Improved exergetic life cycle assessment through matrix reduction technique

Purpose

The concept of exergy can be used in LCA to quantify the value of natural resources consumed in production processes, as well as to assess the environmental impacts of waste streams. Prior studies noted the complexity of exergy accounting for wastes due to the diversity and complexity of waste streams. We develop an improved method to allow for rigorous exergy accounting of both resources and wastes.

Methods

The exergy content of a mass stream depends on many physical characteristics, including temperature, pressure, and chemical composition. We develop a novel matrix reduction technique to reduce data gathering requirements by multiple orders of magnitude. This method predivides the impact matrix into key rows and processes and “rest of economy” flows. Thermodynamic data can then be gathered for key flows emitted by key processes, and all other flows can be modeled using default values with little loss of accuracy.

Results and discussion

Our method is applied to an example LCA of electricity production via a natural gas combined cycle (NGCC) system. The case study finds that life cycle (economy-wide) exergetic efficiency of NGCC electricity production is ≈43 %, compared to a plant-level (local) exergetic efficiency of ≈54 %. The exergy content of life cycle waste flows is contained primarily in chemical exergy and physical exergy of flue gases, with nearly equal contributions. These waste exergy fluxes represent ≈3 % each of total input exergy.

Conclusions

The matrix reduction technique is found to be robust to assumptions about flows that are not directly modeled. By examining ranges of reasonable assumptions about mass flows not specifically modeled, we show that key rows and processes account for the vast majority of exergy content of interventions.

     

An extended life cycle analysis of packaging systems for fruit and vegetable transport in Europe

Purpose

The year-round supply of fresh fruit and vegetables in Europe requires a complex logistics system. In this study, the most common European fruit and vegetable transport packaging systems, namely single-use wooden and cardboard boxes and re-useable plastic crates, are analyzed and compared considering environmental, economic, and social impacts.

Methods

The environmental, economic, and social potentials of the three transport packaging systems are examined and compared from a life cycle perspective using Life Cycle Assessment (LCA), Life Cycle Costing (LCC) and Life Cycle Working Environment (LCWE) methodologies. Relevant parameters influencing the results are analyzed in different scenarios, and their impacts are quantified. The underlying environmental analysis is an ISO 14040 and 14044 comparative Life Cycle Assessment that was critically reviewed by an independent expert panel.

Results and discussion

The results show that wooden boxes and plastic crates perform very similarly in the Global Warming Potential, Acidification Potential, and Photochemical Ozone Creation Potential categories; while plastic crates have a lower impact in the Eutrophication Potential and Abiotic Resource Depletion Potential categories. Cardboard boxes show the highest impacts in all assessed categories. The analysis of the life cycle costs show that the re-usable system is the most cost effective over its entire life cycle. For the production of a single crate, the plastic crates require the most human labor. The share of female employment for the cardboard boxes is the lowest. All three systems require a relatively large share of low-qualified employees. The plastic crate system shows a much lower lethal accident rate. The higher rate for the wooden and cardboard boxes arises mainly from wood logging. In addition, the sustainability consequences due to the influence of packaging in preventing food losses are discussed, and future research combining aspects both from food LCAs and transport packing/packaging LCAs is recommended.

Conclusions

For all three systems, optimization potentials regarding their environmental life cycle performance were identified. Wooden boxes (single use) and plastic crates (re-usable) show preferable environmental performance. The calibration of the system parameters, such as end-of-life treatment, showed environmental optimization potentials in all transport packaging systems. The assessment of the economic and the social dimensions in parallel is important in order to avoid trade-offs between the three sustainability dimensions. Merging economic and social aspects into a Life Cycle Assessment is becoming more and more important, and their integration into one model ensures a consistent modeling approach for a manageable effort.     

Assessment of ecological sustainability of a building subjected to potential seismic events during its lifetime

Purpose

Sustainable development aims to enhance the quality of life by improving the social, economic and environmental conditions for present and future generations. A sustainable engineering decision-making strategy for design and assessment of construction works (i.e., civil engineering and buildings) should take into account considerations regarding the society, the economy and the environment. This study presents a novel approach for the life cycle assessment (LCA) of a case-study building subjected to seismic actions during its service life, accounting for structural reliability.

Methods

A methodology is presented that evaluates the time-dependent probability of exceeding a limit state considering the uncertainty in the representation of seismic action. By employing this methodology, the earthquake-induced damages are related to the environmental and social losses caused by the occurrence of the earthquake. A LCA of a case-study building accounting for the time-dependent seismic reliability is conducted using a damage-oriented LCA approach.

Results and discussion

The contributions of the different life cycle phases to the total environmental impact related to the building lifetime are in agreement with previous results in this field of study. However, the LCA results revealed significant risk-based contributions for the rehabilitation phase due to the induced damage resulting in seismic events. Particularly, the rehabilitation phase is expected to contribute to the total environmental impact with around the 25 % of the initial environmental impact load (related to the pre-use phase) as a consequence of seismic damage.

Conclusions and recommendations

The probability of occurrence of seismic events affects the LCA results for various life cycle phases of a building in terms of all the indicators adopted in the analysis. The time-dependent probability of collapse in a year can represent a benchmark indicator for human safety in the context of social sustainability for the building sector. The proposed approach can be implemented in a sustainable decision-making tool for design and assessment.     

Life Cycle Impact Assessment—where we are, trends, and next steps: a late report from a UNEP/SETAC Life Cycle Initiative workshop and a few updates from recent developments

Purpose

The paper provides a late report from the United Nations Environment Program (UNEP)/Society of Environmental Toxicology and Chemistry (SETAC) Life Cycle Initiative workshop “Life Cycle Impact Assessment (LCIA)—where we are, trends, and next steps;” it embeds this report into recent development with regard to the envisaged development of global guidance on environmental life cycle impact assessment indicators and related methodologies.

Methods

The document is the output of the UNEP/SETAC Life Cycle Initiative’s workshop on “Life Cycle Impact Assessment—where we are, trends, and next steps.” The presentations and discussions held during the workshop reviewed the first two phases of the Life Cycle Initiative and provided an overview of current LCIA activities being conducted by the Initiative, governments and academia, as well as corporate approaches. The outcomes of the workshop are reflected in light of the implementation of the strategy for Phase 3 of the Life Cycle Initiative.

Results

The range of views provided during the workshop indicated different user needs, with regards to, amongst other things, the required complexity of the LCIA methodology, associated costs, and the selection of LCIA categories depending on environmental priorities. The workshop’s results signified a number of potential focus areas for Phase 3 of the Initiative, including capacity building efforts concerning LCIA in developing countries and emerging economies, the preparation of training materials on LCIA, the production of global guidance on LCIA, and the potential development of a broader sustainability indicators framework.

Conclusions

These suggestions have been taken into account in the strategy for Phase 3 of the Life Cycle Initiative in two flagship projects, one on global capability development on life cycle approaches and the other on global guidance on environmental life cycle impact assessment indicators. In the context of the latter project, first activities are being organized and planned. Moreover, UNEP has included the recommendations in its Rio + 20 Voluntary Commitments: UNEP and SETAC through the UNEP/SETAC Life Cycle Initiative commit to facilitate improved access to good quality life cycle data and databases as well as expanded use of key environmental indicators that allows the measurement and monitoring of progress towards the environmental sustainability of selected product chains.     

Application of LCSA to used cooking oil waste management

Purpose

Used cooking oil (UCO) is a domestic waste generated as the result of cooking and frying food with vegetable oil. The purpose of this study is to compare the sustainability of three domestic UCO collection systems: through schools (SCH), door-to-door (DTD), and through urban collection centres (UCC), to determine which systems should be promoted for the collection of UCO in cities in Mediterranean countries.

Methods

The present paper uses the recent life cycle sustainability assessment (LCSA) methodology. LCSA is the combination of life cycle assessment (LCA), life cycle costing, and social life cycle assessment (S-LCA).

Results and discussion

Of the three UCO collection systems compared, the results show that UCC presents the best values for sustainability assessment, followed by DTD and finally SCH system, although there are no substantial differences between DTD and SCH. UCC has the best environmental and economic performance but not for social component. DTD and SCH present suitable values for social performance but not for the environmental and economic components.

Conclusions

The environmental component improves when the collection points are near to citizens’ homes. Depending on the vehicle used in the collection process, the management costs and efficiency can improve. UCO collection systems that carry out different kind of waste (such as UCC) are more sustainable than those that collect only one type of waste. Regarding the methodology used in this paper, the sustainability assessment proposed is suitable for use in decision making to analyse processes, products or services, even so in social assessment an approach is needed to quantify the indicators. Defining units for sustainability quantification is a difficult task because not all social indicators are quantifiable and comparable; some need to be adapted, raising the subjectivity of the analysis. Research into S-LCA and LCSA is recent; more research is needed in order to improve the methodology.     

Towards life cycle sustainability assessment: an implementation to photovoltaic modules

Purpose

The main goal of the paper is to carry out the first implementation of sustainability assessment of the assembly step of photovoltaic (PV) modules production by Life Cycle Sustainability Assessment (LCSA) and the development of the Life Cycle Sustainability Dashboard (LCSD), in order to compare LCSA results of different PV modules. The applicability and practicability of the LCSD is reported thanks to a case study. The results show that LCSA can be considered a valuable tool to support decision-making processes that involve different stakeholders with different knowledge and background.

Method

The sustainability performance of the production step of Italian and German polycrystalline silicon modules is assessed using the LCSD. The LCSD is an application oriented to the presentation of an LCSA study. LCSA comprises life cycle assessment (LCA), life cycle costing and social LCA (S-LCA). The primary data collected for the German module are related to two different years, and this led to the evaluation of three different scenarios: a German 2008 module, a German 2009 module, and an Italian 2008 module.

Results and discussion

According to the LCA results based on Ecoindicator 99, the German module for example has lower values of land use [1.77 potential disappeared fractions (PDF) m²/year] and acidification (3.61 PDF m²/year) than the Italian one (land use 1.99 PDF m²/year, acidification 3.83 PDF m²/year). However, the German module has higher global warming potential [4.5E?C05 disability-adjusted life years (DALY)] than the Italian one [3.00E?05 DALY]. The economic costs of the German module are lower than the Italian one, e.g. the cost of electricity per FU for the German module is 0.12??/m² compared to the Italian 0.85??/m². The S-LCA results show significant differences between German module 2008 and 2009 that represent respectively the best and the worst overall social performances of the three considered scenarios compared by LCSD. The aggregate LCSD results show that the German module 2008 has the best overall sustainability performance and a score of 665 points out of 1,000 (and a colour scale of light green). The Italian module 2008 has the worst overall sustainability performance with a score of 404 points, while the German module 2009 is in the middle with 524 points.

Conclusions

The LCSA and LCSD methodologies represent an applicable framework as a tool for supporting decision-making processes which consider sustainable production and consumption. However, there are still challenges for a meaningful application, particularly the questions of the selection of social LCA indicators and how to weigh sets for the LCSD.     

A UNEP/SETAC approach towards a life cycle sustainability assessment—our contribution to Rio+20

Purpose

To contribute to the upcoming United Nations Conference on Sustainable Development (Rio+20) in 2012 by introducing a life cycle sustainability assessment (LCSA) and showing how it can play a crucial role in moving towards sustainable consumption and production. The publication, titled Towards a Life Cycle Sustainability Assessment, and published by the UNEP/SETAC Life Cycle Initiative aims to show how three life cycle techniques—(environmental) LCA, S-LCA and LCC—can be combined as part of an over-arching LCSA.

Methods

The method was demonstrated by evaluating the characteristics of each phase for each life cycle technique. In defining the goal and scope of an LCSA, for example, different aspects should be taken into account to establish the aim of the study as well as the functional unit, system boundaries, impact category and allocation. Then, the data to be collected for the life cycle sustainability inventory can be either in a unit process or on an organisational level. They can also be quantitative or qualitative. Life cycle sustainability impact assessment should consider the relevance of the impacts as well as the perspective of stakeholders. The interpretation should not add up the results, but rather evaluate them jointly. In order to clarify the approach, a case study is presented to evaluate three types of marble according to the proposed method.

Results and discussion

The authors have identified that while LCSA is feasible, following areas need more development: data production and acquisition, methodological development, discussion about LCSA criteria (e.g. cutoff rules), definitions and formats of communication and dissemination of LCSA results and the expansion of research and applications combining (environmental) LCA, LCC and S-LCA. The authors also indicate that it is necessary to develop more examples and cases to improve user capacity to analyse the larger picture and therefore address the three dimensions or pillars of sustainability in a systematic way. Software and database providers are called for in order to facilitate user-friendly and accessible tools to promote LCSAs.

Conclusions

The application demonstrated that, although methodological improvements are still needed, important steps towards an overarching sustainability assessment have been accomplished. LCSA is possible and should be pursued; however, more efforts should be made to improve the technique and facilitate the studies in order to contribute to a greener economy.     

Comparative life cycle assessment and social life cycle assessment of used polyethylene terephthalate (PET) bottles in Mauritius

Purpose

Improper disposal of used polyethylene terephthalate (PET) bottles constitute an eyesore to the environmental landscape and is a threat to the flourishing tourism industry in Mauritius. It is therefore imperative to determine a suitable disposal method of used PET bottles which not only has the least environmental load but at the same time has minimum harmful impacts on peoples employed in waste disposal companies. In this respect, the present study investigated and compared the environmental and social impacts of four selected disposal alternatives of used PET bottles.

Methods

Environmental impacts of the four disposal alternatives, namely: 100 % landfilling, 75 % incineration with energy recovery and 25 % landfilling, 40 % flake production (partial recycling) and 60 % landfilling and 75 % flake production and 25 % landfilling, were determined using ISO standardized life cycle assessment (ISO 14040:2006) and with the support of SimaPro 7.1 software. Social life cycle assessments were performed based on the UNEP/SETAC Guidelines for Social Life Cycle Assessment of products. Three stakeholder categories (worker, society and local community) and eight sub-category indicators (child labour, fair salary, forced labour, health and safety, social benefit/social security, discrimination, contribution to economic development and community engagement) were identified to be relevant to the study. A new method for aggregating and analysing the social inventory data is proposed and used to draw conclusions.

Results and discussion

Environmental life cycle assessment results indicated that highest environmental impacts occurred when used PET bottles were disposed by 100 % landfilling while disposal by 75 % flake production and 25 % landfilling gave the least environmental load. Social life cycle assessment results indicated that least social impacts occurred with 75 % flake production and 25 % landfilling. Thus both E-LCA and S-LCA rated 75 % flake production and 25 % landfilling to be the best disposal option.

Conclusions

Two dimensions of sustainability (environmental and social) when investigated using the Life Cycle Management tool, favoured scenario 4 (75 %?% flake production and 25 % landfilling) which is a partial recycling disposal route. One hundred percent landfilling was found out to be the worst scenario. The next step will be to explore the third pillar of sustainability, economic, and devise a method to integrate the three dimensions with a view to determine the sustainable disposal option of used PET bottles in Mauritius.     

Simulation and analysis for sustainable product development

Purpose

Simulation plays a critical role in the design of products, materials, and manufacturing processes. However, there are gaps in the simulation tools used by industry to provide reliable results from which effective decisions can be made about environmental impacts at different stages of product life cycle. A holistic and systems approach to predicting impacts via sustainable manufacturing planning and simulation (SMPS) is presented in an effort to incorporate sustainability aspects across a product life cycle.

Methods

Increasingly, simulation is replacing physical tests to ensure product reliability and quality, thereby facilitating steady reductions in design and manufacturing cycles. For SMPS, we propose to extend an earlier framework developed in the Systems Integration for Manufacturing Applications (SIMA) program at the National Institute of Standards and Technology. SMPS framework has four phases, viz. design product, engineer manufacturing, engineer production system, and produce products. Each phase has its inputs, outputs, phase level activities, and sustainability-related data, metrics and tools.

Results and discussion

An automotive manufacturing scenario that highlights the potential of utilizing SMPS framework to facilitate decision making across different phases of product life cycle is presented. Various research opportunities are discussed for the SMPS framework and corresponding information models.

Conclusions

The SMPS framework built on the SIMA model has potential in aiding sustainable product development.     

Environmental and economic optimisation of the floor on grade in residential buildings

Purpose

The goal of the study was to determine the preferred composition of the floor on grade in residential buildings in the Belgian context from a life cycle environmental and financial perspective. In addition to the life cycle costs, the required investments were evaluated to take into account budget restrictions. The analysis of current available materials and techniques allows both the designer and building owner to extend their decision criteria from mainly investment cost to life cycle aspects as well.

Methods

In this study, the potential environmental impact was assessed by considering the environmental external cost of the floors. Several existing methods were combined to enable a full assessment, taking the ExternE methodology (willingness to pay) as the main base. The ecoinvent database was used to gather the inventory data but was adapted to increase the representativeness for Belgium. The financial evaluation included both the investment and life cycle aspects. The latter was analysed through the sum of the present values of all costs occurring during the life span of the floor.

Results and discussion

The necessary assumptions (e.g. transport, end-of-life treatment, cleaning, life span, economic parameters) and the adaptations to the ecoinvent data are transparently reported. The methodological steps (e.g. monetary valuation, transmission losses, equivalent degree days, Pareto optimisation) are elaborated in detail. This allows the results, which are graphically presented, to be correctly interpreted. The contribution of the life cycle stages and the optimisation potential of the considered impacts are discussed.

Conclusions

The environmental external cost based on the willingness to pay to reduce environmental impacts proved to be relatively low, representing about 9?% of the financial cost. The cost reduction of current common practice was estimated to be about 20 and 60?% from a financial and environmental perspective, respectively. The insulation level and the floor covering were identified as the most important optimisation parameters.

Recommendations

Internalisation of environmental external costs might be an important step to achieve more sustainable solutions. However, it is recommended to consider financial and environmental external costs separately too because both contain important information for the decision maker. Because it is hard (if not impossible) to increase the insulation level of the floor on grade later on in the life cycle of the building, a high insulation value should be a priority during construction. The floor covering can more easily be adapted and is thus considered a secondary priority.     

Thermodynamic resource indicators in LCA: a case study on the titania produced in Panzhihua city, southwest China

Purpose

While life cycle assessment (LCA) has standardized methods for assessing emission impacts, some comparable methods for the accounting or impact assessment of resource use exist, but are not as mature or standardized. This study contributes to the existing research by offering a comprehensive comparison of the similarities and differences of different resource indicators, in particular those based on thermodynamics, and testing them in a case study on titania (titanium dioxide pigment) produced in Panzhihua city, southwest China.

Materials and methods

The system boundary for resource indicators is defined using a thermodynamic hierarchy at four levels, and the case data for titania also follow that hierarchy. Seven resource indicators are applied. Four are thermodynamics-based??cumulative energy demand (CED), solar energy demand (SED), cumulative exergy demand (CExD), and cumulative exergy extraction from the natural environment (CEENE)??and three have different backgrounds: abiotic resource depletion potential, environmental priority strategies, and eco-indicator 99. Inventory data for the foreground system has been collected through on-site interviews and visits. Background inventory data are from the database ecoinvent v2.2. Characterizations factors are based on the CML-IA database covering all major methods. Computations are with the CMLCA software.

Results and discussion

The scores of resource indicators of the chloride route for titania system are lower than that of the sulfate route by 10?C35?%, except in terms of SED. Within the four thermodynamic indicators for resources, CED, CExD, and CEENE have similar scores, while their scores are five orders of magnitude lower than the SED score. Atmospheric resources do not contribute to the SED or CEEND score. Land resources account for a negligible percentage to the SED score and a small percentage to the CEENE score. Non-renewable resources have a dominant contribution to all seven resource indicators. The global production of titania would account for 0.12 and 0.14?% of the total anthropogenic non-renewable resource demand in terms of energy and exergy, respectively.

Conclusions

First, we demonstrate the feasibility of thermodynamic resource indicators. We recommend CEENE as the most appropriate one within the four thermodynamic resource indicators for accounting and characterizing resource use. Regarding the case study on the titania produced in China, all the resource indicators except SED show that the sulfate route demands more resource use than the chloride route.     

Environmental footprint of cooking fuels: a life cycle assessment of ten fuel sources used in Indian households

Purpose

Cooking energy is an essential requirement of any human dwelling. With the recent upsurge in petroleum prices coupled with intrinsic volatility of international oil markets, it is fast turning into a politico-socio-economic dilemma for countries like India to sustain future subsidies on liquefied petroleum gas (LPG) and kerosene. The aim of this paper is to evaluate and compare the environmental performance of various cooking fuel options, namely LPG (NG), LPG (CO), kerosene, coal, electricity, firewood, crop residue, dung cake, charcoal, and biogas, in the Indian context. The purpose of this study is to find environmentally suitable alternatives to LPG and kerosene for rural and urban areas of the country.

Methods

The study assessed the cooking fuel performance on 13 ReCiPe environmental impact categories using the life cycle assessment methodology. The study modeled the system boundary for each fuel based on the Indian scenario and prepared a detailed life cycle inventory for each cooking fuel taking 1 GJ of heat energy transferred to cooking pot as the functional unit.

Results and discussion

The cooking fuels with the lowest life cycle environmental impacts are biogas followed by LPG, kerosene, and charcoal. The environmental impacts of using LPG are about 15 to 18 % lower than kerosene for most environmental impact categories. LPG derived from natural gas has about 20 to 30 % lower environmental impact than LPG derived from crude oil. Coal and dung cake have the highest environmental impacts because of significant contributions to climate change and particulate formation, respectively. Charcoal produced from renewable wood supply performs better than kerosene on most impact categories except photochemical oxidation, where its contribution is 19 times higher than kerosene.

Conclusions

Biogas and charcoal can be viewed as potentially sustainable cooking fuel options in the Indian context because of their environmental benefits and other associated co-benefits such as land farming, local employment opportunities, and skill development. The study concluded that kerosene, biogas, and charcoal for rural areas and LPG, kerosene, and biogas for urban areas have the lower environmental footprint among the chosen household cooking fuels in the study.     

Tackling environmental impacts in simple trigeneration systems operating under variable conditions

Purpose

Environmental concerns have been a growing issue when planning energy supply systems for buildings, as the energy demands (presenting seasonal and daily variations) represent one of the most energy-intensive consumptions in industrialized societies. The optimal operation corresponding to different energy demands of a trigeneration system was analyzed by an integrated methodology combining Thermoeconomic analysis and life cycle assessment, in order to adequately allocate the energy resources and the generated environmental loads to the different energy services produced.

Methods

Thermoeconomic analysis, which is usually used to allocate energy and economic costs, is herein applied to the evaluation of environmental costs and distribution of resources throughout the trigeneration system. Attention is focused on the correct allocation of energy resources and environmental loads to internal flows and final products. Appropriate rules were established to calculate energy and environmental costs.

Results and discussion

Operation of the system considered the possibilities that surplus electricity could be exported to the national grid and part of the cogenerated heat could be wasted if this resulted in a decrease of operation costs and/or environmental loads. The results obtained show a low-cost and low-emission production with respect to the separate production in different operation modes. It was observed that, in specific periods, the trigeneration system operates wasting part of the cogenerated heat, and, in other periods, part of the electricity produced is exported to the electric grid. The trigeneration system operates in these modes because it results beneficial from environmental or economic viewpoints, achieving a lower economic cost or fewer CO₂ emissions.

Conclusions

The methodology presented as well as the allocation method proposal were congruent with the objectives of installing trigeneration systems that supplied energy services with fewer emissions than those of separate production and of equally benefitting the consumers of heat, coolth (“coolth” is used as the noun form of “cool”; opposite of warmth. Not to be confused with cooling, which is the opposite of heating.) (alias cooling energy), and electricity.     

ILCD Handbook Public Consultation Workshop

Introduction

The European Commission is supporting the development of the International Reference Life Cycle Data System (ILCD). This consists primarily of the ILCD Handbook and the ILCD Data Network. This paper gives an insight into the scientific positions of business, governments, consultants, academics, and others that were expressed at this public consultation workshop.

Workshop focus

The workshop focused on four of the topics of the main guidance documents of the ILCD Handbook: (1) general guidance on life cycle assessment (LCA); (2) guidance for generic and average life cycle inventory (LCI) data sets; (3) requirements for environmental impact assessment methods, models and indicators for LCA; and (4) review schemes for LCA.

Workshop participation

This consultation workshop was attended by more than 120 participants during the 4 days of the workshop. Representatives came from 23 countries, from both within and outside the European Union.

Workshop structure

Approximately half of the participants were from business associations or individual companies. Another 20% were governmental representatives. Others came predominantly from consultancies and academia.

Results

This public consultation workshop provided valuable inputs into the overall ILCD Handbook developments as well as for further development. This paper focuses on some of the main scientific issues that were raised.     

Water supply and sustainability: life cycle assessment of water collection, treatment and distribution service

Purpose

The aim of the present paper is to describe the development of a life cycle assessment study of the service of potable water supply in Sicily, Italy. The analysis considers the stages of collection, treatment and distribution of potable water through the regional network, whilst the use stage of water is not included.

Methods

The selection of a methodological pattern coherently with the requirements of an environmental label, such as the EPDs, aims at allowing comparability among different studies.

Results and discussion

The analysis shows the shares of impacts along the life cycle chain, i.e. outputs by well fields and spring groups, purification and desalination plants, water losses in the waterworks, electrical consumption of waterworks systems and impacts of network maintenance. With regard to global warming potential (GWP), the impact of purification plants represents a 6–7 % share of the total, whilst desalination is at 74 %. Water losses in the waterworks show an impact of 15–17 %; the contribution owing to electrical consumption of waterworks systems and network maintenance results to be 3 %. Desalination plants represent the major contribution to all impact categories considered.

Conclusions

In respect to management issues, the most relevant impact categories resulted to be GWP, non-renewable energy resources and water consumption. Since the results for non-renewable energy resources are strictly connected to GWP emissions, carbon footprint and water footprint can be profitably used as single-issue indicators without the risk of burden shifting in studies aiming to evaluate the impact of potable water distribution.     

Life cycle assessment of nanocomposites made of thermally conductive graphite nanoplatelets

Purpose

Polymers typically have intrinsic thermal conductivity much lower than other materials. Enhancement of this property may be obtained by the addition of conductive fillers. Nanofillers are preferred to traditional ones, due to their low percolation threshold resulting from their high aspect ratio. Beyond these considerations, it is imperative that the development of such new fillers takes place in a safe and sustainable manner. A conventional life cycle assessment (LCA) has been conducted on epoxy-based composites, filled with graphite nanoplatelets (GnP). In particular, this study focuses on energy requirements for the production of such composites, in order to stress environmental hot spots and primary energy of GnP production process (nano-wastes and nanoparticles emissions are not included).

Methods

A cradle-to-grave approach has been employed for this assessment, in an attributional modeling perspective. The data for the LCA have been gathered from both laboratory data and bibliographic references. A technical LCA software package, SimaPro (SimaPro 7.3), which contains Ecoinvent (2010) life cycle inventory (LCI) database, has been used for the life cycle impact assessment (LCIA), studying 13 mid-point indicators. Sensitivity and uncertainty analyses have also been performed.

Results and discussion

One kilogram of GnP filler requires 1,879 MJ of primary energy while the preparation of 1 kg of epoxy composite loaded with 0.058 kg of GnP 303 MJ. Besides energy consumption in the filler preparation, it is shown that the thermoset matrix material has also a non-negligible impact on the life cycle despite the use of GnP: the primary energy required to make epoxy resin is 187 MJ, i.e., 62 % of the total energy to make 1 kg of composite.

Conclusions

Raw material extraction and filler and resin preparation phase exhibit the highest environmental impact while the composite production is negligible. Thermosetting resin remains the highest primary energy demand when used as matrix for GnP fillers. The result of the sensitivity analysis carried out on the electricity mix used during the GnP and the composite production processes does not affect the conclusions.     

Rigor in social life cycle assessment: improving the scientific grounding of SLCA

Purpose

Social life cycle assessment (SLCA) is developing rapidly and represents a valuable complement to other life cycle methods. As methodological development continues, a growing number of case studies have noted the need for more scientific rigor in areas like data collection, allocation methods, and incorporation of values and cultural context. This work aims to identify opportunities, especially in the social sciences, to improve rigor in SLCA.

Methods

A review of existing literature and tools is based on both hand coding of the SLCA literature as represented in Web of Science’s “All Collections” database and on computer-aided review of the SLCA and other related literatures (including social impact assessment (SIA), life cycle sustainability assessment (LCSA), and corporate social responsibility (CSR)) using a text mining technique known as topic modeling. Rapid diagnosing of potentially valuable contributions from literatures outside of SLCA through computer-aided review led to more detailed, manual investigation of those literatures for further insight.

Results and discussion

Data collection can benefit from increased standardization and integration with social science methods, especially frameworks for surveys and interviews. Sharing examples of questionnaires and ethics committee protocols will likely improve SLCA’s accessibility. SIA and CSR also represent empirical data sources for SLCA. Impact allocation techniques can benefit from reintegration with those in ELCA, in particular by allocating (when necessary) at facility—rather than product—level. The focus on values and subjectivity in SLCA is valuable not only for SLCA but also for other methods, most notably ELCA. Further grounding in social science is likely to improve rigor in SLCA.

Conclusions

SLCA is increasingly robust and contributing to interdisciplinary discussions of how best to consider social impacts. This work makes three major recommendations for continued growth: first, that SLCA standardize human subject research used for data gathering; second, that SLCA adopt allocation techniques from ELCA; and third, that SLCA continue to draw on social science and other literatures to rigorously include value systems.

     

Environmental evaluation and comparison of selected industrial scale biomethane production facilities across Europe

Purpose

The two main reasons for producing biomethane as renewable fuel are reduction of climate impacts and depletion of fossil resources. Biomethane is expected to be sustainable, but how sustainable is it actually? This article contributes to the clarification. Therefore, the environmental impacts of several biomethane facilities all over Europe were assessed. A special focus is put on the differences between the facilities as they follow different production routes.

Methods

The method used for evaluation is life cycle assessment (LCA) applied in a well-to-wheel approach. This enables to show the overall performance in terms of global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), photochemical ozone creation potential (POCP) and PE fossil. The system boundary includes the entire chain from biogas production to upgrading, distribution and use. For evaluating the different production routes several years of measuring data, calculating and improving the LCA models in close cooperation with the plant operators were carried out.

Results and discussion

The evaluation of the production routes shows a high reduction potential compared to fossil fuels. Regarding the depletion of fossil resources, the amounts vary between the sites, but the reduction is at least 50 % and reaches almost 100 % reductions at some sites. The reduction of GWP is at least 65 %, because waste flows free of environmental burdens are used almost exclusively as substrate. Other dominant factors are power and heat demand, methane losses to the environment and the use of by-products, e.g. fertilizer.

Conclusions

Despite this caveat, the evaluated systems demonstrate the possible positive results of renewable fuel production if done properly.