Chemical Utilization of CO2 for grid-scale energy storage: a prospective scenario of China and global energy connection

Utilizing carbon dioxide (CO2) sequestered from large point sources to produce fuels and chemicals has been proposed as an energy carrier of storing intermittent renewable energy. The integrated technology is Power to Gas (PtG), or Power to Liquid (PtL) process. In the scenario of very-high installed renewable energy source (RES\u3e80%) or curtailed wind/solar energy, the RES+PtG/ PtL will play an important role of energy transition while fossil fuels are phased out. The study reviews and assesses the technology development, economic feasibility, system impact and future outlook in prospective of grid-scale analysis and global energy interconnection

Household Energy Consumption Analysis-based Electricity Plan Recommender System

Deregulation of the retail electricity market has led to an increasing number of electricity plans with competitive rates. Also, the extensive integration of renewable energy resources and the broad deployment of energy conversion facilities have led to a shift in how energy is produced, consumed, and traded. These shifts will significantly affect customers' energy usage patterns, affecting the choice of electricity plan. As a result, customers now have more flexibility in choosing an electricity plan based on individual consumption needs. However, faced with many electricity plans and a more complex energy consumption structure in the electricity market, it is increasingly difficult for customers to choose suitable and cost-effective electricity plans. In this thesis, an electricity plan recommender system (EPRS) is proposed for helping the customer get the right electricity plan. This system integrates missing feature values estimation, Feature Crosses construction, the residential PV system and energy sharing modelling, and electricity plan recommendation. Furthermore, through feature engineering and optimization methods proposed in this thesis, the EPRS with improved performance can be obtained. EPRS only takes easy-to-obtain household appliance usage features as inputs and outputs optimal electricity plans for customers. Through the real electricity market data test, the EPRS shows excellent performance. The missing feature values estimation and Feature Crosses construction methods proposed in this research can significantly enhance the recommendation accuracy. Considering residential PV systems and energy sharing can make the EPRS more practical. This thesis constructs a complete EPRS with high application values, which provides more accurate customer recommendations and more reasonable pricing references for retailers

An empirical analysis of dockless bike-sharing utilization and its explanatory factors: Case study from Shanghai, China

Revealing dockless bike-sharing utilization pattern and its explanatory factors are essential for urban planners and operators to improve the utilization and turnover of public bikes. This study explores the dockless bike-sharing utilization pattern from the perspective of bike using GPS-based bike origin-destination data collected in Shanghai, China. In this paper, utilization patterns are captured by decoupling several spatially cohesive regions with intensive bike use via non-negative matrix factorization. We then measure the utilization efficiency of bikes within each sub-region by calculating Time to booking (ToB) for each bike and explore how the built environment and social-demographic characteristics influence the bike-sharing utilization with ordinary least squares (OLS) regression and geographically weighted regression (GWR) models. The matrix factorization results indicate that the shared bikes mainly serve a certain area instead of the whole city. In addition, the GWR model shows higher explanatory power (Adjusted R2 = 0.774) than the OLS regression model (Adjusted R2 = 0.520), which suggests a close relationship between bike-sharing utilization and the selected explanatory variables. The coefficients of the GWR model reveal the spatial variations of the linkage between bike-sharing utilization and its explanatory factors across the study area. This study can shed light on understanding the demand and supply of shared bikes for rebalancing and provide support for operators to improve the dockless bike-sharing utilization efficiency

Key technologies for extraction and identification of gas target area for pressure relief in inclined thick coal seam

In order to study the dip angle effect on the evolution law of the target area for pressure relief gas drainage in inclined thick coal seams, the physical similarity simulation test and theoretical analysis were combined to study the fracture evolution in the target area under different coal seam dip angles. The evolution law of broken fracture’s width, the area proportion of bed-separated fracture, and the fractal dimension of fracture with the change of coal seam dip angle in the target area were obtained, and then the coal seam dip angle effect model of the targeted area evolution was established. The results showed that the broken fracture’s width presented the distribution characteristics that the boundary area on both sides of the goaf was greater than that in the middle, and the low horizon was greater than that in the higher horizon. What’s more, the broken fracture’s width was strongly affected by the hinged beam. With the increase of the coal seam dip angle (0° < 15° < 30°), the broken fracture’s width in the upper region of the first layer of hinged beam is significantly reduced compared with that in the lower region, which is only 52.8%, 64.3%, and 71.1%, respectively. The area proportion of bed-separated fracture in the dominant gas migration channel zone was the largest at the bottom, followed by the top, and the smallest in the middle. The fractal dimension of overlying fractures decreased first and then increased as a whole. The fracture evolution laws were obviously different on both sides of the layer where the hinged beam of the first layer and the minimum fractal dimension of the fracture were located. Therefore, the dominant channel belt of gas migration was divided into low-layer target areas, middle-layer target areas, and high-layer target areas according to the level of the spatial horizon. Finally, based on the theory of mining fracture ellipse belts and the dominant gas migration channel zone at the working face side, the mathematical equation of the target area in inclined thick coal seams was established considering the coal seam dip angle, and the basis for selection of pressure relief gas drainage methods in the targeted area was formed. It provided a reference for optimizing the parameters of pressure relief gas drainage in an inclined, thick coal seam working face

Continental-scale magnetic properties of surficial Australian soils

Soil magnetism reflects the physical properties of mainly iron oxide and oxyhydroxide minerals, which provides important information for deciphering soil environments. Establishing national scale soil magnetic databases can provide important reference information that can assist mineral surveying and agricultural planning. Our aims are to provide visualizations and to describe multiple magnetic properties across Australia, to evaluate the relationship between soil magnetism and soil forming factors, and to interpret the mechanisms responsible for surface soil magnetism in Australia. We present the first surficial Australian soil magnetic database, which contains 471 topsoil samples of natural and unpolluted materials. The samples were characterized with detailed magnetic measurements, which show that the magnetic properties of Australian soils vary considerably, but most surficial soils have small concentrations of coarse-grained magnetic minerals. The vast central Australian interior is characterized by weak magnetism, with more hematite and goethite contribution. Strong magnetic hotspots occur in the northwestern plateau, Nullarbor Plain, and eastern highlands. Parent material acts as the dominant control on soil magnetic properties, influencing magnetic mineral concentration and grain size, and controlling the contribution and relative importance of hematite to goethite. Temperature and rainfall both have a weak negative influence on superfine ferrimagnetic particles, due to progressive transformation to hematite and particle migration driven by intensive rainfall in sandy soils. Biota and land use changes tend to have a more complex and integrated local influence on hematite and goethite formation and preservationThis work was supported by the Australian Research Council through grants DP160100805 and DP19010087