Anthropogenic land use substantially increases riverine CO2 emissions

Carbon dioxide (CO₂) emissions from inland waters to the atmosphere are a pivotal component of the global carbon budget. Anthropogenic land use can influence riverine CO₂ emissions, but empirical data exploring cause-effect relationships remain limited. Here, we investigated CO₂ partial pressures (pCO₂) and degassing in a monsoonal river (Yue River) within the Han River draining to the Yangtze in China. Almost 90% of river samples were supersaturated in CO₂ with a mean ± standard deviation of 1474 ± 1614 µatm, leading to emissions of 557 - 971 mmol/m²/day from river water to the atmosphere. Annual CO₂ emissions were 1.6 - 2.8 times greater than the longitudinal exports of riverine dissolved inorganic and organic carbon. pCO₂ was positively correlated to anthropogenic land use (urban and farmland), and negatively correlated to forest cover. pCO₂ also had significant and positive relationships with total dissolved nitrogen and total dissolved phosphorus. Stepwise multiple regression models were developed to predict pCO₂. Farmland and urban land released nutrients and organic matter to the river system, driving riverine pCO₂ enrichment due to enhanced respiration in these heterotrophic rivers. Overall, we show the crucial role of land use driving riverine pCO₂, which should be considered in future large-scale estimates of CO₂ emissions from streams. Land use change can thus modify the carbon balance of urban-river systems by enhancing river emissions, and reforestation helps carbon neutral in rivers.     

Employing the shared socioeconomic pathways to predict CO2 emissions

Predicting CO₂ emissions is of significant interest to policymakers and scholars alike. The following article contributes to earlier work by using the recently released “shared socioeconomic pathways” (SSPs) to empirically model CO₂ emissions in the future. To this end, I employ in-sample and out-of-sample techniques to assess the prediction accuracy of the underlying model, before forecasting countries’ emission rates until 2100. This article makes three central contributions to the literature. First, as one of the first studies, I improve upon the Representative Concentration Pathways (RCPs) by incorporating the SSPs, which did not exist when the RCPs have been released. Second, I calculate predictions and forecasts for a global sample in 1960–2100, which circumvents issues of limited time periods and sample selection bias in previous research. Third, I thoroughly assess the prediction accuracy of the model, which contributes to providing a guideline for prediction exercises in general using in-sample and out-of-sample approaches. This research presents findings that crucially inform scholars and policymakers, especially in light of the prominent 2 °C goal: none of the five SSP scenarios is likely to be linked to emission patterns that would suggest achieving the 2 °C goal is realistic.     

Root- and peat-based CO2 emissions from oil palm plantations

Measured carbon dioxide (CO₂) flux from peat soils using the closed chamber technique combines root-related (autotrophic + heterotrophic where rhizosphere organisms are involved) and peat-based (heterotrophic) respiration. The latter contributes to peat loss while the former is linked to recent CO₂ removal through photosynthesis. The objective of this study was to separate root- from peat-based respiration. The study was conducted on peatland under 6 and 15 year old oil palm (Elaeis guineensis Jacq.) plantations in Jambi Province, Indonesia in 2011 to 2012. CO₂ emissions were measured in the field from 25 cm diameter and 25 cm tall closed chambers using an infrared gas analyser. Root sampling and CO₂ emissions measurements were at distances of 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 m from the centre of the base of the palm tree. The emission rate for the six and 15 year old oil palm plantations at ≥3.0 m from the centre of the tree were 38.2?±?9.5 and 34.1?±?15.9 Mg CO₂ ha^?1 yr^?1, respectively. At distances <2.5 m, total respiration linearly decreased with distances from the trees. Heterotrophic respirations were 86 % of the 44.7?±?11.2 and 71 % of 47.8?±?21.3 Mg CO₂ ha^?1 yr^?1 of weighted surface flux, respectively for the 6 and 15 year old plantations. We propose that CO₂ flux measurements in oil palm plantations made at a distance of ≥3 m from the tree centre be used to represent the heterotrophic respiration that is relevant for the environmental impact assessment.     

中国4个城市范围CO2排放比较研究

基于点排放源和辅助数据,自下而上构建重庆1km CO2排放空间网格,分析市域(UB1)、市辖区(UB2)、建成区(UB3)和城区(UB4)4个城市范围的CO2排放特征.UB4是重庆城市合理表征,而UB1更适合于区域边界.城市边界选择的不同,将导致很大的排放差异.UB4的CO2总排放量仅为UB1的17.13%,但UB4的人均CO2排放量是UB1的1.6倍.UB4形成了重庆UB1的CO2排放核心,其内单位网格的平均排放量超过了10000t,而UB1内超过70%的范围内单位网格的排放水平都低于200t.工业排放占据绝对主体导致UB4人均排放水平较高,并且高于临近周边及区域人均水平,这和国际城市的情况正好相反.全局和局部显著空间正自相关性说明部分地区高强度的经济活动和能源活动对周边区域的排放有显著影响.基于网格的累积排放分析显示,个别网格的排放量已经占到UB4总排放的40%以上.UB4内7.00%的面积,UB1内1.21%的面积和UB2内3.84%的面积,其CO2排放都超过了其相应范围内总排放的85%.     

CO2 emissions from tropical drained peat in Sumatra,Indonesia

With the increasing use of tropical peatland for agricultural development, documentation of the rate of carbon dioxide (CO₂) emissions is becoming important for national greenhouse gas inventories. The objective of this study was to evaluate soil-surface CO₂ fluxes from drained peat under different land-use systems in Riau and Jambi Provinces, Sumatra, Indonesia. Increase of CO₂ concentration was tracked in measurement chambers using an Infrared Gas Analyzer (IRGA, LI-COR 820 model). The results showed that CO₂ flux under oil palm (Elaeis guineensis) plantations ranged from 34?±?16 and 45?±?25 Mg CO₂ ha^–1 year^–1 in two locations in Jambi province to 66?±?25 Mg CO₂ ha^–1 year^–1 for a site in Riau. For adjacent plots within 3.2 km in the Kampar Peninsula, Riau, CO₂ fluxes from an oil palm plantation, an Acacia plantation, a secondary forest and a rubber plantation were 66?±?25, 59?±?19, 61?±?25, 52?±?17 Mg ha^–1 year^–1, respectively, while on bare land sites it was between 56?±?30 and 67?±?24 Mg CO₂ ha^–1 year^–1, indicating no significant differences among the different land-use systems in the same landscape. Unexplained site variation seems to dominate over land use in influencing CO₂ flux. CO₂ fluxes varied with time of day (p?<?0.001) with the noon flux as the highest, suggesting an overestimate of the mean flux values with the absence of night-time measurements. In general, CO₂ flux increased with the depth of water table, suggesting the importance of keeping the peat as wet as possible.     

Energy modeling on cleaner vehicles for reducing CO2 emissions in Japan

This study is to evaluate the impact of cleaner vehicles on energy systems and CO₂ emissions in the transportation sector in Japan. The transportation sector has the characteristic of spending petroleum. Even when the cost of petroleum rises, conventional vehicles cannot switch fuels to alternative energy right away. Cleaner vehicles, such as fuel cell vehicles, would be one of the alternative technologies in the transportation sector. It is supposed to have excellent performance in fuel efficiency and has strong possibility to reduce CO₂ drastically. This paper uses a multi-period market equilibrium model to explore the impacts of cleaner vehicles on the passenger transportation sector in Japanese energy system out to the year 2040. A Btu tax is tentatively imposed to evaluate the effect of fuel cost on energy consumption in the transportation sector. Financial parameters such as capital cost and operating cost are considered to summarize the profit in taxation case. The result of this study shows that fuel cell vehicles have a great effect on reducing CO₂ emissions especially when Btu taxes are imposed, which in turn has the advantage of encouraging a more diverse set of technologies and fuels. The analysis that petroleum consumption can be reduced using fuel cell vehicles will have effects on perspectives on energy systems in Japan.     

Avoiding CO2 capture effort and cost for negative CO2 emissions using industrial waste in chemical-looping combustion/gasification of biomass

Chemical-looping combustion (CLC) is a combustion process with inherent separation of carbon dioxide (CO₂), which is achieved by oxidizing the fuel with a solid oxygen carrier rather than with air. As fuel and combustion air are never mixed, no gas separation is necessary and, consequently, there is no direct cost or energy penalty for the separation of gases. The most common form of design of chemical-looping combustion systems uses circulating fluidized beds, which is an established and widely spread technology. Experiments were conducted in two different laboratory-scale CLC reactors with continuous fuel feeding and nominal fuel inputs of 300 W_th and 10 kW_th, respectively. As an oxygen carrier material, ground steel converter slag from the Linz–Donawitz process was used. This material is the second largest flow in an integrated steel mill and it is available in huge quantities, for which there is currently limited demand. Steel converter slag consists mainly of oxides of calcium (Ca), magnesium (Mg), iron (Fe), silicon (Si), and manganese (Mn). In the 300 W unit, chemical-looping combustion experiments were conducted with model fuels syngas (50 vol% hydrogen (H₂) in carbon monoxide (CO)) and methane (CH₄) at varied reactor temperature, fuel input, and oxygen-carrier circulation. Further, the ability of the oxygen-carrier material to release oxygen to the gas phase was investigated. In the 10 kW unit, the fuels used for combustion tests were steam-exploded pellets and wood char. The purpose of these experiments was to study more realistic biomass fuels and to assess the lifetime of the slag when employed as oxygen carrier. In addition, chemical-looping gasification was investigated in the 10 kW unit using both steam-exploded pellets and regular wood pellets as fuels. In the 300 W unit, up to 99.9% of syngas conversion was achieved at 280 kg/MW_th and 900 °C, while the highest conversion achieved with methane was 60% at 280 kg/MW_th and 950 °C. The material’s ability to release oxygen to the gas phase, i.e., CLOU property, was developed during the initial hours with fuel operation and the activated material released 1–2 vol% of O₂ into a flow of argon between 850 and 950 °C. The material’s initial low density decreased somewhat during CLC operation. In the 10 kW, CO₂ yields of 75–82% were achieved with all three fuels tested in CLC conditions, while carbon leakage was very low in most cases, i.e., below 1%. With wood char as fuel, at a fuel input of 1.8 kW_th, a CO₂ yield of 92% could be achieved. The carbon fraction of C₂-species was usually below 2.5% and no C₃-species were detected. During chemical-looping gasification investigation a raw gas was produced that contained mostly H₂. The oxygen carrier lifetime was estimated to be about 110–170 h. However, due to its high availability and potentially low cost, this type of slag could be suitable for large-scale operation. The study also includes a discussion on the potential advantages of this technology over other technologies available for Bio-Energy Carbon Capture and Storage, BECCS. Furthermore, the paper calls for the use of adequate policy instruments to foster the development of this kind of technologies, with great potential for cost reduction but presently without commercial application because of lack of incentives.

     

Gridded estimates of CO2 emissions: uncertainty as a function of grid size

Mitigation and Adaptation Strategies for Global Change - A crucial aspect of constructing a gridded model of anthropogenic fossil fuel CO2 (FFCO2) emissions involves careful consideration of...     

中国能源消费排放的CO2测算

基于“能源-经济-环境”的MARKAL-MACRO模型和数理人口学中的Keyfitz模型,测算未来中国能源消费需求;考虑能源效率、能源结构的变化以及气候变化问题的约束,设定了能源消费的3种情景,并分别测算了CO2排放量.结果表明,在基准情景下,中国的CO2排放在2042年达到峰值,为118.47亿t;在能源结构优化情景下,CO2排放在2036年达到峰值,为107.53亿t;在气候变化约束情景下,CO2排放在2031年达到峰值,为94.72亿t,相对于基准情景,排放峰值降低了23.75亿t,且峰值时间提前11a.随着城市化与工业化的推进,电力、水泥、钢铁行业的碳排放将先上升后下降;由于机动车保有量的增加,交通运输业的碳排放将持续上升.     

跨区电力传输对大气污染物和CO2的区域排放影响研究

跨区电力传输作为新的区域间能源调配形式将会改变我国未来各区域能源使用、大气污染物排放、温室气体排放等的发展路径,模拟、分析这种影响能为统筹协调全国以及区域的能源资源使用策略和电力行业节能减排相关政策提供参考.本研究应用基于区域电网的中国电力行业优化模型(BOMCES-ED),结合特高压输电线路的相关发展预期,以2010年我国各区域电网的发电装机信息为基准年数据,模拟研究了跨区电力传输对各区域电力行业发展以及环境排放造成的影响.结果显示,到2020年,最大的电力输出区域西北电网因电力输出而导致的电煤消耗量增加12351.2万t,SO2、NOx、CO2和Hg排放增加量分别达到22.1万t、11.6万t、2.28亿t和3.80t.由跨区电力传输导致的区域间环境排放和环境健康损失转移需要引起关注.     

风电场生命周期CO2排放核算与不确定性分析

提出了风力发电技术生命周期能耗和CO2排放核算的详细方法.应用上海某风电场数据进行核算,结果认为,风机生产阶段能耗和CO2排放占风电场生命周期能耗和CO2排放的比例均为最大,分别为68.23%和67.18%.不确定性分析认为,在所有强度参数中,钢生产综合能耗最为灵敏.风电场能耗强度和CO2强度分别为3.24gce/(kW?h)和9.47g/(kW?h),明显低于300MW火力发电机组的相同指标,分别为330gce/(kW?h)和915g/(kW?h). 20a服役期的50MW风电场满期后,同比300MW火电机组少排放CO2约234万t.     

基于粗糙集与灰色SVM的中国CO2排放量预测

从我国CO2排放量的不确定性、不完整性、小样本等特征出发,以灰色系统(GM)模型和支持向量机(SVM)模型为基础,建立基于粗糙集的组合预测模型.利用该模型以我国1990~2011年CO2排放量的数据以及同期的人口数量、GDP和能源消耗总量数据为基础对我国同期CO2排放量进行预测来验证其有效性,最后对我国2012~2017的CO2排放量进行预测.结果表明,灰色系统理论与支持向量机模型仅能够反应我国CO2排放的长期变化趋势,在预测精度上存在一定缺陷而基于粗糙集与灰色SVM的组合预测模型在预测精度上明显优于以上两种方法,能够对我国未来CO2排放量进行准确有效的预测分析.     

International inequality in CO2 emissions: A new factorial decomposition based on Kaya factors

In this paper, we analyze the determinants of inequality in the global distribution of CO₂ emissions across the regions considered by the International Energy Agency during the period 1990–2010. The inequality analysis is carried out using a factorial decomposition of the second Theil index of inequality. Specifically, based on Kaya factors, CO₂ emissions by active population are decomposed into four factors: carbon intensity of electricity production, electricity intensity of GDP, economic growth in terms of labour productivity and employment rate. The results show that global inequality in CO₂ emissions by active population declined by 22 percent between 1990 and 2010, where the economic growth in terms of labour productivity is the main item responsible for the whole inequality value. Then, a second decomposition by multiplying factors for analyzing the within- and the between-group inequality components is described. In relation to the study of inequality by population groups, it was found that the within-group inequality component had been the main contributor to the whole inequality during all the period. Finally, some economic policy implications are discussed.     

CO2 from fossil fuel burning: a comparison of ORNL and EDGAR estimates of national emissions

There is increasing interest and importance in estimating national emissions of greenhouse gases. We enquire whether two (partially) independent estimates of emissions of CO₂ from fossil-fuel combustion provide insight into the quality or uncertainty of emissions estimates. Using two published data sets that estimate CO₂ emissions for all countries, we show that the two ostensibly similar efforts to estimate emissions using ostensibly similar energy statistics have produced results that differ significantly for many countries. There is no obvious systematic bias between the two data sets and the two produce very similar estimates for the total of global emissions. Absolute differences between the two estimates are largest for a few countries with very large total emissions, but the largest relative differences occur in countries with small total emissions and weaker national systems of energy statistics. The magnitude of the differences reported has important implications for monitoring and verification of national emissions and potential national commitments.     

中国流通业CO2排放的因素分解和脱钩分析

参照IPCC清单中的方法估算了2000~2012年中国流通业CO2排放量;运用LMDI方法分解分析了研究期间流通业CO2排放变化的影响因素;并基于DPSIR框架构建流通业脱钩努力指数模型测度了流通业CO2排放脱钩效应.结果表明:2000~2012年间,流通业CO2排放量增长明显,期间累计排放总量为692482.37万t;产业规模效应是CO2排放增量的主要因素,能源强度效应是CO2排放减量的主要因素,分别引起CO2排放量增加了67435.72万t和减少了12358.67万t,能源结构和排放因子效应对CO2排放影响有限,分别引起CO2排放量增加了519.89万t和减少了2590.94万t;流通业CO2排放脱钩状态呈“弱脱钩—未脱钩—弱脱钩—未脱钩”的变化特征,脱钩努力指数值呈“ ”型变化趋势;目前能源强度是决定流通业CO2排放脱钩状态的关键因素,但随着能源强度的下降幅度越来越小,未来更需要通过调整能源结构和降低排放因子来实现流通业CO2排放脱钩.     

Chemical looping with oxygen uncoupling: an advanced biomass combustion technology to avoid CO2 emissions

Mitigation and Adaptation Strategies for Global Change - Bioenergy with carbon dioxide (CO2) capture and storage (BECCS) technologies represent an interesting option to reach negative carbon...     

Determinants of CO2 emissions in Brazil and Russia between 1992 and 2011: A decomposition analysis

This paper deals with the decomposition analysis of energy-related CO₂ emissions in Brazil and Russia from 1992 to 2011. The refined Laspeyres index (RLI) method applied and both aggregated and sectoral changes in CO₂ emissions decomposed. Brazil’s and Russia’s economies divided into three economic sectors including agriculture, industry and services. Impact of four main factors, such as economic activity, employment, energy intensity, and carbon intensity in CO₂ emissions changes were analyzed. The aggregated decomposition analysis revealed that Brazil is still far from a decoupling between economic growth and carbon dioxide emissions where Russia achieved a substantial decline in carbon emissions mainly due to the improved energy intensity. The empirical findings of sectoral decomposition analysis emphasized that the economic activity was the major CO₂ increasing factor in Brazil’s economic sectors. On the other hand the economic activity effect followed a reducing impact in Russia’s sectoral emissions until 2000. The structural changes between sectors and their impacts on CO₂ emissions were captured by employment effect. Energy intensity and carbon intensity effects underlined that environmental sustainability widely neglected in Brazil and Russia during the study period. The results yield important hints for energy planning and sustainable environment.     

Identification of main influencing factors of life cycle CO2 emissions from the integrated steelworks using sensitivity analysis

The amount of CO₂ emissions from steelworks accounts for a great share of the total CO₂ emissions from industry in China. Thus, reducing CO₂ emissions from steelworks is urgent for China's environmental protection and sustainable development. This study aims at identifying factors that influence CO₂ emissions from steelworks and proposing measures to reduce CO₂ emissions. The life cycle inventory (LCI) of iron and steel products implies the relationship between the CO₂ emissions of the steelworks and the input variables of the LCI. The Tornado Chart Tool is utilized to calculate the variation of CO₂ emissions caused by the change of each input variables of LCI. Then, mean sensitivity of each input variable is calculated and the ranking criterion developed is used to identify the main factors influencing the integrated steelworks. Subsequently, measures for reducing CO₂ emissions are proposed. The results indicate that the very important influencing factors of CO₂ emissions in steelworks are the CO₂ emission factor of Blast Furnace Gas (BFG), liquid steel unit consumption of continuous casting, continuous casting slab unit consumption of hot rolling and hot metal ratio of steel making. Consequently, many efficient measures for reducing CO₂ emissions have been proposed, such as removing CO₂ contained in BFG, decreasing the hot metal ratio of Basic Oxygen Furnace (BOF), recycling BFG, optimizing the products' structure, etc.     

The Tropical Peatland Plantation-Carbon Assessment Tool: estimating CO2 emissions from tropical peat soils under plantations

Land use change on Indonesian peatlands contributes to global anthropogenic greenhouse gas (GHG) emissions. Accessible predictive tools are required to estimate likely soil carbon (C) losses and carbon dioxide (CO₂) emissions from peat soils under this land use change. Research and modelling efforts in tropical peatlands are limited, restricting the availability of data for complex soil model parameterisation and evaluation. The Tropical Peatland Plantation-Carbon Assessment Tool (TROPP-CAT) was developed to provide a user friendly tool to evaluate and predict soil C losses and CO₂ emissions from tropical peat soils. The tool requires simple input values to determine the rate of subsidence, of which the oxidising proportion results in CO₂ emissions. This paper describes the model structure and equations, and presents a number of evaluation and application runs. TROPP-CAT has been applied for both site specific and national level simulations, on existing oil palm and Acacia plantations, as well as on peat swamp forest sites to predict likely emissions from future land use change. Through an uncertainty and sensitivity analysis, literature reviews and comparison with other methods of estimating soil C losses, the paper identifies opportunities for future model development, bridging between different approaches to predicting CO₂ emissions from tropical peatlands under land use change. TROPP-CAT can be accessed online from www.redd-alert.eu in both English and Bahasa Indonesia.     

Fairness aspects of linking the European emissions trading scheme under a long-term stabilization scenario for CO2 concentration

Climate equity is a crucial but difficult element in negotiations on a post-2012 climate regime. With respect to the trading of greenhouse gas emissions the equity aspect is considered in the Kyoto Protocol which demands that emissions trading should be supplemental to domestic abatement efforts. The question arises whether a linking of the European Union Emissions Trading Scheme (EU ETS) to non-EU emission trading schemes or the Clean Development Mechanism (CDM) could have an impact on principles of climate justice and thus potentially affect ongoing negotiations. In this study, we present the results of a three step analysis: In a first step, it estimates mid-term greenhouse gas emission entitlements for Annex B and Non-Annex B countries for the year 2020 which keep within reach a stabilization of the CO₂ concentration at 450 ppmv in the long-term. In the second step, the resulting emission entitlements are used as an input to an economic partial-equilibrium model in order to assess the shift of abatement efforts under different scenarios of linking the EU ETS. In a third step, we analyze the outcome of the economic model with respect to the future trend of European per capita emissions under the current EU ETS relative to different scenarios of linking the EU ETS. The model results indicate that European per capita emissions have to be reduced to a considerably smaller extent if a linking of the EU ETS is accompanied by an optimal design of the National Allocation Plans and if low-cost CO₂ permits became available via the CDM to a large extent.