Life cycle assessment of agro-industrial residues valorization processes to obtain phenolic-rich extracts

PurposeIdentification of environmentally preferable alternatives in a comparative life cycle assessment (LCA) can be challenging in the presence of multiple incommensurate indicators. To make the problem more manageable, some LCA practitioners apply external normalization to find those indicators that contribute the most to their respective environmental impact categories. However, in some cases, these results can be entirely driven by the normalization reference, rather than the comparative performance of the alternatives. This study evaluates the influence of normalization methods on interpretation of comparative LCA to facilitate the use of LCA in decision-driven applications and inform LCA practitioners of latent systematic biases. An alternative method based on significance of mutual differences is proposed instead.MethodsThis paper performs a systematic evaluation of external normalization and describes an alternative called the overlap area approach for the purpose of identifying relevant issues in a comparative LCA. The overlap area approach utilizes the probability distributions of characterized results to assess significant differences. This study evaluates the effects in three LCIA methods, through application of four comparative studies. For each application, we call attention to the category indicators highlighted by each interpretation approach.Results and discussionExternal normalization in the three LCIA methods suffers from a systematic bias that emphasizes the same impact categories regardless of the application. Consequently, comparative LCA studies that employ external normalization to guide a selection may result in recommendations dominated entirely by the normalization reference and insensitive to data uncertainty. Conversely, evaluation of mutual differences via the overlap area calls attention to the impact categories with the most significant differences between alternatives. The overlap area approach does not show a systematic bias across LCA applications because it does not depend on external references and it is sensitive to changes in uncertainty. Thus, decisions based on the overlap area approach will draw attention to tradeoffs between alternatives, highlight the role of stakeholder weights, and generate assessments that are responsive to uncertainty.ConclusionsThe solution to the issues of external normalization in comparative LCAs proposed in this study call for an entirely different algorithm capable of evaluating mutual differences and integrating uncertainty in the results.

PurposeTwo life cycle assessment (LCA) studies comparing a new low-particulate-matter-emission disc brake and a reference disc brake were presented. The purpose was to identify the difference in potential environmental impacts due to a material change in the new disc brake parts. Additionally, the validity was investigated for the simplification method of omitting identical parts in comparative LCA. This was done by comparing the results between the simplified and the full LCA model.MethodsThe two disc brakes, new disc brake and reference disc brake, were assessed according to the LCA ISO standards. The ReCiPe 2016 Midpoint (hierarchist) impact assessment method was chosen. Simplifying a comparative LCA is possible, all identical parts can be omitted, and only the ones that differ need to be assessed. In this paper, this simplification was called comparative LCA with an omission of identical parts.Results and discussionThe comparative impacts were analysed over seventeen impact categories. The new disc brake alternative used more resources during the manufacture of one disc compared to the reference disc brake alternative. The shorter life length of the reference disc demanded a higher number of spare part discs to fulfil the same functional unit, but this impact was reduced due to material recycling. The new disc brake impacts were connected primarily to the coating and secondly to the pad manufacture and materials. The validity of the simplification method was investigated by comparing the results of the two LCA models. The impact differences were identical independent of the LCA model, and the same significant impact categories could be identified. Hence, the purpose of the study could be fulfilled, and the simplification was valid.ConclusionsBoth LCA models, simplified and full, revealed that the new disc brake had limited environmental advantages. The omission of identical parts made it more challenging to determine if an impact was significant or insignificant. The simplification seemed to be reasonable.

This study compares a life cycle assessment (LCA) of pork production in the Western Cape with pork production in Flanders. The objectives of this study were to map and quantify the environmental impacts of producing pork in the Western Cape and exporting it to Antwerp in Flanders with the environmental impacts of producing pork in Flanders and delivering it to the same location. The impact categories included are (i) global warming potential (GWP), (ii) eutrophication potential, (iii) acidification potential, and (iv) energy use. By pointing out weak points in the different environmental impact categories, suggestions are made to lower the environmental burdens of pork production. Four main activities of the pork production chain were covered by the LCA, namely: (i) the feed provision activity, which includes the production of raw materials and feed, (ii) the pig farming activity, (iii) the slaughter house activity and (iv) the slurry (treatment) activity. An additional (v) pork shipping activity was added in the case of the Western Cape pork chain. A cradle-to-gate life cycle assessment was carried out, with a functional unit (FU) of one kg of Western Cape or Flemish pork (carcass weight) delivered to the distribution centre in Antwerp. Flemish GWP, eutrophication potential, acidification potential and energy use are 56%, 65%, 62% and 59% respectively of the Western Cape equivalents. The exporting of pork accounts for less than 8% of environmental impacts in all impact categories. Potential exists in the Western Cape to compete on an environmental par when impacts are measured in terms of a per-area unit. It is therefore recommended that for future comparative South African-European LCA studies of pork or other intensive livestock or poultry production chains, an FU of one kg meat as well as an area unit be used when measuring total eutrophication and acidification impacts.

In the context of South Africa’s water scarcity, desalination has emerged as a possible solution for coastal areas. However, the quality of the intake water for desalination is often problematic, prompting the need for pre-treatment. The aim of this study was to conduct a comparative environmental life cycle assessment (LCA) on 4 seawater filtration systems intended for the pre-treatment of a reverse osmosis desalination project. These systems were implemented in a pilot trial and are based on modern water treatment technologies, namely, granular filtration (pressure driven and gravity driven), dissolved air flotation (DAF), and ultrafiltration (UF). For all 4 systems, data were collected for both the construction and operation phases, and LCAs were performed, resulting in environmental scores that allow for comparison based on the pre-treatment of 1 kL of seawater of the same quality. The SimaPro LCA tool and the ReCiPe midpoint method were used and environmental scores were calculated for 18 impact categories, including climate change, acidification, toxicity, eutrophication, resource depletion, etc. This methodology also allowed the identification of the highest environmental burdens/scores within each system. The most significant finding is that local electricity consumption is responsible for the greatest proportion of environmental impacts. Thus, the systems consuming more energy for operating equipment such as blowers, pumps, and mixers were found to have the highest environmental burdens. Hence, the DAF system has the highest environmental scores for most impacts, followed by the single-phase gravity filtration system, then the two-phase partial pressure filtration system and finally the UF system. Therefore, focus should shift towards energy optimisation of process units, especially the rotary ones, as well as energy mitigation and recovery strategies. The use of renewable energy for pre-treatment should also be considered locally.

Research into methods for collecting product economic inventory data for inclusion into a comparative product life cycle assessment (LCA) are limited, while the rules governing such LCA based comparative product studies are strict in their requirements. As comparative assertions are to be made, it would seem appropriate that such studies be approached in a robust manner. Reference is made to the use of product stakeholders as the source of product economic inventory data for input into LCA and yet research reveals numerous examples of studies in which these stakeholders were evidently absent. Research shows that it is highly likely that in studies of comparative products, the stakeholders of some or all of the products may be absent, or unable or unwilling to cooperate in a comparative product study. Alternatives to stakeholder cooperation in product data collection are limited, leading to the question as to how a comparative product LCA, in support of a comparative product environmental claim statement, could be addressed from a product economic inventory data collection perspective. The criminal justice system has been shown to use a variety of analytical instruments to convict individuals based on “beyond reasonable doubt” evidence. To what extent could this forensic approach be used to derive product economic inventory data for input to a comparative LCA study and how would this data differ from the alternative collection methods? To what extent can such a forensic type method be used to establish intended product like-functionality for comparison purposes and to identify the individual product materials composition, associated conversion processes and country-of-origin, all of this information being of value as product economic inventory data for LCA input? Research shows a significant difference in comparative product ranking when a forensic approach is applied to an existing study that was reliant on assumptions in the absence of stakeholders. Many of these existing studies also show that their authors were potentially lacking in product technologically relevant knowledge, this being a reported critique of LCA. Interpretation of the results of forensic studies would require the study author to have such knowledge in order to interpret the results. The use of technologically relevant product knowledge and a forensic approach to product economic inventory data collection could help in rendering comparative product environmental claims more robust.

Comparative life-cycle assessments (LCAs) today lack robust methods of interpretation that help decision makers understand and identify tradeoffs in the selection process. Truncating the analysis at characterization is misleading and existing practices for normalization and weighting may unwittingly oversimplify important aspects of a comparison. This paper introduces a novel approach based on a multi-criteria decision analytic method known as stochastic multi-attribute analysis for life-cycle impact assessment (SMAA-LCIA) that uses internal normalization by means of outranking and exploration of feasible weight spaces. To contrast different valuation methods, this study performs a comparative LCA of liquid and powder laundry detergents using three approaches to normalization and weighting: (1) characterization with internal normalization and equal weighting, (2) typical valuation consisting of external normalization and weights, and (3) SMAA-LCIA using outranking normalization and stochastic weighting. Characterized results are often represented by LCA software with respect to their relative impacts normalized to 100 %. Typical valuation approaches rely on normalization references, single value weights, and utilizes discrete numbers throughout the calculation process to generate single scores. Alternatively, SMAA-LCIA is capable of exploring high uncertainty in the input parameters, normalizes internally by pair-wise comparisons (outranking) and allows for the stochastic exploration of weights. SMAA-LCIA yields probabilistic, rather than discrete comparisons that reflect uncertainty in the relative performance of alternatives. All methods favored liquid over powder detergent. However, each method results in different conclusions regarding the environmental tradeoffs. Graphical outputs at characterization of comparative assessments portray results in a way that is insensitive to magnitude and thus can be easily misinterpreted. Typical valuation generates results that are oversimplified and unintentionally biased towards a few impact categories due to the use of normalization references. Alternatively, SMAA-LCIA avoids the bias introduced by external normalization references, includes uncertainty in the performance of alternatives and weights, and focuses the analysis on identifying the mutual differences most important to the eventual rank ordering. SMAA-LCIA is particularly appropriate for comparative LCAs because it evaluates mutual differences and weights stochastically. This allows for tradeoff identification and the ability to sample multiple perspectives simultaneously. SMAA-LCIA is a robust tool that can improve understanding of comparative LCA by decision or policy makers.

A novel ZSM-5@SiC structured catalytic packing (ZSM-5@SiC SCP) was recently proposed to combine catalysis and separation functionality in one unit for reactive distillation (RD) towards the synthesis of green solvent ethyl lactate (EL). This work conducts life cycle assessment (LCA) and economic analysis for the RD process to identify relevant hot spots and suggest further development. Based on the cradle-to-gate LCA, the major environmental hot spots of the proposed RD process based on SCP are identified as in the section of raw materials extraction and RD. Compared to the petrochemical counterparts, bio-derived lactic acid and ethanol show the advantage to reduce carbon emission and resource depletion, but having significant impacts on aggravate stratospheric ozone depletion and land use especially. LCA results also show that preparation ZSM-5@SiC SCP creates environmental impacts due to the usage of electricity and relevant raw materials. Comparative LCA and economic analysis were conducted for the RD processes using ZSM-5@SiC SCP and seepage catalytic packing internal (SCPI), respectively, and a conventional process with separated reaction and separation unit operations. The findings suggest that compared to the conventional process RD processes can reduce greenhouse gas emissions and total annual cost (TAC) due to process intensification. The process employing ZSM-5@SiC SCP incurs a higher TAC than that based on SCPI (with resin catalysts), which is due to its comparatively low catalytic activity, requiring more ZSM-5@SiC SCP and higher column to achieve the production target.

Purpose African countries are increasingly exploring anaerobic digestion (AD) for biogas production to improve waste management and reduce environmental impact. However, AD adoption, utilization, and long-term environmental implications remain largely unassessed in the region. This study presents the first comparative life cycle assessment (LCA) of its kind in West Africa, evaluating the environmental footprint of disposing 15 tons of agricultural fruit waste via AD versus open-dump landfill. Additionally, we conducted the first prospective LCA (pLCA) to provide future-oriented insights into the long-term environmental impacts of AD in the region. Methods Following ISO 14040 and 14,044 standards, we quantified five key impact categories, global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), smog potential (SP), and freshwater ecotoxicity (EF), using the Ecoinvent database 3.9.1 cutoff, TRACI 2.1 assessment method, and OpenLCA software. For the pLCA, we use premise, based on different SSPs generated by IMAGE, an integrated assessment model (IAM). Results and discussion The result reveals that AD significantly outperforms open-dump landfilling, achieving a net-negative GWP of –100.25 kg CO₂-eq due to avoided emissions from co-product benefits from biogas and digestate, compared to 3,794.8 kg CO₂-eq from landfill disposal. Across all impact categories, open-dump landfills impose over 98% higher environmental burdens than AD. The pLCA under future electricity grid scenarios reveals divergent trajectories. Excluding co-product benefits, AD’s GWP declines by up to 60% by 2050 under the SSP1 sustainability pathway, driven by energy grid decarbonization. AP and SP also decline steadily. Under SSP2, however, GWP increases in 2030 and 2050, reflecting slower energy transitions, with only a temporary decline in 2040. While AP and SP still trend downward, EP, EF, and ODP rise under both scenarios, more sharply under SSP2, due to continued fossil fuel use and limited policy progress. Comparative scenario analysis of different waste treatment options for the fruit waste shows that landfills generate the highest GWP, EP, and EF; composting contributes most to AP and ODP; incineration leads in SP; and AD performs best in EF and EP. These results highlight the critical need to evaluate multiple environmental indicators when selecting sustainable waste management strategies. Conclusions We conducted a case study based on primary data that offers regional- and continent-specific insights into the potential of anaerobic digestion as a sustainable waste management strategy. The results provide practical guidance for policymakers seeking to promote AD for both waste treatment and renewable energy production.

The value of reusable feminine hygiene products evaluated by comparative environmental life cycle assessment

Whereas life cycle assessment (LCA) is more and more used for assessing the environmental load of waste management systems and of biomass production and valorization systems, various scientific issues are still to be dealt with. The purpose of this paper is to enlighten these scientific issues and to describe the current attempt to overcome them. The method used has been to go through the steps of the LCA standardized framework (ISO 14040) and to outline at each step the points that could be improved and still deserve research efforts. The various identified issues are: in step 1 (goal and scope), the choice of attributional/consequential modelling, the difficult choice of the functional unit due to the highly multi-functional nature of such systems, the allocation choices and the need for spatial differentiation; in step 2 (inventory), the thorny issue of modelling such complex systems and properly estimating field emissions; in step 3 (impact assessment), the lack of appropriate impacts (such as odours) in current LCA impact categories; in step 4 (interpretation and use), research efforts are needed to understand and facilitate the way actors take over and use LCA multi-criteria results. A transversal issue, i.e. uncertainty characterization and reduction, is also analyzed. These various scientific bottlenecks are currently under study; some are handled by this “Waste and Biomass Valorization” special topic, which includes a selection of papers presented in 2011 at the Ecotech&Tools conference (Montpellier, France).

PurposeIntegrated multi-trophic aquaculture (IMTA), growing different species in the same space, is a technology that may help manage the environmental impacts of coastal aquaculture. Nutrient discharges to seawater from monoculture aquaculture are conceptually minimized in IMTA, while expanding the farm economic base. In this study, we investigate the environmental trade-offs for a small-to-medium enterprise (SME) considering a shift from monoculture towards IMTA production of marine fish.MethodsA comparative life cycle assessment (LCA), including uncertainty analysis, was implemented for an aquaculture SME in Italy. Quantification and simultaneous propagation of uncertainty of inventory data and uncertainty due to the choice of allocation method were combined with dependent sampling to account for relative uncertainties and statistical testing and interpretation to understand the uncertainty analysis results. Monte Carlo simulations were used as a propagation method. The environmental impacts per kilo of fish produced in monoculture and in IMTA were compared. Twelve impact categories were considered. The comparison is first made excluding uncertainty (deterministic LCA) and then accounting for uncertainties.Results and discussionDeterministic LCA results evidence marginal differences between the impacts of IMTA and monoculture fish production. IMTA performs better on all impacts studied. However, statistical testing and interpretation of the uncertainty analysis results showed that only mean impacts for climate change are significantly different for both productive systems, favoring IMTA. For the case study, technical variables such as scales of production of the species from different trophic levels, their integration (space and time), and the choice of species determine the trade-offs. Also, LCA methodological choices such as that for an allocation method and the treatment of relative uncertainties were determinant in the comparison of environmental trade-offs.ConclusionsThe case study showed that environmental trade-offs between monoculture and IMTA fish production depend on technical variables and methodological choices. The combination of statistical methods to quantify, propagate, and interpret uncertainty was successfully tested. This approach supports more robust environmental trade-off assessments between alternatives in LCAs with uncertainty analysis by adding information on the significance of results. It was difficult to establish whether IMTA does bring benefits given the scales of production in the case study. We recommend that the methodology defined here is applied to fully industrialized IMTA systems or bay-scale environments, to provide more robust conclusions about the environmental benefits of this aquaculture type in Europe.

Complementary to VITO’s demonstration project on the use of biodiesel as engine fuel (including on the road emission measurements), a comparative life cycle assessment (LCA) has been performed for rapeseed methyl ester (RME) and fossil diesel fuel. The LCA study covers: (1) a description of the LCA methodology used; (2) an inventory of the consumption of energy and materials and the discharges to the environment for both alternative fuels; and (3) a comparative impact assessment. The LCA inventoried all environmental impacts (resource consumption, emissions, waste) from cradle to grave. After the classification of these burdens into environmental impact categories, the environmental profiles of the two automotive fuels have been compared. Moreover, sensitivity analyses on the most important parameters have been carried out (e.g. type of fertiliser, data source, allocation method). The results of this comparative LCA can be used in the final decision-making process including the results of a social and economical assessment.

In life cycle assessment (LCA), performing Monte Carlo simulation (MCS) using fully dependent sampling typically involves repeated inversion of a technology matrix for a sufficiently large number of times. As the dimension of technology matrices for life cycle inventory (LCI) databases grows, MCS using fully dependent sampling is becoming a computational challenge. In our previous work, we pre-calculated the distribution functions of the entire LCI flows in the ecoinvent ver. 3.1 database to help reduce the computation time of running fully dependent sampling by individual LCA practitioners. However, it remains as a question whether the additional errors due to the use of pre-calculated uncertainty values are large enough to alter the conclusion of a comparative study, and, if so, what is the odds of such cases. In this study, we empirically tested the probability of altering the conclusion of a comparative LCA due to the use of pre-calculated uncertainty values. We sampled 10,000 random pairs of elementary flows of ecoinvent LCIs (ai and bi) and ran MCSs (1) using pre-calculated uncertainty values and (2) using fully dependent sampling. We analyzed the distribution of the differences between ai and bi (i.e., ai−bi) of each run, and quantified the probability of reversing (e.g., ai > bi became ai < bi) or moderating the conclusion (e.g., ai > bi became ai ≈ bi). In order to better replicate the situation under a comparative LCA setting, we also sampled 10,000 random pairs of elementary flows from the processes that produce electricity, and repeated the same procedure. The results show that no LCIs derived using pre-calculated uncertainty values constitute large enough differences from those using fully dependent sampling to reverse the conclusion. However, in 5.3% of the cases, the conclusion from one approach is moderated under the other approach or vice versa. When elementary flow pairs are sampled only from the electricity-producing processes, the probability of moderating the conclusions increases to 10.5%, while that of reversing the conclusions remains nil. As the number of unit processes in LCI databases increases, running full MCSs in a PC-environment will continue to be a challenge, which may lead some LCA practitioners to avoid uncertainty analysis altogether. Our results indicate that pre-calculated distributions for LCIs can be used as a proxy for comparative LCA studies in the absence of adequate computational resources for full MCS. Depending on the goal and scope of the study, LCA practitioners should consider using pre-calculated distributions if the benefits of doing so outweighs the associated risks of altering the conclusion.

Infilled cementitious composites (ICC) – A comparative life cycle assessment with UHPC

Efficient use and consumption of natural resources is an important strategy in sustainable development. This chapter discusses available methods and indicators to assess “resource efficiency” beyond the assessment of the quantities of materials used and toward available indicators in life cycle assessment (LCA). According to the classical definition in LCA, natural resources encompass input-oriented environmental interventions (e.g., extraction of abiotic resources, such as oil, ore deposits, fossil, and fresh surface water, as well as biotic resources such as fish and trees). LCA and existing life cycle impact assessment (LCIA) methods are seen as a good basis for measuring resource efficiency. Despite several models to assess resource use and depletion within LCA, important challenges remain. Available models do not fully evaluate resource use and availability in the context of their functional relevance for human purposes. For the efficient use of resources, all dimensions of sustainability need to be addressed. Environmental, economic, and social implications of material use and availability have to also be considered. Assessment of resource utilization and efficiency associated with product systems needs to shift toward life cycle sustainability assessment (LCSA).