CAS Guangzhou Institute of Energy Conversation

Guangzhou, China

CAS Guangzhou Institute of Energy Conversation

Guangzhou, China

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Cathles L.M.,Cornell University | Su Z.,CAS Guangzhou Institute of Energy Conversation | Chen D.,CAS Guangzhou Institute of Geochemistry
Marine and Petroleum Geology | Year: 2010

Pockmarks form where fluids discharge through seafloor sediments rapidly enough to make them quick, and are common where gas is present in near-seafloor sediments. This paper investigates how gas might lead to pockmark formation. The process is envisioned as follows: a capillary seal traps gas beneath a fine-grained sediment layer or layers, perhaps layers whose pores have been reduced in size by hydrate crystallization. Gas accumulates until its pressure is sufficient for gas to invade the seal. The seal then fails completely (a unique aspect of capillary seals), releasing a large fraction of the accumulated gas into an upward-propagating gas chimney, which displaces water like a piston as it rises. Near the seafloor the water flow causes the sediments to become "quick" (i.e., liquefied) in the sense that grain-to-grain contact is lost and the grains are suspended dynamically by the upward flow. The quickened sediment is removed by ocean-bottom currents, and a pockmark is formed. Equations that approximately describe this gas-piston-water-drive show that deformation of the sediments above the chimney and water flow fast enough to quicken the sediments begins when the gas chimney reaches half way from the base of its source gas pocket to the seafloor. For uniform near-surface sediment permeability, this is a buoyancy control, not a permeability control. The rate the gas chimney grows depends on sediment permeability and the ratio of the depth below seafloor of the top of the gas pocket to the thickness of the gas pocket at the time of seal failure. Plausible estimates of these parameters suggest gas chimneys at Blake Ridge could reach the seafloor in less than a decade or more than a century, depending mainly on the permeability of the deforming near-surface sediments. Since these become quick before gas is expelled, gas venting will not provide a useful warning of the seafloor instabilities that are related to pockmark formation. However, detecting gas chimney growth might be a useful risk predictor. Any area underlain by a gas chimney that extends half way or more to the surface should be avoided. © 2009 Elsevier Ltd. All rights reserved.


Xu C.-G.,CAS Guangzhou Institute of Energy Conversation | Xu C.-G.,CAS Guangzhou Center for Gas Hydrate Research | Li X.-S.,CAS Guangzhou Institute of Energy Conversation | Li X.-S.,CAS Guangzhou Center for Gas Hydrate Research
RSC Advances | Year: 2014

Hydrate-based CO2 separation and capture from gas mixtures containing CO2 has gained growing attention as a new technology for gas separation, and it is of significance for reducing anthropogenic CO 2 emissions. Previous studies of the technology include the thermodynamics and kinetics of hydrate formation/dissociation, hydrate formation additives, analytical methods, separation and capture progress, equipment and applications. Presently, the technology is still in the experimental research stages, and there are few reports of industrial application. This review examines research progress in the hydrate formation process and analytical methods with a special focus on laboratory studies, including the knowledge developed in analog computation, laboratory experiments, and industrial simulation. By comparing the various studies, we propose original comments and suggestions on further developing hydrate-based CO2 separation and capture technology. © 2014 The Partner Organisations.


Li X.-S.,CAS Guangzhou Institute of Energy Conversation | Li B.,CAS Guangzhou Institute of Energy Conversation | Li G.,CAS Guangzhou Institute of Energy Conversation | Yang B.,CAS Guangzhou Institute of Energy Conversation
Energy | Year: 2012

Based on the geological data of the Qinghai-Tibet plateau permafrost, such as the permafrost ground temperature, the thermal gradient within and below the frozen layer, we numerically investigate the gas production potential from hydrates at the DK-3 drilling site of the Qilian Mountain permafrost, which is located in the north of the Qinghai-Tibet plateau. We employ the huff and puff method using a single horizontal well in the middle of the Hydrate-Bearing Layer (HBL). The simulation results indicate that desirable gas-to-water ratio and energy efficiency can be obtained under suitable injection and production conditions in the huff and puff process. However, the absolute gas production rate remains low during the whole production process. The sensitivity analysis indicates that the gas production performance is strongly dependent on the intrinsic permeability of the hydrate deposits, the sediment porosity, the injection and production rates, the temperature of the injected water, the irreducible water saturation and P 01. The relative permeability exponents appear to have limited effect on the gas production behavior using the huff and puff method. The sensitivity analysis also indicates that the production potential of the natural gas hydrate deposit will be better than that of pure methane hydrate in this simulation. © 2012 Elsevier Ltd.


Li H.,CAS Guangzhou Institute of Energy Conversation | Ma W.,CAS Guangzhou Institute of Energy Conversation | Wang X.,CAS Guangzhou Institute of Energy Conversation | Lian Y.,CAS Guangzhou Institute of Energy Conversation
Renewable Energy | Year: 2011

Solar radiation measurements are not easily available, especially for the diffuse solar radiation. In this study, two models for estimating the diffuse solar radiation are proposed based on multiple predictors including the clearness index, relative sunshine duration, ambient temperature and relative humidity. One of them aims to increase the estimation accuracy, and the other aims to estimate the diffuse solar radiation direct from other meteorological elements in the absence of the global solar radiation. For a case study, the performance of the proposed models is validated by comparing with eight existing models selected from literature against the measured data at Guangzhou station in China. Through the analysis based on statistical error tests, results show that the two models can estimate the monthly average daily diffuse solar radiation with good accuracy. © 2011 Elsevier Ltd.


Ma L.,CAS Guangzhou Institute of Energy Conversation | Wang T.,CAS Guangzhou Institute of Energy Conversation | Liu Q.,CAS Guangzhou Institute of Energy Conversation | Zhang X.,CAS Guangzhou Institute of Energy Conversation | And 2 more authors.
Biotechnology Advances | Year: 2012

Biomass, a renewable, sustainable and carbon dioxide neutral resource, has received widespread attention in the energy market as an alternative to fossil fuels. Thermal-chemical conversion of biomass to produce biofuels is a promising technology with many commercial applications. This paper reviewed the state-of-the-art research and development of thermal-chemical conversion of biomass in China with a special focus on gasification, pyrolysis, and catalytic transformation technologies. The advantages and disadvantages, potential of future applications, and challenges related to these technologies are discussed. Conclusively, these transformation technologies for the second-generation biofuels with using non-edible lignocellulosic biomass as feedstocks show prosperous perspective for commercial applications in near future. © 2012 Elsevier Inc.


Zhu Z.,Nankai University | Hong M.,Nankai University | Guo D.,Nankai University | Shi J.,CAS Guangzhou Institute of Energy Conversation | And 2 more authors.
Journal of the American Chemical Society | Year: 2014

The cathode capacity of common lithium ion batteries (LIBs) using inorganic electrodes and liquid electrolytes must be further improved. Alternatively, all-solid-state lithium batteries comprising the electrode of organic compounds can offer much higher capacity. Herein, we successfully fabricated an all-solid-state lithium battery based on organic pillar[5]quinone (C35H20O10) cathode and composite polymer electrolyte (CPE). The poly(methacrylate) (PMA)/poly(ethylene glycol) (PEG)-LiClO4-3 wt % SiO2 CPE has an optimum ionic conductivity of 0.26 mS cm-1 at room temperature. Furthermore, pillar[5]quinine cathode in all-solid-state battery rendered an average operation voltage of ∼2.6 V and a high initial capacity of 418 mAh g-1 with a stable cyclability (94.7% capacity retention after 50 cycles at 0.2C rate) through the reversible redox reactions of enolate/quinonid carbonyl groups, showing favorable prospect for the device application with high capacity. © 2014 American Chemical Society.


Yan X.,CAS Guangzhou Institute of Energy Conversation | Zhang L.,CAS Guangzhou Institute of Energy Conversation
Journal of Applied Electrochemistry | Year: 2013

Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) counter electrodes, doped with polyethylene glycol (PEG) and acetylene black as binding and conductivity promoting agent, were prepared by a simple mixing method for dye-sensitized solar cell. The electrochemical properties of the electrodes were characterized by cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and Tafel polarization curves. Using PEG dopant, the electrocatalytic activity of PEDOT:PSS electrode was much improved, and further improved by adding a small amount of conducting acetylene black (0.2 wt%). The DSSC cells, using the PEDOT:PSS electrode with PEG (5 wt%) dopant and the composite electrode with PEG (5 wt%)/acetylene black, exhibited an energy conversion efficiency of 3.57 and 4.39 %, comparable with 4.50 % of the commonly used Pt electrode under the same experimental conditions. These results demonstrate that PEG-modified PEDOT:PSS counter electrode is promising to replace the expensive Pt for low cost DSSC, especially to meet the large-scale fabrication demands. © 2013 Springer Science+Business Media Dordrecht.


Dong L.,CAS Guangzhou Institute of Energy Conversion | Dong L.,CAS Guangzhou Institute of Energy Conversation | Zhenhong Y.,CAS Guangzhou Institute of Energy Conversion | Yongming S.,CAS Guangzhou Institute of Energy Conversion
Bioresource Technology | Year: 2010

An innovative municipal solid waste separation technology - water separation was developed in China recently. The purpose of this study was to evaluate the feasibility of anaerobic digestion from water sorted organic fraction of municipal solid waste (WS-OFMSW) to methane. A group of bench-scale (35 L) mesophilic (30 ± 2 °C) batch anaerobic digestions were carried out with three total solids in reactor (TSr = 16.0%, 13.5% and 11.0%). The biodegradability of WS-OFMSW with VS/TS of 61.6% was better than that of mechanically sorted OFMSW but still poor than that of source sorted OFMSW. No inhibitions of metal ions, volatile fatty acids and ammonia on anaerobic digestion were found. The reactors with TSr 16.0%, 13.5% and 11.0% achieved methane yield of 273, 283 and 314 L/kgVS and VS removal rate of 26.1%, 35.8% and 41.8%, respectively. The average methane content in biogas was about 66% for all reactors. © 2009 Elsevier Ltd. All rights reserved.


Li G.,CAS Guangzhou Institute of Energy Conversation | Li X.-S.,CAS Guangzhou Institute of Energy Conversation | Li B.,CAS Guangzhou Institute of Energy Conversation | Wang Y.,CAS Guangzhou Institute of Energy Conversation
Energy | Year: 2014

The combination forms of the hydrate dissociation methods in different well systems are divided into 6 main patterns. Dissociation processes of methane hydrate in porous media using the inverted five-spot water flooding method (Pattern 4) are investigated by the experimental observation and numerical simulation. In situ methane hydrate is synthesized in the Cubic Hydrate Simulator (CHS), a 5.832-L cubic reactor. A center vertical well is used as the hot water injection well, while the four vertical wells at the corner are the gas and water production wells. The gas production begins simultaneously with the hot water injection, while after approximately 20min of compression, the water begins to be produced. One of the common characteristics of the inverted five-spot water flooding method is that both the gas and water production rates decrease with the reduction of the hydrate dissociation rate. The evaluation of the energy efficiency ratio might indicate the inverted five-spot water flooding as a promising gas producing method from the hydrate reservoir. © 2013 Elsevier Ltd.


Jiang F.,CAS Guangzhou Institute of Energy Conversation | Luo L.,CAS Guangzhou Institute of Energy Conversation | Chen J.,CAS Guangzhou Institute of Energy Conversation
International Communications in Heat and Mass Transfer | Year: 2013

Understanding the subsurface heat exchange process in enhanced geothermal systems (EGS) is crucial to the efficiency of heat extraction and the sustainable utilization of geothermal reservoir. In the present work we develop a novel three-dimensional transient model for the study of the subsurface heat exchange process in EGS. The novelty of this model is embodied by a couple of salient features. First, the geometry of interest physically consists of multiple domains: open channels for injection and production wells, the artificial heat reservoir, and the rock enclosing the heat reservoir, while computationally we treat it as a single-domain of multiple sub-regions associated with different sets of characteristic properties (porosity and permeability etc.). This circumvents typical difficulties about matching boundary conditions between sub-domains in traditional multi-domain approaches and facilitates numerical implementation and simulation of the complete subsurface heat exchange process. Second, the heat reservoir is treated as an equivalent porous medium of a single porosity, while we consider thermal non-equilibrium between solid and fluid components and introduce two sets of heat transfer equations to describe the heat advection and conduction for fluid in rock apertures and the heat conduction in rock matrix, respectively, thus enabling the simulation and analysis of convective heat exchange between rock matrix and fluid flowing in the apertures. Case study with respect to an imaginary EGS demonstrates the validity and capability of the developed model. © 2012 Elsevier Ltd.

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