环境足迹的核算与整合框架——基于生命周期评价的视角

环境足迹及其与生命周期评价(LCA)的关系是工业生态学关注的新热点。从探讨环境足迹与LCA的关系入手,以碳足迹、水足迹、土地足迹和材料足迹为例,分别对每一项足迹指标两个版本的核算方法进行了比较。根据清单加和过程的特点,将所有足迹指标划分为基于权重因子和基于特征因子两类,总结了两者的适用性和局限性。在此基础上提出了一个环境足迹核算与整合的统一框架。该框架基于LCA视角建立,但对系统边界和清单数据的要求相对灵活,因而也适用于生命周期不甚明确的情形。研究在一定程度上揭示了足迹指标的方法学实质,同时也为环境影响综合评估提供了一条规范化的途径。     

基于碳足迹的传统农业系统环境影响评价——以青田稻鱼共生系统为例

现代农业在带来粮食高产的同时也产生许多生态环境问题,这促使人们再次把目光转向传统农业系统。一些传统农业系统不仅具有突出的经济、社会和文化价值,还具有多种重要的生态功能,如温室气体减排。然而,已有研究缺乏对传统农业系统整个生命周期的固碳减排能力的测算及其环境影响的评价。为此,基于农户调研数据,运用生命周期评价法对青田稻鱼共生系统的碳足迹进行了测算,并与当地水稻单作系统进行比较。研究发现:(1)青田稻鱼共生系统和水稻单作系统碳足迹分别为6266.7 kgCO_2-eq/hm~2和7520.0 kgCO_2-eq/hm~2,单位产值碳足迹分别为0.12 kgCO_2-eq/元和0.21 kgCO_2-eq/元。与水稻单作系统相比,稻鱼共生系统排放的温室气体更少,环境影响更小,生态和经济效益更高。(2)农业生产过程中积累的CH_4是碳足迹的最主要来源,农业生产资料投入中的化肥是碳足迹的的第二大来源。农业生产资料投入中的饲料则是稻鱼共生系统碳足迹的另一重要来源。通过碳足迹的方法对青田稻鱼共生系统的环境影响进行量化,不仅丰富了碳足迹在实际应用中的适用类型,对于其他传统农业系统的环境影响评价也具有借鉴意义。     

Human Footprint Variation while Performing Load Bearing Tasks

Human footprint fossils have provided essential evidence about the evolution of human bipedalism as well as the social dynamics of the footprint makers, including estimates of speed, sex and group composition. Generally such estimates are made by comparing footprint evidence with modern controls; however, previous studies have not accounted for the variation in footprint dimensions coming from load bearing activities. It is likely that a portion of the hominins who created these fossil footprints were carrying a significant load, such as offspring or foraging loads, which caused variation in the footprint which could extend to variation in any estimations concerning the footprint’s maker. To identify significant variation in footprints due to load-bearing tasks, we had participants (N = 30, 15 males and 15 females) walk at a series of speeds carrying a 20kg pack on their back, side and front. Paint was applied to the bare feet of each participant to create footprints that were compared in terms of foot length, foot width and foot area. Female foot length and width increased during multiple loaded conditions. An appreciation of footprint variability associated with carrying loads adds an additional layer to our understanding of the behavior and morphology of extinct hominin populations.     

足迹家族研究综述

综合测度人类社会的可持续发展状态是生态经济学者追求的重要目标。足迹家族由生态足迹、碳足迹和水足迹等一系列足迹类指标整合而成,旨在为决策者系统评估与权衡人类活动的环境影响提供理论和技术支持。从理论探索、整合实践和分类比较等三方面对足迹家族的研究现状进行了综述;在此基础上围绕极具争议的足迹定义、计算方法和加权方式等问题,深入分析了阻碍当前研究进一步推进的关键性因素;指出未来应从建立足迹类型学、完善跨区域投入产出模型、细化产品和机构环境足迹标准等方面入手,推动实现足迹家族的量化整合;并首次提出了足迹家族与行星边界耦合的构想,以期为监测和预警人类活动的生态阈值、促进环境影响评价向可持续性评价转变提供科学依据。     

北京市住宅建筑生命周期碳足迹

从生命周期角度看,建筑碳足迹与能源和建材生产系统具有密切关系。随着技术的进步和节能政策的推进,中国能源的生产和使用,以及建材生产过程中的环境排放都随着时间在持续降低,这将间接地影响到建筑的环境表现。依据1990—2010年期间每5a的中国能源与建材生命周期清单数据,对北京市20年间住宅建筑系统开展生命周期评价和碳足迹核算,以揭示北京市住宅建筑系统的环境负荷变化特征。结果表明,北京市住宅建筑生命周期碳足迹随时间推移呈现降低趋势,主要来自能源系统和建材生产系统的碳减排贡献。不同结构建筑的碳足迹尽管有差异,但也呈现了相似的下降趋势。从生命周期阶段看,建筑碳足迹主要体现在建筑使用阶段和建材生产阶段。尽管建筑使用阶段的节能对于降低建筑生命周期碳足迹具有重要贡献,但节能在经济成本及环境成本方面而言是有限度的。在可持续的环境政策管理制定中,应从生命周期角度,统筹考虑协调各行业减碳的协调发展。论文同时也验证了在生命周期评价中考虑时间变量将有助于更好地利用生命周期评价结果支持环境可持续管理。结论对于城市规划的政策制定、量化环境表现是有益的。     

Fast Carbon Footprinting for Large Product Portfolios

Publicly Available Specification 2050‐2011 (PAS 2050), the Green House Gas Product Protocol (GHGPP) standard and forthcoming guideline 14067 from the International Organization for Standardization (ISO) have helped to propel carbon footprinting from a subdiscipline of life cycle assessment (LCA) to the mainstream. However, application of carbon footprinting to large portfolios of many distinct products and services is immensely resource intensive. Even if achieved, it often fails to inform company‐wide carbon reduction strategies because footprint data are disjointed or don't cover the whole portfolio. We introduce a novel approach to generate standard‐compliant product carbon footprints (CFs) for companies with large portfolios at a fraction of previously required time and expertise. The approach was developed and validated on an LCA dataset covering 1,137 individual products from a global packaged consumer goods company. Three novel techniques work in concert in a single approach that enables practitioners to calculate thousands of footprints virtually simultaneously: (i) a uniform data structure enables footprinting all products and services by looping the same algorithm; (ii) concurrent uncertainty analysis guides practitioners to gradually improve the accuracy of only those data that materially impact the results; and (iii) a predictive model generates estimated emission factors (EFs) for materials, thereby eliminating the manual mapping of a product or service's inventory to EF databases. These autogenerated EFs enable non‐LCA experts to calculate approximate CFs and alleviate resource constraints for companies embarking on large‐scale product carbon footprinting. We discuss implementation roadmaps for companies, including further road‐testing required to evaluate the effectiveness of the approach for other product portfolios, limitations, and future improvements of the fast footprinting methodology.     

Towards Regional,Error-Bounded Landscape Carbon Storage Estimates for Data-Deficient Areas of the World

Monitoring landscape carbon storage is critical for supporting and validating climate change mitigation policies. These may be aimed at reducing deforestation and degradation, or increasing terrestrial carbon storage at local, regional and global levels. However, due to data-deficiencies, default global carbon storage values for given land cover types such as ‘lowland tropical forest’ are often used, termed ‘Tier 1 type’ analyses by the Intergovernmental Panel on Climate Change (IPCC). Such estimates may be erroneous when used at regional scales. Furthermore uncertainty assessments are rarely provided leading to estimates of land cover change carbon fluxes of unknown precision which may undermine efforts to properly evaluate land cover policies aimed at altering land cover dynamics. Here, we present a repeatable method to estimate carbon storage values and associated 95% confidence intervals (CI) for all five IPCC carbon pools (aboveground live carbon, litter, coarse woody debris, belowground live carbon and soil carbon) for data-deficient regions, using a combination of existing inventory data and systematic literature searches, weighted to ensure the final values are regionally specific. The method meets the IPCC ‘Tier 2’ reporting standard. We use this method to estimate carbon storage over an area of33.9 million hectares of eastern Tanzania, reporting values for 30 land cover types. We estimate that this area stored 6.33 (5.92–6.74) Pg C in the year 2000. Carbon storage estimates for the same study area extracted from five published Africa-wide or global studies show a mean carbon storage value of ∼50% of that reported using our regional values, with four of the five studies reporting lower carbon storage values. This suggests that carbon storage may have been underestimated for this region of Africa. Our study demonstrates the importance of obtaining regionally appropriate carbon storage estimates, and shows how such values can be produced for a relatively low investment.     

足迹家族:概念、类型、理论框架与整合模式

足迹研究是当前生态经济学和可持续发展领域的热点与前沿课题。探讨了足迹类指标的内涵,将其定义为一类评估人类资源消费和废弃物排放等活动环境影响的指标;介绍了生态足迹、碳足迹、水足迹、能源足迹、化学足迹、氮足迹和生物多样性足迹7类典型足迹指标的概念与研究进展;在此基础上提出了普适性的足迹家族概念,总结了足迹家族的选择性、开放性、系统性和不确定性特征,并根据足迹类指标的一般运算流程构建了足迹家族的理论框架;基于大量文献成果系统比较了生态足迹、碳足迹和水足迹3类关键足迹的特征差异,提出了在足迹家族层面增强指标兼容性的措施;通过逐一测试各关键足迹与27项环境问题的相关程度,从决策相关性的角度初步探索了该足迹家族的整合模式;展望了未来足迹(家族)研究的重点方向。     

基于水足迹理论的煤制油产业布局评价

煤制油是我国应对石油危机的重要途径之一,但其高耗水的特点使其备受争议。利用水足迹理论对全国五大煤炭基地2015年规划的煤制油产业进行了蓝水足迹和灰水足迹的测算,分析了煤制油产业对这些区域水资源的耗用情况及冲击程度。结果显示,神东、晋东和新疆伊犁3个基地的煤制油产业蓝水足迹超过了1亿t、灰水足迹超过了3亿t,其中神东地区作为最大的煤制油产地两项数值分别达到1.9亿t和4.1亿t与当地水资源总量对比,宁东地区煤制油耗水冲击最大,占当地水资源总量的28.2%;新疆伊犁地区比例最小,为0.36%。通过对这5个煤炭基地以区域为尺度的水足迹结构分析和评价比较,得出了两种煤制油工艺的水资源消耗差异,并且为煤制油产业在五大基地的合理布局给出了依据,与此同时为接下来煤制油产业的技术革新和流程优化也提出了相应的建议。     

中国区域间贸易碳转移特征及其对碳中和的影响

优化贸易模式对实现"碳达峰,碳中和"这一中长期计划至关重要。基于多区域投入产出模型和碳生态承载力模型,分析了我国2017年30个省份(本研究不含中国港澳台和西藏的统计数据)碳足迹和碳生态承载力剩余量的空间分布特征。研究表明:(1)经济或人口总量较大的省份(如广东、江苏、河南等)碳足迹较大,而万元GDP碳足迹较大的省份主要分布在西部和东北地区,虚拟碳主要是向经济发达的省份转移。(2)总体上,中国的区域间贸易不具备碳中和特征,但就地区而言,区域间贸易使得山西、内蒙古、辽宁、宁夏、新疆地区碳足迹有所降低,但碳中和程度较低(<20%);就行业而言,建筑业贸易的碳中和特征最为明显,特别是在东北三省。(3)经济富裕的几个省份碳减排压力较大,如:北京、天津等地的碳生态承载力出现赤字,而黑龙江、河南、吉林、山东碳生态承载力剩余量超过10×10⁸ t,碳减排压力较小。未来在制定相关政策时,应综合考虑省际间碳的转移特征,合理分配碳排放定额,以保障碳排放权交易市场的顺利运行。     

A methodology for separating uncertainty and variability in the life cycle greenhouse gas emissions of coal-fueled power generation in the USA

Purpose

Results of life cycle assessments (LCAs) of power generation technologies are increasingly reported in terms of typical values and possible ranges. Extents of these ranges result from both variability and uncertainty. Uncertainty may be reduced via additional research. However, variability is a characteristic of supply chains as they exist; as such, it cannot be reduced without modifying existing systems. The goal of this study is to separately quantify uncertainty and variability in LCA.

Methods

In this paper, we present a novel method for differentiating uncertainty from variability in life cycle assessments of coal-fueled power generation, with a specific focus on greenhouse gas emissions. Individual coal supply chains were analyzed for 364 US coal power plants. Uncertainty in CO₂ and CH₄ emissions throughout these supply chains was quantified via Monte Carlo simulation. The method may be used to identify key factors that drive the range of life cycle emissions as well as the limits of precision of an LCA.

Results and discussion

Using this method, we statistically characterized the carbon footprint of coal power in the USA in 2009. Our method reveals that the average carbon footprint of coal power (100 year time horizon) ranges from 0.97 to 1.69 kg CO₂eq/kWh of generated electricity (95 % confidence interval), primarily due to variability in plant efficiency. Uncertainty in the carbon footprints of individual plants spans a factor of 1.04 for the least uncertain plant footprint to a factor of 1.2 for the most uncertain plant footprint (95 % uncertainty intervals). The uncertainty in the total carbon footprint of all US coal power plants spans a factor of 1.05.

Conclusions

We have developed and successfully implemented a framework for separating uncertainty and variability in the carbon footprint of coal-fired power plants. Reduction of uncertainty will not substantially reduce the range of predicted emissions. The range can only be reduced via substantial changes to the US coal power infrastructure. The finding that variability is larger than uncertainty can obviously not be generalized to other product systems and impact categories. Our framework can, however, be used to assess the relative influence of uncertainty and variability for a whole range of product systems and environmental impacts.     

Life cycle assessment of a field-grown red maple tree to estimate its carbon footprint components

Purpose  

This study analyzes the interrelated components in the production of a 5-cm caliper, field-grown, spade-dug Acer rubrum ‘October Glory’ tree in terms of their contributions to the carbon footprint, global warming potential (GWP), of this balled and burlapped product during production and its complete life cycle.     

碳足迹核算的国际标准概述与解析

各种层面上的碳足迹核算在全球气候变化控制领域得到了越来越多的关注。但是,这些关于碳足迹核算的相关国际标准繁多,彼此之间的关系复杂,不利于研究领域和工业界对这些标准进行应用与交流,限制了碳足迹核算的发展进度与深度。对目前已有的国际主要碳足迹核算标准及生命周期评价标准进行了整理,梳理出这些国际标准的一些基本特征,绘制了国际标准之间的关系图;并进一步从生命周期评价步骤的角度出发,解析了各种国际标准在这些阶段上的相关内容,以及每一个阶段上各标准相关规定中的不同特点及逻辑关系。对促进我国碳足迹核算相关研究与实践工作具有一定的理论与现实参考意义。     

Life cycle carbon footprint of the National Geographic magazine

Purpose  

Climate change is an urgent and serious global problem. Life cycle assessment methods may be used to evaluate the life cycle carbon footprint of a product, such as the National Geographic magazine. The results of the study provide the publisher and material suppliers with information to reduce life cycle greenhouse gas (GHG) emissions. The study also informs consumers of the GHG emissions associated with the product. The purpose of this study was to document the life cycle carbon footprint of the National Geographic magazine.     

基于ISO 14046的工业产品水足迹评价研究——以电缆为例

水足迹国际标准(ISO 14046)于2014年发布,基于生命周期评价(LCA)的思想,水足迹被定义为量化与水相关潜在环境影响的指标。在ISO14046的原则、要求和方法学框架基础上,介绍了工业产品水足迹的计算和评价方法,并以铜电缆和铝合金电缆为例进行研究,分别评价了两类电缆生命周期过程产生的与水相关环境影响。与水足迹网络(WFN)的方法侧重于计算生产产品所需要的水资源总量不同,ISO的方法更关注于产品全生命周期过程的环境影响评价。案例研究表明:铜电缆生命周期全过程耗水量与铝合金电缆相比少24.8%,水短缺足迹相比则少97.9%。这是因为铜电缆生产地江苏的水压力指数(WSI)小于铝合金电缆生产地河北的WSI。由此,在江苏地区生产电缆使用的水资源对当地水环境压力造成的影响远小于在河北地区生产电缆造成的影响。采用科学合理的水足迹评价方法,量化工业产品全生命周期带来的环境影响,能为我国实现工业布局的合理规划和水资源的可持续利用提供科学依据。     

Environmental impacts of wooden,plastic, and wood-polymer composite pallet: a life cycle assessment approach

Purpose

Waste recycling is one of the essential tools for the European Union’s transition towards a circular economy. One of the possibilities for recycling wood and plastic waste is to utilise it to produce composite product. This study analyses the environmental impacts of producing composite pallets made of wood and plastic waste from construction and demolition activities in Finland. It also compares these impacts with conventional wooden and plastic pallets made of virgin materials.

Methods

Two different life cycle assessment methods were used: attributional life cycle assessment and consequential life cycle assessment. In both of the life cycle assessment studies, 1000 trips were considered as the functional unit. Furthermore, end-of-life allocation formula such as 0:100 with a credit system had been used in this study. This study also used sensitivity analysis and normalisation calculation to determine the best performing pallet.

Result and discussion

In the attributional cradle-to-grave life cycle assessment, wood-polymer composite pallets had the lowest environmental impact in abiotic depletion potential (fossil), acidification potential, eutrophication potential, global warming potential (including biogenic carbon), global warming potential (including biogenic carbon) with indirect land-use change, and ozone depletion potential. In contrast, wooden pallets showed the lowest impact on global warming potential (excluding biogenic carbon). In the consequential life cycle assessment, wood-polymer composite pallets showed the best environmental impact in all impact categories. In both attributional and consequential life cycle assessments, plastic pallet had the maximum impact. The sensitivity analysis and normalisation calculation showed that wood-polymer composite pallets can be a better choice over plastic and wooden pallet.

Conclusions

The overall results of the pallets depends on the methodological approach of the LCA. However, it can be concluded that the wood-polymer composite pallet can be a better choice over the plastic pallet and, in most cases, over the wooden pallet. This study will be of use to the pallet industry and relevant stakeholders.

     

Case study on the carbon consumption of two metropolitan cities

Purpose  

The cities merit special attention in global warming since they produce up to 80% of the global greenhouse gas emissions. Even though this has been widely acknowledged, only few papers exist that have studied cities holistically from a demand, i.e., consumption, perspective. The study presents a detailed analysis of the carbon footprint of two metropolitan cities from a consumption perspective. With the analysis of consumer carbon footprints (carbon consumption), the distribution of emissions in the key source categories is presented and compared.     

Theoretical exploration for the combination of the ecological,energy, carbon,and water footprints: Overview of a footprint family

Over the past two decades, a continuously expanding list of footprint-style indicators has been introduced to the scientific community with the aim of raising public awareness of how humanity exerts pressures on the environment. A deeper understanding of the connections and interactions between different footprints is required in an attempt to support policy makers in the measurement and choice of environmental impact mitigation strategies. Combining a selection of footprints that address different aspects of environmental issues into an integrated system is, therefore, a natural step. This paper starts with the idea of developing a footprint family from which most important footprints can be compared and integrated. On the basis of literature review in related fields, the ecological, energy, carbon, and water footprints are employed as selected indicators to define a footprint family. A brief survey is presented to provide background information on each of the footprints with an emphasis on their main characteristics in a comparative sense; that is, the footprints differ in many aspects more than just the impacts they are addressed. This allows the four footprints to be complementarily used in assessing environmental impacts associated with natural resource use and waste discharge. We evaluate the performance of the footprint family in terms of data availability, coverage complementarity, methodological consistency, and policy relevance and propose solutions and suggestions for further improvement. The key conclusions are that the footprint family, which captures a broad spectrum of sustainability issues, is able to offer a more complete picture of environmental complexity for policy makers and, in particular, in national-level studies. The research provides new insights into the distinction between environmental impact assessment and sustainability evaluation, properly serving as a reference for multidisciplinary efforts in estimating planetary boundaries for global sustainability.     

Comparing product category rules from different programs: learned outcomes towards global alignment

Purpose

Product category rules (PCRs) provide category-specific guidance for estimating and reporting product life cycle environmental impacts, typically in the form of environmental product declarations and product carbon footprints. Lack of global harmonization between PCRs or sector guidance documents has led to the development of duplicate PCRs for the same products. Differences in the general requirements (e.g., product category definition, reporting format) and LCA methodology (e.g., system boundaries, inventory analysis, allocation rules, etc.) diminish the comparability of product claims.

Methods

A comparison template was developed to compare PCRs from different global program operators. The goal was to identify the differences between duplicate PCRs from a broad selection of product categories and propose a path toward alignment. We looked at five different product categories: milk/dairy (two PCRs), horticultural products (three PCRs), wood?Cparticleboard (two PCRs), and laundry detergents (four PCRs).

Results and discussion

Disparity between PCRs ranged from broad differences in scope, system boundaries, and impacts addressed (e.g., multi-impact vs. carbon footprint only) to specific differences of technical elements. The differences primarily reflected the different purposes of the PCR (e.g., label/report), the different standards they were based on (e.g., ISO 14025/PAS 2050), the use of different product categorization systems, or simply the result of being developed independently. Differing degrees of specificity and terminology between PCRs allowed for varied interpretation??at times making direct comparison difficult. For many of the differences between PCRs, however, there was no clear rationale why they could not be consistent in the future.

Conclusions

These results were used to outline a general guidance document for global alignment of PCRs which recommends (1) alignment of PCRs for different purposes, (2) provision of guidance for the adoption of aspects of other PCRs, and (3) provision of greater specificity on content. The overall recommendations also suggest collaboration among program operators to facilitate alignment on issues that evolve from independent development.     

A Systems Approach to Sustainable Technical Product Design

Many existing methods for sustainable technical product design focus on environmental efficiency while lacking a framework for a holistic, sustainable design approach that includes combined social, technical, economic, and environmental aspects in the whole product life cycle, and that provides guidance on a technical product development level. This research proposes a framework for sustainable technical product design in the case of skis. We developed a ski under the Grown brand, benchmarked according to social, environmental, economic, and technical targets, following an initial sustainability assessment, and delivered the first environmental life cycle assessment (ELCA) and the first social life cycle assessment (SLCA) of skis. The framework applies a virtual development process as a combination of ELCA to calculate the environmental footprint as carbon equivalents of all materials and processes and a technical computer‐aided design (CAD) and computer‐aided engineering (CAE) simulation and virtual optimization using parameter studies for the nearly prototype‐free development of the benchmarked skis. The feedback loops between life cycle assessment (LCA) and virtual simulation led to the elimination of highly energy intensive materials, to the pioneering use of basalt fibers in skis, to the optimization of the use of natural materials using protective coatings from natural resins, and to the optimization of the production process. From an environmental perspective, a minimum 32% reduction in carbon equivalent emissions of materials in relation to other comparably performing skis has been achieved, as well as a pioneering step forward toward transparent communication of the environmental performance by the individual, comparable, and first published ski carbon footprint per volume unit.