Exploring the Use of Ecological Footprint in Life Cycle Impact Assessment

Ecological footprint (EF) is a metric that estimates human consumption of biological resources and products, along with generation of waste greenhouse gas (GHG) emissions in terms of appropriated productive land. There is an opportunity to better characterize land occupation and effects on the carbon cycle in life cycle assessment (LCA) models using EF concepts. Both LCA and EF may benefit from the merging of approaches commonly used separately by practitioners of these two methods. However, few studies have compared or integrated EF with LCA. The focus of this research was to explore methods for improving the characterization of land occupation within LCA by considering the EF method, either as a complementary tool or impact assessment method. Biofuels provide an interesting subject for application of EF in the LCA context because two of the most important issues surrounding biofuels are land occupation (changes, availability, and so on) and GHG balances, two of the impacts that EF is able to capture. We apply EF to existing fuel LCA land occupation and emissions data and project EF for future scenarios for U.S. transportation fuels. We find that LCA studies can benefit from lessons learned in EF about appropriately modeling productive land occupation and facilitating clear communication of meaningful results, but find limitations to the EF in the LCA context that demand refinement and recommend that EF always be used along with other indicators and metrics in product‐level assessments.     

Combining Material Flow Analysis,Life Cycle Assessment,and Multiattribute Utility Theory

Three assessment methods, material flow analysis (MFA), life cycle analysis (LCA), and multiattribute utility theory (MAUT) are systematically combined for supporting the choice of best end‐of‐life scenarios for polyethylene terephthalate (PET) waste in a municipality of a developing country. MFA analyzes the material and energy balance of a firm, a region, or a nation, identifying the most relevant processes; LCA evaluates multiple environmental impacts of a product or a service from cradle to grave; and MAUT allows for inclusion of other aspects along with the ecological ones in the assessment. We first systematically coupled MFA and LCA by defining “the service offered by the total PET used during one year in the region” as the functional unit. Inventory and impacts were calculated by multiplying MFA flows with LCA impacts per kilogram. We used MAUT to include social and economic aspects in the assessment. To integrate the subjective point of view of stakeholders in the MAUT, we normalized the environmental, social, and economic variables with respect to the magnitude of overall impacts or benefits in the country. The results show large benefits for recycling scenarios from all points of view and also provide information about waste treatment optimization. The combination of the three assessment methods offers a powerful integrative assessment of impacts and benefits. Further research should focus on data collection methods to easily determine relevant material flows. LCA impact factors specific to Colombia should be developed, as well as more reliable social indicators.     

Life Cycle Impacts and Benefits of Wood along the Value Chain: The Case of Switzerland

Sustainable use of wood may contribute to coping with energy and material resource challenges. The goal of this study is to increase knowledge of the environmental effects of wood use by analyzing the complete value chain of all wooden goods produced or consumed in Switzerland. We start from a material flow analysis of current wood use in Switzerland. Environmental impacts related to the material flows are evaluated using life cycle assessment–based environmental indicators. Regarding climate change, we find an overall average benefit of 0.5 tonnes carbon dioxide equivalent per cubic meter of wood used. High environmental benefits are often achieved when replacing conventional heat production and energy‐consuming materials in construction and furniture. The environmental performance of wood is, however, highly dependent on its use and environmental indicators. To exploit the mitigation potential of wood, we recommend to (1) apply its use where there are high substitution benefits like the replacement of fossil fuels for energy or energy‐intensive building materials, (2) take appropriate measures to minimize negative effects like particulate matter emissions, and (3) keep a systems perspective to weigh effects like substitution and cascading against each other in a comprehensive manner. The results can provide guidance for further in‐depth studies and prospective analyses of wood‐use scenarios.     

Final Energy Requirements of Steam for Use in Environmental Life Cycle Assessment

Steam is an important utility that is required in nearly all industrial process chains and hence needs to be modeled in life cycle assessment studies. Industrial steam systems are often very complex, with different steam flows varying in pressure and temperature and being transported over different distances. This should be accounted for when calculating the energy requirements related to steam supply. In this article, we constructed a generic model that allows estimating final energy requirements (i.e., gate‐to‐gate energy required to generate the steam) of various types of single‐fuel steam systems without turbines (i.e., open and closed cycles) with or without flash steam and expressed per tonne (t) of steam supplied to a process (before heat exchange) or per gigajoule (GJ) heat delivered within the process (after heat exchange, i.e., as useful energy). The model focuses on steam provided for covering process heat requirements and hence excludes cogeneration schemes with steam turbines. Based on the final energy requirements estimated with our generic model, primary energy requirements and environmental impacts can be calculated for various circumstances. Depending on the conditions chosen, final energy requirements for natural gas–fueled systems, as estimated in this study, are 2.71 to 3.44 GJ/t produced steam or 1.33 to 1.78 GJ/GJ delivered heat.     

Comparing Three Life Cycle Impact Assessment Methods from an Endpoint Perspective

The impact assessment methods Eco‐Indicator 99 (H), Stepwise2006, and ReCiPe2008 (H) are compared with respect to the relative and absolute importance that they assign to the different mid‐point impact categories. The comparison is done by a common monetary valuation of the three endpoints that are common to the three methods: human well‐being, nature, and resources. Land use, global warming, and respiratory inorganic pollutants together make up between 86% and 97% of the overall impacts compared in all three methods. The overall monetarized impacts amount to 30%, 28%, and 165% of the gross domestic product (GDP), respectively. Resource depletion, land use, and global warming explain 99.5% of the positive deviation of ReCiPe2008, relative to the other two methods. The main causes for these differences are investigated and discussed, pointing to possibly questionable calculations and assumptions, for example, regarding the nonsubstitutability of resources and the very long relaxation time for transformed forestland in the relatively new ReCiPe2008 method, which leads us to recommend users to be cautious and critical when interpreting the results. Sensitivity analysis is made for other cultural perspectives and normalization references.     

Material and Energy Flows and Environmental Impacts of the Internet in Switzerland

The Internet leads to material and energy consumption as well as various environmental impacts on both the regional and global scale. Yet, assessments of the Internet's energy consumption and resulting greenhouse gas emissions are still rare, and assessments of material flows and further environmental impacts are virtually non‐existent. This article investigates material flows, the direct energy consumption during the use phase, as well as environmental impacts linked to the service, “Internet in Switzerland.” In our model, the service, Internet in Switzerland, is divided into various Internet participant categories. All devices used to access or provide Internet services are merged in a limited number of equipment families and, as such, included in an inventory of the existing infrastructure (stock). Based on this inventory, a material flow analysis (MFA) is performed, which includes the current stock as well as flows resulting from growth and disposal. The direct energy consumption for the operation of the infrastructure is quantified. Environmental impacts are calculated with a life cycle assessment approach, using the ecoinvent database and the software, SimaPro, applying four different methods. The MFA results in a 2009 stock of 98,100 tonnes. Approximately 4,130 gigawatt hours per year, or 7% of the total Swiss electricity consumption, were used in 2009 to operate the Swiss infrastructure. The environmental impacts caused during the production and use phases vary significantly depending on the assessment method chosen. The disposal phase had mainly positive impacts as a result of material recovery.     

Using the Lashof Accounting Methodology to Assess Carbon Mitigation Projects With Life Cycle Assessment

As governments elaborate strategies to counter climate change, there is a need to compare the different options available on an environmental basis. This study proposes a life cycle assessment framework integrating the Lashof accounting methodology, which enables the assessment and comparison of different carbon mitigation projects (e.g., biofuel use, a sequestering plant, an afforestation project). The Lashof accounting methodology is chosen amid other methods of greenhouse gas (GHG) emission characterization for its relative simplicity and capability to characterize all types of carbon mitigation projects. Using the unit of megagram‐year (Mg‐year), which accounts for the mass of GHGs in the atmosphere multiplied by the time it stays there, the methodology calculates the cumulative radiative forcing caused by GHG emission within a predetermined time frame. Basically, the developed framework uses the Mg‐year as a functional unit and isolates impacts related to the climate mitigation function with system expansion. The proposed framework is demonstrated with a case study of tree ethanol pathways (maize, sugarcane, and willow). The study shows that carbon mitigation assessment through life cycle assessment is possible and that it could be a useful tool for decision makers, as it can compare different projects regardless of their original context. The case study reveals that system expansion, as well as each carbon mitigation project's efficiency at reducing carbon emissions, are critical factors that have a significant impact on the results. Also, the framework proves to be useful for treating land‐use change emissions, as they are considered through the functional unit.     

Life Cycle Assessment Software: Selection Can Impact Results

When software is used to facilitate life cycle assessments (LCAs), the implicit assumption is that the results obtained are not a function of the choice of software used. LCAs were done in both SimaPro and GaBi for simplified systems of creation and disposal of 1 kilogram each of four basic materials (aluminum, corrugated board, glass, and polyethylene terephthalate) to determine whether there were significant differences in the results. Data files and impact assessment methodologies (Impact 2002, ReCiPe, and TRACI 2) were ostensibly identical (although there were minor variations in the available ReCiPe version between the programs that were investigated). Differences in reported impacts of greater than 20% for at least one of the four materials were found for 9 of the 15 categories in Impact 2002+, 7 of the 18 categories in ReCiPe, and four of the nine categories in TRACI. In some cases, these differences resulted in changes in the relative rankings of the four materials. The causes of the differences for 14 combinations of materials and impact categories were examined by tracing the results back to the life cycle inventory data and the characterization factors in the life cycle impact assessment (LCIA) methods. In all cases examined, a difference in the characterization factors used by the two programs was the cause of the differing results. As a result, when these software programs are used to inform choices, the result can be different conclusions about relative environmental preference that are functions purely of the software implementation of LCIA methods, rather than of the underlying data.     

From Life Cycle Assessment to Life Cycle Management

Life cycle assessment (LCA) is a widely accepted methodology to support decision‐making processes in which one compares alternatives, and that helps prevent shifting of environmental burdens along the value chain or among impact categories. According to regulation in the European Union (EU), the movement of waste needs to be reduced and, if unavoidable, the environmental gain from a specific waste treatment option requiring transport must be larger than the losses arising from transport. The EU explicitly recommends the use of LCA or life cycle thinking for the formulation of new waste management plans. In the last two revisions of the Industrial Waste Management Programme of Catalonia (PROGRIC), the use of a life cycle thinking approach to waste policy was mandated. In this article we explain the process developed to arrive at practical life cycle management (LCM) from what started as an LCA project. LCM principles we have labeled the “3/3” principle or the “good enough is best” principle were found to be essential to obtain simplified models that are easy to understand for legislators and industries, useful in waste management regulation, and, ultimately, feasible. In this article, we present the four models of options for the management of waste solvent to be addressed under Catalan industrial waste management regulation. All involved actors concluded that the models are sufficiently robust, are easy to apply, and accomplish the aim of limiting the transport of waste outside Catalonia, according to the principles of proximity and sufficiency.     

Using Attributional Life Cycle Assessment to Estimate Climate‐Change Mitigation Benefits Misleads Policy Makers

Life cycle assessment (LCA) is generally described as a tool for environmental decision making. Results from attributional LCA (ALCA), the most commonly used LCA method, often are presented in a way that suggests that policy decisions based on these results will yield the quantitative benefits estimated by ALCA. For example, ALCAs of biofuels are routinely used to suggest that the implementation of one alternative (say, a biofuel) will cause an X% change in greenhouse gas emissions, compared with a baseline (typically gasoline). However, because of several simplifications inherent in ALCA, the method, in fact, is not predictive of real‐world impacts on climate change, and hence the usual quantitative interpretation of ALCA results is not valid. A conceptually superior approach, consequential LCA (CLCA), avoids many of the limitations of ALCA, but because it is meant to model actual changes in the real world, CLCA results are scenario dependent and uncertain. These limitations mean that even the best practical CLCAs cannot produce definitive quantitative estimates of actual environmental outcomes. Both forms of LCA, however, can yield valuable insights about potential environmental effects, and CLCA can support robust decision making. By openly recognizing the limitations and understanding the appropriate uses of LCA as discussed here, practitioners and researchers can help policy makers implement policies that are less likely to have perverse effects and more likely to lead to effective environmental policies, including climate mitigation strategies.     

Impact Assessment of Biodiversity and Carbon Pools from Land Use and Land Use Changes in Life Cycle Assessment,Exemplified with Forestry Operations in Norway

There is a strong need for methods within life cycle assessment (LCA) that enable the inclusion of all complex aspects related to land use and land use change (LULUC). This article presents a case study of the use of one hectare (ha) of forest managed for the production of wood for bioenergy production. Both permanent and temporary changes in above‐ground biomass are assessed together with the impact on biodiversity caused by LULUC as a result of forestry activities. The impact is measured as a product of time and area requirements, as well as by changes in carbon pools and impacts on biodiversity as a consequence of different management options. To elaborate the usefulness of the method as well as its dependency on assumptions, a range of scenarios are introduced in the study. The results show that the impact on climate change from LULUC dominates the results, compared to the impact from forestry operations. This clearly demonstrates the need to include LULUC in an LCA of forestry products. For impacts both on climate change and biodiversity, the results show large variability based on what assumptions are made; and impacts can be either positive or negative. Consequently, a mere measure of land used does not provide any meaning in LCA, as it is not possible to know whether this contributes a positive or negative impact.     

Assessment of Environmental Impacts of an Aging and Stagnating Water Supply Pipeline Network

Aging urban infrastructure is a common phenomenon in industrialized countries. The urban water supply pipeline network in the city of Oslo is an example. Even as it faces increasing operational, maintenance, and management challenges, it needs to better its environmental performance by reducing, for instance, the associated greenhouse gas emissions. In this article the authors examine the environmental life cycle performance of Oslo's water supply pipelines by analyzing annual resource consumption and emissions as well as life cycle assessment (LCA) impact potentials over a period of 16 years, taking into account the production/manufacture, installation, operation, maintenance, rehabilitation, and retirement of pipelines. It is seen that the water supply pipeline network of Oslo has already reached a state of saturation on a per capita basis, that is, it is not expanding any more relative to the population it serves, and the stock is now rapidly aging. This article is part of a total urban water cycle system analysis for Oslo, and analyzes more specifically the environmental impacts from the material flows in the water distribution network, examining six environmental impact categories using the SimaPro (version 7.1.8) software, Ecoinvent database, and the CML 2001 (version 2.04) methodology. The long‐term management of stocks calls for a strong focus on cost optimization, energy efficiency, and environmental friendliness. Global warming and abiotic depletion emerge as the major impact categories from the water pipeline system, and the largest contribution is from the production and installation phases and the medium‐size pipelines in the network.     

Environmental Life Cycle Assessment of a Canned Sardine Product from Portugal

This study aims to assess the environmental impacts of canned sardines in olive oil, by considering fishing, processing, and packaging, using life cycle assessment (LCA) methodology. The case study concerns a product of a canning factory based in Portugal and packed in aluminum cans. It is the first LCA of a processed seafood product made with the traditional canning method. The production of both cans and olive oil are the most important process in the considered impact categories. The production of olives contributes to the high environmental load of olive oil, related to cultivation and harvesting phases. The production of aluminum cans is the most significant process for all impact categories, except ozone depletion potential and eutrophication potential, resulting from the high energy demand and the extraction of raw materials. To compare to other sardine products consumed in Portugal, such as frozen and fresh sardines, transport to the wholesaler and store was added. The environmental cost of canned sardines is almost seven times higher per kilogram of edible product. The main action to optimize the environmental performance of canned sardines is therefore to replace the packaging and diminish the olive oil losses as much as possible. Greenhouse gas emissions are reduced by half when plastic packaging is considered rather than aluminum. Frozen and fresh sardines represent much lower environmental impacts than canned sardines. Nevertheless, when other sardine products are not possible, it becomes feasible to use sardines for human consumption, preventing them from being wasted or used suboptimally as feed.     

Insights on the Use of Hybrid Life Cycle Assessment for Environmental Footprinting

Establishing a comprehensive environmental footprint that indicates resource use and environmental release hotspots in both direct and indirect operations can help companies formulate impact reduction strategies as part of overall sustainability efforts. Life cycle assessment (LCA) is a useful approach for achieving these objectives. For most companies, financial data are more readily available than material and energy quantities, which suggests a hybrid LCA approach that emphasizes use of economic input‐output (EIO) LCA and process‐based energy and material flow models to frame and develop life cycle emission inventories resulting from company activities. We apply a hybrid LCA framework to an inland marine transportation company that transports bulk commodities within the United States. The analysis focuses on global warming potential, acidification, particulate matter emissions, eutrophication, ozone depletion, and water use. The results show that emissions of greenhouse gases, sulfur, and particulate matter are mainly from direct activities but that supply chain impacts are also significant, particularly in terms of water use. Hotspots were identified in the production, distribution, and use of fuel; the manufacturing, maintenance, and repair of boats and barges; food production; personnel air transport; and solid waste disposal. Results from the case study demonstrate that the aforementioned footprinting framework can provide a sufficiently reliable and comprehensive baseline for a company to formulate, measure, and monitor its efforts to reduce environmental impacts from internal and supply chain operations.     

The Design of a Sustainability Assessment Standard Using Life Cycle Information

Sustainability assessment standards are currently being developed for a range of building products. This activity has been stimulated through the considerable success of the U.S. Green Building Council's (USGBC) LEED? standard. Transparent life cycle–based standards can guide manufacturers to design products that have reduced environmental impact. The use of a sustainability standard can certify performance and avoid green washing. In this article we present a logical framework for designing a sustainability assessment standard through the creation of tables that award points in the standard to be consistent with life cycle information. Certain minimum principles of consistency are articulated. In the case that the life cycle impact assessment method maps the life cycle inventory to impact through a linear weighting, two design approaches—impact category and activity substitution—are constructed to be consistent with these principles. The approach is illustrated in a case study of a partial redesign of a carpet sustainability assessment standard (NSF/ANSI‐140).     

Estimation of Life Cycle Material Costs of Cadmium Telluride– and Copper Indium Gallium Diselenide–Photovoltaic Absorber Materials based on Life Cycle Material Flows

Chalcogenide and chalcopyrite photovoltaic (PV) technologies are highly suitable for solar energy conversion because of their high efficiency, long‐term stable performance, and low‐cost production. However, the absorber materials that are used, such as indium, gallium, and tellurium, are regarded as critical, and their limited availability can hinder market expansion. Therefore, we assess how material efficiency measures along the PV module's life cycle can reduce the net material demand of the absorber materials and thus the material costs. In order to estimate the material flows, we developed a closed‐loop model for the life cycle representing the phases module production, module collection, module recycling, and refinement. In order to reflect the variety and uncertainty in each phase, we compose three different efficiency scenarios by varying material efficiency measures on process and product levels. For each scenario, we compute the life cycle material costs based on the computed material flows. The results show that, in the long term, the material demand can be reduced down to one fourth of the required feedstock for module manufacturing; that is, three fourths of the absorber material stays in the life cycle in a very efficient scenario. Thus, total material costs along the life cycle could be significantly reduced, because the costs for material recycling are lower than the costs for “new” technical‐grade material. This reduction in life cycle material costs means that cadmium telluride– and copper indium gallium diselenide–PV can still be financially viable even if the price of the absorber materials increases significantly. Hence those technologies will still be competitive against crystalline silicon PV in the mid to long term.     

Beyond Global Warming Potential: A Comparative Application of Climate Impact Metrics for the Life Cycle Assessment of Coal and Natural Gas Based Electricity

In the ongoing debate about the climate benefits of fuel switching from coal to natural gas for power generation, the metrics used to model climate impacts may be important. In this article, we evaluate the life cycle greenhouse gas emissions of coal and natural gas used in new, advanced power plants using a broad set of available climate metrics in order to test for the robustness of results. Climate metrics included in the article are global warming potential, global temperature change potential, technology warming potential, and cumulative radiative forcing. We also used the Model for the Assessment of Greenhouse‐gas Induced Climate Change (MAGICC) climate‐change model to validate the results. We find that all climate metrics suggest a natural gas combined cycle plant offers life cycle climate benefits over 100 years compared to a pulverized coal plant, even if the life cycle methane leakage rate for natural gas reaches 5%. Over shorter time frames (i.e., 20 years), plants using natural gas with a 4% leakage rate have similar climate impacts as those using coal, but are no worse than coal. If carbon capture and sequestration becomes available for both types of power plants, natural gas still offers climate benefits over coal as long as the life cycle methane leakage rate remains below 2%. These results are consistent across climate metrics and the MAGICC model over a 100‐year time frame. Although it is not clear whether any of these metrics are better than the others, the choice of metric can inform decisions based on different societal values. For example, whereas annual temperature change reported may be a more relevant metric to evaluate the human health effects of increased heat, the cumulative temperature change may be more relevant to evaluate climate impacts, such as sea‐level rise, that will result from the cumulative warming.     

Evaluation of Life Cycle Assessment Recycling Allocation Methods

Life cycle assessment practitioners struggle to accurately allocate environmental burdens of metals recycling, including the temporal dimension of environmental impacts. We analyze four approaches for calculating aluminum greenhouse gas emissions: the recycled content (RC) or cut‐off approach, which assumes that demand for recycled content displaces primary production; end‐of‐life recycling (EOLR), which assumes that postuse recycling displaces primary production; market‐based (MB) approaches, which estimate changes in supply and demand using price elasticities; and value‐corrected substitution (VCS), which allocates impact based on price differences between primary and recycled material. Our analysis suggests that applications of the VCS approach do not adequately account for the changing scrap to virgin material price ratio over time, whereas MB approaches do not address stock accumulation and depletion. The EOLR and RC approaches were analyzed using two case studies: U.S. aluminum beverage cans and vehicle engine blocks. These approaches produced similar results for beverage cans, which have a closed material loop system and a short product life. With longer product lifetimes, as noted with the engine blocks, the magnitude and timing of the emissions differs greatly between the RC and EOLR approaches. The EOLR approach indicates increased impacts at the time of production, offset by negative impacts in future years, whereas the RC approach assumes benefits to increased recycled content at the time of production. For vehicle engine blocks, emissions using EOLR are 140% higher than with RC. Results are highly sensitive to recycled content and future recycling rates, and the choice of allocation methods can have significant implications for life cycle studies.     

Estimating Environmental Behavior Without Performing a Life Cycle Assessment

Many authors have agreed on the interest of considering environmental concerns in the early stages of product development. However, most eco‐design tools are based on life cycle assessment principles and require a model to give information about the product's environmental performance. This modeling can have negative effects on team performance and on the potential for innovation, not to mention on the project's duration. Additionally, the model requires information that is not available in the early design stages. This article analyzes the potential of inferring conclusions about the life cycle stages with the highest impact by using similar products. From a database of previous products, environmental profile estimations are carried out, that is, the assessments of the contribution of each life cycle stage to the total impact and the variability of this measure. It is then possible to discard—or ensure consideration of—life cycle stages. Furthermore, the level of the conclusions is assessed on a five‐point scale. The proposed approach is applied to four case studies with different levels of abstraction and the relevance of the conclusions is assessed. The article resolves the problems regarding potential for estimating the distribution of the environmental impacts along the life cycle.