Life Cycle Assessment

Life cycle assessment of organic and conventional non-Bt cotton products from Mali Abstract Introduction Cotton is the most produced natural fibre in the world, with an annual output of 23 million t of lint in the period 2000–2013. Africa produced in average 6% of that output, and despite being a relatively minor contributor to global cotton supply chains, it has been estimated that a large percentage of the continent’s population depends on cotton cultivation for their livelihood. Most published cotton LCAs focused on the main global producers (India, China, USA), a few consider African cotton, and none to date Malian cotton. This work presents an LCA of the Malian cotton sector, consisting of an agricultural phase and ginning operations, in contrast with other African and global cotton LCAs. Material and methods The goal of the study is to assess the absolute and relative environmental impacts of Malian cotton, per agricultural production system type, including the processing of seed cotton in ginning plants to produce cotton fibre bales (cradle to processing plant gate). Inventories were built for the two initial phases in the production cycle of cotton fibre, namely, the agricultural phase and the ginning phase. The main agricultural production system types were identified, according to distinctive differences in yields and technical processes―such as phytosanitary strategies―as well as the main processes performed in ginning plants. Operational data, representing the period 2002–2010, were provided by the Malian Company for the Development of Textiles (CMDT). It included yields and input and their uncertainty data. Direct field emissions of the agricultural phase were estimated following the AGRIBALYSE methodology, adapted when necessary to tropical conditions (e.g. a modified version of the Indigo-N model set was used to estimate N losses). Impact assessment was based on the European-sanctioned ILCD 2011 Midpoint+ v1.0.9, May 2016 method. Sensitivity was explored with scenarios and uncertainty data was propagated with Monte Carlo. Results and discussion The agricultural phase of cotton production in Mali differs from that of the largest producing countries, in that it is non-irrigated and non-mechanised and that non-Bt varieties are used. Instead, Malian cotton is rainfed―thus produced during the rainy season, from April/May to October/November―in rotation with maize or sorghum, manual work is prevalent up to the harvest, ploughs are towed by animals, and local varieties are grown (mainly STAM 59A and NTA 90-5). Malian yields were in the order of 400 kg lint/ha in the period 2001–2018, corresponding to ~ 1 t seed cotton/ha. The dominant production system, conventional agriculture, was sub-classified into three sub-types based on the phytosanitary strategy followed: calendar (81%), threshold control (15%) and targeted (4%). An average conventional system type was also constructed, as a production-weighted average of calendar, targeted and threshold. An existing marginal production of organic (0.5‰) cotton was also modelled. Organic cotton products (seed cotton, lint and cottonseed) feature lower impacts than conventional both per t and per ha (except for the toxicity, climate change and eutrophication impact categories), despite comparatively lower yields, due to lower input intensity. A single score–based contribution analysis confirms that, for conventional cotton, pesticide application is the main contributor to impacts, followed by mineral fertilisers. For organic cotton, the main drivers of impacts are natural pesticides and organic fertilisation. The overwhelming contribution of pesticides is largely due to the provision of organophosphorus compounds, specifically the insecticide profenofos. Moreover, the ginning phase contributed very little to the overall impacts (up to 3%). When data uncertainty is considered, the impacts per t of lint are always lower for organic cotton. Conclusions Impacts were generally larger for conventional than from organic cotton. The main hotspots are related to pesticide use, and therefore, efforts should focus on that factor, despite pesticide inputs being already relatively lower than elsewhere. Climate change indicators for Malian cotton products were compared with literature values, having similar orders of magnitude. Malian cotton production features lower yields than the main global producers do, which is mainly due to low soil fertility and, to a lesser extent, to its dependence on rainwater. A shift towards organic cotton would be desirable only if the yield gap can be overcome.

Mineral resources in life cycle impact assessment—part I: a critical review of existing methods Abstract Purpose The safeguard subject of the Area of Protection “natural Resources,” particularly regarding mineral resources, has long been debated. Consequently, a variety of life cycle impact assessment methods based on different concepts are available. The Life Cycle Initiative, hosted by the UN Environment, established an expert task force on “Mineral Resources” to review existing methods (this article) and provide guidance for application-dependent use of the methods and recommendations for further methodological development (Berger et al. in Int J Life Cycle Assess, 2020). Methods Starting in 2017, the task force developed a white paper, which served as its main input to a SETAC Pellston Workshop® in June 2018, in which a sub-group of the task force members developed recommendations for assessing impacts of mineral resource use in LCA. This article, based mainly on the white paper and pre-workshop discussions, presents a thorough review of 27 different life cycle impact assessment methods for mineral resource use in the “natural resources” area of protection. The methods are categorized according to their basic impact mechanisms, described and compared, and assessed against a comprehensive set of criteria. Results and discussion Four method categories have been identified and their underlying concepts are described based on existing literature: depletion methods, future efforts methods, thermodynamic accounting methods, and supply risk methods. While we consider depletion and future efforts methods more “traditional” life cycle impact assessment methods, thermodynamic accounting and supply risk methods are rather providing complementary information. Within each method category, differences between methods are discussed in detail, which allows for further sub-categorization and better understanding of what the methods actually assess. Conclusions We provide a thorough review of existing life cycle impact assessment methods addressing impacts of mineral resource use, covering a broad overview of basic impact mechanisms to a detailed discussion of method-specific modeling. This supports a better understanding of what the methods actually assess and highlights their strengths and limitations. Building on these insights, Berger et al. (Int J Life Cycle Assess, 2020) provide recommendations for application-dependent use of the methods, along with recommendations for further methodological development.

CO 2 methanation activated by magnetic heating: life cycle assessment and perspectives for successful renewable energy storage Abstract Purpose Technologies with low environmental impacts and promoting renewable energy sources are required to meet the energetic demand while facing the increase of gas emissions associated to the greenhouse effect and the depletion of fossil fuels. CO2 methanation activated by magnetic heating has recently been reported as a highly efficient and innovative power-to-gas technology in a perspective of successful renewable energy storage and carbon dioxide valorisation. In this work, the life cycle assessment (LCA) of this process is performed, in order to highlight the environmental potential of the technology, and its competitivity with in respect to conventional heating technologies. Methods The IMPACT 2002+ was used for this LCA. The process studied integrates methanation, water electrolysis and CO2 capture and separation. This “cradle-to-gate” LCA study does not consider the use of methane, which is the reaction product. The functional unit used is the energy content of the produced CH4. The LCA was carried out using the energy mix data for the years 2020 and 2050 as given by the French Agency for Environment and Energy management (ADEME). Consumption data were either collected from literature or obtained from the LPCNO measurements as discussed by Marbaix (2019). The environmental impact of the CO2 methanation activated by magnetic heating was compared with the environmental impact of a power-to-gas plant using conventional heating (Helmeth) and considering the environmental impact of the natural gas extraction. Results It is shown that the total flow rate of reactants, the source of CO2 and the energy mix play a major role on the environmental impact of sustainable CH4 production, whereas the lifetime of the considered catalyst has no significant influence. As a result of the possible improvements on the above-mentioned parameters, the whole process is expected to reduce by 75% in its environmental impact toward 2050. This illustrates the high environmental potential of the methanation activated by magnetic heating when coupled with industrial exhausts and renewable electricity production. Conclusions The technology is expected to be environmentally competitive compared with existing similar processes using external heating sources with the additional interest of being extremely dynamic in response, in line with the intermittency of renewable energy production.

Screening LCA of French organic amendments and fertilisers Abstract Introduction In France, agricultural recycling of organic waste is widespread, but LCIs of organic waste treatments are scarce. This work presents LCIs of the most relevant organic waste treatments yielding residual organic amendments and fertilisers, and organic residue–based industrial processes yielding commercial organic amendments and fertilisers, in France. It also presents the results from a screening LCA performed on these LCIs. Material and methods LCIs were built from mainly secondary data sources. Four functional units were retained: 1 t fresh mass of final product and 1 t of N, P, or K in fresh mass. Economic allocation was applied, following the French Environment and Energy Management Agency position. The International Reference Life Cycle Data System 2011 suit for impact assessment was retained, and all impacts were expressed as single scores to facilitate comparisons. Organic wastes considered were liquid and solid manures, agro-industrial residues, sewage sludge, green wastes and harvest residues, and biowaste. Treatment steps modelled were stocking, shredding, sieving, and mixing of substrates; anaerobic and aerobic treatments; thickening, dewatering, drying, and pelletising; various biological and physicochemical treatments of phase-separated liquid fractions; and the industrial production of organic amendments and fertilisers. Comparisons were performed among products classified as amendments or fertilisers. Results and discussion LCIs of typical treatment routes are presented, complemented with screening life cycle impact assessment results. Dried sludge and treated solid fractions of agricultural digestates present consistently higher impacts than any other amendment, mainly due to their associated energy use, relatively low N contents, and the use of maize silage as input. These items contribute in average > 50% of the aggregated impacts. Untreated manure and slurry feature the lowest relative impacts for all functional units. Compost-based commercial organic amendments have similar impacts to other composts per t of fresh mass, but slightly lower per t of nutrients or C, due to the inclusion of additional nutrient-rich inputs. Regarding fertilisers, the impact intensity of commercial organo-mineral fertilisers and treated liquid fractions of slurry and agricultural digestate is within similar orders of magnitude. Manure-based digestates feature relatively low impacts per all functional units. Only some digestates and untreated poultry manure feature impacts similar to those of N mineral fertilisers. Conclusions Energy provision and direct emissions are the main contributors to impacts in organic waste treatments. Modelling choices such as the allocation of impacts to agricultural by-products heavily influence specific impact categories, mainly climate change. Overall, these results represent a needed contribution to background data used in agricultural LCA.

Leveraging life cycle assessment and simplex lattice design in optimizing fossil fuel blends for sustainable desalination Abstract Purpose This study aims to minimize the environmental impacts of thermal seawater desalination by optimizing the required fossil fuel mixture. Life cycle assessment (LCA) is applied to simulate the environmental impacts for each fuel mixture. To prevent mixture designs inherited collinearly from correlating LCA results, fuel mixtures are first sampled prior to conducting LCA and then later optimized using a regression-based methodology to reduce entailed environmental impacts. Method Setting the functional unit to 1 m3 of desalinated water induces different reference flows of energy requirements depending on the fuels used. Increasing the level of any fuel type within the fuel mixture scenario will cause a decrease in the level of the other fuel type(s) included. An augmented simplex lattice mixture (ASLM) design is applied to indicate correct experimental conditions and to prevent the correlation due to collinearity inherited from the nature of mixture problems. Regression models are formulated to represent life cycle impact assessment (LCIA) results in a closed form suitable for response surface methodology (RSM) optimization. An overall composite sustainability index (CSI) is a single index calculated by aggregating and normalizing corresponding LCIA responses of different units, ranges, and scales using the geometric mean-based method. Results and discussion The results indicate that marine sediment ecotoxicity (MSE) is the category most adversely affected by multistage flash distillation (MSF). On a nationwide scale, the LCA optimized results scored a 17% reduction in associated environmental impacts, which corresponds to a 4.2% reduction in the county’s carbon footprint and a 62% reduction in MSE while incurring a minor retrofitting cost to desalination facilities. Conclusions High MSE results due to excessive fossil fuel consumption/burning in MSF should gain as much attention as paid toward global warming potential. High MSE entails the risk of having heavy metals entering the food chain. On the other hand, the geometric mean approach is found to be an effective model to aggregate the LCIA results into a single index while avoiding the subjectivity of the value judgment used in LCIA weighting. This approach serves as a unit-free rescaling method that is robust to outliers or large values examined across different LCIA impacts.

Correction to: Abiotic resource depletion potentials (ADPs) for elements revisited—updating ultimate reserve estimates and introducing time series for production data The original version of this article unfortunately contained a mistake which was missed during typesetting. The caption to Fig. 5 was incorrect. The correct version is given below.

Different paths in social life cycle impact assessment (S-LCIA)—a classification of type II impact pathway approaches Abstract Purpose In social life cycle assessment (S-LCA), we can distinguish two main types of impact assessment (LCIA): type I can be seen as a reporting approach with the use of performance reference points and type II aims at including cause-effect chains or impact pathways in the analysis. Given the heterogeneity of those type II approaches, this review provides a classification of existing type II approaches. Methods We reviewed a total of 28 articles against the background of their main purpose, the method used, the issues covered and the origin of data (observation/characterization/ measurement). We checked the articles against (i) the reflection of an impact pathway, (ii) the availability of so-called inventory and impact indicators, and (iii) the presence of characterization models or factors translating correlations or causality. Results and discussion The analysis reveals three main paths to include impact pathways in S-LCA, which differ in authors’ intentions: (1) some studies identify and propose variables composing impact pathways, or frameworks gathering several pathways; (2) other studies investigate or test known pathways empirically, and until now seek mainly to link income data with health impacts at a macro scale, and (3) a last batch applies known and already quantified characterization models or factors from other research works in case studies. Until now, these case studies focus mainly on income-related social effects or on health impacts. Further, each path is further characterized and classified under nine approaches. Our findings highlight not only the heterogeneous nature of approaches, but also their common denominator which is to not consider phenomena or impacts in isolation but to consider them in relation to their sources or further impacts. It should be noted that type II studies are not only limited to quantitative approaches and variables, but can also use more qualitative variables and methods. Conclusions The presented classification may be used as a guidance tool for authors to make their methodological choices. Also, our findings indicate the opportunity of extending future type II S-LCA research to variables tackled in type I studies (e.g., safe and fair employment and working conditions), beyond pathways including incomes and health impacts. This can be done by using theories from social sciences for the identification of impact pathways. Those could then further be investigated through statistical approaches or in the framework of S-LCA case studies, with specific data and potentially more qualitative methods to analyze causality or social mechanisms.

Integrating diversity of smallholder coffee cropping systems in environmental analysis Abstract Purpose Coffee represents an important trade asset internationally. Around 70% of global coffee production is provided by 25 million smallholders farmers. In recent decades, coffee systems have been transformed into more intensified systems of coffee monoculture. The general objectives of this paper are to provide a better picture of the traditional coffee cropping systems and postharvest processes on-farm and to assess the environmental impacts, integrating the diversity of smallholder cropping systems. Methods A Life Cycle Assessment from cradle to farm gate was performed for three cropping systems representative of Colombian coffee cultivation according to the associated crops and shadow trees: coffee alone (CA), coffee with transition shade (CTS), and coffee with permanent shade (CPS). The system studied includes inputs, agricultural production and postharvest operations using the wet method. The final product of farms is parchment bean coffee at farm gate. The technology used is representative of the average practices of smallholder coffee growers in the region. To address multiple functions of coffee, three functional units (FU) were selected: area by time (ha*year−1 unit area), productivity (ton of parchment coffee) and farmers income (1000 USD$). Seven midpoint categories were selected: climate change, acidification, terrestrial eutrophication, freshwater eutrophication, marine eutrophication, freshwater ecotoxicity, and water resource depletion. Results and discussion We present the life cycle inventory and impact assessment results from three types of cropping systems CA, CTS and CPS. For all FU, the CPS system has the lowest potential impact, excepted for marine eutrophication. CPS also has the highest coffee yields, however it has also the highest costs. Even if cropping system diversification is only one of multiple factors that influence environmental performance, agroforestry seems to be a promising path to reduce and mitigate environmental impacts by decreasing off-fam contributions (input fabrication). Conclusions Results show the possibility that diversified cropping systems have an influence when assessing potential environmental impacts of coffee at farm gate and differences found might be influenced by shading in traditional coffee systems. Future work is needed to consider the real potential of CTS cropping system including land use and carbon dynamics. Assessments including social indicators and the rest of the value chain in particular coffee industrial transformation and utilization are also needed since the consumption stages are also a key driver to reduce the environmental footprint of coffee.

From the allocation debate to a substitution paradox in waste bioenergy life cycle assessment studies

A tool to operationalize dynamic LCA, including time differentiation on the complete background database Abstract Purpose The objective is to demonstrate an operational tool for dynamic LCA, based on the model by Tiruta-Barna et al. (J Clean Prod 116:198-206, Tiruta-Barna et al. 2016). The main innovation lies in the combination of full temporalization of the background inventory and a graph search algorithm leading to full dynamic LCI, further coupled to dynamic LCIA. The following objectives were addressed: (1) development of a database with temporal parameters for all processes of ecoinvent 3.2, (2) implementation of the model and the database in integrated software, and (3) demonstration on a case study comparing a conventional internal combustion engine car to an electric one. Methods Calculation of dynamic LCA (including temporalization of background and foreground system) implies (i) a dynamic LCI model, (ii) a temporal database including temporal characterization of ecoinvent 3.2, (iii) a graph search algorithm, and (iv) dynamic LCIA models, in this specific case for climate change. The dynamic LCI model relies on a supply chain modeling perspective, instead of an accounting one. Unit processes are operations showing a specific functioning over time. Mass and energy exchanges depend on specific supply models. Production and supply are described by temporal parameters and functions. The graph search algorithm implements the dynamic LCI model, using the temporal database, to derive the life cycle environmental interventions scaled to the functional unit and distributed over time. The interventions are further combined with the dynamic LCIA models to obtain the temporally differentiated LCA results. Results and discussion A web-based tool for dynamic LCA calculations (DyPLCA) implementing the dynamic LCI model and temporal database was developed. The tool is operational and available for testing (http://dyplca.univ-lehavre.fr/). The case study showed that temporal characterization of background LCI can change significantly the LCA results. It is fair to say that temporally differentiated LCI in the background offers little interest for activities with high downstream emissions. It can provide insightful results when applied to life cycle systems where significant environmental interventions occur upstream. Those systems concern, for example, renewable electricity generation, for which most emissions are embodied in an infrastructure upstream. It is also observed that a higher degree of infrastructure contribution leads to higher spreading of impacts over time. Finally, a potential impact of the time window choice and discounting was observed in the case study, for comparison and decision-making. Time differentiation as a whole may thus influence the conclusions of a study. Conclusions The feasibility of dynamic LCA, including full temporalization of background system, was demonstrated through the development of a web-based tool and temporal database. It was showed that considering temporal differentiation across the complete life cycle, especially in the background system, can significantly change the LCA results. This is particularly relevant for product systems showing significant environmental interventions and material exchanges over long time periods upstream to the functional unit. A number of inherent limitations were discussed and shall be considered as opportunities for further research. This requires a collegial effort, involving industrial experts from different sectors.