Abstract

Using the Gompertz method and the elastic coefficient approach, we forecast vehicle ownership and GHG emissions, focusing on Shenzhen City as case study. We also factor in the learning curve associated with EV battery costs into our dynamic cost-benefit model. Scenario analysis reveals that Shenzhen’s incremental car restriction policy decreased the number of cars by 18.7% in 2017 alone. By actively promoting EVs in a net zero carbon scenario, it’s feasible that CO2 emissions might reach their peak as soon as 2020. Our cost-benefit analysis indicates that improving fuel economy policies for vehicles yields higher marginal abatement benefits. Although the initial push for EVs may result in elevated marginal abatement costs due to infrastructure investments, anticipated long-term reductions in battery costs, driven by economies of scale, could offset these costs, potentially even leading to net benefits.

Abstract

Rooftop photovoltaics (RPVs) play a crucial role in reducing urban carbon emissions and aiding the shift toward net-zero energy systems. However, the complexities of urban settings introduce significant variability in RPV costs across different locations and times. This study focuses on the Pingshan District in Shenzhen, a representative example of cities in southern China. The study analyzes geometric characteristics and community types from various urban areas to perform K-means++ clustering. These typical community types are then used to comprehensively assess RPV deployment in terms of energy, environment, and economics. The study provides practical strategies for integrating RPVs, offering insights that contribute to sustainable urban energy transitions.

Abstract

The rapid adoption of shared electric micro-mobility solutions, such as e-scooters and e-mopeds, has addressed the need for low-carbon transportation and efficient last-mile travel. However, challenges persist due to insufficient parking and charging infrastructure. This study introduces an innovative shared electric micro-mobility hub prototype, incorporating PV panels to provide energy and shared power bank stations for battery storage. Through a comprehensive case study, the economic and environmental benefits of different micro-mobility configurations and energy management strategies are evaluated. The results demonstrate that the micro-mobility with appropriately configured PV and shared power bank station can reduce carbon emissions by 99% and achieve a net income within one year. This research not only advances sustainable urban transportation but also provides a model for integrating various shared services, contributing to a more environmentally friendly and versatile urban lifestyle.

Abstract

The booming electric vehicle (EV) charging facilities play a vital role in connecting road transport networks to the urban power grid, as they have internal smart converters with four-quadrant power regulation capability. These converters can provide reactive power to regulate the voltages of urban distribution power grids. Considering the high scarcity of urban spatial resources, there are many restrictions on configuring additional capacitors or other voltage regulating devices. It is of significance to accurately assess the volt/var support capability from the charging facilities on urban grid voltage regulation. This paper constructs a road traffic network model and EV behavior characteristic models for private cars, cabs, and urban service vehicles, respectively. Then, a method for spatial and temporal charging load prediction as well as reactive power flexibility assessment is proposed considering dynamic traffic flow. The assessment results are adopted as boundaries for chargers participating the volt/var regulation of urban power distribution system. The voltage qualification rate indicators are investigated to verify the effectiveness of the proposed regulation method. The results of this paper are helpful for understanding the coupled urban electrified road transportation and power system facilities from a new perspective of volt/var regulation.

Abstract

Due to their environmentally friendly and energy-saving characteristics, regional distributed energy systems (RDES) have become one of the important ways to enhance renewable energy consumption and promote low-carbon society in recent years. The bottleneck of using peak load of user nodes in the division of energy supply scope at energy stations without full considering the load timing characteristics is addressed in this paper. Furthermore, this paper proposes a collaborative optimization method that considers load timing characteristics. Firstly. the coupling characteristics between energy stations and pipeline network are analyzed. Then a collaborative optimization design model for energy stations and pipeline networks is constructed based on K-means and graph theory algorithms. Subsequently, considering the load timing characteristics to analyze their impact on REDS. The research results indicate that considering the load timing of user nodes can reduce the cooling load demand of energy stations by 19.05% and the total pipeline cost by 8% compared to using peak loads. This paper provides theoretical and technical guidance significance for decision-makers of regional distributed energy systems.

Abstract

The CO2 methanation (that is, Sabatier reaction), has been considered as a promising way to recycle and utilize CO2. However, the industrial Sabatier process is energy intensive and traditionally powered by fossil fuels. Harvesting solar energy for the conversion of CO2 into solar fuels offers a sustainable and green solution to alleviating energy and environmental issues. In this work, solar-driven CO2 methanation over nickel-based catalysts was investigated under concentrated solar irradiation. A CO2 conversion rate of approximately 87%, with 100% selectivity towards CH4 and a reaction rate of 380 mmol/gNi/h were achieved under concentrated UV-visible-IR irradiation at 350 °C on 15 wt% Ni/Al2O3. The temperature required to achieve maximum CO2 conversion for the nickel-based catalysts were 25 °C lower in the solar-driven process compared to conventional thermocatalytic process. Meanwhile, the apparent activation energy of the solar-driven reaction is 25% lower than that of the thermocatalytic reaction. Moreover, in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments were performed to gain an in-depth insight into the enhancement mechanisms of light in the solar-driven process. This study emphasizes the merits of utilizing concentrated solar energy for driving chemical reactions, revealing the promotion of the reaction by light and offering new insights into the reaction mechanism of solar-driven CO2 methanation over Ni-based catalysts.

Abstract

The smart PV window, integrated of solar cells and electrochromic coating, is of great significance in the pursuit of building decarbonization, as it combines power generation and radiation modulation capabilities. This study aims to unraveling the untapped potential of smart PV windows in the realm of enhancing building energy conservation and flexibility in hot climates. To achieve this objective, a co-simulation approach utilizing EnergyPlus and Radiance software is employed, along with the implementation of the EMS module to control the coloring states of the smart PV window. The findings reveal that, compared to the Low-E window, the smart PV window with solar radiation control improves the proportion of the useful daylight illuminance by 61.8%, yields a significant reduction in peak load by 72.3%, a decrease in monthly net energy consumption by 53.9%, and an enhancement in energy flexibility by 51.8% in Hong Kong (22.32°N, 114.17°E).

Abstract

An optimization model is used to design a hydrogen production system under different constraints for CO2 emissions, focusing on Japan as case of study. Two scenarios were considered: Base scenario, focusing on minimizing cost; and WEC scenario focusing on balancing energy use, water use and CO2 emissions. Domestic natural gas alone is not enough to produce 1 Mt-H2/year and electrolysis is used for all CO2 intensities. For low CO2 intensities, Base scenario uses hydroelectricity and geothermal electricity; while WEC scenario uses solar electricity and wind electricity. Zero-emission hydrogen production needs installed capacities for electrolyzers of 8.45 and 30.3 GW in Base and WEC scenarios, respectively.

Abstract

This work proposes a combined cycle, a gas turbine power generation system and a CO2 cycle power generation system built on the basis of the Ericsson cycle. In this paper, the structure of the combined cycle system is firstly constructed, the temperature-entropy diagram of the gas-CO2 system is plotted, the simulation model is built on the simulation software platform and its accuracy and validity are verified, and the effects of CO2 flow rate, pressure ratio, ambient temperature and gas turbine loading rate on the power generation efficiency and primary energy utilization efficiency of the combined system are studied and analyzed. The simulation results have led to the optimal operating conditions of the gas-CO2 combined cycle, which provides a new technical idea for the future utilization of waste heat energy.

Abstract

In this study, a microcosm experiment for 120 days exposure of microplastics (MPs) on cold seep sediment was conducted. The results showed that different types and doses of MPs addition negatively affected the anaerobic oxidation of CH4. The CH4 oxidation rates with 0.05 % PA and PET addition were only account for approximately 33% of that for the biotic control group. MPs addition did not significantly influence the archaeal community structures but caused a redistribution of bacterial community compositions. The addition of PA, PE, and PET could significantly increase the relative abundance of Desulfobacterota and made Caldatribacteriota almost undetectable. By the present study, we can have a preliminary understanding of the effects of microplastics on anaerobic oxidation of CH4 and prokaryotic communities in the cold seep sediment.