The impact of heterogeneity on the distribution of CO2: Numerical simulation of CO2 storage at Ketzin

Numerical modelling of multiphase flow is an essential tool to ensure the viability of long-term and safe CO₂ storage in geological formations. Uncertainties arising from the heterogeneity of the formation and lack of knowledge of formation properties need to be assessed in order to create a model that can reproduce the data available from monitoring. In this study, we investigated the impact of unknown spatial variability in the petrophysical properties within a sandy channel facies of a fluviatile storage formation using stochastic methods in a Monte Carlo approach. The stochastic method has been applied to the Ketzin test site (CO₂SINK), and demonstrates that the deterministic homogeneous model satisfactorily predicts the first CO₂ arrival time at the Ketzin site. The equivalent permeability was adjusted to the injection pressure and is in good agreement with the hydraulic test. It has been shown that with increasing small-scale heterogeneity, the sharpness of the CO₂ front decreases and a greater volume of the reservoir is affected, which is also seen in an increased amount of dissolved CO₂. Increased anisotropy creates fingering effects, which result in higher probabilities for earlier arrival times. Generally, injectivity decreases with increasing heterogeneity.     

An economic and environmental assessment of carbon capture and storage (CCS) power plants: a case study for the City of Kiel

In the not too distant future several power plants throughout Europe will have to be replaced and the decision has to be made whether to build coal-fired power plants with carbon capture and storage (CCS). In a study for the city of Kiel in northern Germany only an 800 MW coal power plant reaches a required minimum for rentability. This study looks at an additional economic and environmental evaluation of a coal plant with CCS. We find that in two out of three carbon and energy price scenarios integrated gasification combined cycle (IGCC) plants with CCS have the greatest rentability. Pulverised coal (PC) plants with CCS can only compete with other options under very favourable assumptions. Life-cycle emissions from CCS are less than 70% of a coal plant – compared with at least more than 80% when only considering direct emissions from plants. However, life-cycle emissions are lower than in any other assessed option.     

Post-tsunami changes in the littoral environment along the southeast coast of India

The 26th December 2004 Indian Ocean tsunami devastated coastal regions of the Indian subcontinent. Andaman and Nicobar Islands, coastal stretches of Tamil Nadu, Andhra Pradesh and Kerala were the most affected regions of India. Changes in the beach profiles, long shore currents, breaking wave characteristics in the surf zone at selected locations along the Tamil Nadu coast were studied during January, April, October 2005 and January 2006. Long shore sediment transport rates were estimated from the observed parameters. Studies were carried out earlier (1995-1996 and 1998) to understand the coastal environment over a one-year cycle in the study region. The post-tsunami observations were compared with the earlier studies to establish the variations in the littoral environment and to ascertain the normalcy of the littoral environment in the post-tsunami scenario. From the changes in the beach profiles, the shoreline was observed to recede by about 20m and built-up of backshore by about 0.5m at most locations. Observations from the field investigations and comparisons with earlier studies along this stretch of the coastline indicate that the coastline is yet to return completely to normalcy.     

Dissolution of a CO2 lake, modeled by using an advanced vertical turbulence mixing scheme

The dissolution of CO₂ from a CO₂ lake with and without a hydrate layer, located at a flat bottom at 3000 m depth has been modeled using the MIT General Circulation Model coupled with the General Ocean Turbulence Model (GOTM). The vertical turbulent mixing scheme takes into account density effects and should give more realistic results for the CO₂ plume than previously used constant eddy diffusivity models. The introduction of a third direction gives qualitatively different results for the spreading of the CO₂ plume than previous 2D results. The dissolution rate and near field dissolved CO₂ concentrations approach a steady state for a given far field ocean current within less than a day. The dissolution rate is highly dependent on the velocity of the ambient current and is reduced with 1.6 when a hydrate layer is introduced.     

Ⅲ型储氢气瓶内胆6061-T6铝合金的氢致损伤研究进展

基于在多次循环充、放氢过程中,Ⅲ型储氢气瓶6061-T6铝合金内胆内部结构中渗入氢,从而导致性能衰减,影响气瓶服役安全可靠性,文中从氢渗透损伤、高压气体渗氢、溶液渗氢等几个方面综述了国内外开展包括6061铝在内的铝及铝合金中氢渗透行为及对铝合金拉伸力学性能、疲劳性能的影响的研究进展.简述了采用高压气体渗氢及溶液渗氢开展...     

无锡马山抽水蓄能电站堆石料工程特性平行试验研究

通过马山抽水蓄能电站坝体堆石料平行试验研究,认为三种堆石料两次大型三轴剪切试验、侧限单向压缩试验和渗透试验的结果都很接近;堆石料的应力应变关系符合邓肯-张双曲线模型,低围压下会发生剪胀;其压缩性比较低,卸荷回弹量很小,基本都是塑性变形;堆石料的渗透规律基本满足达西定律。堆石料平行试验结果验证了材料的性质能满足工程设计的要求,也说明材料性质的稳定性、试验方法的可行性和试验仪器的准确性均比较令人满意。     

浙北典型稻作区近30年表层土壤碳氮含量变化

农业土壤碳库作为表生碳库的重要组成部分,对研究陆地生态系统碳循环具有重要意义。水稻土作为农业土壤的重要类型之一,其固碳能力研究对研究陆地生态系统碳循环具有现实意义。文章通过嘉善县20世纪80年代、2002年、2008年3次土壤调查数据,对嘉善县表层土壤中有机碳、氮含量及分布进行了分析,有机碳平均值在80年代到2002年呈下降趋势,2002—2008年微弱上升。全氮的平均值在80年代到2002年亦呈下降趋势,2002—2008年呈较快上升。以高密度网格化（1点/4km2）实测数据,计算得到2008年表层土壤有机碳、氮平均密度为44.36t·hm-2和5.3t·hm-2,平均容量为22.182kg·m-3和2.67kg·m-3,总储量分别为1.122×109kg和0.135×109kg,依据2002年、2008年两次可对比的实测数据,采用GIS和地统计学工具,进行了含量的空间分析,以1点/4km2精度,计算了2002—2008年县域内农用地表层土壤的有机碳、氮的变化。2002—2008年每年平均储碳速率为30.8kg·hm-2,储氮速率为156kg·hm-2。2002—2008年碳氮比平均值下降了2.3,依据土壤粒级数据和Hassink的碳保持容量公式,计算出嘉善县土壤平均固定容量为2.478%,初步估算,全县耕地表层土壤还具有42.43万t的固碳潜力,影响表土有机碳储汇的自然因素主要为土壤含水量和质地。     

大兴安岭南部温带山杨天然次生林不同生长阶段生物量及碳储量

基于内蒙古赛罕乌拉森林生态系统定位研究站山杨（Populus davidiana Dode）天然次生林幼龄林、中龄林、近熟林、成熟林及过熟林生物量调查,探讨了不同龄组山杨天然次生林单株木、林分、林下植被和枯落物的生物量及群落碳储量的时空变化规律。结果表明：随林龄的增大,山杨天然次生林木和各器官生物量总体呈增加趋势,树干所占比例增加,中龄林增加尤为明显;林下植被层、枯落物层生物量随林龄增大呈增加趋势。群落总碳储量的空间分布序列是：乔木层〉枯落物层〉林下植被层。幼龄林、中龄林、近熟林、成熟林和过熟林群落的碳储量分别为27.146 6、53.545 1、60.889 8、77.915 8、79.135 3t.hm-2,乔木层碳储量分别为22.206 5、47.215 7、52.056 3、68.445 3、68.773 1 t.hm-2,枯落物层和林下植被层碳储量平均值分别为5.814 4、2.172 7 t.hm-2。乔木层、枯落物层和林下植被层碳储量占总量的平均率分别为86.05%、10.39%和3.57%。研究认为山杨天然次生林群落碳储量随林龄增加的变化规律明显,碳汇潜力巨大;中龄林为碳储量增长迅速期,且持续较长一段时间,是林分管理的关键阶段;自然稀疏有利于促进林木生长,林分碳储量并未随林分密度下降而减小。     

未来不同情景下陕西省碳储量的时空演变分析

为了解陕西省不同情景下的土地利用发展趋势,并有效评估土地利用变化下陕西省陆地生态碳储量时空演变,研究运用Markov-FLUS和InVEST模型,分析2000~2020年的土地利用变化对于陕西省碳储量变化的影响,并模拟和评估陕西省2025年和2030年3种不同情景下的土地利用结构,碳储量和碳密度的时空变化.结果表明： ①耦合的Markov-FLUS模型中各地类的ROC值均在0.7以上,表现出较高精度与优秀的分类性能,模型对研究区的土地利用驱动因子解释能力较好,具有高精度和优秀的分类性能.②2000~2020年,陕西省的耕地大幅减少,林地显著增加,高固碳效益的林地面积增加使得陕西省的碳储量从1 546.95 Tg上升到1 616.25 Tg. 2000~2020年陕西省内各地区的变化互有差异,其中延安的碳储量显著增加了18.89 Tg,榆林的碳储量则在20年间显著减少了3.29 Tg. ③海拔、降水和气温成为影响2020~2030年陕西省碳储量时空变化的主要因素,在2025年与2030年的3种不同情景下,在生态优先情景下碳储量分别为1 632.27 Tg和1 647.43 Tg,碳储量及其增速明显高于自然发展情景和耕地保护情景. ④生态优先情景下碳储量增加区占比高于耕地保护情景,减少区占比低于自然发展情景,碳储量的分布表现最为均衡。同时,陕北黄土高原区的南部和北部区域在未来的发展中需要重点关注生态环境的保护.研究结果一定程度上可以为推进生态陕西建设和制定碳中和战略规划提供参考.     

某型金属减振器的加速贮存验证试验方法研究

目的 研究一种金属减振器的库房贮存寿命的实验室加速贮存试验验证方法.方法 首先分析某型金属减振器的性能指标参数和贮存薄弱环节,然后设计并实施相关的加速贮存试验.通过对试验数据进行回归分析,获得金属减振器常温下的应力松弛关系式,进而开展金属减振器的加速贮存验证试验,验证其贮存后的性能指标参数能够否满足要求.结果 根据验证...