Energy intensity of computer manufacturing: hybrid assessment combining process and economic input-output methods

The total energy and fossil fuels used in producing a desktop computer with 17-in. CRT monitor are estimated at 6400 megajoules (MJ) and 260 kg, respectively. This indicates that computer manufacturing is energy intensive: the ratio of fossil fuel use to product weight is 11, an order of magnitude larger than the factor of 1-2 for many other manufactured goods. This high energy intensity of manufacturing, combined with rapid turnover in computers, results in an annual life cycle energy burden that is surprisingly high: about 2600 MJ per year, 1.3 times that of a refrigerator. In contrast with many home appliances, life cycle energy use of a computer is dominated by production (81%) as opposed to operation (19%). Extension of usable lifespan (e.g. by reselling or upgrading) is thus a promising approach to mitigating energy impacts as well as other environmental burdens associated with manufacturing and disposal.     

Combinatorial life cycle assessment to inform process design of industrial production of algal biodiesel

The use of algae as a feedstock for biodiesel production is a rapidly growing industry, in the United States and globally. A life cycle assessment (LCA) is presented that compares various methods, either proposed or under development, for algal biodiesel to inform the most promising pathways for sustainable full-scale production. For this analysis, the system is divided into five distinct process steps: (1) microalgae cultivation, (2) harvesting and/or dewatering, (3) lipid extraction, (4) conversion (transesterification) into biodiesel, and (5) byproduct management. A number of technology options are considered for each process step and various technology combinations are assessed for their life cycle environmental impacts. The optimal option for each process step is selected yielding a best case scenario, comprised of a flat panel enclosed photobioreactor and direct transesterification of algal cells with supercritical methanol. For a functional unit of 10 GJ biodiesel, the best case production system yields a cumulative energy demand savings of more than 65 GJ, reduces water consumption by 585 m(3) and decreases greenhouse gas emissions by 86% compared to a base case scenario typical of early industrial practices, highlighting the importance of technological innovation in algae processing and providing guidance on promising production pathways.     

一种虾头综合利用模式的生命周期评价

以虾头为研究对象,针对一种常见的综合利用模式,运用生命周期评价方法评价其环境性能和经济性能。虾头的综合利用模式:用复合酶对虾头进行酶解后离心,上清液制成富含游离氨基酸的复合调味基料,滤渣制成多功能饲料添加剂。按照生命周期评价方法,设计构建了由4个步骤组成的评价体系对虾头综合利用模式的特性进行评价。结果显示:该利用模式属于清洁生产模式,产生的固体废弃物很少、富营养化程度低,主要潜在影响是温室效应;该利用模式能创造较大的附加值,同时对环境的影响较小,属于较好的综合利用模式。      

Comparative life cycle assessment of standard and green roofs

Life cycle assessment (LCA) is used to evaluate the benefits, primarily from reduced energy consumption, resulting from the addition of a green roof to an eight story residential building in Madrid. Building energy use is simulated and a bottom-up LCA is conducted assuming a 50 year building life. The key property of a green roof is its low solar absorptance, which causes lower surface temperature, thereby reducing the heat flux through the roof. Savings in annual energy use are just over 1%, but summer cooling load is reduced by over 6% and reductions in peak hour cooling load in the upper floors reach 25%. By replacing the common flat roof with a green roof, environmental impacts are reduced by between 1.0 and 5.3%. Similar reductions might be achieved by using a white roof with additional insulation for winter, but more substantial reductions are achieved if common use of green roofs leads to reductions in the urban heat island.     

Prospective environmental life cycle assessment of nanosilver T-shirts

A cradle-to-grave life cycle assessment (LCA) is performed to compare nanosilver T-shirts with conventional T-shirts with and without biocidal treatment. For nanosilver production and textile incorporation, we investigate two processes: flame spray pyrolysis (FSP) and plasma polymerization with silver co-sputtering (PlaSpu). Prospective environmental impacts due to increased nanosilver T-shirt commercialization are estimated with six scenarios. Results show significant differences in environmental burdens between nanoparticle production technologies: The "cradle-to-gate" climate footprint of the production of a nanosilver T-shirt is 2.70 kg of CO(2)-equiv (FSP) and 7.67-166 kg of CO(2)-equiv (PlaSpu, varying maturity stages). Production of conventional T-shirts with and without the biocide triclosan has emissions of 2.55 kg of CO(2)-equiv (contribution from triclosan insignificant). Consumer behavior considerably affects the environmental impacts during the use phase. Lower washing frequencies can compensate for the increased climate footprint of FSP nanosilver T-shirt production. The toxic releases from washing and disposal in the life cycle of T-shirts appear to be of minor relevance. By contrast, the production phase may be rather significant due to toxic silver emissions at the mining site if high silver quantities are required.     

Estimates of embodied global energy and air-emission intensities of Japanese products for building a Japanese input-output life cycle assessment database with a global system boundary

To build a life cycle assessment (LCA) database of Japanese products embracing their global supply chains in a manner requiring lower time and labor burdens, this study estimates the intensity of embodied global environmental burden for commodities produced in Japan. The intensity of embodied global environmental burden is a measure of the environmental burden generated globally by unit production of the commodity and can be used as life cycle inventory data in LCA. The calculation employs an input-output LCA method with a global link input-output model that defines a global system boundary grounded in a simplified multiregional input-output framework. As results, the intensities of embodied global environmental burden for 406 Japanese commodities are determined in terms of energy consumption, greenhouse-gas emissions (carbon dioxide, methane, nitrous oxide, perfluorocarbons, hydrofluorocarbons, sulfur hexafluoride, and their summation), and air-pollutant emissions (nitrogen oxide and sulfur oxide). The uncertainties in the intensities of embodied global environmental burden attributable to the simplified structure of the global link input-output model are quantified using Monte Carlo simulation. In addition, by analyzing the structure of the embodied global greenhouse-gas intensities we characterize Japanese commodities in the context of LCA embracing global supply chains.     

提高周期炉退火料架使用寿命的方法

介绍周期炉退火料架的材质、结构、使用寿命和损坏原因。给出提高料架使用寿命的方法:(1)料型较散的料装架时与料架内径尺寸差不可超过料架内径的1/6,料架使用时间超过3 a或750次需进行一次维护性修复。(2)为方便退火后料的脱架,料架4个支撑柱向上需带一定锥度,支撑柱上下部直径差不大于50 mm。(3)料架承重底部尽量减少焊点。(4)底部环形连接圈直径超过750 mm应采用钢管弯制。(5)支撑柱上部增加加强筋。(6)装炉时将重的、偏心大的料放在下层。(7)托料盘出现变形、开裂等应及时修复。(8)将重载料架和正常料架区分设计、使用。(9)料架制作后应进行固溶处理。     

Toward meaningful end points of biodiversity in life cycle assessment

Halting current rates of biodiversity loss will be a defining challenge of the 21st century. To assess the effectiveness of strategies to achieve this goal, indicators and tools are required that monitor the driving forces of biodiversity loss, the changing state of biodiversity, and evaluate the effectiveness of policy responses. Here, we review the use of indicators and approaches to model biodiversity loss in Life Cycle Assessment (LCA), a methodology used to evaluate the cradle-to-grave environmental impacts of products. We find serious conceptual shortcomings in the way models are constructed, with scale considerations largely absent. Further, there is a disproportionate focus on indicators that reflect changes in compositional aspects of biodiversity, mainly changes in species richness. Functional and structural attributes of biodiversity are largely neglected. Taxonomic and geographic coverage remains problematic, with the majority of models restricted to one or a few taxonomic groups and geographic regions. On a more general level, three of the five drivers of biodiversity loss as identified by the Millennium Ecosystem Assessment are represented in current impact categories (habitat change, climate change and pollution), while two are missing (invasive species and overexploitation). However, methods across all drivers can be greatly improved. We discuss these issues and make recommendations for future research to better reflect biodiversity loss in LCA.     

A comparative life cycle assessment of petroleum and soybean-based lubricants

A comparative life cycle assessment examining soybean and petroleum-based lubricants is compiled using Monte Carlo analysis to assess system variability. Experimental data obtained from an aluminum manufacturing facility indicate significantly less soybean lubricant is required to achieve similar or superior performance. With improved performance and a lower use rate, a transition to soybean oil results in lower aggregate impacts of acidification, smog formation, and human health from criteria pollutants. Regardless of quantity consumed, soybean-based lubricants exhibit significant climate change and fossil fuel use benefits; however, eutrophication impacts are much greater due to non-point nutrient emissions. Fundamental tradeoffs in the carbon and nitrogen cycles are addressed in the analysis, demonstrating that a transition to soybean oil may result in climate change benefits at the expense of regional water quality.     

食品生命周期碳排放评价研究

基于生命周期评价（LCA）理论,探讨界定食品生命周期碳排放的核算范围,对食品生命周期从原料生产、加工、消费到废物处理各阶段的碳排放进行清单分析,并提出了食品生命周期碳排量的评价框架和方法。     

产品生命周期评价体系研究

为更好地用量化的数据来判断产品的绿色程度，以利于产品生命周期评价，建立了由产品层次维、生命周期维、指标维构成的生命周期评价的三维集成体系结构以及由环境属性指标、资源属性指标、能源属性指标和经济性指标构成的生命周期评价指标体系，并针对评价过程中生命周期权重的确定，产品环境属性数据库的建立以及环境影响因子的确定，给出了有效的解决方法。     

Identifying improvement potentials in cement production with life cycle assessment

Cement production is an environmentally relevant process responsible for 5% of total anthropogenic carbon dioxide emissions and 7% of industrial fuel use. In this study, life cycle assessment is used to evaluate improvement potentials in the cement production process in Europe and the USA. With a current fuel substitution rate of 18% in Europe and 11% in the USA, both regions have a substantial potential to reduce greenhouse gas emissions and save virgin resources by further increasing the coprocessing of waste fuels. Upgrading production technology would be particularly effective in the USA where many kiln systems with very low energy efficiency are still in operation. Using best available technology and a thermal substitution rate of 50% for fuels, greenhouse gas emissions could be reduced by 9% for Europe and 18% for the USA per tonne of cement. Since clinker production is the dominant pollution producing step in cement production, the substitution of clinker with mineral components such as ground granulated blast furnace slag or fly ash is an efficient measure to reduce the environmental impact. Blended cements exhibit substantially lower environmental footprints than Portland cement, even if the substitutes feature lower grindability and require additional drying and large transport distances. The highest savings in CO(2) emissions and resource consumption are achieved with a combination of measures in clinker production and cement blending.     

面向产品全生命周期评价环境决策模型研究

在ISO14000系列国际标准的基础上,提出了在数据清单分析和影响评价的过程中,利用模糊层次分析法建立产品全生命周期评价环境决策模型的方法。模型在获得产品全生命周期环境影响数据清单之后,通过对环境影响因子的权重 的确定,可以对产品的环境影响进行量化分析,并根据分析结果评价产品的环境影响值,从而实现产品环境友好度评价由定性向定量的转化。     

钢丝绳失效过程及延长其使用寿命原理分析

微动疲劳和腐蚀疲劳是造成钢丝绳失效的主要原因。微动疲劳是微动磨损与疲劳的复合作用,腐蚀疲劳则是腐蚀与疲劳的复合作用,磨损与腐蚀的交替作用通常表现为彼此加速。应力集中促进疲劳裂纹的萌生与扩展。抑制微动磨损、防止腐蚀和应力集中的发生、减缓疲劳微裂纹的萌生与扩展是确定延长钢丝绳使用寿命技术措施的基本准则。对钢丝进行表面处理如耐磨磷化使制绳钢丝成为复合材料,使用复合材料制造钢丝绳芯将是金属制品行业的发展方向。     

造纸废水治理工艺的生命周期评价

对苏州某造纸企业新旧两条废水处理工艺的生命周期环境影响进行了对比研究。研究范围划定为：污水处理设施的建设阶段、运行阶段、污水处理设施的拆除阶段,通过统一的功能单位计算整理得到两条不同废水处理工艺的清单数据表。采用日本的AIST-LCAVer4评价软件进行影响评价,最终求得单一的生态指标：生态化的币值Yen。研究结果表明：上超滤前和上超滤后两套处理工艺的生态化币值分别为1.40Yen和1.15Yen,可见上超滤后对环境的影响比上超滤前的影响要小,其中药品对环境影响最大的为PAC的生产及使用。两套废水处理装置单项污染物排放量所占份额最大的是CO2,但上超滤后比上超滤前CO2的排放量下降了一半多,由原先的45.5kg/t纸降到21.9kg/t纸。造纸废水治理工艺的主要环境影响为城市空气污染、全球变暖、固体废弃物和资源消耗。我们认为,所获得的结论较为客观地反映了两种造纸废水治理工艺对环境的影响,可以作为中国造纸废水治理决策的参考依据。     

Biodiesel production in a semiarid environment: a life cycle assessment approach

While the use of biodiesel appears to be a promising alternative to petroleum fuel, the replacement of fossil fuel by biofuel may not bring about the intended climate cooling because of the increased soil N2O emissions due to N-fertilizer applications. Using a life cycle assessment approach, we assessed the influence of soil nitrous oxide (N2O) emissions on the life cycle global warming potential of the production and combustion of biodiesel from canola oil produced in a semiarid climate. Utilizing locally measured soil N2O emissions, rather than the Intergovernmental Panel on Climate Change (IPCC) default values, decreased greenhouse gas (GHG) emissions from the production and combustion of 1 GJ biodiesel from 63 to 37 carbon dioxide equivalents (CO2-e)/GJ. GHG were 1.1 to 2.1 times lower than those from petroleum or petroleum-based diesel depending on which soil N2O emission factors were included in the analysis. The advantages of utilizing biodiesel rapidly declined when blended with petroleum diesel. Mitigation strategies that decrease emissions from the production and application of N fertilizers may further decrease the life cycle GHG emissions in the production and combustion of biodiesel.