Photochemical Oxidant Formation Research Articles

Life-cycle assessment of system alternatives for the Water-Energy-Waste Nexus in the urban building stock

Generally water-wastewater systems in developed cities contribute significantly to public health. But, the related systems are resource intensive and lack circularity. Supplying and heating up drinking water as well as treating domestic wastewater are related to relatively high energy consumption and require a major infrastructure. However, there are potentials to reduce the environmental impacts of these systems by using the thermal and chemical energies and nutrients contained in the wastewater. If organic municipal waste is added the energy efficiency of the entire system could further enhanced.Using a regional Life Cycle Assessment approach, the overarching aim of the paper is to assess the environmental impacts of different systems alternatives which aim to increase the resource and energy efficiency by separating wastewater at the source in greywater and blackwater and co-digest the latter with organic municipal solid waste. The results are compared to an existing system of a German medium-sized urban neighborhood. The impacts assessed are two resource-related (fossil and metal depletion) and three emissions-related (climate change, photochemical oxidant formation and terrestrial acidification).Under the conditions of the settlement investigated, the discussed alternative systems show a noteworthy decline of the environmental impacts compared to the status quo: from -68.0 (metal depletion) up to −96.5% (climate change). Thus, even in existent settlements transforming the current linear system in a more circular one could be a promising strategy to enhance the resource efficiency of water-wastewater-waste-energy systems. A slight advantage of a “sewerless” system can be identified.

Avaliação do ciclo de vida do queijo muçarela de um laticínio na região norte do Brasil

O presente trabalho utilizou da técnica de Avaliação do Ciclo de Vida (ACV) para avaliar os impactos ambientais da produção de queijo Muçarela nos recursos naturais. A unidade funcional determinada foi 1 kg de queijo Muçarela, em que os aspectos ambientais foram considerados desde o recebimento do leite no portão da indústria até a expedição do produto final, fronteira de estudo conhecida como gate-to-gate. Em acordo com o determinado pelas normas ISO 14040 (2006) e 14044 (2006), os cálculos de impactos foram realizados pelo software SimaPro®, com aplicação do método ReCiPe Midpoint H. As categorias de impacto avaliadas foram: Depleção Fóssil, Depleção de Água, Formação de Material Particulado, Formação de Oxidantes Fotoquímicos, Eutrofização de Água Doce, Acidificação Terrestre, Depleção de Ozônio e Mudanças Climáticas. Foi observado que a produção de leite consistiu o principal responsável pelos impactos gerados no ciclo de vida avaliado, com contribuições em todas as categorias avaliadas, variando de 3% para depleção de ozônio a 99,5% para eutrofização de água doce. Logo, é de suma importância a adoção de alternativas sustentáveis pelo Laticínio, de modo a mitigar os impactos ambientais gerados no processo produtivo, a despeito do reaproveitamento do soro já realizado na empresa.

A condom\u2019s footprint - life cycle assessment of a natural rubber condom

PurposeWorldwide, billions of condoms are used each year, and many brands popped up that are working on sustainable solutions. However, none has published an analysis of a condom’s life using a standardized and quantitative approach such as the life cycle assessment (LCA). This study presents the first LCA of a natural rubber condom from einhorn products GmbH. It has been conducted to identify environmental hotspots, future research needs along the entire life of a condom and to open up a discussion among interested stakeholder.MethodsThe assessed environmental impacts are climate change, water depletion, eutrophication, ecotoxicity, acidification, human toxicity, and photochemical oxidant formation. The data were obtained by intensive literature research and consultation of customers and suppliers.Results and discussionThe hotspot assessment showed that, on average, more than 90% of impacts are contributed by the production and downstream phases. Activities contributing most are energy consumption and packaging material used during condom production, production of tissue paper used to discard condoms, international transport, and business travels. The upstream life cycle phases do show minor contributions to most of the categories except for ecotoxicity, where the plantation activities are responsible for around 50% of the emissions. However, the impact of plantation might be underestimated because of missing analysis of biodiversity and especially for countries where rubber is responsible for deforestation the contribution of the plantation could increase.ConclusionsThe results highlight the importance of the condom's production, packaging, and the end-of-life stage. Future research should address the sensitivity of the results regarding further impact categories and should verify assumptions made and fill data gaps within the inventory.

Life cycle assessment of petroleum refining process: A case study in China

Climate change mainly caused by transportation fuel consumption has attracted global concern. In life cycle environmental burdens generated from transportation fuel production, petroleum refining stage is the hotspot. However, the in-depth environmental analysis of petroleum refining is very limited. China is the second largest petroleum refining country, so it is very essential to break petroleum refining stage into specific unit to analyze how Chinese refinery can be improved in environment performance. To achieve this goal, a systematic life cycle analysis of the environmental burden generated from petroleum refining process was conducted to identify the control emphasis and seek potential improvement measures. Sensitive analysis and volatile organic compounds (VOCs) emission characteristics were additional discussed to improve the accuracy of results. The significant burdens generated from petroleum refining process were freshwater ecotoxicity and climate change. Crude oil extraction and transport dominated most environmental categories, which indicated that the environmental problem exist in upstream supply chain. Catalytic cracking, feedstock and product handling, catalytic reforming, crude oil distillation, cooling water system and diesel hydrotreating were the major control units due to their direct emissions and electricity consumption. VOCs (e.g., acrolein and chlorofluorocarbons) produced from refinery fugitive emissions were the main substances for refinery to reduce human toxicity, ozone depletion and photochemical oxidant formation influences. 14% of Climate change were derived from organic chemicals emission in this study, which suggested that VOCs-related carbon emission should be involved in current carbon accounting work or greenhouse gases (GHGs) studies on the petroleum refining industry. The identified control emphasis included equipment leaks from core refining units, storage tank emissions control, energy structure optimization and catalysts consumption intensity reduction. Some feasible and useful reduction measures targeted the control emphasis were proposed for policy makers and refinery managers to formulate reduction strategies and improve the sustainability of the petrochemical industry.

Environmental trade-offs of renewable jet fuels in Brazil: Beyond the carbon footprint

The use of renewable jet fuels (RJFs) is an option for meeting the greenhouse gases (GHG) reduction targets of the aviation sector. Therefore, most of the studies have focused on climate change indicators, but other environmental impacts have been disregarded. In this paper, an attributional life cycle assessment is performed for ten RJF pathways in Brazil, considering the environmental trade-offs between climate change and seven other categories, i.e., fossil depletion, terrestrial acidification, eutrophication, human and environmental toxicity, and air quality-related categories, such as particulate matter and photochemical oxidant formation. The scope includes sugarcane and soybean for first-generation (1G) pathways and residual materials (wood and sugarcane residues, beef tallow, and used cooking oil-UCO) for second-generation (2G) pathways. Three certified technologies to produce RJF are considered: hydroprocessed esters and fatty acids (HEFA), alcohol-to-jet (ATJ), and Fischer-Tropsch (FT). Assuming the residual feedstocks as wastes or by-products, the 2G pathways are evaluated by two different approaches, in which the biomass sourcing processes are either accounted for or not. Results show that 1G pathways lead to significant GHG reductions compared to fossil kerosene from 55% (soybean/HEFA) to 65% (sugarcane/ATJ). However, the sugarcane-based pathway generated three-fold higher values than fossil kerosene for terrestrial acidification and air quality impacts, and seven-fold for eutrophication. In turn, soybean/HEFA caused five-fold higher levels of human toxicity. For 2G pathways, when the residual feedstock is assumed to be waste, the potential GHG emission reduction is over 74% with no relevant trade-offs. On the other hand, if the residual feedstocks are assumed as valuable by-products, tallow/HEFA becomes the worst option and pathways from sugarcane residues, even providing a GHG reduction of 67% to 94%, are related to higher impacts than soybean/HEFA for terrestrial acidification and air quality. FT pathways represent the lowest impacts for all categories within both approaches, followed by UCO/HEFA.

Eco-efficiency Level of Production Process of Waste Cooking Oil to be Biodiesel with Life Cycle Assessment

Lack of awareness and knowledge of environmental protection, many people discard cooking oil waste. According to several studies, cooking oil waste can be processed into more valuable products through certain processes that require energy and material. Biodiesel is an example. Beside biodiesel, the production process also produces non-product output. Thus, efforts to utilize cooking oil waste into more valuable products also have a negative impact on the environment. This study aims to measure the environmental impact of biodiesel production from waste cooking oil and compare it if it is discharged to landfill without the recycling process. Measurement of environmental impacts is carried out using a Life Cycle Assessment. Measurement of the environmental impact of biodiesel processing from cooking oil waste is based on a process carried out at a research institute. The measurement results state that the disposal of cooking oil waste has an adverse effect on the ecotoxicity category. Whereas the processing of cooking oil waste into biodiesel has advantages in the categories of climate change, the formation of photochemical oxidants, fine dust, oil and gas depletion, and water pressure indicators. the level of eco efficiency from processing waste cooking oil to biodiesel produces a value close to one which means that the production process is affordable but not yet sustainable.

Towards a contribution to sustainable management of a dairy supply chain

Paper aims The paper proposes an enhancement to a focal company in the dairy supply chain, in order to support sustainable performance. Originality The authors conclude that previous life cycle assessment (LCA) studies did not recommend for dairy supply chain or use this approach to assess the environmental impacts in this chain. Research method A cradle-to-gate attributional life cycle assessment (LCA) study performed in a focal company and considering its transport and processing stages, and three scenarios were proposed as suitable. Main findings The impacts derive from energy use and transportation of feedstocks, and the use of cleaning products and certain types of packaging materials. A decrease of 46.5% of the impact in the photochemical oxidant formation category was achieved. Implications for theory and practice The results can identify the different impacts throughout the dairy chain associated with the main product’s life cycle, and the possibility of mitigating them.

Barley production in Spain and Italy: Environmental comparison between different cultivation practices

In Europe, around 12 million ha are cultivated with barley and Spain and Italy are two important producers' countries.This study aims to compare the cultivation of barley of two different contexts, Spain and Italy, evaluating the related environmental performances; this is carried out considering the similar latitude and climatic conditions of the two countries, but taking into account the different average mechanisation solutions that differentiate considerably the two production frameworks. Inventory data about barley cultivation were gathered mainly by questionnaires with farmers and technical expert interviews. To quantify the environmental performances of barley production in the two Countries, the Life Cycle Assessment approach was applied and 1 ton of grain at the commercial moisture was selected as reference unit and 12 impact categories were evaluated.The outcomes of the impact assessment highlight how for 7 of the 12 evaluated impact categories, barley production in Spain shows a higher impact respect to the Italian production (from +7% for photochemical oxidant formation to +120% for freshwater ecotoxicity) mainly due to the lower grain yield and to the higher consumption of mineral fertilisers. For the other evaluated environmental effects, the Spanish production performs better than the Italian one, mostly because of the lower emissions of ammonia into the air. Yield is the main driver of the environmental effects. Additionally, due to mechanisation of field operations and to fertilisations, wide differences on the environmental side emerge from the comparison.There is a trade-off between the Spanish production, where the use of mineral fertilisers reduces all the environmental effects related to ammonia volatilisation, and the Italian barley cultivation, where the use of animal slurry improves the results on the impact categories affected by the fertiliser production but worsens those affected by the nitrogen emissions.

Life cycle assessment of melange yarns from the manufacturer perspective

Different proportions of colored fibers are able to spin into melange yarns with different colors and textures. With the advantages of energy saving, water saving, and emissions reduction in their production, melange yarns become more and more popular in manufacturers. However, the environmental performance of melange yarns with different colors has not been well investigated, which makes fashion designers unable to consider environmental performance when determining the color scheme of their design works. This study focuses on evaluating the environmental impacts of melange yarns spun from different colored fibers and identifying the environmental hotspots, in order to seek opportunities for improvement from the manufacturer’s perspective. A cradle-to-gate life cycle assessment (LCA) of melange yarns was performed, where the investigated phases include raw material acquisition, transportation, dyeing, mixing, and spinning. The functional unit is 1 ton of the finished melange yarns. The primary data of nine melange yarns spun from monochrome fibers, i.e., white, brown, blue, purple, green, yellow, red, black, and gray, were collected by on-site investigation in a large manufacturer in China. The environmental impacts of the nine melange yarns were evaluated using the ReCiPe method. The environmental impacts were indicated by 15 impact categories including climate change, terrestrial acidification, freshwater eutrophication, marine eutrophication, ozone depletion, water depletion, metal depletion, fossil depletion, freshwater ecotoxicity, marine ecotoxicity, terrestrial ecotoxicity, human ecotoxicity, ionizing radiation, particulate matter formation, and photochemical oxidant formation. The results obtained from the LCA demonstrated that spinning phase and dyeing phase in the production of melange yarns are main contributors to environmental impacts. The electricity and tap water consumptions are found to be the dominant contributors to most of impact categories, except terrestrial ecotoxicity, metal depletion, and ionizing radiation, whereas these environmental impacts are related to the wastewater treatment process. The recycled water is beneficial to reduce environmental burdens and can bring over 30% environmental benefits to the category of freshwater ecotoxicity. Melange yarns spun from white fibers have the least impact on the environment because of the lower electricity and water consumptions. The potential hotspots identified are tap water use, reactive dyestuffs and auxiliaries use in the dyeing phase, and the electricity consumption in spinning phase. This work points out the future direction for the textile industry to improve the environmental performance.

ENVIRONMENTAL IMPACTS ASSESSMENT OF BIODIESEL PRODUCTION FROM JATROPHA AND WASTE COOKING OIL (WCO)

Biodiesel that is produced from renewable resources has been rising as a promising candidate to replace conventional energy. Vietnam, with a large amount of land used in agriculture or forestry, has advantaged conditions to produce and develop renewable energy from biomass resources. However, developing biodiesel from agricultural product may affect food security significantly. Therefore, Jatropha that is inedible and waste cooking oil (WCO) could be suitable to biodiesel production. One of the most important aims of using biodiesel to replace fossil diesel is to reduce environmental impacts, particularly impact on Climate Change. It is necessary to analyze the environmental performance of biodiesel through the entire life cycle. In this paper, life cycle assessment of biodiesel production and use was applied to measure the environmental performance of biodiesel produced from jatropha oil and WCO under Vietnam conditions. Some main emissions, such as CO2, NOx, PM, CH4, VOC and land use, were computed through a cradle-to-grave analysis. The result shows that when using Jatropha biodiesel to replace diesel, global warming potential (GWP) and photochemical oxidant formation potential (POFP) could be improved, but some other impacts, such as acidification potential (AP) and eutrophication potential (EP), could tend to increase. The environmental impacts of WCO biodiesel are all reduced in comparison with fossil diesel.

Environmental impact assessment model for buildings’ construction activities

Building construction tasks generate many environmental impacts during their execution. The assessment and comparison of the ecological effects of different construction tasks can aid in reducing emissions from these tasks. This study introduces an impact assessment methodology to assess the ecological effects of different building construction tasks according to the construction equipment used. In this study, global warming potential (GWP100), acidification potential (AP), eutrophication potential (EP), photochemical oxidation formation potential (POFP) and human toxicity potential (HTP) are considered as impact categories and evaluated at the global, regional and local levels. A case study of an administrative building in Egypt is used to validate the practicality of the developed model. The results demonstrate that the developed model can efficiently evaluate the ecological effects of construction tasks, and contractors can use it as a tool for choosing ecologically friendly construction strategies.

Resources Sustainability. N Application in Crops to Determine the Best Environmental Performance Using Life Cycle Assessment Methodology

The use of mineral fertilizer in horticultural crops is a very important issue due to its effects on crop yield and its environmental impact. For the period 2011-2012, the total mineral fertilizer consumption in EU-27 reached 10.4 million tons of nitrogen (N), 1.0 million tons of phosphorus (K) and 2.2 million tons of potassium (K). Though many recent studies have examined horticultural crops, few have focused on mineral fertilizers in order to make an environmental assessment of a tomato crop. Therefore, the aim of this research was to study the agronomical (i.e. yield) and the environmental performance of a horticultural tomato crop fertilized with four different doses of mineral fertilizer (N0, N1, N2 and N3), using Life Cycle Assessment methodology. Data and conditions for the crop were taken from a real field trial with an experimental design carried out in North-east Catalonia, Spain. Following the guidelines of the ISO 14044, the study considered all stages of the life cycle of a horticultural tomato crop (i.e. mineral fertilizer production, transport and cultivation phase). Six impact categories were included in the study: climate change, photochemical oxidation formation, land acidification, freshwater and marine eutrophication and fossil depletion. Overall, the results showed that the best result was for the N1 treatment, with a yield of 61 ton ha-1 and 55 ton ha-1 for total and commercial yield, respectively. N1 showed the best environmental performance in all categories assessed.

How sustainable is electric mobility? A comprehensive sustainability assessment approach for the case of Qatar

Electric mobility is a trending topic around the world, and many countries are supporting electric vehicle technologies to reduce environmental impacts from transportation such as greenhouse gas emissions and air pollution in cities. While such environmental impacts are widely studied in the literature, there is not much emphasis on a comprehensive sustainability assessment of these vehicle technologies, encompassing the three pillars of sustainability as the environment, society, and economy. In this study, we presented a novel comprehensive life cycle sustainability assessment for four different support utility electric vehicle technologies, including hybrid, plug-in hybrid, and full battery electric vehicles. A hybrid multi-regional input-output based life cycle sustainability assessment model is developed to quantify fourteen sustainability indicators representing the three pillars of sustainability. As a case study, we studied the impacts for Qatar, a country where 100% of electricity generation is from natural gas and have a very unique supply-chain, mainly due to a wide range of exported products and services. The analysis results showed that all-electric vehicle types have significant potential to lower global warming potential, air pollution, and photochemical oxidant formation. A great majority (above 90%) of the emissions occurs within the region boundaries of Qatar. In the social indicators, internal combustion vehicles performed better than all other electric vehicles in terms of employment generation, compensation of employees, and taxes. The results highlighted that adoption of electric vehicle alternatives doesn't favor macro-economic indicators and they have slightly less for a life-cycle cost. The proposed assessment methodology can be useful for a comprehensive regionalized life cycle sustainability assessment of alternative vehicle technologies and developing regionalized sustainable transportation policies worldwide.

Comparative LCA of recycled and natural aggregate concrete using Particle Packing Method and conventional method of design mix

In construction industry, apart from cement, the aggregate type, mix design method and transport distance of raw materials also contribute significantly to the environment related issues. This paper compares environment impacts of recycled coarse aggregate (RCA) and Particle Packing Method (PPM) of mix design approach with the concrete proportioned using natural coarse aggregate (NCA) and IS code method. The system boundary is determined based on cradle-to-gate theory. The primary data regarding the preparation of NCA and RCA are collected from the respective production facilities and Ecoinvent 3.01 is used as background database. Abiotic depletion, abiotic depletion due to fossil fuels, global warming potential, depletion of ozone layer, formation of tropospheric ozone photochemical oxidants, acidification potential, and eutrophication potential are measured using CML baseline method with the help of SimaPro software. Lower environmental impacts are observed for PPM mix designed concrete owing to the requirement of lesser cement quantity. The combination of RCA and PPM mix design approach exhibits minimum environmental impacts. Transport activities are the second largest contributor after cement and hence, sensitivity analysis is carried out to evaluate the influence of different transport scenarios and distances in Indian context. For comparable environmental impact with natural aggregate concrete proportioned using IS code method, the maximum possible supply distance of RCA is determined for different collection distance of C&D waste. The collection distance of C&D waste can be incremented by 9–12 km for each 50 km increment in the supply distance of processed RCA to prepare recycled aggregate concrete.

IMPACT World+: a globally regionalized life cycle impact assessment method

IMPACT World+: a globally regionalized life cycle impact assessment method

Environmental impact of strawberry production in Italy and Switzerland with different cultivation practices

In this study, the environmental impact of strawberry production in Italy and Switzerland was evaluated using the Life Cycle Assessment (LCA) approach. The main differences between the two countries are the cultivation practices: crop cycle duration (1 year in Switzerland and 2 or 3 years in Italy), soil management and cultivation in open and protected fields.For all the environmental impact categories evaluated with LCA, strawberry production in Switzerland shows higher impacts respect to the Italian production. The impact reduction related to the Italian production in open fields without soil sterilisation ranges from 96% (for photochemical oxidant formation) to 35% (for freshwater eutrophication). For Swiss production, soil sterilisation is by far the main environmental hotspot for all the evaluated environmental effects except for toxicity-related impact categories and for resources consumption (i.e. manufacturing, maintenance and disposal of tunnel). Conversely, the main hotspot in Italy differs depending on the considered categories. Moreover, the 3-years cycle duration has a higher impact respect to the 2-years one because of the low yield in the third year that worsens the outcomes.Finally, sensitivity and uncertainty analysis were performed. The environmental results are deeply affected by yield variation and only slightly by changes in the life span of the tunnels while the uncertainty related to the selection of the data source, the model imprecision, and the variability of data does not affect significantly the results, except for the toxicity-related impact categories.

Life cycle environmental impact comparison of solid oxide fuel cells fueled by natural gas, hydrogen, ammonia and methanol for combined heat and power generation

This study aims to provide a comprehensive environmental life cycle assessment of heat and power production through solid oxide fuel cells (SOFCs) fueled by various chemical feeds namely; natural gas, hydrogen, ammonia and methanol. The life cycle assessment (LCA) includes the complete phases from raw material extraction or chemical fuel synthesis to consumption in the electrochemical reaction as a cradle-to-grave approach. The LCA study is performed using GaBi software, where the selected impact assessment methodology is ReCiPe 1.08. The selected environmental impact categories are climate change, fossil depletion, human toxicity, water depletion, particulate matter formation, and photochemical oxidant formation. The production pathways of the feed gases are selected based on the mature technologies as well as emerging water electrolysis via wind electricity. Natural gas is extracted from the wells and processed in the processing plant to be fed to SOFC. Hydrogen is generated by steam methane reforming method using the natural gas in the plant. Methanol is also produced by steam methane reforming and methanol synthesis reaction. Ammonia is synthesized using the hydrogen obtained from steam methane reforming and combined with nitrogen from air in a Haber-Bosch plant. Both hydrogen and ammonia are also produced via wind energy-driven decentralized electrolysis in order to emphasize the cleaner fuel production. The results of this study show that feeding SOFC systems with carbon-free fuels eliminates the greenhouse gas emissions during operation, however additional steps required for natural gas to hydrogen, ammonia and methanol conversion, make the complete process more environmentally problematic. However, if hydrogen and ammonia are produced from renewable sources such as wind-based electricity, the environmental impacts reduce significantly, yielding about 0.05 and 0.16 kg CO2 eq., respectively, per kWh electricity generation from SOFC.

Sustainable Peach Compote Production: A Life Cycle Thinking Approach

Peach production as well as the fruit canning industry is one of the most important agricultural supply chain sectors in Greece. In 2016 Greek canned peach production reached 300,000 tones. In this study we perform an environmental analysis of a peach compote production system in Greece, using Life Cycle Assessment. The system studied includes the stages of cultivation, transportation of peaches to the peach compote plant, the canning and finally packaging. The data used were collected directly from an orchard located in Larissa, in central Greece, and covers the production year of 2016. The functional unit adopted is the production of one paper box containing 24 cans of peach compotes. The Life Cycle Analysis results indicate that 48.41%, 25% and 20.98% of the environmental burdens are attributed to the acidification potential, global warming potential and particular matter formation impact categories, respectively; whereas eutrophication impact potential and photochemical oxidation formation impact accounted for 5.38% and 0.23%, respectively. The results of this study provide an understanding of the key environmental impact issues related to peach compote production in Greece.

Environmental life cycle assessment of cemented carbide (WC-Co) production

Cemented carbides are of great importance for the manufacturing industry. The outstanding properties of high hardness and wear resistance of this material, consisting mainly of tungsten carbide cemented with cobalt (WC-Co), have caused its use in a wide range of applications. The aim of this study is to provide comprehensive and detailed cradle-to-gate life cycle inventory (LCI) data for the typical non-Chinese production of WC-Co, which is assumed to take place in Canada and the United States. Different scenarios are presented regarding recycling rate and a life cycle impact assessment (LCIA) is conducted to illustrate the applicability of the LCI data. The LCI results in this study are of similar magnitude or lower compared to previous studies and indicate that the typical non-Chinese production requires less energy compared to Chinese production. The LCIA results show that the mining, hydrometallurgy and powder metallurgy phases in general dominate the cradle-to-gate life cycle impacts. Most of the impacts are caused by a limited number of inputs and outputs (e.g. kerosene, sulfidic tailings, water use during mining and electricity use), and recycling greatly reduces the impacts. A comparison with Chinese tungsten carbide (WC) powder production showed that the LCIA results in non-Chinese WC production were lower for climate change, photochemical oxidant formation and water depletion, but higher for terrestrial acidification, ozone depletion and freshwater eutrophication. The LCI data and the LCIA results for non-Chinese production can subsequently be used in product-specific cradle-to-grave life cycle assessments involving WC-Co or any of its precursors.

Energy efficiency and environmental assessment of papermaking from chemical pulp - A Finland case study

Abstract Pulp and paper manufacturing sector constitutes one of the largest industry segments in the world in terms of water and energy usage as well as of significant use and release of chemicals and combustion products. Since its chief feedstock –wood fiber– is renewable, this industry can play an important role in sustainable development, becoming an example of how a resource can be managed to provide a sustained supply to meet society's current and future needs. This calls for a thorough assessment of environmental costs and impacts associated to pulp and paper operations, including both direct and indirect inputs supporting the whole papermaking process as well as the main outputs, co-products and by-products. By means of Life Cycle Assessment (LCA) methodology, this paper aims at assessing the environmental sustainability of the pulp and paper production so as to identify those phases across the whole supply chain that entail the highest environmental loads, thus requiring improvements. To determine the environmental impacts as accurately as possible, the manufacturing stages performed in the pulp and paper mill complex of Stora Enso Oyj Veitsiluoto Mills at Kemi, Northern Finland, were taken as a model and assessed by means of the SimaPro 8 LCA software, utilizing ReCiPe Midpoint (H) method for the impact assessment. As expected, most of the resulting impacts are caused by the industrial production phase. The production processes of pulp and paper jointly affect all the investigated impact categories with the highest shares, ranging from 50% of generated impacts on water depletion up to 88% on freshwater eutrophication. Generally, the main contributions to environmental loads come from the electricity and heat requirements and, only at a minor extent, from the use of chemicals such as the sodium hydroxide and sodium chlorate. In particular, pulp production process generates the main loads on global warming (46% of the total impacts), ozone depletion (39%), freshwater eutrophication (55%), human toxicity (46%), metal depletion (42%) and fossil depletion (46%). In the remaining investigated impact categories, namely terrestrial acidification, photochemical oxidant formation and terrestrial ecotoxicity, most of impacts derive from the use of optical brighteners and fillers in the final steps of paper production and from the intensive consumption of water in the recycling step of end-of-life affecting water depletion. Moreover, the implementation of measures for material and energy efficiency in the assessed system, such as the use of renewable energy generated in situ from black liquor and residual biomass to support the requirements of the integrated pulp and paper mills and the waste paper recycling, resulted to be crucial in lowering the environmental burdens. In particular, the partial fulfillment of electricity and heat requirements by means of a circular use of residues within the system leads to a noteworthy reduction of impacts in all the investigated impact categories, up to more than 70% in global warming and fossil depletion potentials, thus contributing to higher process sustainability compared with other averaged European systems for paper production. The obtained research results are a valuable source of management information for the decision makers, at both company and national levels, with the aim to improve the environmental performance of pulp and paper industry.