Large Amount Of CO2 Emissions Research Articles

Idea paper: Community‐interaction analyses contribute to improving the performance of microbial fuel cells

AbstractRenewable energy resources can potentially solve global warming issues that arise from the large amounts of CO2 emissions from currently used energy resources. Microbial fuel cells (MFC) can produce electrical energy from the environment, making them attractive for energy harvesting. The structures and mechanisms of MFC have been studied for a few decades, and the performance of MFC has constantly been improved using new materials in the devices or by interacting microbial species on the anode chamber of MFC. However, the ecological phenomena, especially inter‐species interactions, within the microbial community in MFC are still largely unknown. Analysis and control of the microbial community have high potential to improve the MFC performance. In this idea paper, I have provided ways to analyze the species interactions in the microbial communities of MFC: (a) empirical dynamic modeling for detecting species interactions in MFC, and (b) network analysis to explore the core microbe species in the MFC. The interaction analyses of the microbial communities in MFC devices can potentially contribute to improving the performance of MFC.

English

U Minh Thuong National Park is one of the two significant areas of peatland swamp forest remaining in Vietnam, and is recognized as one of the three highest priority sites for wetland conservation in Mekong Delta. A large area of Melaleuca Forest in the park was destroyed and degraded by a devastating fire in 2002. Besides this, an artificial flooding technique for controlling fire applied all over the park for several years changed the natural development of Melaleuca Forest. As the natural condition of the forest has changed, water management (artificial flooding) needs to be implemented to save this situation. Flooding regime has changed the structure and composition of the peatland, making it to be loose and reduced in structure. The peatland area in the park has water level of 30 cm underground and occupies 15% of the total park area. It emits very large amount of CO2 emissions. The main objective of this work is to study how to protect the forest biodiversity from fire by controlling its water level optimally after rainy season and to study the chemical and physical characteristics of the peatland soil of the forest that affect its water level Key words: Melaleuca Forest, peatland, flooding,

Examining the spatiotemporal variations and inequality of China's provincial CO2 emissions.

Tremendous energy consumption appears as rapid economic development, leading to large amount of CO2 emissions. Although plentiful studies have been made into the driving factors of CO2 emissions, the existing literatures that take the spatial differences and temporal changes into consideration are few. Therefore, this study first analyzes the variations of total CO2 emissions' spatial distribution from 2008 to 2017 and present the changes of driving factors, finding significant spatial autocorrelation in CO2 emissions at the province level, and that urbanization rate, per capita GDP and per capita CO2 emissions increased significantly, but energy consumption structure and trade openness decreased. We then compared the effects of different factors affecting CO2 emissions, using classic linear regression model, panel data model, and the geographically weighted regression (GWR) model, and the three models roughly agree on the effects of factors. The GWR model considering spatial heterogeneity provides more detailed results. Population, urbanization rate, per capita carbon emissions, energy consumption structure, and trade openness all have positive effects, while per capita GDP has a two-way impact on CO2 emissions. The influence of urbanization rate and energy consumption structure in the central and western regions increased even faster than in eastern regions, and the impacts of trade openness in lower and higher opening areas are more significant. The population and per capita CO2 emission have declining influences, among which the influence of population in coastal areas declined more slowly, while the rate of decline of per capita CO2 emission was positively correlated with the local total CO2 emissions. The Lorenz curve and the Gini coefficient reveal the inequality distribution of CO2 emissions in various regions, with the highest CO2 emissions growth in the medium-economic-level areas, where the key area of carbon mitigation is. Finally, per capita GDP reveals that China as a whole has the trend of inverted N-shape Kuznets curve, and the underdeveloped regions are in the rising stage between the two inflection points, while developed regions are at the end of the rising stage and about to reach the second inflection point.

Bioproduct Potential of Outdoor Cultures of Tolypothrix sp.: Effect of Carbon Dioxide and Metal-Rich Wastewater.

Rising CO2 levels, associated climatic instability, freshwater scarcity and diminishing arable land exacerbate the challenge to maintain food security for the fast growing human population. Although coal-fired power plants generate large amounts of CO2 emissions and wastewater, containing environmentally unsafe concentrations of metals, they ensure energy security. Nitrogen (N2)-fixation by cyanobacteria eliminate nitrogen fertilization costs, making them promising candidates for remediation of waste CO2 and metals from macronutrient-poor ash dam water and the biomass is suitable for phycocyanin and biofertilizer product development. Here, the effects of CO2 and metal mixtures on growth, bioproduct and metal removal potential were investigated for the self-flocculating, N2-fixing freshwater cyanobacterium Tolypothrix sp. Tolypothrix sp. was grown outdoors in simulated ash dam wastewater (SADW) in 500 L vertical bag suspension cultures and as biofilms in modified algal-turf scrubbers. The cultivation systems were aerated with air containing either 15% CO2 (v/v) or not. CO2-fertilization resulted in ∼1.25- and 1.45-fold higher biomass productivities and ∼40 and 27% increased phycocyanin and phycoerythrin contents for biofilm and suspension cultures, respectively. CO2 had no effect on removal of Al, As, Cu, Fe, Sr, and Zn, while Mo removal increased by 37% in both systems. In contrast, Ni removal was reduced in biofilm systems, while Se removal increased by 73% in suspension cultures. Based on biomass yields and biochemical data obtained, net present value (NPV) and sensitivities analyses used four bioproduct scenarios: (1) phycocyanin sole product, (2) biofertilizer sole product, (3) 50% phycocyanin and 50% biofertilizer, and (4) 100% phycocyanin and 100% biofertilizer (residual biomass) for power station co-located and not co-located 10 ha facilities over a 20-year period. Economic feasibility for the production of food-grade phycocyanin either as a sole product or with co-production of biofertilizer was demonstrated for CO2-enriched vertical and raceway suspension cultures raised without nitrogen-fertilization and co-location with power stations significantly increased profit margins.

Influencing factors and application prospects of CO2 flooding in heterogeneous glutenite reservoirs

In recent years, large amounts of CO2 emissions have led to many environmental problems. Developing a reasonable approach to carbon dioxide emissions is one of the most important issues for the sustainable development of human civilization. Compared with CO2 geological storage, CO2 flooding has greater advantages and a higher utilization efficiency. CO2 flooding technology has been successfully applied to many types of reservoirs, such as conventional sandstone reservoirs, low-permeability reservoirs, and carbonates. In this paper, the feasibility of CO2 flooding in glutenite reservoirs is studied. First, the glutenite reservoir is divided into fine stages, and reasonable vertical development units are determined. On this basis, the distribution scale, genetic environment and formation mode of the glutenite reservoir are characterized in detail and their spatial distribution rules are depicted in three dimensions. Then, the influencing factors of CO2 flooding in the glutenite reservoir are analysed via reservoir numerical simulation technology. The effects of reservoir thickness, reservoir heterogeneity, macropores, dominant channels and fracturing on CO2 flooding efficiency are evaluated individually, and a set of reasonable parameters constituting an evaluation system for CO2 flooding in the glutenite reservoir is established. Finally, based on parameter optimization, the disadvantaged conditions of CO2 flooding in glutenite reservoirs are optimized, and their effects are gradually eliminated. In view of the characteristics of glutenite reservoirs, a unique three-dimensional well pattern arrangement is designed, different injection modes are optimized, and suitable injection agents are tested. These methods are conducive to improving the effect of reservoir parameters on CO2 flooding efficiency, allowing these reservoirs to be used for CO2 flooding. Based on these new methods, the displacement effect of the Yanjia-Yongan glutenite reservoir is predicted. Our results show that the reservoir has been developed efficiently and achieved a high recovery rate, the displacement front of the CO2 has become more uniform, and the sweep range has become wider. After extending the successful application of CO2 flooding in this reservoir to all of the glutenite reservoirs in the entirety of the Bohaiwan Basin, we predict that the oil recovery rate may reach 40%, with a cumulative oil recovery rate of approximately 3.04 × 108 t and a total CO2 consumption of 1.672 × 108 t. Thus, the proposed approach not only can improve the atmospheric environment but can also greatly improve the efficiency of oil displacement.

DyF3 : An Efficient Electrocatalyst for N2 Fixation to NH3 under Ambient Conditions.

NH3 synthesis by the Haber-Bosch method is regarded as the dominant method in industry. Such a process is energy-intensive, accompanied by a large amount of CO2 emission. Electrocatalytic N2 reduction is a sustainable avenue for NH3 production at ambient conditions. However, it needs a catalyst to boost the N2 reduction reaction. Here, we demonstrate that DyF3 is an efficient electrocatalyst. In 0.1 m Na2 SO4 , DyF3 attains a large NH3 yield of 10.9 μg h-1 mg-1 cat. at -0.45 V vs. the reversible hydrogen electrode, with the corresponding Faradaic efficiency of 8.8 %. Furthermore, this catalyst exhibits high electrochemical stability.

A Study on the Effect of Ceramic Polishing Powder on the Nucleation and Growth of Hydrates in Cement Paste

The production of cement leads to a large amount of CO2 emission. Using industrial waste slag, such as ceramic polishing powder (PP), to replace part of Portland cement can reduce the pollution caused by the cement industry and solid waste disposal. In order to use PP as a replacement for cement, its effects on the properties of cement paste need to be clarified. In this study, the effect of PP on the nucleation and growth of hydrates in cement paste at very early ages was investigated. Quartz was used as a reference. The interactions of their surface with various ions in cement paste solution, which has an important effect on the nucleation and growth of hydrates, were studied by using the zeta potential test. The morphology of the nucleus and crystal of hydrates was investigated by using SEM. The zeta potential measurements showed that the affinity of the surface of PP and quartz to ions in the pore solution of cement paste is similar. The image of SEM indicated that there is also not much difference in the crystallization of hydrates on the surfaces of PP and quartz. These evidences suggested that PP has similar surface charge properties as quartz, and its effects on the properties of cement paste are the same as that of quartz. From the viewpoint of the effect on very early hydration, PP can be used in cement paste, similar to quartz power.

Optimizing virtual machine placement in IaaS data centers: taxonomy, review and open issues

The unprecedented growth of energy consumption in data centers created critical concern in recent years for both the research community and industry. Besides its direct associated cost; high energy consumption also results in a large amount of CO2 emission and incurs extra cooling expenditure. The foremost reason for overly energy consumption is the underutilization of data center resources. In modern data centers, virtualization provides a promising approach to improve the hardware utilization level. Virtual machine placement is a process of mapping a group of virtual machines (VMs) onto a set of physical machines (PMs) in a data center with the aim of maximizing resource utilization and minimizing the total power consumption by PMs. An optimal virtual machine placement algorithm substantially contributes to cutting down the power consumption through assigning the input VMs to a minimum number of PMs and allowing the dispensable PMs to be turned off. However, VM Placement Problem is a complex combinatorial optimization problem and known to be NP-Hard problem. This paper presents an extensive review of virtual machine placement problem along with an overview of different approaches for solving virtual machine placement problem. The aim of this paper is to illuminate challenges and issues for current virtual machine placement techniques. Furthermore, we present a taxonomy of virtual machine placement based on various aspects such as methodology, number of objectives, operation mode, problem objectives, resource demand type and number of clouds. The state-of-the-art VM Placement techniques are classified in single objectives and multi-objective groups and a number of prominent works are reviewed in each group. Eventually, some open issues and future trends are discussed which serve as a platform for future research work in this domain.

Identification and evolution of critical betweenness sectors and transactions from the view of CO2 reduction in supply chain network

Sectors tend to generate pressure on the environment due to its large amounts of emissions. The aim of this study is to identify critical betweenness sectors and transactions that play an important intermediate role in the supply chain, which can provide additional insights for CO2 emissions. Based on the input-output and energy consumption data in China, the notion of network centrality and structural path analysis method are employed in this paper to identify critical betweenness sectors and transactions, and then the evolutionary trends of betweenness sectors and transactions are analyzed from 2005 to 2015. The results show that some critical betweenness sectors, such as Metal products sector and Electrical equipment sector, have huge potential for carbon emission reduction, which fail to receive sufficient attention from the perspective of production or consumption. Some critical transactions, such as the transaction from Nonmetal products sector to Construction sector, have a large amount of CO2 emissions. The transaction from Metallurgy sector to Electrical equipment sector became increasingly important in China from 2005 to 2015. Additionally, the evolutionary trends of different transactions are significantly different. The findings reveal that special attention should be paid to these critical betweenness sectors and transactions and policy development should be dynamic to respond to changes in CO2 emissions that are generated by different betweenness sectors and transactions.

What drives CO2 emissions from the transport sector? A linkage analysis

Abstract The objective of this study is an analysis of the relationship between the transportation sector and the rest of the Chinese economy as it impacts the generation of carbon dioxide (CO2) emissions. Using data from input-output tables of China for 2002, 2007, and 2012, the hypothetical extraction method (HEM) was used to quantify these inter-sectoral linkages and decompose the CO2 emissions associated with each transport modal sub-sector (i.e. the rail, road, water, and air sub-sectors). The transport services required by other sectors of the economy are found to induce more carbon emissions than the emissions associated with transportation's own final demands. As the principal CO2 emitter, the road sub-sector's export of CO2 emissions increased substantially from 11.31 to 55.22 million tons (Mt) between 2002 and 2012. In contrast, technological advances within the rail sub-sector resulted in a net decrease in exported CO2 emissions, from 9.99 Mt to 5.16 Mt. Taken as a whole, the transportation sector transferred large CO2 emissions through the economy's various supply chains, notably exporting to the service (63.78 Mt in 2012) and construction (83.88 Mt in 2012) sectors while importing a large amount of CO2 emissions from the nation's energy producing industry (223.52 Mt in 2012).

Mn3O4 nanoparticles@reduced graphene oxide composite: An efficient electrocatalyst for artificial N2 fixation to NH3 at ambient conditions

Currently, industrial-scale NH3 production almost relies on energy-intensive Haber-Bosch process from atmospheric N2 with large amount of CO2 emission, while low-cost and high-efficient catalysts are demanded for the N2 reduction reaction (NRR). In this study, Mn3O4 nanoparticles@reduced graphene oxide (Mn3O4@rGO) composite is reported as an efficient NRR electrocatalyst with excellent selectivity for NH3 formation. In 0.1 M Na2SO4 solution, such catalyst obtains a NH3 yield of 17.4 μg·h−1·mg−1cat. and a Faradaic efficiency of 3.52% at −0.85 V vs. reversible hydrogen electrode. Notably, it also shows high electrochemical stability during electrolysis process. Density functional theory (DFT) calculations also demonstrate that the (112) planes of Mn3O4 possess superior NRR activity.

A perovskite La2Ti2O7 nanosheet as an efficient electrocatalyst for artificial N2 fixation to NH3 in acidic media.

The synthesis of NH3 heavily relies on the Haber-Bosch process suffering from a large amount of CO2 emission and energy consumption. Possessing eco-friendly and sustainable characteristics, electrochemical reduction is considered as a promising candidate for artificial N2 fixation under ambient conditions, but efficient electrocatalysts are crucial for the N2 reduction reaction (NRR). In this communication, we report that perovskite La2Ti2O7 nanosheets behave as an efficient NRR electrocatalyst with excellent selectivity under ambient conditions. In 0.1 M HCl, this catalyst achieves a high NH3 yield rate of 25.15 μg h-1 mgcat.-1 with a faradaic efficiency of 4.55% at -0.55 V vs. a reversible hydrogen electrode. Notably, it also shows high electrochemical stability.

Measuring interregional spillover and feedback effects of economy and CO2 emissions: A case study of the capital city agglomeration in China

Interregional trade not only contributes to economic output but also causes a large amount of CO2 emissions. We measure the spillover and feedback effects of economy and CO2 emissions in the capital city agglomeration of China by a four-region input-output model. The results reveal that the contribution of spillover effects on both economic output and CO2 emissions is remarkable. First, both of net economic and CO2 emissions spillovers flow from Beijing to Hebei and Tianjin. Second, net economic spillovers flow from Hebei to Tianjin, however net CO2 emissions spillovers flow from Tianjin to Hebei. Thirdly, there are some sectors, such as mining and washing of coal sector, whose economic and CO2 emissions net spillovers flow in opposite directions between any two cities. The results indicate that the economic driving function from Tianjin to Hebei needs to be strengthened, and Tianjin should assume part of the CO2 emissions responsibility for Hebei. The most important is that cities should work together to replace coal with clean energy technologies such as those based on wind and solar.

The contribution of China’s bilateral trade to global carbon emissions in the context of globalization

Controlling and reducing carbon emissions for mitigation of climate change are a global common consensus. It is imperative for legitimately and effectively ascertaining responsibilities among countries to study CO2 emissions embodied in the international trade. As the largest exporter and the second largest importer in the world, the large amount of CO2 emissions embodied in China’s bilateral trade have a significant impact on China’s and global carbon emissions. Based on the single region input-output tables using the non-competitive imports assumption, this study estimated CO2 emissions embodied in China’s bilateral trade with 219 countries/regions over the period of 2000–2014, and analyzed the contribution of China’s bilateral trade to global carbon emissions under the assumption of non-trade scenario. The results show that, CO2 emissions embodied in China’s exports and imports in 2014 were 2561.1 Mt and 1209.9 Mt respectively, and CO2 emissions embodied in exports were higher than those in imports throughout the period. It is indicated that China had produced a large amount of CO2 emissions for other countries through the international trade. And meanwhile, China avoided a large amount of CO2 emissions with the rapid growth of imports. And furthermore, the net CO2 emissions embodied in China’s bilateral trade had been declining since 2011. At last, China’s bilateral trade had extremely little impact on global carbon emissions. It is concluded that there is a possibility of reducing global carbon emissions based on the results of China’s bilateral trade with countries along the routes of Silk Road Economic Belt and 21st-Century Maritime Silk Road.

Life-cycle CO2 emissions and influential factors for asphalt highway construction and maintenance activities in China

ABSTRACTThis study tried to clarify the magnitude of CO2 emissions from highway construction and maintenance in China through life cycle assessment (LCA) method. For this, 227 real highway projects constructed from the year 2000 to 2011 in Zhejiang Province, China are classified into six types by two categories of N road (62 projects without grand bridge, great bridge and tunnel) and Y road (165 projects with the same road structures) and three sub-categories of (i) newly constructed road, (ii) replacing pavement road and (iii) full rehabilitated road. Significant influential factors of LCA results were revealed through multivariate linear regression models, combined with data quality assessment and sensitivity analysis. Numerical interval of assessment results indicate that the construction emissions of N highway project are more centralized to no more than 2900 t/lane-km, while Y project have a normal upper boundary of construction CO2 emissions, about 5000 t/lane-km. The contribution of maintenance to CO2 emissions probably could exceed that of newly construction both for Y project and N project. In addition, the pavement replacing and rehabilitation could bring about large amount of CO2 emissions which even match with the CO2 emissions from cumulative traffic volume during highway's life cycle. There are common factors for six categories. Cement and steel are the top largest CO2 emissions contributors and sensitive factors for N road and Y road. The LCA results are not sensitive to the local construction materials but sensitive to the emission factor of diesel used in transportation and on-site construction.

Using an Advanced Numerical Technique for Improving Pulverized Coal Combustion inside an Industrial Furnace

When it comes to industrial activities, one of the most greenhouse gas emitting industrial sectors is the cement industry. Cement industry as an energy intensive industry is alone responsible for a large amount of CO2 emissions. Compared to the total global CO2 emissions in 2014, cement production contributed to global anthropogenic CO2 emissions with 8 %. Meaning that cement industry needs to adopt more energy efficient technologies and reduce its demand for fossil fuels. The aim of this paper is to present an advanced numerical technique for improving pulverized coal combustion inside an industrial furnace. With the development of increasingly affordable and powerful computers, use of numerical techniques, have become a very useful and cost-effective tool that is increasingly used in industry for detailed understanding of the combustion process and for the appropriate design and optimisation of different combustion units. In order to study the role of pulverized coal combustion inside a cement furnace, appropriate numerical models need to be used. In this study a numerical model of the pulverized coal combustion was used for the numerical analysis. A detailed three dimensional geometry of a cement furnace was simulated. The results gained by this simulation can be used for better understanding of complex thermo-chemical phenomena occurring inside the calculated furnace.

A review on adsorption-enhanced photoreduction of carbon dioxide by nanocomposite materials

The large amount of CO2 emissions from the increasing consumption of fossil fuels is a potential cause for global warming. Photocatalytic reduction of CO2 using sunlight is considered as an attractive method for mitigating CO2 emissions. Extensive amount of researches on CO2 photoreduction are available, which tend to focus on the types of photocatalysts, the photocatalytic activity, and photoconversion efficiency. However, CO2 adsorption in the CO2 photoreduction process has been overlooked, despite it being an initial and important step. Recently, there has been an increase in the number of publications investigating the effects of CO2 adsorption on the CO2 photoreduction process. Thus, this review summarizes the research progress in this regard. This review focuses on the different CO2 adsorption modes and characterization methods as well as the factors influencing CO2 adsorption such as surface area, surface basicity, surface functional groups, surface defects, and exposed crystal facets. Furthermore, the design of nanocomposites that consist of photocatalysts and CO2 adsorption promoters are reviewed and discussed. It has been demonstrated that the CO2 photoreduction performance can be increased by utilizing CO2 adsorption in various types of nanocomposites, including metal oxides, chalcogenides, layered double hydroxides, and metal organic frameworks. This review provides a unique perspective in the design of nanocomposite photocatalysts with the goal of efficient CO2 photoreduction.

Minimization of energy and surface roughness of the products machined by milling

Metal cutting represents a large portion in the manufacturing industries, which makes this process the largest consumer of energy. Energy consumption is an indirect source of carbon footprint, we know that CO2 emissions come from the production of energy. Therefore high energy consumption requires a large production, which leads to high cost and a large amount of CO2 emissions. At this day, a lot of researches done on the Metal cutting, but the environmental problems of the processes are rarely discussed. The right selection of cutting parameters is an effective method to reduce energy consumption because of the direct relationship between energy consumption and cutting parameters in machining processes. Therefore, one of the objectives of this research is to propose an optimization strategy suitable for machining processes (milling) to achieve the optimum cutting conditions based on the criterion of the energy consumed during the milling. In this paper the problem of energy consumed in milling is solved by an optimization method chosen. The optimization is done according to the different requirements in the process of roughing and finishing under various technological constraints.

Analysis on the regional difference and impact factors of CO2 emissions in China

China has become the largest CO2 emitter in the world for the rapid economic growth, and the large amount of CO2 emissions has caused worldwide concern. Based on the energy‐related data of CO2 emissions in eight economic zones from 2000 to 2012, this paper built a STIRPAT‐based multivariate linear model fitted by a ridge regression to examine the relationships between net CO2 emissions and a list of socioeconomic factors, including GDP per capita, population, energy intensity, and urbanization level. Regression results show that population, GDP per capita and urbanization level contribute to the increase of net CO2 emissions while energy intensity expresses an inhibitory effect. In addition, the elastic coefficients of different variables indicate that population scale and urbanization level play more important roles than GDP per capita and energy intensity in net CO2 emissions, where population scale contributes most significantly. Since the influence mechanisms of impact factors vary with scales of regional economy and characteristics of industry structure, some specific policy suggestions are also presented on how to mitigate the growth of CO2 emissions in each economic zone. This study have an important reference value for examining the impact factors of energy‐related CO2 emissions and the academic value in terms of enriching low carbon economy research systems in China. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1282–1289, 2017

Committed CO2 emissions of China's coal-fired power generators from 1993 to 2013

Coal-fired power plants generate large amount of CO2 emissions during their lifetimes of operation, which thus influences future CO2 emission space under specific targets on mitigating global climate change (e.g., the 2℃ warming limit relative to pre-industrial levels). In this study, we calculated China's committed CO2 emissions from coal-fired power generators installed during 1993–2013, and analyzed their effects on future emissions at a provincial level. Our results indicate that these relatively recently installed coal-fired power plants will lead to 106Gt of CO2 emissions over the course of their average lifetime, which is more than three times the global CO2 emissions from fossil fuels in 2010. More than 80% (85Gt) of their total committed CO2 will be emitted after 2013, which are referred to as the remaining emissions. These remaining emissions would increase by 45Gt if the average lifetime of China's coal-fired power generators were prolonged to be 45 years. Furthermore, the remaining emissions are very different among various provinces owing to local developments and policy disparities. China's CO2 emission mitigation objectives might be greatly restricted by the existing and planned power plants, which have important policy implications for other rapidly developing countries.