Bacterial methane oxidation in landfill cover layers - a coupled FE multiphase description

Landfill gas is composed of methane (CH₄) and (CO₂) at a ratio of about (60% – 40%), whereby the impact of methane on the greenhouse effect is about 25 times higher than that of carbon dioxide. Bacterial methane oxidation, taking place in the landfill cover layer, helps to reduce the climate active emissions from landfill sites. This contribution presents a theoretical and numerical approach to model the coupled processes of bacterial methane oxidation. An isothermal biphasic model based on the Theory of Porous Media (TPM) and Mixture Theory is introduced as well as the coupled finite element (FE) calculation concept. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Validation of a coupled FE-model for the simulation of methane oxidation via thermal imaging

To simulate the processes of methane oxidation in landfill cover layers, a new computational model was created. The purpose of the model is to allow a forecast on the performance of methanotrophic activity in landfill cover layers under changing environmental conditions. Therefore, a thermodynamic consistent model based on the well-known Theory of Porous Media (TPM) combined with the mixture theory was developed, which analyzes the relevant gas productions of methane, oxygen and carbon dioxide. Diffusion, advection and conversion processes are considered as well as the energy production during methane oxidation. With the help of the thermal imaging technique a new experimental setup was developed in order to validate the coupled model in terms of the heat generation. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Mass Transfer in Porous Media

In this contribution, a constitutive model based on the macromechanical Theory of Porous Media (TPM) for a saturated thermo elastic porous body has been developed. The body under investigation consists of an organic and inorganic moisturized phases and a gas phase. Based on a consistent thermomechanical treatment, the governing equations and constitutive equations will be given. Thus, we obtain a mathematical concept describing the motion of the solid phase, the pressure of the gas phase, the temperature of the mixture and the biodegradation of organic material into a gas mixture of methane and carbon dioxide produced by bacterial decomposition during stable methane fermentation (biogas). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

基于组合赋权法的我国CO2排放量影响因素的评价研究

为客观和准确地挖掘和评价我国CO₂排放量影响因素,选取技术投入、对外贸易开放程度、产业结构、能源消费结构、经济增长水平、人口规模和绿色植被用地面积等因素作为评价依据,构建我国CO₂排放量影响因素指标体系。在此基础上,基于组合赋权法构建我国CO₂排放量影响因素评价模型,实证分析2000~2011年我国CO₂排放量影响因素。组合赋权法结果显示:技术投入、产业结构、能源消费结构、经济增长和绿色植被用地面积是影响我国CO₂排放量的主要因素。组合赋权法在我国CO₂排放量影响因素评价分析的运用,提高了评价的客观性和科学性,为进一步确定CO₂排放量影响因素提供有价值的参考。     

A Multiphasic Model Describing the CO2 Injection Problem

According to the annual data, the portion of ejected carbon dioxide (CO₂) into the atmosphere is much higher in comparison to other greenhouse gases. Therefore, the development of various scenarios in order to reduce the CO₂ concentration in the atmosphere is nowadays a challenge and a relevant subject in research. The current investigation is dedicated to the modelling of a CO₂ injection into a water-saturated aquifer as the most capable reservoir, where its upward migration is blocked by a dense cap-rock layer. The major part of the study is focused on two specific processes taking place in the stored reservoir: the phase transfer phenomenon of the supercritical CO₂ which occurs under changeable surrounding conditions and the sequestration-driven deformation of the solid skeleton acting under the pressure of the pumped CO₂. For the numerical simulations within a continuum-mechanical framework, a multiphasic model based on the Theory of Porous Media is introduced. Moreover, the main principles of developing a constitutive equation for the mass production term for the mass balance equation are discussed here. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

考虑碳减排成本的内生经济增长路径研究

为了分析碳减排对内生经济增长的影响,将碳减排比例引入生产函数,将对气候变化的警惕意识引入效用函数,建立了考虑碳减排成本的内生经济增长模型,比较分析了各参数对经济增长路径的影响.长期来看,碳强度、碳减排比例与经济增长之间呈负向关系.低碳技术应用越广泛,研发成果对技术积累贡献率越大,消费者对当前消费的偏好程度越小,人们对气候变化的警惕意识越强,越有利于经济可持续发展.     

中国碳排放灰色预测

中国碳排放问题成为世界关注的焦点问题.预测中国未来碳排放有助于实现2020年的碳减排目标.选取2002-2009年中国碳排放数据,通过灰色GM(1,1)模型,对中国碳排放进行了短期预测.模型检验结果表明:预测精度为二级,关联度、均方差比值和小误差概率均为一级,预测结果与实际值出入较小,到2015年中国碳排放量将超过三十二亿吨碳,"十二五"期间二氧化碳减排形势严峻.针对研究结果,提出发展低碳经济,提高能源效率和发展非化石能源来降低碳排放的策略.     

A multiphase finite element simulation of biological conversion processes in landfills

Worldwide, landfills are the most common way to dispose of waste, but have an impact on the environment as a result of harmful gas and leachate production. Estimating the long-term behaviour of a landfill in regard to this gas production and organic degrading, as well as to settlement and waste water production, is of high importance. Therefore, a model has been developed to simulate these processes. This constitutive model is based on the multiphase Theory of Porous Media. The body under investigation consists of an organic and an inorganic phase as well as a liquid and a gas phase. The equations of the model are developed on the basis of a consistent thermo-mechanical approach including the momentum balance for the solid phase and the mixture, the energy balance for the mixture and the mass balance for the gas phase. All interactions between the constituents such as mass transfers, interaction forces and energy fluxes are taken into consideration. The strongly coupled set of partial differential equations is implemented in the finite element code FEAP. The theoretical framework and the results of meantime successfully performed simulation of a real landfill body will be shown. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

基于最小碳排放的广义TSP模型研究

以货车由公司仓库向各个销售节点送货这一典型的物流过程为研究对象.建立基于最小碳排放的广义TSP模型,并利用动态规划求解.模型综合考虑了货车行驶路程、运输途中载货量及CO_2排放量,并将货车装载量与CO_2排放量的函数关系体现在目标函数中,与只考虑行驶路程的传统模型相比更具实用性.最后用算例进行了验证,并与传统方法作了比较.     

中国碳排放变化的因素分解与减排路径研究

能源及其引致的碳排放等相关问题已经成为影响人类社会发展全局和全球政治经济格局的重大战略问题.中国是世界上最大的发展中国家,面临着更严峻的能源挑战.节约能源、大幅度改善能源效率是我国应对能源和气侯变化挑战的一条极其重要且有效途径.本文综合考量了能源结构、能源强度、能源效率及经济增长等4个因素对碳排放的影响,基于因素分解模型,应用LMDI分解方法对中国一次能源利用的CO2排放及碳排放强度变化进行了研究,研究发现二氧化碳排放增加主要是由于经济增长、人口规模扩大引起的.在此基础上提出了碳减排的政策建议.     

Estimation of the atmospheric greenhouse gas spatial distribution in the Arctic using a back trajectory model

We present a method and results of the retrieval of average effective fields of atmospheric impurity concentration using a passive wind sensing (remote sensing) numeric technology referred to as Fluid Location of the Atmosphere (FLA). The quasi-two-dimensional problem of reconstruction of the spatial distribution of the greenhouse gases assuming the diffusion Peclet number infinitely large was solved numerically. The study is based on in-situ measurements of the atmospheric methane and carbon dioxide during the expeditions to Belyy Island in the Kara Sea in July and August of 2016 to 2017. The differences and common features of CH₄ and CO₂ spatial distribution in this region of the Arctic during specified periods were analyzed. CH₄ concentrations tended to decrease with moving from the continent to the remote sea areas. For CO₂ on the contrary, lower values were observed over the continent, and they increased with a distance from the coastline. For both greenhouse gases, average atmospheric concentrations increased in 2017 relative to 2016.     

碳排放交易机制下的供应链运作策略及协调研究

碳排放权交易是控制和减少碳排放的有效工具,同时也使得企业的运作成本增加,供应链的决策管理更复杂。考虑由零售商和制造商组成的二阶段供应链,研究不同碳排放权交易政策(供应链成员内部碳排放权交易、外部市场碳排放权交易)下基于数量折扣契约的供应链协调问题,并与无碳排放约束的情形进行比较。研究结果表明:在不同碳排放权交易政策下,数量折扣契约能够实现供应链的协调;无碳排放约束的供应链最优订货量大于外部碳排放权交易的供应链最优订货量,成员内部碳排放交易下的供应链最优订货量和供应链期望利润随着碳排放配额的增加最终等于无碳排放约束下的供应链最优订货量和供应链期望利润;外部市场碳排放交易政策下供应链的期望利润随着碳排放配额的增加而增加。     

中国碳排放的省域差异及影响因素的实证研究

参照IPCC(2006)以及国家气候变化对策协调小组办公室和国家发改委能源研究所)的方法,估算了我国30个省(直辖市、自治区)的1997—2011年期间的二氧化碳排放量.数据显示,我国各省(直辖市、自治区)的二氧化碳排放量从整体上基本都呈现出上升趋势,地区差异比较显著.总体上来讲,我国的二氧化碳排放量呈现出由东到西依次递减的规律特征,东部地区的二氧化碳排放量最多,中部地区次之,西部地区二氧化碳排放量最少,而且东部地区的二氧化碳排放在绝对量上大大超过中西两大区域.产业结构和经济发展是影响各地区二氧化碳排放量的主要因素,能源消费结构和出口贸易对各地区碳排放量的影响不显著.     

Computational analysis of CO2 emission,O2 depletion and thermal decomposition in a cylindrical pipe filled with reactive materials

In this paper we present a nonlinear mathematical model for estimating the CO₂ emission, O₂ depletion and thermal decomposition in a stockpile of a reactive material undergoing an exothermic chemical reaction inside a long cylindrical pipe with convective heat and mass transfer characteristics at its surface. By employing a semi-implicit finite difference scheme, the problem is solved numerically. The graphical results are discussed in terms of the relationships between the processes that affect the oxidation reactions on the one hand and oxygen depletion as well as carbon dioxide emission on the other hand. The relationships between thermal stability and the processes that influence the oxidation reactions are also explored and discussed.     

碳交易驱动下建筑业主最优碳减排决策研究

对碳排放总量和强度都持续刚性增长的建筑领域,利用市场机制,借助碳交易来控制和减少其碳排放是一项重大的制度创新。本文通过构建多目标决策优化模型,探讨建筑业主在碳交易驱动形成的复杂动态环境下的最优碳减排策略;并基于实证数据进行情景耕耘,模拟和预测业主减排策略的动态适应性调整。研究发现:①业主碳减排决策受政府补贴强度和违规惩罚倍率调整的冲击更为显著;②目前碳市场“一刀切”的惩罚倍率极易使建筑业主陷入“明罚实奖”的惩罚悖论;③政府应采用“补贴退坡”政策并对不同类型的建筑业主进行精准补贴。     

Numerical simulation of methane partial oxidation in the burner and combustion chamber of autothermal reformer

This study aims to model the methane partial oxidation process in the burner and combustion chamber of autothermal reactor. The numerical simulation based on this model offers a powerful tool that can assist in reactor design and optimization and scale up of the process saving expensive pilot work. The steady-state governing equations were solved using the SIMPLE algorithm and the effect of turbulence on the mean flow field was accounted for using the RNG k–ε model. A two-step reaction mechanism was used for the gas combustion with CO as the intermediate species. The reaction rates were modeled using an Eddy-Dissipation Model. In terms of the geometrical model, a 3D model for burner was developed while an axis-symmetric model for the combustion chamber was implemented to reduce the computational costs. The model formulated was validated against a currently operating autothermal reactor and then has been used to investigate different aspects of these reactors. Results show that effect of oxygen to methane ratio is more than that of feed temperature. It is demonstrated that a 60% increase in O₂/CH₄ ratio causes a 15.4% decrease and 42.7% increase in H₂/CO ratio and methane conversion, respectively. In contrast, a 60% increase in feed temperature does not have a significant effect on the process.     

碳减排补贴与碳税下的供应链碳减排决策优化与协调

针考虑碳税政策和政府对制造商的碳减排技术创新投入补贴,构建了供应链博弈模型,根据协调条件给出了相应的契约形式及参数。通过对供应链模型的求解,得到了碳税和碳减排技术创新投入补贴下的最优碳减排量和最优订货量。数值分析结果表明:碳减排技术创新投入的补贴比例变化对供应链的最优碳减排量、订货量及期望利润的影响有较大影响,而且是成正向变化关系,而且在其他参数不变及供应链碳减排量一定的情况下,碳税与碳减排补贴比例呈反向变化关系,进而可为政府碳减排补贴政策制定及供应链碳减排优化提供科学的决策依据。     

CO2 emissions trading planning in combined heat and power production via multi-period stochastic optimization

The EU emissions trading scheme (ETS) taking effect in 2005 covers CO₂ emissions from specific large-scale industrial activities and combustion installations. A large number of existing and potential future combined heat and power (CHP) installations are subject to ETS and targeted for emissions reduction. CHP production is an important technology for efficient and clean provision of energy because of its superior carbon efficiency. The proper planning of emissions trading can help its potential into full play, making it become a true “winning technology” under ETS. Fuel mix or fuel switch will be the reasonable choices for fossil fuel based CHP producers to achieve their emissions targets at the lowest possible cost. In this paper we formulate CO₂ emissions trading planning of a CHP producer as a multi-period stochastic optimization problem and propose a stochastic simulation and coordination approach for considering the risk attitude of the producer, penalty for excessive emissions, and the confidence interval for emission estimates. In test runs with a realistic CHP production model, the proposed solution approach demonstrates good trading efficiency in terms of profit-to-turnover ratio. Considering the confidence interval for emission estimates can help the producer to reduce the transaction costs in emissions trading. Comparisons between fuel switch and fuel mix strategies show that fuel mix can provide good tradeoff between profit-making and emissions reduction.     

基于分位数回归的二氧化碳排放与经济增长

选取我国1960～2009年的年度数据,建立了二氧化碳排放与经济增长关系模型,并利用分位数回归方法对我国二氧化碳排放与经济增长倒U假说进行实证研究.研究结果表明,Kuznets的假说在我国二氧化碳与经济增长之间并不稳定,随着碳排放量的增加,我国二氧化碳与经济增长之间先呈现"N型",之后呈现Kuznets的"倒U型",最后演变成一条水平的直线.