Assessing freshwater use impacts in LCA,part 2: case study of broccoli production in the UK and Spain

Background, aim and scope  

Milà i Canals et al. (Int J Life Cycle Ass 14(1):28-42, 2009) referred to as ‘Part 1’ in this paper) showed that impacts associated with use of freshwater must be treated more rigorously than is usual in life cycle assessment (LCA), going beyond the conventional consideration only of ‘blue’ water (i.e. irrigation and other abstractions), and suggested an operational method to include the impacts on freshwater ecosystems (freshwater ecosystem impact) and abiotic resource depletion (freshwater depletion). The inclusion of water-related impacts in LCA is of paramount importance, particularly for agricultural systems due to their large water consumption worldwide. A case study of UK consumption of broccoli grown in the UK and Spain is presented here to illustrate the method suggested in Part 1.     

Integrating human health impact from indoor emissions into an LCA: a case study evaluating the significance of the use stage

Purpose

Indoor emissions of toxic substances from products can have a negative effect on human health. These are typically not considered in a life cycle assessment (LCA), potentially underestimating the importance of the use stage. The purpose of this paper is to develop a method that, based on a set of measured emission rates, calculates the impact on human health during the use stage of products that are used indoors and that emit volatile organic compounds (VOCs).

Methods

Emissions from a product are measured in a test chamber and reported as a set of emission rates (microgrammes per hour) at specific points in time (hour/day). Constrained non-linear regression (CNLR) analysis is then used to determine parameters for three emission models, and a model is selected based on goodness of fit with the measured emission rates (R ² and expert judgement). The emission model is integrated over a defined time period to estimate the total use stage emissions per functional unit (FU). The total emissions are subsequently integrated in a homogeneously mixed one-box model within the USEtox model. Intake fraction (iF) is calculated based on size of residential home, inhalation rate, exposure time, ventilation rate, mixing factor and number of people exposed.

Results and discussion

The method is tested in a case study of a chair, with the results showing that the impacts in the use stage are in most cases significantly higher than from the production and disposal stages combined. The sensitivity to parameter variations is evaluated. Intake fraction (factor of 761), replacement frequency (factor of 70) and emission model (factor of 24) are found to be the most important model parameters. Limiting early exposure (>14 % of emissions may occur in the first month and >50 % in the first year) and replacing furniture less frequently will reduce exposure.

Conclusions

The case study shows that the impact on human health from indoor emissions can be of significance, when compared to the impact on human health from total outdoor emissions. Without specific exposure data (e.g. ventilation rates) the uncertainty will be high. The developed method is applicable to all products that emit VOCs, provided that the emission rate can be modelled using an exponential decay model and that the product amount is related to a meaningful functional unit. It is recommended that when performing an LCA of products that emit VOCs, the indoor use stage is included in the life cycle impact assessment.     

Land use impacts on biodiversity in LCA: a global approach

Purpose

Land use is a main driver of global biodiversity loss and its environmental relevance is widely recognized in research on life cycle assessment (LCA). The inherent spatial heterogeneity of biodiversity and its non-uniform response to land use requires a regionalized assessment, whereas many LCA applications with globally distributed value chains require a global scale. This paper presents a first approach to quantify land use impacts on biodiversity across different world regions and highlights uncertainties and research needs.

Methods

The study is based on the United Nations Environment Programme (UNEP)/Society of Environmental Toxicology and Chemistry (SETAC) land use assessment framework and focuses on occupation impacts, quantified as a biodiversity damage potential (BDP). Species richness of different land use types was compared to a (semi-)natural regional reference situation to calculate relative changes in species richness. Data on multiple species groups were derived from a global quantitative literature review and national biodiversity monitoring data from Switzerland. Differences across land use types, biogeographic regions (i.e., biomes), species groups and data source were statistically analyzed. For a data subset from the biome (sub-)tropical moist broadleaf forest, different species-based biodiversity indicators were calculated and the results compared.

Results and discussion

An overall negative land use impact was found for all analyzed land use types, but results varied considerably. Different land use impacts across biogeographic regions and taxonomic groups explained some of the variability. The choice of indicator also strongly influenced the results. Relative species richness was less sensitive to land use than indicators that considered similarity of species of the reference and the land use situation. Possible sources of uncertainty, such as choice of indicators and taxonomic groups, land use classification and regionalization are critically discussed and further improvements are suggested. Data on land use impacts were very unevenly distributed across the globe and considerable knowledge gaps on cause–effect chains remain.

Conclusions

The presented approach allows for a first rough quantification of land use impact on biodiversity in LCA on a global scale. As biodiversity is inherently heterogeneous and data availability is limited, uncertainty of the results is considerable. The presented characterization factors for BDP can approximate land use impacts on biodiversity in LCA studies that are not intended to directly support decision-making on land management practices. For such studies, more detailed and site-dependent assessments are required. To assess overall land use impacts, transformation impacts should additionally be quantified. Therefore, more accurate and regionalized data on regeneration times of ecosystems are needed.     

Ecoinvent 3: assessing water use in LCA and facilitating water footprinting

Purpose

Water footprinting and the assessment of water use in life cycle assessment have become of major interest in sustainability assessments. Various initiatives for combining water resource issues with consumption of products and services have been initiated in the last decade. However, comprehensive databases fulfilling the requirements for addressing these issues have been lacking and are necessary to facilitate efficient and consistent assessments of products and services. To this purpose, ecoinvent focused on integrating appropriate water use data into version 3, since previously water use data has been inconsistently reported and some essential flows were missing. This paper describes the structure of the water use data in ecoinvent, how the data has been compiled and the way it can be used for water footprinting.

Methods

The main changes required for proper assessment of water use are the addition of environmental and product flows in order to allow a water balance over each process. This is in accordance with the strict paradigm in ecoinvent 3 to focus on mass balances, which requires the inclusion of water contents of all products (also for e.g. waste water flows), as well as emissions of water to soil, air and various water bodies. Water inputs from air (e.g. rainwater harvesting) is introduced but is not yet used by any activity.

Results and discussion

Ecoinvent version 3.1 consistently includes the relevant flows to address water use in life cycle assessment (LCA) and calculate water footprints on the product level for most processes including uncertainty information. Although some problems regarding data quality and spatial resolution remain, this is an important step forward and can limit efforts for detailed data collection to the most sensitive processes in the product system. With the combination of data on water use and emissions to water for each process, concentration and corresponding water classes can also be calculated and assessed with existing impact assessment methods.

Conclusions

This comprehensive collection of water use data on the process level facilitates the proper assessment of water use within an LCA and water footprints beyond agricultural production. Especially in LCA, but also in tools for eco-design and specific water footprint, this data is essential and leads to a cost-efficient way of assessing consumption choices and product design decisions with full transparency. It enhances the effectiveness of investing in data collection by performing sensitivity analyses using ecoinvent data to identify the most relevant flows and processes.

     

Towards a methodology for taking physical degradation of ecosystems into account in LCA

An analytic procedure has been followed to select adequate methods to express ecosystem degradation in LCA. This procedure consisted of problem definition, identification of relevant issues, of a quantitative expression for ecosystem degradation and of possible nature value indicators and building a framework of criteria for selecting adequate methods. With the selection framework a first screening of methods was performed. For full quantification the following formula is proposed: ED = L (N_r- N_a), with land use I. = A t and nature value change (N_r- N_a) Degradation due to an activity appears difficult to operationalise, but ecosystem suppression by activities can well be assessed. N_r is then the natural background or would-be natural situation. N_a can best be described by the actual state during the activity, unless hard data on restoration is available. N_a and N_r can be expressed in the biomass production indicator NPP - NCR Biodiversity and/or erosion may be added to include irreversible effects.     

Characterisation of social impacts in LCA

Background, aim, and scope  

The authors have suggested earlier a framework for life cycle impact assessment to form the modelling basis of social LCA. In this framework, the fundamental labour rights were pointed out as obligatory issues to be addressed, and protection and promotion of human dignity and well-being as the ultimate goal and area of protection of social LCA. The intended main application of this framework for social LCA was to support management decisions in companies who wish to conduct business in a socially responsible manner, by providing information about the potential social impacts on people caused by the activities in the life cycle of a product. Environmental LCA normally uses quantitative and comparable indicators to provide a simple representation of the environmental impacts from the product lifecycle. This poses a challenge to the social LCA framework because due to their complexity, many social impacts are difficult to capture in a meaningful way using traditional quantitative single-criterion indicators. A salient example is the violation of fundamental labour rights (child labour, discrimination, freedom of association, and right to organise and collective bargaining, forced labour). Furthermore, actual violations of these rights somewhere in the product chain are very difficult to substantiate and hence difficult to measure directly.     

Developing characterisation factors for land fragmentation impacts on biodiversity in LCA: key learnings from a sugarcane case study

Purpose

Habitat change was identified by the Millennium Ecosystem Assessment as the main direct driver of biodiversity loss. However, while habitat loss is already implemented in Life Cycle Impact Assessment (LCIA) methods, the additional impact on biodiversity due to habitat fragmentation is not assessed yet. Thus, the goal of this study was to include fragmentation effects from land occupation and transformation at both midpoint and endpoint levels in LCIA.

Methods

One promising metric, combining the landscape spatial configuration with species characteristics, is the metapopulation capacity λ, which can be used to rank landscapes in terms of their capacity to support viable populations spatially structured. A methodology to derive worldwide regionalised fragmentation indexes based on λ was used and combined with the Species Fragmented-Area Relationship (SFAR), which relies on λ to assess a species loss due to fragmentation. We adapted both developments to assess fragmentation impacts due to land occupation and transformation at both midpoint and endpoint levels in LCIA. An application to sugarcane production occurring in different geographical areas, more or less sensitive to land fragmentation, was performed.

Results and discussion

The comparison to other existing LCIA indicators highlighted its great potential for complementing current assessments through fragmentation effect inclusion. Last, both models were discussed through the evaluation grid used by the UNEP-SETAC land use LCIA working group for biodiversity impact assessment models.

Conclusions

Midpoint and endpoint characterisation factors were successfully developed to include the impacts of habitat fragmentation on species in LCIA. For now, they are provided for bird species in all forest ecoregions belonging to the biodiversity hotspots. Further work is required to develop characterisation factors for all taxa and all terrestrial ecoregions.

     

Land use impacts on biodiversity in LCA: proposal of characterization factors based on functional diversity

Purpose

The focus of land use modeling in life cycle impact assessment has been mainly on taxonomic measures of biodiversity, namely species richness (SR). However, increasing availability of trait data for species has led to the use of functional diversity (FD) as a promising metric to reflect the distinctiveness of species; this paper proposes the use of an FD index to calculate characterization factors (CFs) for land use impacts. Furthermore, we compare the results of the CFs to current practice and assess the increase in complexity introduced by the use of the new indicator.

Methods

The model proposed is based on data compiled by previous regional meta-analysis on SR and FD, in different land use types in the Americas. The taxonomic groups included were mammals, birds, and plants. Within each study, calculated values for FD for different land use types were compared with the natural or close-to-natural state, taken as the reference situation. FD values among different land uses were standardized, and CFs were calculated. The final results were then analyzed and compared by analysis of variance and post hoc tests. A sensitivity analysis was also applied to verify the influence on the choice of the reference state.

Results and discussion

The results show that significant differences exist between CFs for SR and FD metrics. Across all taxa, CFs differ significantly between land use types. The results support the use of CF for FD, as a complement to current practice. Distinct CFs should be applied for at least six groups of land use categories. The choice of reference land use type did not significantly alter the results but can be a source of variability. A sensitivity analysis evaluating the impact of alternate land use types as reference types found only few significant changes on the results.

Conclusions and recommendations

Given the results, we believe the use of CFs based on FD can help on the establishment of possible links between species loss and key ecosystem functions, i.e., on the association between the midpoint indicator (e.g., biodiversity loss) and the damage caused to ecosystem quality, in terms of functions lost. Basing CFs on FD is not without challenges. Such indices are data hungry (requiring species composition and traits) require more complex calculations than current common practice, including decisions on the choice of a method to calculate FD and the selection of traits.     

Characterisation of social impacts in LCA. Part 2: implementation in six company case studies

Background, aim and scope

A characterisation model based on multi-criteria indicators has been developed for each of four impact categories representing the labour rights according to the conventions of the International Labour Organisation (ILO) covering: forced labour, discrimination, restrictions of freedom of association and collective bargaining and child labour (Dreyer et al., Int J Life Cycle Assess, 2010a, in press). These impact categories are considered by the authors to be among the obligatory impact categories in a Social LCA. The characterisation models combine information about the way a company manages its behaviour towards some of its important stakeholders, its employees, with information about the geographical location and branch of industry of the company and the risk of violations of these workers' rights inherent in the setting of the company. The result is an indicator score which for each impact category represents the risk that violations occur in the company. In order to test the feasibility and relevance of the developed methodology, it is tested on real cases.

Materials and methods

The developed characterisation models are applied to six cases representing individual manufacturing companies from three different continents. Five of the case companies are manufacturing companies while the sixth is a knowledge company. The application involves scoring the management efforts of the case company in a multi-criteria scorecard and translating the scores into an aggregated performance score, which represents the effort of the management in order to prevent violations of the workers' rights to occur in the company. The company performance score is multiplied by a contextual adjustment score which reflects the risk of violations taking place in the context (in terms of geographical location or industrial branch or sector) of the company. The resulting indicator score represents the risk that violations take place of the labour right represented by the impact category.

Results

The social impact characterisation is performed for each of the six case studies using the methodology earlier developed. The procedure and outcome are documented through all the intermediary results shown for all four obligatory impact categories for each of the six case studies.

Discussion

The results are judged against the risk which was observed during visits and interviews at each of the six case companies, and their realism and relevance are discussed. They are found to be satisfactory for all four impact categories for the manufacturing companies, but there are some problems for two of the impact categories in the case company which represents knowledge work, and it is discussed how these problems may be addressed through change of the underlying scorecard or the way in which the scoring is translated into a company performance score.

Conclusions

It is concluded that it is feasible to perform a characterisation of the impacts related to the four obligatory impact categories representing the labour rights according to the conventions of the ILO covering: forced labour, discrimination, restrictions of freedom of association and collective bargaining and child labour. When compared with the observed situation in the companies, the results are also found to be relevant and realistic.

Recommendations and perspectives

The proposed characterisation method is rather time-consuming and cannot realistically be applied to all companies in the product system. It must therefore be combined with less time-requiring screening methods which can help identify the key companies in the life cycle for which a detailed analysis is required. The possibility to apply country- or industry sector-based information is discussed, and while it is found useful to identify low-risk companies and eliminate them from more detailed studies, the ability of the screening methods to discriminate between companies located in medium and high-risk contexts is questionable.     

Taking into account local practices and indigenous knowledge in an emergency conservation context in Madagascar

At the 5th World Parks Congress, held in Durban, South Africa in 2003, the President of Madagascar committed his government to tripling the country’s protected zones over the next 5 years. The announcement reflected a desire to combine rapid conservation efforts with sustainable development. Conservationists in Madagascar focused their attention on the endemic baobab tree, Adansonia grandidieri. This paper aims to identify the contradictions between the political emergency of the biodiversity conservation effort and local development needs. Eighty-three semi-structured interviews were conducted in two villages near the protected area of “Baobab Alley” in the Menabe region. Malagasy conservationists believed the area’s protected status would benefit the local economy through eco-tourism. However, the conservation actions undertaken there display limited understanding of local dynamics and conflict with farmers’ needs. To protect the baobabs, the government has prohibited rice cultivation without providing compensation. We show that the multifunctional baobab tree is integrated into an agroforestry system and protected by farmers. Based on these results, we address the issue of how to combine conservation and local development objectives through the involvement of farmers and the recognition of local knowledge in tree management. We also demonstrate that an emergency approach to conservation is not conducive to the successful integration of conservation and development.     

Taking into account electron-electron collisions in classical absorption of short laser pulses

The previously derived universal expression for the plasma permittivity is used to solve the problem of absorption of a short laser pulse incident on a semibounded solid-dense plasma. It is shown that the results of the exact theory may differ significantly from those obtained with the generally accepted models, especially in a weakly collisional regime corresponding to temperatures in the range 0.5–1 keV.     

The politics of the social economy: a case study of the Argentinean empresas recuperadas

This paper offers an ethnographically grounded analysis of the transformative possibilities of the Argentinean empresas recuperadas (ERs), which speaks to current debates on the ‘social economy’. The ERs emerged in a context shaped by the crisis of neoliberalism and of the Argentinean political system and a huge upsurge in popular self-organisation. In response to widespread factory closures, thousands of workers occupied abandoned companies, forming cooperatives and often introducing assembly-based decision-making. By 2002, they established a national organisation, which connected workers’ struggles to a wider movement for institutional change. However, by 2006, the organisation had fragmented and many ERs had reinstalled traditional control methods. Much of the literature divides between idealistic and deterministic interpretations, which conceive as a technical material process. The paper proposes an alternative, a concept of labour as a process of creating value—subjective needs and values, and surplus value—which links organisations to society. Conceiving the ‘politics of value creation’ highlights continuities within the financial management and institutional relations of many ERs, but most importantly, it also recognises the different ways in which emerging social identities articulated a new need for control. Through two case studies, the paper explores the social processes through which these actors shaped their cooperatives in very different ways—highlighting innovations in accounting techniques and state-society relations. This reveals why a focus on accounting can enable anthropologists to recognise the general limitations of cooperatives and also their specific cultural diversity. In conclusion, the paper reconciles current discussions on the concept of the social economy by theorising it as the internal socialisation of capitalism and as an institutional expression of new cultural needs.     

The assessment of positive impacts in LCA of products

The International Journal of Life Cycle Assessment - The objective of this paper is to open a discussion on the implications and challenges of including positive impacts in LCAs of products and to...     

Taking into account the conformational dynamics of macromolecules when analyzing luminescent probe signals

A mathematical model is proposed that takes into account the specific features of electronic excitation energy transfer between the molecular probes sorbed on a polymeric chain in a liquid solution. The kinetics of the process is described from the standpoint of the stochastic changes in macromolecular conformations. The results of numerical solution of the problem are described, as well as the analytical expressions obtained in the context of perturbation theory for a low transfer rate and/or fast conformational dynamics of the macrochain. A channel of nonlinear (with respect to excitation) deactivation resulting from binary annihilation of closely spaced excited centers is considered. Expressions for the efficient rate of mutual quenching and delayed annihilation fluorescence of the probe are obtained. The time dependences of characteristic luminescent signals and the parametric curves of relative fluorescence quantum yield are given.     

Evaluation of water services system through LCA. A case study for Iasi City,Romania

Purpose

The main objective of this paper is to analyse through life cycle assessment (LCA), the entire water services system in Iasi City (Romania): a representative city for the problems faced by the water services sector in Romania. Furthermore, the study is aimed at demonstrating the usefulness of the LCA approach as a support instrument for water resources management.

Methods

The life cycle inventory (LCI) of the Iasi water system was organized considering the water system components, as well as their function related to the water use life cycle: before the tap system as production phase (water abstraction, transport, treatment and distribution) and after the tap section as post-use phase (wastewater collection, treatment and discharge). The foreground data describing the LCI processes were provided directly by the company operating the Iasi water system, while the data for the background processes were sourced or selected from Ecoinvent 2.0 database. The assessment considers the quantification of environmental impacts (according to the CML 2000 baseline and Ecological Scarcity 2006 methodologies) of water supply (abstraction, treatment and distribution) and wastewater disposal (collection and treatment) relative to 1 m³ of tap water.

Results and discussion

For this given system, the results have pointed out that the before the tap system generates higher impacts than the after tap system, mainly due to the energetic effort needed for water supply and the fairly high water losses in the distribution system. However, the after the tap system, specifically the discharge of treated wastewater is still responsible for many of the water-related impact such as Eutrophication (when using CML) or Emissions to surface waters (when using the Ecological Scarcity method). Apart from the LCA approach, this study presents several scenarios for the improvement of the environmental performance of the water services, such as: changing between water sources, improving the distribution system and upgrading the wastewater treatment plant.

Conclusions

This study has demonstrated the usefulness of LCA to describe, compare and predict the environmental performance of complex water services systems (and all its components). The results have provided a reference case for the environmental profile of Iasi city water system, and have enabled the identification of its improvement alternatives. Also, this study, which represents a premiere for Romania, has opened future research directions which may include the development perspectives of the Iasi water services system, as well as improvements of LCIA methodologies to better represent the local specific water-related impacts.     

Soil water status influences plant nitrogen use: a case study

We studied differences in nitrogen use efficiency (NUE) among six species [Calamagrostis epigejos (L.) Roth., Carex duriuscula C.A. Mey., Phragmites communis (L.) Trin., Salix gordejevii Y.L. Chang, Salix cheilophila Schneid., and Typha minima Funk.] growing in two contrasting habitat types, i.e., a riverine wetland with high water supply and a riparian zone with low water supply. The two sites were different in soil water supply, but not in nitrogen supply. Here, NUE was defined as the total net primary production per unit nitrogen absorbed. There was no significant difference in NUE between the species growing in the riverine wetland (Carex duriuscula, P. communis, S. cheilophila, T. minima) and the species growing in the river bank (Carex duriuscula, Calamagrostis epigejos, P. communis, S. gordejevii). We further analyzed NUE as the product of the nitrogen productivity (A, the rate of dry matter production per unit of nitrogen in the plant) and the mean residence time of nitrogen (MRT, the period of time a unit of nitrogen is present in the plant). The species growing in the riverine wetland had larger A but lower MRT than the species growing in the river bank. There was an inverse relationship between A and MRT. Consequently, NUE was similar among species and habitats. These results suggested that environmental factors, such as soil water supply, can influence N use by plants.     

Allocation issues in LCA methodology: a case study of corn stover-based fuel ethanol

Background, aim, and scope

Facing the threat of oil depletion and climate change, a shift from fossil resources to renewables is ongoing to secure long-term low carbon energy supplies. In view of the carbon dioxide reduction targets agreed upon in the Kyoto protocol, bioethanol has become an attractive option for one energy application, as transport fuel. Many studies on the LCA of fuel ethanol have been conducted, and the results vary to a large extent. In most of these studies, only one type of allocation is applied. However, the effect of allocation on outcomes is of crucial importance to LCA as a decision supporting tool. This is only addressed in a few studies to a limited extent. Moreover, most of the studies mainly focus on fossil energy use and GHG emissions. In this paper, a case study is presented wherein a more complete set of impact categories is used. Land use has been left out of account as only hectare data would be given which is obviously dominated by agriculture. Moreover, different allocation methods are applied to assess the sensitivity of the outcomes for allocation choices.

Materials and methods

This study focuses on the comparison of LCA results from the application of different allocation methods by presenting an LCA of gasoline and ethanol as fuels and with two types of blends of gasoline with ethanol, all used in a midsize car. As a main second-generation application growing fast in the USA, corn stover-based ethanol is chosen as a case study. The life cycles of the fuels include gasoline production, corn and stover agriculture, cellulosic ethanol production, blending ethanol with gasoline to produce E10 (10% of ethanol) and E85 (85% of ethanol), and finally the use of gasoline, E10, E85, and ethanol. In this study, a substantially broader set of eight environmental impacts is covered.

Results

LCA results appear to be largely dependent on the allocation methods rendered. The level of abiotic depletion and ozone layer depletion decrease when replacing gasoline by ethanol fuels, irrespective of the allocation method applied, while the rest of the impacts except global warming potential are larger. The results show a reduction of global warming potential when mass/energy allocation is applied; in the case of economic allocation, it gives contrary results. In the expanded systems, global warming potential is significantly reduced comparing to the ones from the allocated systems. A contribution analysis shows that car driving, electricity use for cellulase enzyme production, and ethanol conversion contribute largely to global warming potential from the life cycle of ethanol fuels.

Discussion

The reason why the results of global warming potential show a reverse trend is that the corn/stover allocation ratio shifts from 7.5 to 1.7 when shifting from economic allocation to mass/energy allocation. When mass/energy allocation is applied, both more credits (CO₂ uptake) and more penalties (N₂O emission) in agriculture are allocated to stover compared to the case of economic allocation. However, more CO₂ is taken up than N₂O (in CO₂ eq.) emitted. Hence, the smaller the allocation ratio is between corn and stover, the lower the share of the overall global warming emissions being allocated to ethanol will be. In the system expansion approach, global warming potentials are significantly reduced, resulting in the negative values in all cases. This implies that the system expansion results are comparable to one another because they make the same cutoffs but not really to the results related to mass, energy, and economic value-based allocated systems.

Conclusions

The choice of the allocation methods is essential for the outcomes, especially for global warming potential in this case. The application of economic allocation leads to increased GWP when replacing gasoline by ethanol fuels, while reduction of GWP is achieved when mass/energy allocation is used as well as in the system where biogenic CO₂ is excluded. Ethanol fuels are better options than gasoline when abiotic depletion and ozone layer depletion are concerned. In terms of other environmental impacts, gasoline is a better option, mainly due to the emissions of nutrients and toxic substances connected with agriculture. A clear shift of problems can be detected: saving fossil fuels at the expense of emissions related to agriculture, with GHG benefits depending on allocation choices. The overall evaluation of these fuel options, therefore, depends very much on the importance attached to each impact category.

Recommendations and perspectives

This study focuses only on corn stover-based ethanol as one case. Further studies may include other types of cellulosic feedstocks (i.e., switchgrass or wood), which require less intensive agricultural practice and may lead to better environmental performance of fuel ethanol. Furthermore, this study shows that widely used but different allocation methods determine outcomes of LCA studies on biofuels. This is an unacceptable situation from a societal point of view and a challenge from a scientific point of view. The results from applying just one allocation method are not sufficient for decision making. Comparison of different allocation methods is certainly of crucial importance. A broader approach beyond LCA for the analysis of biorefinery systems with regard to energy conservation, environmental impact, and cost–benefit will provide general indications on the sustainability of bio-based productions.