Purpose
Uncertainty is present in many forms in life cycle assessment (LCA). However, little attention has been paid to analyze the variability that methodological choices have on LCA outcomes. To address this variability, common practice is to conduct a sensitivity analysis, which is sometimes treated only at a qualitative level. Hence, the purpose of this paper was to evaluate the uncertainty and the sensitivity in the LCA of swine production due to two methodological choices: the allocation approach and the life cycle impact assessment (LCIA) method.Methods
We used a comparative case study of swine production to address uncertainty due to methodological choices. First, scenario variation through a sensitivity analysis of the approaches used to address the multi-functionality problem was conducted for the main processes of the system product, followed by an impact assessment using five LCIA methods at the midpoint level. The results from the sensitivity analysis were used to generate 10,000 independent simulations using the Monte Carlo method and then compared using comparison indicators in histogram graphics.Results and discussion
Regardless of the differences between the absolute values of the LCA obtained due to the allocation approach and LCIA methods used, the overall ranking of scenarios did not change. The use of the substitution method to address the multi-functional processes in swine production showed the highest values for almost all of the impact categories, except for freshwater ecotoxicity; therefore, this method introduced the greater variations into our analysis. Regarding the variation of the LCIA method, for acidification, eutrophication, and freshwater ecotoxicity, the results were very sensitive. The uncertainty analysis with the Monte Carlo simulations showed a wide range of results and an almost equal probability of all the scenarios be the preferable option to decrease the impacts on acidification, eutrophication, and freshwater ecotoxicity. Considering the aggregate result variation across allocation approaches and LCIA methods, the uncertainty is too high to identify a statistically significant alternative.Conclusions
The uncertainty analysis showed that performing only a sensitivity analysis could mislead the decision-maker with respect to LCA results; our analysis with the Monte Carlo simulation indicates no significant difference between the alternatives compared. Although the uncertainty in the LCA outcomes could not be decreased due to the wide range of possible results, to some extent, the uncertainty analysis can lead to a less uncertain decision-making by demonstrating the uncertainties between the compared alternatives.Purpose
Cheese is one of the world’s most widely consumed dairy products and its popularity is ever growing. However, as concerns for the environmental impact of industries increase, products like cheese, which have a significant environmental impact, may lose their popularity. A commonly used technique to assess the environmental impact of a product is life cycle assessment (LCA). In this paper, a state-of-the-art review of LCA studies on the environmental impact of cheese production is presented.Methods
Sixteen LCA studies, which explored the impact from the production of a variety of cheese types (fresh, mature and semi-hard) were examined and discussed. The four stages of the LCA were examined and the range of results of selected environmental impact categories (global warming potential, acidification potential and eutrophication potential) were detailed and discussed.Results and discussion
For each of these environmental impact categories, raw milk production was consistently found to be the most significant contributor to the total impact, which was followed by processing. It was found that allocation between cheese and its by-products was crucial in determining the impact of cheese production and standardisation or guidelines may be needed. Very little information relating to wastewater treatment system and processes were reported and this leads to inaccurate environmental impact modelling relating to these aspects of the manufacture of cheese. Very few studies included the design of packaging in terms of reducing food waste, which may significantly contribute to the overall environmental impact.Conclusions
As raw milk production was found to have the greatest contribution to environmental impact, mitigation strategies at farm-level, particularly in relation to enteric fermentation and manure management, need to be implemented. Additionally, based on the literature, there is a suggestion that fresh cheese has less of an environmental impact than semi-hard cheeses, particularly when examining direct energy consumption. However, there needs to be more case studies investigated to justify this statement.Purpose
In order to meet the upscaling demand of food products worldwide, the aquaculture industry has been expanding within the last few years in developed countries. Major expansions of aquaculture farming occurred in many developed countries such as Bangladesh, Indonesia, and Egypt. Egypt ranks ninth in fish farming production worldwide and first on Africa. Egypt has the largest aquaculture industry in Africa which represents two-thirds of African aquaculture production. Tilapia production accounts for 75.5 % of aquaculture production in Egypt. Tilapia aquaculture production has grown exponentially in recent decades until it reached 4.5 million tonnes in 2012 placing Egypt as the second worldwide producer of tilapia after China. The production of tilapia is practiced in different production systems including intensive and semi-intensive systems. These production systems require different resources and impact differently on the environment. The aim of the current study was to model the environmental performance of tilapia production and compare semi-intensive and intensive production systems. The main questions were the following: What are the different impacts of tilapia production on the environment? Which production system is more environmentally friendly? What are the preferable practices for better environmental performance and sustainable ecofriendly industry of Tilapia production?Methods
Life cycle assessment (LCA) was employed to determine the environmental impacts of tilapia production and compare semi-intensive and intensive production systems. Data for life cycle inventory were collected from two case study farms for tilapia production in Egypt. Four impact categories were taken into consideration: Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), and Cumulative Energy Demand (CED).Results and discussion
LCA revealed that production of tilapia in intensive farming has less impact on GWP, AP, and CED, while its impact on EP is higher than in semi-intensive farming. The identified impacts from 1-tonne live weight production of tilapia were the following: GWP 960.7 and 6126.1 kg CO2 eq; AP 9.8 and 24.4 kg SO2 eq; EP 14.1 and 6.3 kg PO2 eq; and CED 52.8 GJ and 238.3 GJ eq in intensive and semi-intensive systems, respectively.Conclusions
Fish meal production and energy consumption were the major contributors to different impact indicators in both systems. An overall improvement in environmental performance for tilapia production can be achieved by novel feed formulations that have better environmental performance. Energy consumption is a major area for improvement as well, as proper energy management practices will reduce the overall impact on the environment.Purpose
This paper will give an overview of LCA studies on lead metal production and use recently conducted by the International Lead Association.Methods
The lead industry, through the International Lead Association (ILA), has recently completed three life cycle studies to assess the environmental impact of lead metal production and two of the products that make up approximately 90 % of the end uses of lead, namely lead-based batteries and architectural lead sheet.Results and discussion
Lead is one of the most recycled materials in widespread use and has the highest end-of-life recycling rate of all commonly used metals. This is a result of the physical chemical properties of the metal and product design, which makes lead-based products easily identifiable and economic to collect and recycle. For example, the end-of-life collection and recycling rates of lead automotive and industrial batteries and lead sheet in Europe are 99 and 95 %, respectively, making them one of the few products that operate in a true closed loop. These high recycling rates, coupled with the fact that both lead-based batteries and architectural lead sheet are manufactured from recycled material, have a beneficial impact on the results of LCA studies, significantly lowering the overall environmental impact of these products. This means that environmental impacts associated with mining and smelting of lead ores are minimised and in some cases avoided completely. The lead battery LCA assesses not only the production and end of life but also the use phase of these products in vehicles. The study demonstrates that the technological capabilities of innovative advanced lead batteries used in start-stop vehicles significantly offset the environmental impact of their production. A considerable offset is realised through the savings achieved in global warming potential when lead-based batteries are installed in passenger vehicles with start-stop and micro-hybrid engine systems which have significantly lower fuel consumption than regular engines.Conclusions
ILA has undertaken LCAs which investigate the environmental impact associated with the European production of lead metal and the most significant manufactured lead products (lead-based batteries used in vehicles and architectural lead sheet for construction) to ensure up-to-date and robust data is publically and widely available.Purpose
The number of scrap tires generated in China has grown dramatically every year. Generation of ground rubber from scrap tires is the dominant management option in China. It is necessary to assess the environmental impacts of ground rubber production from scrap tires to provide technical advices on a cleaner production.Methods
Production of ground rubber from recycled scrap tires consist of three steps: rubber powder preparation, devulcanization, and refining. A process life cycle assessment (LCA) of ground rubber production from scrap tires is carried out, and Eco-indicator 99 method coupled with ecoinvent database is applied to evaluate the environmental impacts of this process.Results and discussion
During the ground rubber production stage, the impact factor of respiratory inorganic is the most serious one. Devulcanization has the highest environmental load of about 66.2 %. Moreover, improvement on the flue gas treatment contributes to a cleaner production and a more environmental-friendly process. Applying clean energy can largely reduce environmental load by about 21.5 %.Conclusions
The results can be a guidance to reduce environmental load when producing ground rubber from scrap tires. Meanwhile, increasing energy efficiency, improving environmental protection equipment, and applying clean energy are the effective measures to achieve this goal. 相似文献The main objective of this paper is to develop a model that will combine economic and environmental assessment tools to support the composite material selection of aircraft structures in the early phases of design and application of the tool for an aircraft elevator.
MethodsAn integrated life cycle cost (LCC) and life cycle assessment (LCA) methodology was used as part of the sustainable design approach for the laminate stacking sequence design. The model considered is the aircraft structure made of carbon fiber reinforce plastic prepreg and processed via hand layup-autoclave process which is the preferred method for the aircraft industry. The model was applied to a cargo aircraft elevator case study by comparing six different laminate configurations and two different carbon fiber prepreg materials across aircraft’s entire life cycle.
Results and discussionThe results show, in line with other studies using different methodologies (e.g., life cycle engineering, or LCE), that the combination of LCA with LCC is a worthwhile approach for comparing the different laminate configurations in terms of cost and environmental impact to support composite laminate stacking design by providing the best trade-off between cost and environment. Elevator LCC reduces 19% by changing the material type and applying different ply orientations. Elevator LCA score reduces 53% by selecting the optimum instead of best technical solution that minimizes the displacement. Improving the structural performance does not always lead to an increase in the cost.
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