooling performance of the PV cells, unsteady and steady heat flux were respectively used and the corresponding pressure drop and heat dissipation of the microchannel under different mass fluxes (G=410.69, 513.36 and 718.71 kg/m2s) were studied. It was found that with the increase of heat flux, the pressure drop first shows a slight downward trend, then increases sharply. The average heat transfer coefficient and local heat transfer coefficient increase with the increase of heat flux and decrease with the increase of mass flux. With the sudden increase of heat flux, a much longer variation of the pressure drop and wall temperature was observed.

Abstract

With the urgent demand on the optimization from both aspects of water quality and energy consumption, the efficiency of WWTPs from a water-energy nexus perspective appears to be increasingly important. In this study, the energy efficiency of 210 WWTPs in Yangtze River Delta of China were assessed through data envelopment analysis (DEA). The operational conditions of DEA were polished through a hierarchical framework. All WWTPs were classified into 4 categories of anaerobic-anoxic-oxic (AAO), anaerobic-oxic (AO), oxidation ditch (OD) and sequencing batch reactor (SBR). And the variables derived from the indicators were revised through production possibility set (PPS) in order to remove the ratio form. The results showed that WWTPs in Yangtze River Delta had a high efficiency overall. It also indicated that advanced treatment process didn’t have a remarkable impact on the efficiency. Moreover, there were much room for the optimization on pollutant removal in terms of the ideal discharge limit converted from the projection.

Abstract

In this paper, Ag nanoparticles (NPs) were synthesized through reduction method and suspended in glycol. The obtained Ag nanofluid (NF) exhibited high absorptivity in the visible light wavelengths and good transmittance in the spectral response range of silicon PV cell. In addition, the effect of high temperature on spectral characteristics and stability of Ag NFs were measured by gravitational sedimentation experiments and transmission spectroscopy. The results showed that a slight increase in transmittance was observed in visible region when Ag NF was heated to 100 °C. In contrast, the spectral characteristics in the near-infrared band (NIR) presented different tendencies along with the rise of temperature. The experimental results also demonstrated that as-obtained Ag NFs performs stable at high temperatures, thus can be an optimal spectral filter for the spectral splitting PV/T system.