Assessing alternative aquaculture technologies: life cycle assessment of salmonid culture systems in Canada

This study employed life cycle assessment (LCA) to quantify and compare the potential environmental impacts of culturing salmonids in a conventional marine net-pen system with those of three reportedly environmentally-friendly alternatives; a marine floating bag system; a land-based saltwater flow-through system; and a land-based freshwater recirculating system. Results of the study indicate that while the use of these closed-containment systems may reduce the local ecological impacts typically associated with net-pen salmon farming, the increase in material and energy demands associated with their use may result in significantly increased contributions to several environmental impacts of global concern, including global warming, non-renewable resource depletion, and acidification. It is recommended that these unanticipated impacts be carefully considered in further assessments of the sustainability of closed-containment systems and in ongoing efforts to develop and employ these technologies on a larger scale.     

中国电动自行车动力铅酸蓄电池生命周期评价

以近年来中国用量增长最快的电动自行车动力铅酸蓄电池为对象,建立了生命周期环境影响评价模型,分析了从原材料生产、电池生产、电池运输、电池使用和废旧铅酸蓄电池及含铅废物回收处理全生命周期的环境影响.研究采用了大量企业调研数据和中国本土LCA数据库,以期反映整个中国铅酸蓄电池产业链的技术工艺和环境管理水平现状.结果表明,原材料生产和电池使用是资源(含能源)消耗的主要阶段,贡献了电池全生命周期绝大部分的环境影响.原材料生产贡献最多的全生命周期环境影响包括非生物资源耗竭(699%)、富营养化(89%)、光化学烟雾(98%)、臭氧层破坏(117%)、人体毒性(159%)和生态毒性(484%).电池使用过程的电耗间接消耗了83%的一次能源,相应地贡献了最多的气候变暖潜值(86%)和酸化潜值(70%).废旧铅酸蓄电池和含铅废物回收再生铅可抵消很大一部分原材料生产造成的环境影响.延长电池寿命,减少电池生产金属用量及提高废旧电池回收处理过程的工艺技术和污染控制水平也是减少铅酸蓄电池生命周期环境影响的关键.     

不同施肥模式下甘薯乙醇生命周期能效与环境影响分析

采用生命周期分析方法,以1 000 L甘薯乙醇为单位功能单元,将甘薯乙醇生产体系分成作物种植、原料运输和乙醇转换等3个单元,对其生命周期能耗与环境排放进行清单分析和影响评价,比较习惯施肥与测土配方施肥下甘薯乙醇生命周期9类环境影响潜力的差异。结果表明：两种施肥模式下甘薯乙醇生产体系的生命周期能源效率分别为1.41和1.43。习惯施肥模式下甘薯乙醇生命周期主要环境影响类型包括人体毒性、富营养化、酸化、淡水生态毒性、能耗和全球变暖,其环境影响潜力分别相当于2000年世界人均影响潜力的40%、40%、31%、29%、25%和20%。测土配方施肥降低了化学氮肥和磷肥使用量,提高了肥料利用效率和甘薯单产,使富营养化、淡水生态毒性、酸化和全球变暖潜力分别降低了31%、15%、9%和7%。可见,测土配方施肥模式可改善甘薯乙醇生命周期的能源效率并显著缓解其负面环境影响。     

2nd Generation biofuels a sure bet? A life cycle assessment of how things could go wrong

Biofuels are heavily debated as to their potential to reduce transport-related greenhouse gas emissions. Life cycle thinking gave rise to formal evaluations of the energy balance of such fuels, which led to the vigorously conducted “corn to ethanol” debates. Just as consensus was building on such evaluations came the “carbon debt” insights, a result of applying consequential Life Cycle Assessment (LCA) backed by advanced economic modeling. Increasingly, hopes have shifted to the 2nd generation biofuels, viewed as a “technological home run”. Could this also backfire? We investigate a simple South African case in which there might not be improvements in environmental performance: a sugar mill sells its bagasse, currently used at low efficiency to provide process heat, to an advanced biofuels producer, and buys an equivalent amount of coal without investing in efficiency improvements. Seven scenarios are generated, ranging from the status quo, where no bagasse is diverted, to 100% bagasse diversion, with one scenario including an energy efficiency improvement in the sugar mill. A consequential LCA is applied to the seven scenarios, covering global warming potential (GWP), non-renewable energy use, aquatic eutrophication and terrestrial acidification. A basic financial analysis of the proposed scenarios shows that they are realistic, with potentially lucrative returns. Results show that diverting bagasse without efficiency improvements from its current use to an ethanol bio-refinery would indeed backfire for all environmental impacts studied. The base case outperforms all the other scenarios, with the 100% bagasse diversion scenario emerging the worst. Investments into energy efficiency are therefore a precondition for diverting cellulosic residues into biofuel production.     

Mass-cultivation of carbohydrate rich macroalgae, a possible solution for sustainable biofuel production

Global demand for bio-fuels continues unabated. Rising concerns over environmental pollution and global warming have encouraged the movement to alternate fuels, the world ethanol market is projected to reach 86 billion litres this year. Bioethanol is currently produced from land-based crops such as corn and sugar cane. A continued use of these crops drives the food versus fuel debate. An alternate feed-stock which is abundant and carbohydrate-rich is necessary. The production of such a crop should be sustainable, and, reduce competition with production of food, feed, and industrial crops, and not be dependent on agricultural inputs (pesticides, fertilizer, farmable land, water). Marine biomass could meet these challenges, being an abundant and carbon neutral renewable resource with potential to reduce green house gas (GHG) emissions and the man-made impact on climate change. Here we examine the current cultivation technologies for marine biomass and the environmental and economic aspects of using brown seaweeds for bio-ethanol production.     

中国水泥生产工艺的生命周期对比分析及建议

为了定量分析各种水泥生产工艺造成的环境影响以及工艺替代时可能造成的环境问题转移,采用生命周期评价(Life Cycle Assessment,LCA)方法,建立了大型、中型、小型新型干法、传统立窑、新型半干法(JT窑)5种典型水泥生产工艺从原材料开采到熟料生产的生命周期模型,对比分析了以上工艺生命周期过程中能耗、温室效应、酸化、可吸入无机物等主要环境影响类型的差异,提出并计算了大型新型干法替代其他工艺时的"平衡运输距离",并推导了其一般表达式.结果表明,由于大型新型干法工艺氮氧化物排放较多,使得工艺替代时可能伴随着环境问题从能耗、温室效应向酸化、可吸入无机物等影响类型转移;同时,由于产能增加,大型新型干法工艺也可能导致环境影响从生产阶段向运输阶段转移.从本文的案例研究可以看出,LCA方法可以定量分析不同环境影响类型之间和不同生命周期阶段之间的环境问题转移,能为技术评价和相关政策制定及实现全社会节能减排目标提供科学的依据与建议.     

水泥窑协同处置工业废弃物的生命周期评价

以废白土、废催化剂和污染土壤等工业废弃物为研究对象,运用生命周期评价(LCA)方法,对水泥窑协同处置废弃物的环境影响进行评价.通过建立生产过程输入、输出清单,从全球变暖潜值、资源消耗潜值、人体毒性潜值等方面,基于Gabi5.0软件进行建模与计算,对水泥窑常规生产工艺与协同处置工业废弃物工艺产生的环境影响进行比较.结果表明:功能单位(1 t)水泥的生产过程中,常规生产工艺和协同处置工艺的环境影响潜值分别为5.78×10~(-11)和5.61×10~(-11),协同处置工艺使得全生命周期环境影响潜值降低了2.94%;水泥生产过程最主要的环境影响是全球变暖和人体毒性,其中,协同处置工艺下这两种环境影响分别降低了0.80%和1.80%,资源消耗相比常规生产降低了11.1%;从全生命周期看,水泥生产中熟料煅烧阶段对环境的影响最大,协同处置工艺下熟料煅烧阶段的环境影响相比常规生产降低了8.0%.协同处置工艺相比常规生产工艺有更好的环境效益.     

Life cycle assessment of MSW-to-energy schemes in Thailand

Life cycle assessment was performed to evaluate environmental impacts of two municipal solid waste (MSW) to energy schemes currently practiced in Thailand: incineration and anaerobic digestion. Potential impacts such as global warming, acidification, stratospheric ozone depletion, and photo-oxidant formation were avoided due to net electricity production and also fertilizer production as by-products from the anaerobic digestion scheme. In addition, the anaerobic digestion resulted in the higher net energy output compared to the incineration scheme. However, the incineration had less potential impact for nutrient enrichment. The LCA results were also useful in determining where the improvements could be made for both the schemes. In order to adopt a sustainable waste management system elsewhere in the country, decision makers may need to consider a combination of techniques, or an integrated method of management. LCA could serve as an invaluable tool for such an analysis.     

Environmental impact assessment of non-wood based pulp production by soda-anthraquinone pulping process

Paper pulp manufacturing is the main non-food industrial utilization of plant biomass. Non-wood and agricultural residues are potential raw materials in the production of specialty papers. This chapter aims to quantify the environmental impacts associated with non-wood high quality paper pulp manufacture via soda-anthraquinone (AQ) cooking process by means of the application of LCA methodology in a cradle-to-gate analysis. Hemp (Cannabis sativa) and Flax (Linum usitatissimum) were evaluated as raw materials for the production of high quality non-porous pulp. A specialty paper pulp mill was analysed in detail and process chain was divided in six subsystems: agricultural activities, chemicals production, electricity production, transport, pulp production and waste treatment. Inventory data came from interviews and surveys (on-site measurements). When necessary, the data were completed with bibliographic resources.Abiotic resources depletion (AD), global warming (GW), ozone layer depletion (OLD), human toxicity (HT), ecotoxicity, photochemical oxidant formation (POF), acidification (A) and eutrophication (E) were the impact categories analysed in this study. According to the results, the environmental impact is mainly caused by the production of chemicals, electricity and fibres (agricultural activities) due to greenhouse gases emissions, phosphorous and nitrogen compounds emissions. The activities inside the pulp mill present minor contribution to almost all impact categories, excluding GW (15%) and E (6%) as well as OLD (25%). This study provides useful information for non-wood based industries related not only to pulp manufacture but also to panels or biorefineries with the aim of increasing their sustainability.     

Inclusion of the variability of diffuse pollutions in LCA for agriculture: the case of slurry application techniques

LCAs (life cycle assessments) are often based on average data to produce a generic evaluation of a good or service. However, ignoring variability and induced uncertainty of LCA results reduces their significance, especially when dealing with agricultural processes that present high natural fluctuations. The objective of the study was to explore the robustness of LCA results when accounting for variable emissions data, illustrated by the case of slurry application techniques. Four application techniques were compared: band spreading, broadcast spreading, harrowing after surface application and direct injection.On the basis of the normalisation results, acidification, eutrophication and global warming potentials were selected. To estimate field nitrogen emissions, an original approach was developed based on relative nitrogen loss factors for each technique from a literature review. The calculated field emissions from different soil and climate conditions were considered equally probable and were propagated into a range of LCA result using the Monte Carlo method. Injection and harrowing both showed reduced acidification and eutrophication potentials compared to band spreading and broadcast spreading but had larger global warming potentials, which could be particularly important with injection. Harrowing consequently appeared as the best compromise. Despite the large range of LCA results, robust conclusions could be drawn. To achieve a more refined comparison between the techniques, the use of process-based models in contrasted situations is suggested.     

The recycling of plastic wastes from discarded TV sets: comparing energy recovery with mechanical recycling in the context of life cycle assessment

Two treatment options, i.e. energy recovery and mechanical recycling of plastic wastes from discarded TV sets, were compared in the context of life cycle assessment (LCA) methodology. An estimate for the environmental burden of each option was calculated as the sum of the depletion of abiotic resources (ADP), the global warming potential (GWP), the acidification potential (AP), the photo-oxidant formation potential (POCP), the eutrophication potential (EP), and the human toxicity potential (HTP). After calculating the environmental burden of each treatment option, a sensitivity analysis was conducted. The ultimate aim was to indicate which parameters of the system have the strongest influence on the results of the LCA in order to find ways for lowering the environmental burden, and ultimately suggest a “design strategy” for TV sets.The main finding of this study was that mechanical recycling of plastics is more attractive treatment option in environmental terms than incineration for energy recovery, which generates a larger environmental burden. Finally, based on the results of sensitivity analysis, a “design strategy” was suggested, i.e. reducing the number of plastic types being used in the manufacturing process of TVs – preferably excluding the PVC.     

设施番茄生产系统的环境影响生命周期评价

应用生命周期评价方法,以陕西省西安市郊区为例,对设施番茄生产系统进行了环境影响评价.结果表明,日光温室和塑料大棚生产1000kg番茄消耗的能源和水资源分别是1740.58 MJ、50.767 m3和1502.346 MJ、53.734 m3;全球变暖潜值(以CO2当量计)、环境酸化潜值(以SO2当量计)、富营养化潜值(以PO3-4当量计)、光化学烟雾潜值(以C2H2当量计)、土壤毒性(以1,4-DCB当量计)、水体毒性(以1,4-DCB当量计)和人类毒性潜值(以1,4-DCB计)分别为271.943 kg、2.151 kg、0.247 kg、0.157 kg、24.217 kg、19.545 kg、0.124 kg和239.163 kg、1.88 kg、0.305 kg、0.109 kg、31.686 kg、19.7 kg、0.304 kg.设施构筑物自身建设和维护带来的主要潜在环境影响是能源耗竭、全球变暖和环境酸化;番茄种植环节引起的主要潜在环境影响是水资源耗竭、富营养化、全球变暖、土壤毒性和水体毒性;农资生产环节的主要潜在环境影响是能源耗竭.设施番茄生产系统中对环境影响大的建材和农资是钢材、聚乙烯材料、氮肥、农药和含过量重金属的有机肥.设施番茄生产系统对环境的影响不容忽视,应展开以降低其环境影响为目标的设施结构与建材、温室内气候条件调控、合理施肥和施药的研究,并对采取的技术方法进行生命周期评价,以确保设施蔬菜的可持续发展.研究结果可为促进设施蔬菜生产系统的可持续发展提供科学依据.     

A life-cycle comparison between inorganic and biological catalysis for the production of biodiesel

Life cycle assessment (LCA) has been used to compare inorganic and biological catalysis for the production of biodiesel by transesterification. The inorganic route, using catalysis by sodium hydroxide, has been compared with a conceptual biological one using enzymatic catalysis by the lipase produced by Candida antarctica. Although biological catalysis has not been used for industrial production of biodiesel to date, results from laboratory experiments suggest that it could have distinct advantages over the inorganic route, particularly with regard to a simplified flowsheet for purification and concomitant energy savings. Five flowsheet options have been included in the study to investigate the alkali and enzyme catalysed production routes from rapeseed oil, use of methanol or ethanol for transesterification and the effect of efficiency of alcohol recovery. The LCA shows that the enzymatic production route is environmentally more favourable. Improvements are seen in all impact categories. Global warming, acidification, and photochemical oxidation are reduced by 5%. Certain toxicity levels have more than halved. These results are mainly due to lower steam requirements for heating in the biological process.     

An occupational chemical priority list for future life cycle assessments

A chemical priority list is presented to screen and identify relevant chemicals, for which more detailed and industrial-sector specific quantitative exposure, risk and life-cycle assessments should be completed. A list of 38 solvents were ranked according to the framework of the LCA toxicity model, USEtox, and according to the framework proposed by the UNEP/SETAC working group on Indoor Exposure Assessment in LCA. An additional method, based on a risk assessment (RA) framework, was used to examine the robustness of the priority rank. Under both schemes dichloromethane, ethanol, formaldehyde, hexane and toluene all rank in the top ten positions. These chemicals are currently relevant with regard to health effects on a population level. Some of these chemicals are known as hazardous, while others, such as ethanol, have a low toxicity but were prioritized because of their extensive use and high exposure levels. This study attempts to combine the knowledge and methods of the LCA and occupational hygiene communities in assessing health impacts. It provides a consistent and transparent method for rapid comparative assessments of different chemicals and identifies the chemicals and workplaces that will require more thorough investigations.     

Attributional life cycle assessment of woodchips for bioethanol production

Besides the apparent need to reduce greenhouse gas emissions, other important factors contributing to the renewed interest in biofuels are energy security concerns and the need of sustainable transportation fuel. Nearly 30% of the annual CO₂ emissions in the U.S. come from the transportation sector and more than half of the fuel is imported. Biofuels appear to be a promising option to reduce carbon dioxide emissions, and the reliance on imported oil concomitantly. The interest on (ligno) cellulosic ethanol is gaining momentum as corn-based ethanol is criticized for using agricultural outputs for fuel production. Among many lignocellulosic feedstocks, woodchips is viewed as one of the most promising feedstocks for producing liquid transportation fuels. The renewable and carbon neutral nature of the feedstocks, similar chemical and physical properties to gasoline, and the low infrastructure cost due to the availability of fuel flex vehicles and transportation networks make (ligno) cellulosic bioethanol an attractive option. An in-depth LCA of woodchips shows that harvesting and woodchips processing stage and transportation to the facility stage emit large amount of environmental pollutants compared to other life cycle stages of ethanol production. Our analysis also found that fossil fuel consumption and respiratory inorganic effects are the two most critical environmental impact categories in woodchips production. We have used Eco-indicator 99 based cradle-to-gate LCA method with a functional unit of 4 m³ of dry hardwood chips production.     

煤与秸秆成型燃料的复合生命周期对比评价

利用复合生命周期对比评价方法,引入能量返还率、资源耗竭系数、环境影响负荷和生命周期成本4个参数,对煤和秸秆成型燃料在整个生命周期内的能源消耗、环境影响和经济性做了对比分析.同时,为了平衡能源、环境与经济三者之间的关系,建立EEE (Energy, Environment, Economic)综合指标进行整体评价.结果表明,在整个生命周期内,与煤相比,秸秆成型燃料的能量返还率低、资源耗竭系数小.秸秆成型燃料的全球变暖潜值、酸化潜值、富营养化潜值、工业烟尘、粉尘潜值及固体废弃物潜值均比煤小,因此,秸秆成型燃料的环境影响负荷比煤小.秸秆成型燃料的EEE指标值比煤小79.8%,所以,从平衡生命周期能源消耗、环境排放和经济性角度出发,秸秆成型燃料具有替代煤的潜力.但是,秸秆成型燃料的生命周期成本比煤高,其大力推广需要政府的财政补贴.     

Life cycle assessment of offset printed matter with EDIP97: how important are emissions of chemicals?

Existing product life cycle assessment (LCA) studies on offset printed matter all point at paper as the overall dominating cause of environmental impacts. All studies focus on energy consumption and the dominating role of paper is primarily based on the energy-related impact categories: global warming, acidification and nutrient enrichment. Ecotoxicity and human toxicity, which are related to emissions of chemicals, etc., are only included to a limited degree or not at all. In this paper we include the impacts from chemicals emitted during the life cycle of sheet fed offset printed matter. This is done by making use of some of the newest knowledge about emissions from the production at the printing industry combined with knowledge about the composition of the printing materials used. In cases with available data also upstream emissions from the production of printing materials are included. The results show that inclusion of the chemical emission-related impacts makes the EDIP97 impact profile of sheet fed offset products much more varied, as well for the normalised profiles as for the profiles weighted by distance to political environmental targets. Especially the ecotoxicity impact potential related to the production stage may contribute significantly, and the use of paper no longer becomes the overall dominating factor driving the environmental impacts.     

我国不同区域玉米施肥的生命周期评价

以吉林、陕西、河南、湖南、广西等玉米主产省份为例,以生产1t玉米为评价的功能单元,应用生命周期评价(LCA)方法,比较了不同生态区玉米生产过程中施肥的资源环境影响潜力.结果表明,五省环境影响综合指数大小依次为广西0.315、湖南0.309、河南0.273、陕西0.238、吉林0.183.几种资源环境影响中,潜力大小依次是富营养化、环境酸化、温室效应、土地利用和能源消耗,其中,施用氮肥引起的氨挥发是导致富营养化和酸化的主要原因.农户间玉米施肥的资源环境影响潜力差异很大,环境影响综合指数变异范围在41.2%～81.6%之间,且以湖南省最高,吉林省最低.如果将玉米追肥由撒施都改为穴施,五省的环境影响综合指数将降低8.5%～34.1%.总体而言,在目前生产条件下,吉林省具有资源环境影响较低的优势;富营养化是最主要的环境影响类型,而改进施肥方式、减少氨挥发是降低玉米施肥资源环境影响的关键技术途径.     

含氧生物质燃料的生命周期评价

为公正评价汽车代用燃料的能耗与环境效益,运用生命周期评价方法,研究了在燃料中分别添加不同比例的乙醇和甲酯2种生物质,带来的生命周期能耗和污染物排放变化,并对含氧生物质燃料的未来情景进行了预测分析.结果表明:乙醇代用燃料未降低化石燃料消耗,甲酯代用燃料可降低约20%的化石燃料消耗;几种配比的代用燃料均可降低石油消耗,甲酯代用燃料降低的趋势更加明显;各种代用燃料的温室气体排放都比较严重;乙醇代用燃料增加了NO_x排放,而甲酯代用燃料可降低约50%的NO_x排放;乙醇和甲酯的加入均能降低车用阶段的PM₁₀排放;燃料生产阶段的SO₂排放在整个生命周期中约占80%,必须严格控制;甲酯代用燃料可降低VOC排放.     

LCA of environmental and socio-economic impacts related to wood energy production in alpine conditions: Valle di Fiemme (Italy)

An extended Life Cycle Assessment (LCA) is performed for evaluating the impacts of a woody biomass supply chain for heating plants in the alpine region. Three main aspects of sustainability are assessed: greenhouse gas emissions, represented by global warming potential (GWP) impact category, costs and direct employment potential. We investigate a whole tree system (innovative logging system) where the harvest of logging residues is integrated into the harvest of conventional wood products. The case study is performed in Valle di Fiemme in Trentino region (North Italy) and includes theoretical and practical elements. The system boundary is the alpine forest fuel system, from logging operations at the forest stand to combustion of woody biofuels at the heating plant. The functional unit is 1 m³ solid over bark of woody biomass, delivered to the district heating plant in Cavalese (Trento). The relative sustainability of traditional and innovative systems is compared and energy use is estimated. Results show that the overall GWP and costs are about 13 kg CO_2equivalent and 42 euro per functional unit respectively for the innovative system. Along the product supply chain, chipping contributes the greatest share of GWP and energy use, while extraction by yarder has the highest financial costs. The GWP is reduced by 2.3 ton CO_2equivalent when bioenergy substitutes fuel oil and 1.7 ton CO_2equivalent when it substitutes natural gas. The sensitivity analysis illustrates that variations in fuel consumption and hourly rates of costs have a great influence on chipping operation and extraction by cable yarder concerning GWP and financial analysis, respectively. This is confirmed by sensitivity analysis. Better technologies, the use of biofuels along the product supply chain and more efficient systems might reduce these impacts. Replacing the traditional system with the innovative one reduces emissions and costs. A low energy input ratio is required for harvesting logging residues. The direct employment potential is a conflicting aspect and needs further investigations.