应对气候变化的有效途径:二氧化碳捕集与封存

全球气候变暖问题日益严重,二氧化碳(CO2)捕集与封存(CCS)技术被看作是最有发展前景的解决该问题的技术之一。CCS技术主要包括三个环节:CO2捕集、运输和封存。本文首先介绍了CO2捕集技术,该技术按工艺主要分为燃烧前捕集、富氧燃烧捕集和燃烧后捕集。随后介绍了CO2封存技术,该技术根据封存地点不同可分为地质封存和海洋封存。在众多的CO2封存技术中,CO2强化采油(CO2-EOR)技术由于其较高的经济效益近年来得到广泛应用。虽然CCS技术发展很快,但仍存在很多问题,如CO2泄漏问题、资金投入大等。但是,随着各国政府越来越重视CCS技术的研究和开发,相信未来该技术在抵制全球气候变暖问题上会发挥重要的作用。     

中国CO_2地质储存问题浅析

CO2地质储存是减少二氧化碳向大气环境排放、控制全球气候变暖的重要措施。本文对CO2地质储存的概念、地质储存的原理、介质类型进行了阐述,分析了国内外CO2地质储存研究现状,同时对我国CO2地质储存条件和可能存在的安全及环境风险进行分析,并对我国CO2地质储存未来的发展方向提出建议。     

中国陆上油藏CO2封存潜力评估

CO2捕集与封存是减缓气候变化的一种关键的碳减排选择方案。将CO2注入油藏作为一种碳埋存方式引起广泛关注。作为判断某一国家、某一区域或某一具体储层是否适合CO2地质封存开展的重要依据之一,有必要在规划碳捕集与封存(CCS)项目前,对潜在的封存库进行封存潜力评估。本文在已有可公开的地质资料的基础上,评估了中国陆上216个油田实施CO2地质封存的潜力,并与相关研究结果进行了比较。结果表明:在满足埋存深度大于800 m的筛选条件下,当假设我国陆上油田全部用于CO2-EOR时,CO2封存潜力约3.6 Gt;当陆上油田全部视为废弃油藏处理时,CO2理论封存潜力约4.6 Gt。其中,东北和华北地区油藏封存CO2潜力巨大,占陆上油田CO2封存总量的60%以上;同时这里CO2集中排放源分布密集,排放源和封存地间的匹配性良好,可以减少CO2运输和封存成本。在这两个地区可以优先考虑实施油藏封存CO2项目。     

气候变化背景下碳减排特点及政策建议

近半个世纪以来,日趋变暖的气候使得碳减排成为世界上很热的一个议题。本文从全球CO2的排放及其对气候的影响入手,引入低碳经济的概念和碳减排国际合作情况,分析了碳减排技术和投资热点。最后对我国碳减排提出几点建议。     

对当前全球气候变化问题的思考

全球气候变化问题已经超越了一般环境问题的范畴,而成为国际政治经济外交关系的重要考虑因素。随着《京都议定书》的实施以及气候变化问题谈判进程的加快．对我国未来经济社会发展提出了挑战。文章分析认为．要求主要发展中国家承诺减限排义务的压力与日俱增,而我国开始进入工业化中期．应对气候变化问题的能力还比较薄弱。因此．提出应对全球气候变化问题的一些思考：（1）充分认识全球气候变化问题的重要性和严峻性,准确把握国际谈判进程;（2）加快制定适应和减缓气候变化的国家战略。采取适合我国国情的有力措施积极应对气候变暖;（3）加强气候变化领域的能力建设．提高我国参与全球气候变化活动的能力;（4）充分利用国际合作机制,提高我国应对气候变化的技术水平与经济能力。     

对全球变暖认识的七个问题的确定与不确定性

全球变暖是国际社会广泛关注的问题。由于以人类目前的认识水平,尚无法完全了解气候变化的内在规律,因此目前对气候变暖认识的确定性与不确定性并存。本文旨在归纳总结目前对全球变暖的认识哪些是确定的,哪些是不确定的,并提出相关建议。气候系统涵盖很多方面,本文重点关注与人类活动造成的气候变暖相关的七个问题。①对全球变暖的认识:近百年全球气候确实在变暖,但为什么又出现了停滞?②对大气中温室气体浓度上升的认识:工业革命以来大气温室气体浓度快速升高是确定的,但未来如何变化有不确定性;③对温室气体排放与气温升高的关系(气候敏感度)的认识:在现代大气CO2浓度加倍会导致全球平均增温约3.0℃,但是在更长时间尺度上气候敏感度是不确定的;④对于气候模式的认识:它能够很好地模拟出近百年的气候变暖趋势,且证明人类活动可能是现代气候变暖的主要原因,但模式不能充分描述地球系统的变化,只能表征地球系统的部分特征;⑤对于气候预估的认识:根据排放情景预估本世纪气候继续变暖,但还将变暖多少不确定;⑥对于2℃阈值的认识:它是人类控制升温的一个设想,作为应对气候变化的约束性目标,但是升温幅度何时达到2℃不确定;⑦对于地球系统临界点的认识:地球系统已有一些危险的信号,但何时达到临界点不确定。在适应和减缓全球变暖、调整产业结构等应对行动中,应全面、综合考虑气候变化认识的确定性与不确定性,应对确定性的变化,规避不确定性的风险。     

基于低碳融资机制的CCS技术融资研究

由于化石能源在全球能源供给中仍占据主要地位,碳捕获与封存(CCS)技术被认为是当前控制温室气体排放的有效途径之一。但是,由于技术与成本的不确定性,政府支持和公众认知程度的不足,融资机制的不完善严重阻碍了该技术的大规模推广。基于此,本文从低碳融资机制与实践经验两个层面对CCS技术的融资问题加以探讨。首先从国际气候融资、政府直接投资与金融机构参与融资三个层面梳理了低碳技术融资政策与渠道,指出低碳技术的发展很大程度上依赖于政府的直接投资与激励政策的扶持。进而,着重分析了CCS技术融资面临的困难,包括:国际气候融资渠道狭窄且缺乏针对CCS技术的专项资金;国内CCS技术的融资渠道单一,严重依赖政府的直接投资与政策激励;金融机构所提供的资金支持远不能满足CCS技术的资金需求。然后,从国内外CCS示范项目的成功与失败案例中总结CCS技术融资机制的经验教训,指出政府的资金与技术支持、市场化减排机制的激励、通过提高采收率(EOR)等碳捕集、利用与封存(CCUS)技术经济收益的获取、CCS关键技术的研发、政府与社会资本的融洽合作机制是保证CCS示范项目资金需求的关键因素。最后,从国际气候融资机制的完善、政府直接投资与政策支持的加强、财税政策的有效实施、市场化减排机制的充分运用、技术风险管理的完善、多主体参与的市场化融资机制的构建等方面对CCS技术未来的融资机制设计提出了政策建议。     

CO2地质储存泄露安全风险评价方法初探

CO2地质储存作为一项有效、直接的碳减排技术,本质上属于环保型工程项目。在总结国内外已有的风险评价方法的基础上,结合CO2地质储存机理及工作属性,借鉴国际风险评价经验,以及我国核废料、一般工业固体废弃物填埋等类似工程项目风险评价工作方法,对适用于我国的CO2地质储存安全风险评价的定义进行了探讨,并将CO2地质储存泄露风险评价分为风险评价、风险评估与风险控制三部分内容。通过CO2地质储存泄露通道及泄露后可能产生的环境危害分析,建立了由地质因素、工程单元因素、施工因素及其它因素四个风险因子指标层及其亚层组成的CO2地质储存泄露的安全风险层次指标体系,初步提出了风险评估方法以及CO2泄露可接受的安全风险标准;最后根据CO2地质储存泄露风险提出了不同风险的控制方法及建议,对CO2地质储存场地选址中的安全风险评价、工程实施及监测具有一定意义。     

CO_2地质封存与高放射性核废物地中处置的地质环境影响对比

高放核废物的地中处置(HLW)与CO2的捕集与封存(CCS)在环境问题方面有一定的相似性。文章从物理性质、封存机理、环境影响角度,就CO2和HLW地质处置的环境问题进行对比研究,旨在为CCS的环境风险管理提供思路。通过对比分析得出,泄漏的CO2在地层和空气中的扩散能力较强,对人体健康、水体质量等都有一定的影响,但危害程度比较浅,持续时间也比较短;而泄漏哪怕极少的核素,其放射性和毒性都会对人体健康和环境安全造成很严重的威胁。因此,同样剂量泄漏的背景下,CO2的环境影响没有HLW的环境影响严重,CO2地质封存可以从核废物地中处置的环境管理中借鉴经验。     

气候临界点及应对——碳中和

基于政府间气候变化专门委员会(IPCC)评估报告及近年的研究文献,文章试图从气候变化的影响和风险的角度出发,诠释气候变暖可能正在触发的全球多个气候临界点,解读国际社会采取碳达峰和碳中和政策措施的由来,讨论不同系统或区域开展适应性研究的重要性与迫切性。主要结论:(1)近百年来,特别是1970年代以来,全球持续快速升温变暖,而中国陆地和海洋的升温速率又高于全球平均,产生了广泛的影响和风险。(2) 2019年,造成全球变暖的主要温室气体CO2浓度已达到410.5 mg/L,为工业化前(1750年)的148%,也是至少200万年以来的最高值。(3)全球的持续升温使得气候变化的风险不成比例地增加,许多系统正在逼近其发生严重突变和不可逆转变化的临界点,并且,某些气候临界点的发生将比预计得更为提前。(4)气候变暖的加剧可能正在触发全球的九个气候临界点,包括暖水珊瑚礁的大规模白化和死亡、格陵兰和南极冰盖的加速融化、大西洋经向翻转环流的减弱等,并有引发多米诺骨牌效应的风险。(5)为应对气候变暖的影响和风险,有必要将本世纪全球升温限制在工业化前水平(1850—1900年平均)之上2℃(最好为1.5℃)以内,相对于2010年,全球净人为CO2排放量到2030年需减少约25%(45%),并在2070年(2050年)左右实现碳中和。(6)以暖水珊瑚礁为例,讨论并分析了中国受损珊瑚礁将可能由于较高的中国海洋升温速率而率先触发临界点,亟需修复并加强受损珊瑚礁等系统或区域气候恢复力(resilience)的建设,以提高其适应气候变化的能力。此外,最近中国受损珊瑚礁原位有性繁殖修复实验取得了突破性进展,这为重构受损珊瑚礁的恢复力提供了积极的前景。     

The United States Department of Energy's Regional Carbon Sequestration Partnerships program: a collaborative approach to carbon management

This paper reviews the Regional Carbon Sequestration Partnerships (RCSP) concept, which is a first attempt to bring the U.S. Department of Energy's (DOE) carbon sequestration program activities into the "real world" by using a geographically-disposed-system type approach for the U.S. Each regional partnership is unique and covers a unique section of the U.S. and is tasked with determining how the research and development activities of DOE's carbon sequestration program can best be implemented in their region of the country. Although there is no universal agreement on the cause, it is generally understood that global warming is occurring, and many climate scientists believe that this is due, in part, to the buildup of carbon dioxide (CO(2)) in the atmosphere. This is evident from the finding presented in the National Academy of Science Report to the President on Climate Change which stated "Greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise. Temperatures are, in fact, rising. The changes observed over the last several decades are likely mostly due to human activities, ...". In the United States, emissions of CO(2) originate mainly from the combustion of fossil fuels for energy production, transportation, and other industrial processes. Roughly one third of U.S. anthropogenic CO(2) emissions come from power plants. Reduction of CO(2) emissions through sequestration of carbon either in geologic formations or in terrestrial ecosystems can be part of the solution to the problem of global warming. However, a number of steps must be accomplished before sequestration can become a reality. Cost effective capture and separation technology must be developed, tested, and demonstrated; a database of potential sequestration sites must be established; and techniques must be developed to measure, monitor, and verify the sequestered CO(2). Geographical differences in fossil fuel use, the industries present, and potential sequestration sinks across the United States dictate the use of a regional approach to address the sequestration of CO(2). To accommodate these differences, the DOE has created a nationwide network of seven Regional Carbon Sequestration Partnerships (RCSP) to help determine and implement the carbon sequestration technologies, infrastructure, and regulations most appropriate to promote CO(2) sequestration in different regions of the nation. These partnerships currently represent 40 states, three Indian Nations, four Canadian Provinces, and over 200 organizations, including academic institutions, research institutions, coal companies, utilities, equipment manufacturers, forestry and agricultural representatives, state and local governments, non-governmental organizations, and national laboratories. These partnerships are dedicated to developing the necessary infrastructure and validating the carbon sequestration technologies that have emerged from DOE's core R&D and other programs to mitigate emissions of CO(2), a potent greenhouse gas. The partnerships provide a critical link to DOE's plans for FutureGen, a highly efficient and technologically sophisticated coal-fired power plant that will produce both hydrogen and electricity with near-zero emissions. Though limited to the situation in the U.S., the paper describes for the international scientific community the approach being taken by the U.S. to prepare for carbon sequestration, should that become necessary.     

Global warming and carbon dioxide through sciences

Increased atmospheric CO(2)-concentration is widely being considered as the main driving factor that causes the phenomenon of global warming. This paper attempts to shed more light on the role of atmospheric CO(2) in relation to temperature-increase and, more generally, in relation to Earth's life through the geological aeons, based on a review-assessment of existing related studies. It is pointed out that there has been a debate on the accuracy of temperature reconstructions as well as on the exact impact that CO(2) has on global warming. Moreover, using three independent sets of data (collected from ice-cores and chemistry) we perform a specific regression analysis which concludes that forecasts about the correlation between CO(2)-concentration and temperature rely heavily on the choice of data used, and one cannot be positive that indeed such a correlation exists (for chemistry data) or even, if existing (for ice-cores data), whether it leads to a "severe" or a "gentle" global warming. A very recent development on the greenhouse phenomenon is a validated adiabatic model, based on laws of physics, forecasting a maximum temperature-increase of 0.01-0.03 degrees C for a value doubling the present concentration of atmospheric CO(2). Through a further review of related studies and facts from disciplines like biology and geology, where CO(2)-change is viewed from a different perspective, it is suggested that CO(2)-change is not necessarily always a negative factor for the environment. In fact it is shown that CO(2)-increase has stimulated the growth of plants, while the CO(2)-change history has altered the physiology of plants. Moreover, data from palaeoclimatology show that the CO(2)-content in the atmosphere is at a minimum in this geological aeon. Finally it is stressed that the understanding of the functioning of Earth's complex climate system (especially for water, solar radiation and so forth) is still poor and, hence, scientific knowledge is not at a level to give definite and precise answers for the causes of global warming.     

Ecosystem carbon budgeting and soil carbon sequestration in reclaimed mine soil

Global warming risks from emissions of green house gases (GHGs) by anthropogenic activities, and possible mitigation strategies of terrestrial carbon (C) sequestration have increased the need for the identification of ecosystems with high C sink capacity. Depleted soil organic C (SOC) pools of reclaimed mine soil (RMS) ecosystems can be restored through conversion to an appropriate land use and adoption of recommended management practices (RMPs). The objectives of this paper are to (1) synthesize available information on carbon dioxide (CO2) emissions from coal mining and combustion activities, (2) understand mechanisms of SOC sequestration and its protection, (3) identify factors affecting C sequestration potential in RMSs, (4) review available methods for the estimation of ecosystem C budget (ECB), and (5) identify knowledge gaps to enhance C sink capacity of RMS ecosystems and prioritize research issues. The drastic perturbations of soil by mining activities can accentuate CO2 emission through mineralization, erosion, leaching, changes in soil moisture and temperature regimes, and reduction in biomass returned to the soil. The reclamation of drastically disturbed soils leads to improvement in soil quality and development of soil pedogenic processes accruing the benefit of SOC sequestration and additional income from trading SOC credits. The SOC sequestration potential in RMS depends on amount of biomass production and return to soil, and mechanisms of C protection. The rate of SOC sequestration ranges from 0.1 to 3.1 Mg ha(-1) yr(-1) and 0.7 to 4 Mg ha(-1) yr(-1) in grass and forest RMS ecosystem, respectively. Proper land restoration alone could off-set 16 Tg CO2 in the U.S. annually. However, the factors affecting C sequestration and protection in RMS leading to increase in microbial activity, nutrient availability, soil aggregation, C build up, and soil profile development must be better understood in order to formulate guidelines for development of an holistic approach to sustainable management of these ecosystems. The ECBs of RMS ecosystems are not well understood. An ecosystem method of evaluating ECB of RMS ecosystems is proposed.     

The United States Department of Energy's Regional Carbon Sequestration Partnerships Program Validation Phase

This paper reviews the Validation Phase (Phase II) of the Department of Energy's Regional Carbon Sequestration Partnerships initiative. In 2003, the U.S. Department of Energy created a nationwide network of seven Regional Carbon Sequestration Partnerships (RCSP) to help determine and implement the technology, infrastructure, and regulations most appropriate to promote carbon sequestration in different regions of the nation. The objectives of the Characterization Phase (Phase I) were to characterize the geologic and terrestrial opportunities for carbon sequestration; to identify CO(2) point sources within the territories of the individual partnerships; to assess the transportation infrastructure needed for future deployment; to evaluate CO(2) capture technologies for existing and future power plants; and to identify the most promising sequestration opportunities that would need to be validated through a series of field projects. The Characterization Phase was highly successful, with the following achievements: established a national network of companies and professionals working to support sequestration deployment; created regional and national carbon sequestration atlases for the United States and portions of Canada; evaluated available and developing technologies for the capture of CO(2) from point sources; developed an improved understanding of the permitting requirements that future sequestration activities will need to address as well as defined the gap in permitting requirements for large scale deployment of these technologies; created a raised awareness of, and support for, carbon sequestration as a greenhouse gas (GHG) mitigation option, both within industry and among the general public; identified the most promising carbon sequestration opportunities for future field tests; and established protocols for project implementation, accounting, and management. Economic evaluation was started and is continuing and will be a factor in project selection. During the Validation Phase, the seven regional partnerships will put the knowledge learned during the Characterization Phase into practice through field tests that will validate carbon sequestration technologies that are best suited to their respective regions of the country. These tests will verify technologies developed through DOE's core R&D effort and enable implementation of CO(2) sequestration on a large scale, should that become necessary. Pilot projects will have a site-specific focus to test technology; assess formation storage capacity and injectivity; validate and refine existing CO(2) formation models used to determine the transport and fate of CO(2) in the formation; demonstrate the integrity of geologic seals to contain CO(2); validate monitoring, mitigation, and verification (MMV) technologies; define project costs and compare costs of alternatives; assess potential operational and long-term storage risks; address regulatory requirements; and engage and evaluate public acceptance of sequestration technologies. Field validation tests involving both sequestration in geologic formations and terrestrial sequestration are being developed. The results from the Validation Phase will help to confirm the estimates made during the Characterization Phase and will be used to update the regional atlases and NatCarb. Answers to many questions about the effectiveness and safety of carbon sequestration technologies will be instrumental in planning for a Deployment Phase, in which large volume tests will be planned to further sequestration as an option that can mitigate GHG emissions in the United States.     

Risk Assessment of Carbon Sequestration for Terrestrial Ecosystems in China

Climate change will alter the capacity of carbon sequestration,and the risk assessment of carbon sequestration for terrestrial ecosystems will be helpful to the decision-making for climate change countermeasures and international climate negotiations.Based on the net ecosystem productivity of terrestrial ecosystems simulated by Atmosphere Vegetation Integrated Model,each grid of the risk criterion was set by time series trend analysis.Then the risks of carbon sequestration of terrestrial ecosystems were investigated.The results show that,in the IPCCSRES-B2 climate scenario,climate change will bring risks of carbon sequestration,and the high-risk level will dominate terrestrial ecosystems.The risk would expand with the increase of warming degree.By the end of the long-term of this century,about 60% of the whole country will face the risk;Northwest China,mountainous areas in Northeast China,middle and lower reaches plain of Yangtze River areas,Southwest China and Southeast China tend to be extremely vulnerable.Risk levels in most regions are likely to grow with the increase of warming degree,and this increase will mainly occur during the near-term to mid-term.Northwest China will become an area of high risks,and deciduous coniferous forests,temperate mixed forests and desert grassland tend to be extremely vulnerable.     

Risk Assessment of Carbon Sequestration for Terrestrial Ecosystems in China

Abstract

Climate change will alter the capacity of carbon sequestration, and the risk assessment of carbon sequestration for terrestrial ecosystems will be helpful to the decision-making for climate change countermeasures and international climate negotiations. Based on the net ecosystem productivity of terrestrial ecosystems simulated by Atmosphere Vegetation Integrated Model, each grid of the risk criterion was set by time series trend analysis. Then the risks of carbon sequestration of terrestrial ecosystems were investigated. The results show that, in the IPCCSRES-B2 climate scenario, climate change will bring risks of carbon sequestration, and the high-risk level will dominate terrestrial ecosystems. The risk would expand with the increase of warming degree. By the end of the long-term of this century, about 60% of the whole country will face the risk; Northwest China, mountainous areas in Northeast China, middle and lower reaches plain of Yangtze River areas, Southwest China and Southeast China tend to be extremely vulnerable. Risk levels in most regions are likely to grow with the increase of warming degree, and this increase will mainly occur during the near-term to mid-term. Northwest China will become an area of high risks, and deciduous coniferous forests, temperate mixed forests and desert grassland tend to be extremely vulnerable.     

中国农业源碳汇估算及其与农业经济发展的耦合分析

农业作为重要的产业部门,在满足人们基本的物质需求的同时具有重要的生态保障和碳汇功能,充分发掘农业的碳汇潜力对于农业绿色化发展和农民增收具有重要意义。本文量化测算了我国1993—2011年的农业源碳汇潜力,并构建农业源浄碳汇与农业经济发展的耦合模型,结果发现农业源碳汇量由1993年的52 318.70万t波动增加到2011年的66 073.77万t,年均增加1.38%,但是农业源的浄碳汇量却呈现波动递减趋势,由1993年的36 691.72万t减少到34 815.67万t,其中粮食作物的CO2吸收总量占据主要部分,经济作物CO2吸收量在农业总的CO2吸收量所占的比重虽小,但是增速较快,年均增幅达到4.15%;从影响因素来看,农业源碳汇和耕地面积关联度不大,农作物单位产量和农业源碳汇呈正相关;农业源浄碳汇与农业经济发展之间处于强负耦合状态,耦合状态不理想,农业产值与农业净碳汇关联度不强,这主要是由高投入、高消耗的农业生产方式引发农业碳排放增加和农业总产出效益提升等原因造成的。最后,本文针对性地提出促进我国农业减排增汇的对策建议:强化政府引导,从农业的规划、生产、消费等多领域进行引导;加大农业减排增汇的技术、资金和人力支持,为农业的减排增汇做好保障;通过林地增汇、农田增汇、草地增汇、综合增汇等多种手段,提升农地的碳汇能力;加快碳市场交易体系建设,以市场杠杆推进农业的减排增汇。     

农田固碳措施对温室气体减排影响的研究进展

农田是CO2,CH4和N2O三种温室气体的重要排放源,在全球范围内农业生产活动贡献了约14%的人为温室气体排放量,以及58%的人为非CO2排放,不合理的农田管理措施强化了农田温室气体排放源特征,弱化了农田固碳作用。土壤碳库作为地球生态系统中最活跃的碳库之一,同时也是温室气体的重要源/汇。研究表明通过采取合理的农田管理措施,既可起到增加土壤碳库、减少温室气体排放的目的,又能提高土壤质量。农田土壤碳库除受温度、降水和植被类型的影响外,还在很大程度上受施肥量、肥料类型、秸秆还田量、耕作措施和灌溉等农田管理措施的影响。本文通过总结保护性耕作/免耕,秸秆还田,氮肥管理,水分管理,农学及土地利用变化等农田管理措施,探寻增强农田土壤固碳作用,减少农田温室气体排放的合理途径。农田碳库的稳定/增加,对于保证全球粮食安全与缓解气候变化趋势具有双重的积极意义。在我国许多有关土壤固碳与温室气体排放的研究尚不系统或仅限于短期研究,这也为正确评价各种固碳措施对温室气体排放的影响增加了不确定性。