The motivation behind the papers “Availability of life-cycle assessment studies in (different countries)”

A Swedish comment on ‘review: the availability of life-cycle studies in Sweden’

Comparison of different tomato puree production phases from an environmental point of view Abstract Purpose Agro-food systems are involved with considerable environmental impacts. Tomato as an important vegetable crop is processed into some products such as puree, ketchup, and paste. This study aimed to investigate the environmental impacts of tomato puree production considering its entire life cycle, including tomato cultivation, processing, packaging, and transportation, to identify the hotspots and potential improvements for each stage to reduce environmental burdens. Methods The primary data were collected from the processing plant located in Urmia County, Iran, and 28 tomato growers which provide tomato to processing plant using a face-to-face questionnaire. The source for secondary data was the Ecoinvent, LCA Food DK, and IDMAT 2001 databases. The functional unit was considered as 500 g tomato puree packaged in a steel can with a plastic cap. The environmental impacts were investigated using the CML 2 baseline method. Results and discussions Results showed that packaging is the most important contributor to all impact categories except acidification (AC) and eutrophication (EP) in which tomato cultivation was indicated as the hotspot. In the cultivation phase, electricity and N-based fertilizers were indicated as the major contributors to most impact categories. Diesel fuel and natural gas were the hotspots in the processing phase. Conclusions Based on the results, packaging and cultivation phases have enough potential to reduce environmental impacts during puree production. It can be realized through applying materials that are involved with negligible environmental burdens during their production for packaging and improving irrigation systems for reducing electricity as a major hotspot in cultivation phases. Also, soil analysis would be helpful to determine the amounts and types of required fertilizers.

Global environmental impacts: data sources and methodological choices for calculating normalization factors for LCA Abstract Purpose Characterizing environmental impacts at the global scale is crucial to define references against which compare the environmental profile of products and systems. Within this study, global emissions and resource uses have been collected and characterized for the following impact categories: climate change, ozone depletion, human toxicity (cancer and non-cancer), ecotoxicity, particulate matter, ionizing radiation, photochemical ozone formation, acidification, eutrophication (terrestrial, marine, and freshwater), land use, water use, and resource use. The results can be used as normalization factors (NFs) in the context of the life cycle assessment (LCA). Material and methods The global NFs are built on an extensive collection of data on emissions and resources extracted at a global scale in 2010, gathering different sources and comparing them. A hierarchical approach was applied to the selection of data sources. Extrapolations, mainly temporal data-gap filling, were applied for complementing the inventories for missing data. In order to calculate NFs, the inventory was characterized by using the International Reference Life Cycle Data System (ILCD) midpoint indicators and the EU Environmental Footprint (EF) set, which includes recently released models. Results and discussion The resulting global NFs (ILCD and EF) were reported and discussed for each impact category. Coverage completeness and robustness of both the underpinning inventories and impact assessment models were used to define the level of uncertainty in the calculations. Based on the contribution analysis of the main elementary flows, it resulted that only few elementary flows drive the overall impact for most of the impact categories. Moreover, the ratio between the NFs at EU27 in 2010 and global level showed that Europe generally covers less than 10% of the global impact. Conclusion and outlook The quantification of the current levels of environmental pressures entails critical aspects, as it consists of accounting of emissions and resources, relying on data often incomplete or based on modeling. Despite the attempts made for increasing NFs coverage and robustness, the calculation in the present study highlights the need of further efforts aiming at overcoming the uncertainties and the limitations identified both at the inventory (i.e., difficulty in retrieving complete and recent data) and characterization levels (e.g., consistency between inventory and impact assessment regarding spatialization, system boundaries). Most importantly, any assessment based on the use of NFs should be carefully discussed and interpreted in light of the limitations discussed in this paper.

Contribution-based prioritization of LCI database improvements: the most important unit processes in ecoinvent Abstract Purpose Improving the quality and quantity of unit process datasets in Life Cycle Inventory (LCI) databases affects every LCA they are used in. However, improvements in data quality and quantity are so far rather directed by the external supply of data and situation-driven requirements instead of systematic choices guided by structural dependencies in the data. Overall, the impact of current data updates on the quality of the LCI database remains unclear and maintenance efforts might be ineffective. This article analyzes how a contribution-based prioritization approach can direct LCI update efforts to datasets of key importance. Methods A contribution-based prioritization method has been applied to version 3 of the ecoinvent database. We identified the relevance of unit processes on the basis of their relative contributions throughout each product system with respect to a broad range of Life Cycle Impact Assessment (LCIA) indicators. A novel ranking algorithm enabled the ranking of unit processes according to their impact on the LCIA results. Finally, we identified the most relevant unit processes for different sectors and geographies. Results and discussion The study shows that a relatively large proportion of the overall database quality is dependent on a small set of key processes. Processes related to electricity generation, waste treatment activities, and energy carrier provision (petroleum and hard coal) consistently cause large environmental impacts on all product systems. Overall, 300 datasets are causing 60% of the environmental impacts across all LCIA indicators, while only 3 datasets are causing 11% of all climate change impacts. In addition, our analysis highlights the presence and importance of central hubs, i.e., sensitive intersections in the database network, whose modification can affect a large proportion of database quality. Conclusions Our study suggests that contribution-based prioritization offers important insights into the systematic and effective improvement of LCI databases. The presented list of key processes in ecoinvent version 3.1 adds a new perspective to database improvements as it allows the allocation of available resources according to the structural dependencies in the data.

Life cycle assessment of the production of gasoline and diesel from forest residues using integrated hydropyrolysis and hydroconversion Abstract Purpose Renewable gasoline and diesel can be produced through integrated hydropyrolysis and hydroconversion (IH2) using renewable feedstocks such as woody biomass from logging residues. This study assesses the potential environmental impacts of IH2 process fuels manufactured in Ontonagon, Michigan, to determine their environmental impacts and if these manufactured fuels will meet Renewable Fuel Standards (RFS) requirements. The energy return on investment (EROI) is also calculated for comparison to other renewable fuels. Methods A cradle-to-grave life cycle assessment was conducted using regional forestry, timber harvest, and transportation data from the region. Regional geographic data was used to determine service areas that may provide woody biomass. The service areas were then developed into inventory data based upon the type and distribution of potential woody biomass feedstocks. Survey data from loggers in the region were used to ensure that harvest types were allocated in accordance with regional activity. Remaining inventory items were derived from existing data in the literature or existing life cycle inventory databases. This study uses a functional unit of one megajoule of gasoline or diesel produced using the IH2 process and assessed several environmental indicators as well as EROI. Results and discussion Fuels produced generate approximately 88% less greenhouse gas (GHG) emissions compared to petroleum fuels given RFS assumptions. Manufacturing and transportation of feedstocks accounts for 92.19% of energy used in production giving a calculated EROI of 4.19 and 4.31 per kilogram of diesel and gasoline, respectively. Pessimistic estimates of soil organic carbon (SOC) loss result in GHG emissions that are approximately 83% lower. If a 1:0.5 displacement ratio of IH2 fuels is considered, the GHG emissions are about 76% lower without SOC loss and 66% lower with. This study demonstrates that while environmental impacts and EROI are sensitive to site selection and SOC estimates, there is a sufficient GHG emission reduction such that IH2 fuels are capable of meeting regulatory requirements. Conclusions Fuels produced at the facility result in a reduction in GHG emissions, but better site selection may result in less fuel being used in transportation. Reducing the quantity of electricity needed in n-th–generation facilities would also reduce environmental impacts while improving the EROI. The energy mix used to supply IH2 facilities should also be considered during the planning process. Finally, future research may be needed to ensure feedstocks recovered from logging operations match expectations.

False confidence: are we ignoring significant sources of uncertainty? Abstract Purpose With the increasing use of stochastic simulation, also known as Monte Carlo simulation, to perform uncertainty analysis in life cycle assessment, it is important to consider whether the predominant methods and practices in the field accurately represent uncertainty in the results. Methods Two quantitative aspects of uncertainty characterization in ecoinvent, namely the derivation of additional uncertainty from the pedigree matrix and the use of static market activities to model consumption mixes, are reviewed with respect to their effects on stochastic simulation results. A discrete choice simulation is applied to model uncertainty in a consumption mix, and the results are compared to the conventional approach. Results and discussion Both practices studied are found to systematically underestimate uncertainty as measured by the size of the confidence interval. In markets with multiple suppliers, the uncertainty in the market average is dramatically narrower than the variability in the suppliers themselves. Conclusions The current state of practice leads to false inferences and may be misleading to the public. Life cycle assessment researchers should distinguish between synthetic variability models, such as those used in ecoinvent, and authentic estimates of uncertainty in foreground models. The community must continue to develop and critically evaluate methods for uncertainty characterization.

Creating a “family tree” on fertilizer inventory use in life cycle assessment of oil palm: visualization of earlier studies and its implications Abstract Purpose This review develops and applies a visualization method for understanding how chemical fertilizer inventory data, including greenhouse gas (GHG) emission factors and fossil fuel energy requirements, have been used in previous life cycle assessment (LCA) studies of oil palm and discusses how inconsistencies detected in previous studies can be decreased. Methods As a visualization method for previous publications, a “family tree” was constructed using a directed graph (digraph) representation. Each node in the graph indicates an article, and an arrow from the source to a destination illustrates that the former article was cited in the latter article as a source of the background inventories. Bibliographical data extracted from the Web of Science were used for constructing the genealogy of fertilizer inventory use. Results and discussion Several groups (“families”) were identified through creation of the family tree. The most noticeable group was formed around the LCA database ecoinvent, which has the maximum number of out-flows (arrows from the node), suggesting a considerable influence of ecoinvent in the LCA of oil palm. In addition, temporal and spatial inconsistencies (outdated technological assumptions and substitutional use of European data) were detected in the visualization; therefore, the severity of the inconsistencies was discussed through an analysis of scenario uncertainty in nitrogen fertilizer production. The importance of devoting attention to fertilizer production technologies rather than simply to regional differences was clarified. Conclusions This study demonstrates the usefulness of applying visualization methods in understanding the overall configuration of earlier studies. It is expected that the visualization and its implications constitute a way forward to good practices in inventory analysis.

Cost-combined life cycle assessment of ferronickel production Abstract Purpose Ferronickel is irreplaceable in modern infrastructure construction because of its use in stainless steel production. This study explored the cost-combined environmental impacts of ferronickel production in China which is the largest producer and consumer of ferronickel in the world. Methods Life cycle impact assessment was combined with life cycle costing analysis to assess the environmental and economic performance of ferronickel production in China. Both internal cost (e.g., raw materials, energy, transport, infrastructure, tax, and labor) and external cost (i.e., human health, ecosystem quality, and environmental emission) were considered. Results and discussion The environmental burden of ferronickel production in this study was mainly attributed to the damage on resources and human health as endpoints caused by indirect processes, such as electricity supply, transportation, coke production, lateritic nickel ore acquisition, and coal mining. Carbon dioxide, mercury, particulates, methane, sulfur dioxide, nitrogen oxides, coal, and nickel ores were the substances pivotal for optimizing environmental performance. The total economic cost was 2734.8 $/t, of which 2333.3 $/t was internal cost and 401.5 $/t was external cost. Lateritic nickel ore, electricity, human health cost, and transport contributed 44.9%, 20.6%, 14.2%, and 4.8% to the total economic cost, respectively. The remaining economic burden was mainly divided to coke, coal, argon, labor, equipment, and tax. Conclusions A win-win case for the environment and economy can be achieved by optimizing electricity and lateritic nickel ore quality, including its transport. Application of other power types (e.g., hydro, wind, and solar electricity) as a substitute for thermal power can also reduce environmental impacts considerably. Sites with high steel yield, low thermal power ratio, and high port proximity, such as Fujian Province, are the primary choices for ferronickel production. Finally, although the economic benefits of coke and coal are minimal, their efficiency in environmental improvement is crucial.