基于生命周期的户用沼气系统可用能核算——以广西恭城瑶族自治县为例

发展沼气生态农业可以实现资源的综合利用,带来经济效益与生态效益,同时解决我国农村地区能源短缺和环境污染问题。明确沼气系统内部的物质能量转化利用情况,可为沼气农业系统优化和效益提升提供科学依据。提出基于生命周期的户用沼气系统可用能核算方法,并以全国生态农业示范县——广西恭城瑶族自治县为例,核算了该县典型户用沼气系统建设、运行和利用单元投入产出的可用能流,分析了整个系统的可用能转化与利用效率。结果表明:系统的可用能投入为(1.06×108)kJ/a,可用能产出为(5.00×107)kJ/a,主要产出形式为沼渣;可用能转化率为48.82%,利用率为21.60%,其中沼气利用效率最高;系统产生的环境排放为(3.42×105)kJ/a,主要形式为系统利用单元沼气燃烧产生的CO2。由此可见,沼气生态农业可通过增加转化环节实现农业废弃物的再利用,系统可用能效率具备极大的提升空间,系统可持续性有待加强。可以考虑从改进工艺技术和改善发酵环境两方面提高户用沼气系统能量转化的能力,通过沼渣沼液综合利用技术方面的创新提高户用沼气系统的可用能利用效率。生命周期可用能核算方法可以更全面的反映系统的能量利用效率,便于诊断薄弱环节,为系统优化提供依据。     

A proposal for accounting for biodiversity in life cycle assessment

Life cycle assessment (LCA) is a methodology for assessing the environmental impacts associated with products throughout their lifecycle. Many impacts are accounted for within the LCA framework, but to date biodiversity impacts have received little attention. There are a number of existing direct and indirect measures of biodiversity within the ecological field, some of which have the potential to be developed into a useable method for LCA. However, our assessment is that considerable development would be required and their implementation for LCA is not likely in the foreseeable future. Here an alternative approach is proposed for rapidly incorporating biodiversity impacts into LCA. The approach relies on expert opinions through a series of questions which aim to encapsulate the main issues relating to biodiversity within a disturbance impact framework. While the technique is in its infancy we outline a foundation for the approach and identify the steps required to develop this method for implementation into LCA.     

Integrating life cycle assessment and material flow cost accounting to account for resource productivity and economic-environmental performance

Purpose

This study contributes to measuring the interactions between human technological activities and the natural environment in an integrative approach to support organisations and supply chain partners in their efforts to increase the resource productivity and economic-environmental performance of their product systems. We expand existing knowledge on the underlying methodological facets of the integrative use of two standardised instruments. We further guide the discussion with a case study and depict areas for future research.

Methods

We discuss the integration of life cycle assessment and material flow cost accounting to examine resource inputs and product and non-product outputs alongside environmental impacts and costs. Life cycle assessment is a non-financial instrument to identify hotspots of resource use and associated environmental burdens, while material flow cost accounting is a powerful financial instrument used to monetise resource use (in)efficiencies and demonstrate the resources bound in product and non-product output. Both are valuable life cycle management instruments to measure and control strategic themes related to improvement measures and investment decisions and support communication between the different decision-makers involved. We highlight the methodological facets of this integrative assessment based on a holistic single case study in order to share the lessons learned.

Results and discussion

Our case study illustrates a typical case where manufacturing costs and environmental burdens are primarily borne by the product, whereas a substantial portion of the resources also flows into by-products and non-products. We highlight the relevance of a shared set of rules and assumptions for systems, functions, system boundaries, inventories, and allocation rules which avoid an undesired interfusion of the physical and monetary dimensions to support a more systematic, consistent, and comparable modelling of integrated life cycle assessment and material flow cost accounting. However, researchers and practitioners should bear in mind the benefits and limitations of such integrated assessments, such as methodological choice, which also affect the decisive direction of the results.

Conclusions

The present study expands existing knowledge on the methodological facets of combining life cycle assessment and material flow cost accounting. By contrasting the hotspots of resource use as well as associated costs and environmental burdens, the instruments jointly provide valuable insights to identify integrated resource saving as well as economic and environmental improvement potentials for present and future business operations. Future research is needed in the following arenas: further development of the environmental impact indicators to capture the temporal and geographical occurrence of impacts; updating allocation criteria for integrated assessments in standards and guidelines; improving the visualisation of revenues in Sankey diagrams, the flow-based classification in the modelling software, as well as cost accounting and information systems; formalisation of indicators in management processes to generate resource efficiency strategies and goals; and finally, assessment of circular economy strategies and negative effects.

     

Liquefied natural gas for the UK: a life cycle assessment

Purpose

Liquefied natural gas (LNG) is expected to become an important component of the UK’s energy supply because the national hydrocarbon reserves on the continental shelf have started diminishing. However, use of any carbon-based fuel runs counter to mitigation of greenhouse gas emissions (GHGs). Hence, a broad environmental assessment to analyse the import of LNG to the UK is required.

Methods

A cradle to gate life cycle assessment has been carried out of a specific but representative case: LNG imported to the UK from Qatar. The analysis covers the supply chain, from gas extraction through to distribution to the end-user, assuming state-of-the-art facilities and ships. A sensitivity analysis was also conducted on key parameters including the energy requirements of the liquefaction and vaporisation processes, fuel for propulsion, shipping distance, tanker volume and composition of raw gas.

Results and discussion

All environmental indicators of the CML methodology were analysed. The processes of liquefaction, LNG transport and evaporation determine more than 50% of the cradle to gate global warming potential (GWP). When 1% of the total gas delivered is vented as methane emissions leakage throughout the supply chain, the GWP increases by 15% compared to the GWP of the base scenario. The variation of the GWP increases to 78% compared to the base scenario when 5% of the delivered gas is considered to be lost as vented emissions. For all the scenarios analysed, more than 75% of the total acidification potential (AP) is due to the sweetening of the natural gas before liquefaction. Direct emissions from transport always determine between 25 and 49% of the total eutrophication potential (EP) whereas the operation and maintenance of the sending ports strongly influences the fresh water aquatic ecotoxicity potential (FAETP).

Conclusions

The study highlights long-distance transport of LNG and natural gas processing, including sweetening, liquefaction and vaporisation, as the key operations that strongly affect the life cycle impacts. Those cannot be considered negligible when the environmental burdens of the LNG supply chain are considered. Furthermore, the effect of possible fugitive methane emissions along the supply chain are critical for the impact of operations such as extraction, liquefaction, storage before transport, transport itself and evaporation.

     

基于生命周期的风电场碳排放核算

风电是实现低碳战略的主力能源技术之一。为全面分析其对环境的影响,将自然植被纳入系统边界,计量风电场建设前后植被破坏及恢复带来的影响。在清单分析中,重点考虑对碳排影响较大的配件生产及运输、建设期工程车耗油排放,更加合理地核算风电场碳排放和量化其环境影响。核算结果表明:案例风电场全生命周期排碳量为2.97×104t C;运营期由于电能损耗造成的CO2排放量远大于其它阶段,占全过程的57.74%;整个过程中,能源消耗造成的碳排放远大于资源损耗排放。     

A life cycle impact assessment procedure with resource groups as areas of protection

Goal and Background  Current Life Cycle Impact Assessment (LCIA) procedures have demonstrated certain limitations in the South African manufacturing industry context. The aim of this paper is to propose a modified LCIA procedure, which is based on the protection of resource groups. Methods  A LCIA framework is introduced that applies the characterisation procedure of available midpoint categories, with the exception of land use. Characterisation factors for land occupation and transformation is suggested for South Africa. A distanceto-target approach is used for the normalisation of midpoint categories, which focuses on the ambient quality and quantity objectives for four resource groups: Air, Water, Land and Mined Abiotic Resources. The quality and quantity objectives are determined for defined South African Life Cycle Assessment (SALCA) Regions and take into account endpoint or damage targets. Following the precautionary approach, a Resource Impact Indicator (RII) is calculated for the resource groups. Subjective weighting values for the resource groups are also proposed, based on survey results from the manufacturing industry sector and the expenditure trends of the South African national government. The subjective weighting values are used to calculate overall Environmental Performance Resource Impact Indicators (EPRIIs) when comparing life cycle systems with each other. The proposed approaches are evaluated with a known wool case study. Results and Discussion  The calculation of a RJI ensures that all natural resources that are important from a South African perspective are duly considered in a LCIA. The results of a LCIA are consequently not reliant on a detailed Life Cycle Inventory (LCI) and the number of midpoint categories that converge on a single resource group. The case study establishes the importance of region-specificity, for LCIs and LCIAs. Conclusions  The proposed LCIA procedure demonstrates reasonable ease of communication of LCIA results. It further allows for the inclusion of additional midpoint categories and is adaptable for specific regions. Recommendations and Outlook  The acceptance of the LCIA procedure must be evaluated for different industry and government sectors. Also, the adequate incorporation of Environmental Performance Resource Impact Indicators (EPRIIs) into decision-making for Life Cycle Management purposes must be researched further. Specifically, the application of the procedures for supply chain management will be investigated.     

Linear programming as a tool in life cycle assessment

Linear Programming (LP) is a powerful mathematical technique that can be used as a tool in Life Cycle Assessment (LCA). In the Inventory and Impact Assessment phases, in addition to calculating the environmental impacts and burdens, it can be used for solving the problem of allocation in multiple-output systems. In the Improvement Assessment phase, it provides a systematic approach to identifying possibilities for system improvements by optimising the system on different environmental objective functions, defined as burdens or impacts. Ultimately, if the environmental impacts are aggregated to a single environmental impact function in the Valuation phase, LP optimisation can identify the overall environmental optimum of the system. However, the aggregation of impacts is not necessary: the system can be optimised on different environmental burdens or impacts simultaneously by using Multiobjective LP. As a result, a range of environmental optima is found offering a number of alternative options for system improvements and enabling the choice of the Best Practicable Environmental Option (BPEO). If, in addition, economic and social criteria are introduced in the model, LP can be used to identify the best compromise solution in a system with conflicting objectives. This approach is illustrated by a real case study of the borate products system. An erratum to this article is available at .     

Surplus cost as a life cycle impact indicator for fossil resource scarcity

Purpose

In life cycle impact assessment, various proposals have been made on how to characterise fossil resource scarcity, but they lack appropriateness or completeness. In this paper, we propose a method to assess fossil resource scarcity based on surplus cost, which is the global future cost increase due to marginal fossil resource used in the life cycle of products.

Methods

The marginal cost increase (MCI in US dollars in the year 2008 per kilogram per kilogram produced) is calculated as an intermediate parameter for crude oil, natural gas and coal separately. Its calculations are based on production cost and cumulative future production per production technique or country. The surplus cost (SC in US dollars in the year 2008 per kilogram) is calculated as an indicator for fossil resource scarcity. The SC follows three different societal perspectives used to differentiate the subjective choices regarding discounting and future production scenarios.

Results and discussion

The hierarchist perspective SCs of crude oil, natural gas, and coal are 2.9, 1.5, and 0.033 US$₂₀₀₈/GJ, respectively. The ratios between the indicators of the different types of fossil resources (crude oil/natural gas/coal) are rather constant, except in the egalitarian perspective, where contrastingly no discounting is applied (egalitarian 100:47:21; hierarchist 100:53:1.1; individualist 100:34:0.6). The ratio of the MCIs (100:48:1.0) are similar to the individualist and hierarchist SC ratios.

Conclusions

In all perspectives, coal has a much lower resource scarcity impact factor per gigajoule and crude oil has the highest. In absolute terms of costs per heating value (US dollars in the year 2008 per gigajoule), there are large differences between the SCs for each perspective (egalitarian > hierarchist > individualist).     

Choice of land reference situation in life cycle impact assessment

Purpose

Land use life cycle impact assessment is calculated as a distance to target value—the target being a desirable situation defined as a reference situation in Milà i Canals et al.’s (Int J Life Cycle Assess 12(1):2–4, 2007) widely accepted framework. There are several reference situations. This work aims to demonstrate the effect of the choice of reference situation on land impact indicators.

Methods

Various reference situations are reported from the perspective of the object of assessment in land in life cycle assessment (LCA) studies and the modeling choices used in life cycle land impact indicators. They are analyzed and classified according to additional LCA modeling requirements: the type of LCA approach (attributional or consequential), cultural perspectives (egalitarian, hierarchist or individualist), and temporal preference. Sets of characterization factors (CF) by impact pathway, land cover, and region are calculated for different reference situations. These sets of CFs by reference situation are all compared with a baseline set. A case study on different crop types is used to calculate impact scores from different sets of CFs and compare them.

Results and discussion

Comparing the rankings of the CFs from two different sets present inversions from 5% to 35% worldwide. Impact scores of the case study present inversions of 10% worldwide. These inversions demonstrate that the choice of a reference situation may reverse the LCA conclusions for the land use impact category. Moreover, these reference situations must be consistent with the different modeling requirements of an LCA study (approach, cultural perspective, and time preference), as defined in the goal and scope.

Conclusions

A decision tree is proposed to guide the selection of a consistent and suitable choice of reference situation when setting other LCA modeling requirements.

     

Towards harmonizing natural resources as an area of protection in life cycle impact assessment

Purpose

In this paper, we summarize the discussion and present the findings of an expert group effort under the umbrella of the United Nations Environment Programme (UNEP)/Society of Environmental Toxicology and Chemistry (SETAC) Life Cycle Initiative proposing natural resources as an Area of Protection (AoP) in Life Cycle Impact Assessment (LCIA).

Methods

As a first step, natural resources have been defined for the LCA context with reference to the overall UNEP/SETAC Life Cycle Impact Assessment (LCIA) framework. Second, existing LCIA methods have been reviewed and discussed. The reviewed methods have been evaluated according to the considered type of natural resources and their underlying principles followed (use-to-availability ratios, backup technology approaches, or thermodynamic accounting methods).

Results and discussion

There is currently no single LCIA method available that addresses impacts for all natural resource categories, nor do existing methods and models addressing different natural resource categories do so in a consistent way across categories. Exceptions are exergy and solar energy-related methods, which cover the widest range of resource categories. However, these methods do not link exergy consumption to changes in availability or provisioning capacity of a specific natural resource (e.g., mineral, water, land etc.). So far, there is no agreement in the scientific community on the most relevant type of future resource indicators (depletion, increased energy use or cost due to resource extraction, etc.). To address this challenge, a framework based on the concept of stock/fund/flow resources is proposed to identify, across natural resource categories, whether depletion/dissipation (of stocks and funds) or competition (for flows) is the main relevant aspect.

Conclusions

An LCIA method—or a set of methods—that consistently address all natural resource categories is needed in order to avoid burden shifting from the impact associated with one resource to the impact associated with another resource. This paper is an important basis for a step forward in the direction of consistently integrating the various natural resources as an Area of Protection into LCA.

     

Accounting for overfishing in life cycle assessment: new impact categories for biotic resource use

Purpose

Overfishing is a relevant issue to include in all life cycle assessments (LCAs) involving wild caught fish, as overfishing of fish stocks clearly targets the LCA safeguard objects of natural resources and natural ecosystems. Yet no robust method for assessing overfishing has been available. We propose lost potential yield (LPY) as a midpoint impact category to quantify overfishing, comparing the outcome of current with target fisheries management. This category primarily reflects the impact on biotic resource availability, but also serves as a proxy for ecosystem impacts within each stock.

Methods

LPY represents average lost catches owing to ongoing overfishing, assessed by simplified biomass projections covering different fishing mortality scenarios. It is based on the maximum sustainable yield concept and complemented by two alternative methods, overfishing though fishing mortality (OF) and overfishedness of biomass (OB), that are less data-demanding.

Results and discussion

Characterization factors are provided for 31 European commercial fish stocks in 2010, representing 74 % of European and 7 % of global landings. However, large spatial and temporal variations were observed, requiring novel approaches for the LCA practitioner. The methodology is considered compliant with the International Reference Life Cycle Data System (ILCD) standard in most relevant aspects, although harmonization through normalization and endpoint characterization is only briefly discussed.

Conclusions

Seafood LCAs including any of the three approaches can be a powerful communicative tool for the food industry, seafood certification programmes, and for fisheries management.     

The economic resource scarcity potential (ESP) for evaluating resource use based on life cycle assessment

Purpose

In life cycle assessment (LCA), resource availability is currently evaluated by means of models based on depletion time, surplus energy, etc. Economic aspects influencing the security of supply and affecting availability of resources for human use are neglected. The aim of this work is the development of a new model for the assessment of resource provision capability from an economic angle, complementing existing LCA models. The inclusion of criteria affecting the economic system enables an identification of potential supply risks associated with resource use. In step with actual practice, such an assessment provides added value compared to conventional (environmental) resource assessment within LCA. Analysis of resource availability including economic information is of major importance to sustain industrial production.

Methods

New impact categories and characterization models are developed for the assessment of economic resource availability based on existing LCA methodology and terminology. A single score result can be calculated providing information about the economic resource scarcity potential (ESP) of different resources. Based on a life cycle perspective, the supply risk associated with resource use can be assessed, and bottlenecks within the supply chain can be identified. The analysis can be conducted in connection with existing LCA procedures and in line with current resource assessment practice and facilitates easy implementation on an organizational level.

Results and discussion

A portfolio of 17 metals is assessed based on different impact categories. Different impact factors are calculated, enabling identification of high-risk metals. Furthermore, a comparison of ESP and abiotic depletion potential (ADP) is conducted. Availability of resources differs significantly when economic aspects are taken into account in addition to geologic availability. Resources assumed uncritical based on ADP results, such as rare earths, turn out to be associated with high supply risks.

Conclusions

The model developed in this work allows for a more realistic assessment of resource availability beyond geologic finiteness. The new impact categories provide organizations with a practical measure to identify supply risks associated with resources. The assessment delivers a basis for developing appropriate mitigation measures and for increasing resilience towards supply disruptions. By including an economic dimension into resource availability assessment, a contribution towards life cycle sustainability assessment (LCSA) is achieved.     

Correlation analysis of life cycle impact assessment indicators measuring resource use

Introduction  

Even though the necessity of a sustainable use of natural resources is widely accepted, there is neither consensus on how “resource use” is clearly defined nor how it should be measured. Depending on the definition, it can comprise raw material consumption only or the consumption and pollution of natural resources. Consequently, lots of indicators can be applied, and the result of a life cycle assessment study aiming to quantify resource use seems to depend on the selection of impact categories. Therefore, this paper aims at analyzing life cycle impact assessment results obtained by means of several indicators to check if different indexes lead to similar results and if the number of indicators can be reduced.     

Evaluating the Sustainability SWOT as a streamlined tool for life cycle sustainability assessment

Purpose

From a management perspective, there are two main issues in the life cycle sustainability assessment framework which require further work: (1) the approaches to quicken the resource-consuming inventory and assessment process and (2) the easy-to-understand communication of the results. This study aims at contributing to these needs for quicker and cost-efficient ways to draft strategies that include the life cycle perspective and encompasses all three dimensions of sustainability in an easily communicable way. The focus of the study is on a streamlined, rapid assessment the tool proposed by Pesonen (2007) called the Sustainability SWOT (Strengths, Weaknesses, Opportunities, Threats) and on the empirical testing of whether or not it is understood in the corporate world and if it leads to concrete changes in either strategic- or operative-level activities.

Methods

The data for the research were empirically collected from a survey targeted to representatives of organizations having used the Sustainability SWOT within the last 5 years. The primary findings, i.e., the generated changes or improvements, were reflected in the various levels of cooperation in a network (along the value chain, in end users, in the institutional framework).

Results and discussion

The results of the analyses of both the usability of the Sustainability SWOT in business as well as the suggested assessment framework leading to any actual changes were promising. It is encouraging that the streamlined approach tailored according to the logic of business decision-makers (i.e., inclusion of the SWOT) is able to find the acceptance and understanding of that vital group. Remarkably, many changes were initiated—not only at an operative level but also at a strategic level and in the entire value chain—by carrying out an exercise such as the Sustainability SWOT.

Conclusions

The Sustainability SWOT has proven to be usable and able to generate changes and improvements along the value chain and, in some cases, in the institutional context as well.     

Weighted matrices as product life cycle assessment tools

Experience demonstrates that comprehensive life cycle assessments (LCAs) for complex manufactured products are too data-intensive and too costly, and the results too uncertain, to be useful as regular tools for the product designer. In their place, streamlined LCAs, preserving the concepts of evaluating all product life stages and a range of environmental concerns yet doing so in semiquantitative and much more efficient ways, are becoming common. They suffer, however, from an inability to prioritize and emphasize the most important life stages and environmental concerns. This paper presents a methodology for using weighted matrices to accomplish this latter goal while preserving much of the straightforward approach and efficient information display attributes typical of unweighted, streamlined LCAs. The techniques are demonstrated by performing assessments on generic automobiles of the 1950s.     

Application typologies for life cycle assessment

Different lists of application areas for life cycle assessment are reviewed together with some suggestions for a typology of these application areas. It is concluded that the scope of a life cycle assessment is determined by the area of validity of the decision with respect to time, space, and interest groups affected. On this basis, six application areas are distinguished. It is further concluded that the application area has limited influence on the inventory analysis and impact assessment phases, although these may be influenced significantly by the decision-maker and the complexity of the trade-offs between the involved environmental impacts. The reporting format for a life cycle assessment depends on the socio-economic importance of the decision, the intended audience, and the time available for decision making.     

Methodologies for social life cycle assessment

Goal, Scope and Background  

In recent years several different approaches towards Social Life Cycle Assessment (SLCA) have been developed. The purpose of this review is to compare these approaches in order to highlight methodological differences and general shortcomings. SLCA has several similarities with other social assessment tools, although, in order to limit the expanse of the review, only claims to address social impacts from an LCA-like framework are considered.     

Parameterised inventories for life cycle assessment

Background and Objective  

Life cycle assessment (LCA) is a highly data intensive undertaking, where collecting the life cycle inventory (LCI) data is the most labour intensive part. The aim of this paper is to show a method for representing the LCI in a simplified manner which not only allows an estimative, quantitative LCA, but also the application of advanced analysis methods to LCA.     

Mineral resource dissipation in life cycle inventories

The International Journal of Life Cycle Assessment - The assessment of potential environmental impacts associated to mineral resource use in LCA is a highly debated topic. Most current...