Life cycle assessment of cheese and whey production in the USA

Purpose

A life cycle assessment was conducted to determine a baseline for environmental impacts of cheddar and mozzarella cheese consumption. Product loss/waste, as well as consumer transport and storage, is included. The study scope was from cradle-to-grave with particular emphasis on unit operations under the control of typical cheese-processing plants.

Methods

SimaPro© 7.3 (PRé Consultants, The Netherlands, 2013) was used as the primary modeling software. The ecoinvent life cycle inventory database was used for background unit processes (Frischknecht and Rebitzer, J Cleaner Prod 13(13–14):1337–1343, 2005), modified to incorporate US electricity (EarthShift 2012). Operational data was collected from 17 cheese-manufacturing plants representing 24 % of mozzarella production and 38 % of cheddar production in the USA. Incoming raw milk, cream, or dry milk solids were allocated to coproducts by mass of milk solids. Plant-level engineering assessments of allocation fractions were adopted for major inputs such as electricity, natural gas, and chemicals. Revenue-based allocation was applied for the remaining in-plant processes.

Results and discussion

Greenhouse gas (GHG) emissions are of significant interest. For cheddar, as sold at retail (63.2 % milk solids), the carbon footprint using the IPCC 2007 factors is 8.60 kg CO₂e/kg cheese consumed with a 95 % confidence interval (CI) of 5.86–12.2 kg CO₂e/kg. For mozzarella, as sold at retail (51.4 % milk solids), the carbon footprint is 7.28 kg CO₂e/kg mozzarella consumed, with a 95 % CI of 5.13–9.89 kg CO₂e/kg. Normalization of the results based on the IMPACT 2002+ life cycle impact assessment (LCIA) framework suggests that nutrient emissions from both the farm and manufacturing facility wastewater treatment represent the most significant relative impacts across multiple environmental midpoint indicators. Raw milk is the major contributor to most impact categories; thus, efforts to reduce milk/cheese loss across the supply chain are important.

Conclusions

On-farm mitigation efforts around enteric methane, manure management, phosphorus and nitrogen runoff, and pesticides used on crops and livestock can also significantly reduce impacts. Water-related impacts such as depletion and eutrophication can be considered resource management issues—specifically of water quantity and nutrients. Thus, all opportunities for water conservation should be evaluated, and cheese manufacturers, while not having direct control over crop irrigation, the largest water consumption activity, can investigate the water use efficiency of the milk they procure. The regionalized normalization, based on annual US per capita cheese consumption, showed that eutrophication represents the largest relative impact driven by phosphorus runoff from agricultural fields and emissions associated with whey-processing wastewater. Therefore, incorporating best practices around phosphorous and nitrogen management could yield improvements.     

Why going beyond standard LCI databases is important: lessons from a meta-analysis of potable water supply system LCAs

Purpose

Our aim is to assess the comparability and generic applicability of harmonized published lifecycle assessment (LCA) studies on water supply systems. In the absence of localized life cycle inventories for water systems, generic or country specific databases may be inadequate if applied elsewhere. The objectives of this paper are to calculate the potential magnitude of errors introduced by this practice and recommend ways to better account for sources of impact variability.

Methods

In this study, harmonization has been carried out rigorously, utilizing a systematic differentiation of the subsystems, functional units, and system boundaries referenced in over 100 candidate studies, resulting in a comparable subset of 34 LCA studies. Statistical techniques (cluster analysis and Welch’s analysis of variance) were used to isolate and validate the main sources of variation in impact scores and identify the sub-systems in which these are most pronounced. The significance of technology-specific contribution to the impacts was compared to the significance of electricity as a contributing factor to the global warming potential (GWP) by applying statistical correlation analysis.

Results and discussion

Our review revealed that most of the published LCAs analyzed water systems in well-developed countries. Large variation was found in the impacts of water supply systems (e.g., GWP between 0.16 and 3.4 kg CO2-eq/m³ of supplied water), with mean value of 0.84 kg CO2-eq/m3 and median of 0.57 kg CO2-eq/m3. The main contributor to GWP is water production and desalination in particular, making water production the most important differentiating factor. Cluster analysis also showed that production technology is the most important differentiating factor with respect to terrestrial acidification, ozone depletion, eutrophication, and abiotic depletion impacts of water production systems. There is a weak correlation between impact scores of electricity mixes and entire water supply systems.

Conclusions

An LCA of water-intensive products drawing from a standard life cycle inventory databases could be substantially inaccurate, especially in a region with desalination. More accurate results can be achieved by taking local water production technology into account. Meta-analysis is a useful tool to explore the sources of variance in the impacts of water systems. Applying harmonized results is a cost-effective way for obtaining more accurate LCA results as compared to applying generic databases only.

     

Life cycle assessment of the supply and use of water in the Segura Basin

Purpose

In this paper, the combined life cycle assessment of the water supply alternatives and the water use in a water-stressed watershed in Spain (the Segura) is presented. Although it is a dry area, agriculture and tourism are very profitable sectors with high water demands. Thus, external water supply alternatives including water transfers or desalination partly balance the reduced natural water availability to cover the existing water demands.

Methods

In order to integrate both the impact of water supply alternatives and water use, the ReCiPe method was used to assess the water supply alternatives at the endpoint approach with the three specific damage categories: human health, ecosystem diversity and damage to resources availability. At the same time, the water use impact was calculated and grouped in the same categories. Firstly, one average cubic metre of water at the user's gate in the Segura Basin area was taken as the functional unit. As irrigation and drinking water constitute the principal water uses, it was considered that to separately analyse 1 m³ used for irrigation and 1 m³ destined to drinking purposes could provide interesting information. Then, these units were also considered as functional units. Then, three additional hypothetical scenarios were introduced: two of them defined by a strong variability in rainfall and the third by a sudden diminution of water transferred from a neighbouring basin.

Results and discussion

Regarding the facilities to provide 1 m³ at user's gate in the Segura Basin, results showed that the seawater desalination plants obtained the highest score for all the three considered damage categories, followed by the Tajo–Segura water transfer, the groundwater, the local surface waters and the water reuse. In relation to the water use impact, the damage to ecosystems diversity was very representative with respect to the one coming from water supply infrastructures because irrigation constituted 85 % of the total demand.

Conclusions

The diversification of water supply alternatives within a region considerably increases any environmental impact, primarily stemming from the additional required infrastructures, and frequently from the use of external water sources for their uses. Thus, users and policy makers should be aware of the costs that a guaranteed water supply entails. In water-scarce territories, the use of external solutions such as desalination or water transfer either increase the environmental impact due to their high energy consumption or they are limited by existing climate variability. Therefore, they cannot be considered as the definite solution, which would be a balance between renewable sources and existing demands.     

Vehicle manufacturing water use and consumption: an analysis based on data in automotive manufacturers’ sustainability reports

Purpose

The goal of this study is to develop an estimate of water use and consumption in automotive manufacturing to enhance the data quality of vehicle life cycle assessments that include life cycle water impacts. A benchmark is developed to compare water resources across manufacturing and nonproduction-related manufacturing processes, including an indication whether indirect water consumption due to electricity generation is significant.

Methods

Data from 12 original equipment manufacturers’ (OEM’s) sustainability reports are examined for the years 2006 to 2010. Distinctions are made between “water use” and “water consumption.” These factors are divided by total reported production to develop use and consumption values in cubic meter/vehicle for comparison. Additionally, total energy consumption is converted to indirect water consumption based on the water consumed in the generation of electricity for the electricity grid mix.

Results and discussion

Excluding outliers, average direct water use is 5.20 and 5.95 m³/vehicle for manufacturing and company-wide activities, respectively, with corresponding standard deviations of 1.42 and 1.20 m³/vehicle. Average direct water consumption was calculated to be 1.25 and 4.29 m³/vehicle for manufacturing and company-wide activities, respectively, with corresponding standard deviations of 0.52 and 1.56 m³/vehicle. Average indirect water consumption due to electricity consumption is found to be 2.21 m³/vehicle. Variability arises through different understandings on the words “consumption” and “use,” reporting continuity between years and in classification of data as it relates to manufacturing, nonmanufacturing, or company-wide activities.

Conclusions

These water values show that needs vary widely across OEMs. Additionally, the magnitude of the indirect water consumption results indicates that OEMs should focus on both indirect and direct water consumption to reduce their overall water footprint. The results also highlight the potential for significance and variability in indirect water consumption, in particular for “cradle-to-gate” type of impact assessments, dependent on electricity generation water consumption assumptions. It is hoped that with the introduction of water reporting standards like the International Organization of Standardization 14046, manufacturers will provide a more comprehensive summary of their water use and consumption in the future.     

Environmental life cycle assessment of a dairy product: the yoghurt

Purpose

The dairy sector covers multiple activities related to milk production and treatment for alimentary uses. Different dairy products are available in the markets, with yoghurt being the second most important in terms of production. The goal of this study was to analyse from a cradle-to-grave approach the environmental impacts and energy balance derived from the yoghurt (solid, stirred and drinking yoghurts) manufacture process in a specific dairy factory processing 100 % Portuguese raw milk.

Methods

The standard framework of life cycle assessment (LCA) was followed and inventory data were collected on site in the dairy factory and completed using the literature and databases. The following impact categories were evaluated adopting a CML method: abiotic depletion (ADP), acidification (AP), eutrophication (EP), global warming (GWP), ozone layer depletion (ODP), land competition (LC) and photochemical oxidants formation (POFP), with the energy analysis carried out based on the cumulative non-renewable fossil and nuclear energy demand (CED). A mass allocation approach was considered for the partitioning of the environmental burdens between the different products obtained since not only yoghurts are produced but also dairy fodder.

Results and discussion

The key processes from an environmental point of view were identified. Some of the potential results obtained were in line with other specific related studies where dairy systems were assessed from an LCA perspective. The production of the milk-based inputs (i.e. raw milk, concentrated and powdered milk) was the main factor responsible of the environmental loads and energy requirements, with remarkable contributions of 91 % of AP, 92 % of EP and 62 % of GWP. Other activities that have important environmental impacts include the production of the energy requirements in the dairy factory, packaging materials production and retailing. Potential alternatives were proposed in order to reduce the contributions to the environmental profile throughout the life cycle of the yoghurt. These alternatives were based on the minimisation of milk losses, reductions of distances travelled and energy consumption at retailing and household use, as well as changes to the formulation of the animal feed. All of these factors derived from light environmental reductions.

Conclusions

The main reductions of the environmental impact derived from yoghurt production can be primarily obtained at dairy farms, although important improvements could also be made at the dairy factory.     

Comparison of two ICT solutions: desktop PC versus thin client computing

Purpose

Information communication technology (ICT) offers the chance of enhancing the efficiency of public services and economic processes. The use of server-based computing is supposed to reduce the energy and material consumption in ICT services. This hypothesis will be investigated and quantified looking at the whole life cycle of the products. In this paper, server-based computing in combination with thin clients (SBCTC) is compared to a typical desktop PC (DPC) workplace over a time period of 5 years.

Materials and methods

The LCA method used in this paper is focused on the impact category of global warming potential. The calculations were performed using the Microsoft® Excel-based methodology for ecodesign of energy-related products tool. This tool includes the requirements of energy-related products (Directive 2009/125/EC). Moreover, an input-orientated method—material input per service unit (MIPS)—is applied which allows for an additional comparison between the two ICT solutions.

Results and discussion

Electricity consumption could be identified as a crucial environmental impact factor of DPC and SBCTC with both methods. Depending on the user behavior, more than 200 kg CO_2e can be saved by switching from DPC to SBCTC. Over 80 kg CO_2e can be saved in the material and extraction life cycle stage. The largest savings are achieved in the material category electronics (about 70 kg CO_2e). A correlation analysis between the results of global warming potential (GWP) and the MIPS category “air” shows that both indicators GWP and air lead to the same conclusions when evaluating life cycle stages and ICT material categories.

Conclusions

Taking into account all assumptions made in this paper, SBCTC saves more than 65 % of greenhouse gas emissions compared to DPC during the entire life cycle. To ensure further profound comparisons of the ICT solutions, current data on the energy demand and detailed information on the composition of the IT products should be made available by industry.     

Life cycle assessment of fuel ethanol from sugarcane in Argentina

Purpose

The production of bioethanol in Argentina is based on the sugarcane plantation system, with extensive use of agricultural land, scarce use of fertilizers, pesticides, and artificial irrigation, and burning of sugarcane prior to harvesting. The objective of this paper is to develop a life cycle assessment (LCA) of the fuel ethanol from sugarcane in Tucumán (Argentina), assessing the environmental impact potentials to identify which of them cause the main impacts.

Methods

Our approach innovatively combined knowledge about the main impact pathways of bioethanol production with LCA which covers the typical emission-related impact categories at the midpoint life cycle impact assessment. Real data from the Argentinean industry subsystems have been used to perform the study: S1—sugarcane production, S2—milling process, S3—sugar production, and S4—ethanol production from molasses, honey, or sugarcane juice.

Results and discussion

The results are shown in the three alternative pathways to produce bioethanol. Different impact categories are assessed, with global warming potential (GWP) having the highest impact. So, the production of 1 kg of ethanol from molasses emitted 22.5 kg CO₂ (pathway 1), 19.2 kg CO₂ from honey (pathway 2), and 15.0 kg CO₂ from sugarcane juice (pathway 3). Several sensitivity analyses to study the variability of the GWP according to the different cases studied have been performed (changing the agricultural yield, including economic and calorific allocation in sugar production, and modifying the sugar price).

Conclusions

Agriculture is the subsystem which shows the highest impact in almost all the categories due to fossil fuel consumption. When an economic and calorific allocation is considered to assess the environmental impact, the value is lower than when mass allocation is used because ethanol is relatively cheaper than sugars and it has higher calorific value.     

Reducing the impact of irrigated crops on freshwater availability: the case of Brazilian yellow melons

Purpose

This study quantifies freshwater consumption throughout the life cycle of Brazilian exported yellow melons and assesses the resulting impact on freshwater availability. Results are used to identify improvement options. Moreover, the study explores the further impact of variations in irrigation volume, yield, and production location.

Methods

The product system boundary encompasses production of seeds, seedlings, and melon plants; melon packing; disposal of solid farm waste; and farm input and melon transportation to European ports. The primary data in the study were collected from farmers in order to quantify freshwater consumption related to packing and to production of seeds, seedlings, and melons. Open-field melon irrigation was also estimated, considering the region's climate and soil characteristics. Estimated and current water consumptions were compared in order to identify impact reduction opportunities. Sensitivity analysis was used to evaluate variations in the impact because of changes in melon field irrigation, yield, and farm location.

Results and discussion

This study shows that the average impact on freshwater availability of 1 kg of exported Brazilian yellow melons is 135 l H₂O-e, with a range from 17 to 224 l H₂O-e depending on the growing season's production period. Irrigation during plant production accounts for 98 % of this impact. Current melon field water consumption in the Low Jaguaribe and Açu region is at least 39 % higher than necessary, which affects the quality of fruits and yield. The impact of melon production in other world regions on freshwater availability may range from 0.3 l H₂O-e/kg in Costa Rica to 466 l H₂O-e/kg in the USA.

Conclusions

The impact of temporary crops, such as melons, on water availability should be presented in ranges, instead of as an average, since regional consumptive water and water stress variations occur in different growing season periods. Current and estimated water consumption for irrigation may also be compared in order to identify opportunities to achieve optimization and reduce water availability impact.     

A methodology for separating uncertainty and variability in the life cycle greenhouse gas emissions of coal-fueled power generation in the USA

Purpose

Results of life cycle assessments (LCAs) of power generation technologies are increasingly reported in terms of typical values and possible ranges. Extents of these ranges result from both variability and uncertainty. Uncertainty may be reduced via additional research. However, variability is a characteristic of supply chains as they exist; as such, it cannot be reduced without modifying existing systems. The goal of this study is to separately quantify uncertainty and variability in LCA.

Methods

In this paper, we present a novel method for differentiating uncertainty from variability in life cycle assessments of coal-fueled power generation, with a specific focus on greenhouse gas emissions. Individual coal supply chains were analyzed for 364 US coal power plants. Uncertainty in CO₂ and CH₄ emissions throughout these supply chains was quantified via Monte Carlo simulation. The method may be used to identify key factors that drive the range of life cycle emissions as well as the limits of precision of an LCA.

Results and discussion

Using this method, we statistically characterized the carbon footprint of coal power in the USA in 2009. Our method reveals that the average carbon footprint of coal power (100 year time horizon) ranges from 0.97 to 1.69 kg CO₂eq/kWh of generated electricity (95 % confidence interval), primarily due to variability in plant efficiency. Uncertainty in the carbon footprints of individual plants spans a factor of 1.04 for the least uncertain plant footprint to a factor of 1.2 for the most uncertain plant footprint (95 % uncertainty intervals). The uncertainty in the total carbon footprint of all US coal power plants spans a factor of 1.05.

Conclusions

We have developed and successfully implemented a framework for separating uncertainty and variability in the carbon footprint of coal-fired power plants. Reduction of uncertainty will not substantially reduce the range of predicted emissions. The range can only be reduced via substantial changes to the US coal power infrastructure. The finding that variability is larger than uncertainty can obviously not be generalized to other product systems and impact categories. Our framework can, however, be used to assess the relative influence of uncertainty and variability for a whole range of product systems and environmental impacts.     

Consequential cradle-to-gate carbon footprint of water treatment chemicals using simple and complex marginal technologies for electricity supply

Purpose

Chemicals produced via chlor-alkali electrolysis are widely used throughout the water industry worldwide, with treatment chemicals often the second largest source of environmental impacts from potable water production after electricity use. Population-driven increases in the future demand for potable water will require concomitant increases in the production of water treatment chemicals, with the associated environmental impacts of chemicals production primarily arising from the additional demand for electricity. Due to the dominance of electricity in the environmental performance of chlor-alkali chemicals, assessment of the future environmental impacts of potable water production is largely dependent on proper identification of the marginal source of electricity. In this paper, we present a consequential cradle-to-gate carbon footprint (cCF) for the most widely used chlor-alkali-produced disinfectant (sodium hypochlorite (13 % w/w)) and coagulant (ferric chloride (42 % w/w)) in Australia, with special emphasis placed upon the identification of future marginal electricity supply and the substitution of hydrogen gas and sodium hydroxide during production. While this analysis is presented in an Australian context, commonalities in potable water and chlor-alkali chemical production processes internationally give the findings a broader relevance.

Methods

Consequential models for sodium hypochlorite (13 % w/w) and ferric chloride (42 % w/w) production were developed, and the identification of the marginal source of electricity was modelled using a “simple marginal technology” approach via operationalisation of the Weidema framework and a “complex marginal technology” using a partial equilibrium model. For the simple marginal technology, the levelised cost of electricity was used to select the most competitive energy generation technologies and those most relevant for the Australian market. For the complex marginal technology, the energy sector model was used to simulate the most likely electricity supply mix. Details of the different paths taken in the substitution of hydrogen gas and sodium hydroxide are also presented. To allow for proper incorporation of uncertainties arising from these key factors in the cCF, several scenarios were developed covering fuel and carbon prices for identifying the marginal supply mix of electricity, as well as the likely production routes for sodium carbonate in the context of sodium hydroxide substitution.

Results and discussion

cCF results of sodium hypochlorite (13 % w/w) and ferric chloride (42 % w/w) are presented using simple and complex marginal technologies, and the implications of choosing one marginal technology over the other in the context of water treatment chemicals are presented. For the simple marginal technology approach, the global warming potential (GWP) per megagram of chemical varied from 68 to 429 kg CO₂-eq for sodium hypochlorite (13 % w/w) and 59–1,020 kg CO₂-eq for ferric chloride (42 % w/w). For the complex marginal technology approach, the GWP per megagram of chemical varied from 266 to 332 kg CO₂-eq for sodium hypochlorite (13 % w/w) and 214–629 kg CO₂-eq for ferric chloride (42 % w/w). Insights are given in relation to the impact of the price of fossil fuels, the carbon price, and the different substitution routes.

Conclusions

The use of a partial equilibrium model (PEM) has enabled a better understanding of the variability of the results in this study. For example, the use of PEM for the identification of the complex marginal source of electricity shows that, for the case of Australia, any benefit from a carbon price is lost with high prices of natural gas due to the incentive to use cheaper fuels such as black and brown coal. Likewise, the use of explorative scenarios was decisive to manage the inherent uncertainty of the parameters included in the model. In relation to substitution, the case of ferric chloride (42 % w/w) indicated that using only one substitution route was not enough to fully understand the potential continuum of cCF results. The simple marginal approach, where an exclusive marginal source of electricity or substitution route is considered, presents significant risks for the modelling accuracy of the cCF as shown here for sodium hypochlorite (13 % w/w) and ferric chloride (42 % w/w), therefore, it is not recommended.     

Cradle-to-gate assessment of environmental impacts for a broad set of biomass-to-product process chains

Purpose

This study advocates a modular approach combining unit processes as building blocks to formulate biomass process chains. This approach facilitates a transparent environmental life cycle impact assessment for bio-based products. It also enhances the ability to develop and assess more complex biorefinery systems, identifies critical parameters and offers useful material to support environmental impact assessment in early design stages.

Methods

Twenty-three different products were assessed with regard to the environmental burden associated with their production paths. Life cycle inventories (LCIs) for 32 unit processes were compiled (using information from pilot plants, simulation and literature data) and organized in biomass process chains. Then, 58 study systems were formed based on various combinations of the unit processes, each study system referring to the production of a selected product. Three indicators were used for quantification of the impacts: non-renewable fossil cumulative energy demand (CED), global warming potential (GWP) and water depletion as defined in the ReCiPe method.

Results and discussion

Factors influencing the variation of results even for similar products are discussed (e.g. production path and allocation method lead to a range of GWP values for ethylene production from 0.43 to 3.37 kg CO₂ eq/kg ethylene). For the majority of bio-products, CED has lower values than fossil-based equivalents (average difference 39–70 MJ eq/kg product depending on the allocation method), while mixed trends are obtained for the GWP and water depletion indicators. Assessments also highlight attributes that have a significant effect in the environmental profile of a production path such as the synthesis path, the process chemistry (water intensity) and process-related factors (energy intensity, degree of energy integration/heat recovery).

Conclusions

The analysis of impacts per unit process is able to demonstrate the particular production stages featuring high environmental intensities along a path further hinting to suggestions for amendments and improvements from an overall performance perspective. The study makes a useful source for biorefinery design studies especially in adopting a modular approach to represent and to analyse biomass process chains; it also provides a reference point for comparison (benchmarking) between different process technologies for biomass utilization. Finally, the analysis is compatible with the standards of the LCA methodology, and it is based on the use of the most common LCA databases, which facilitates the comparison of the results with other relevant studies.

     

Life cycle assessment of biodiesel production from beef tallow in Brazil

Purpose

Renewable energy sources, particularly biofuels, are being promoted as possible solutions to address global warming and the depletion of petroleum resources. In this context, biodiesel is a solution to the growing demand for renewable fuels. Beef tallow is the second leading raw material after soybean oil used in biodiesel production in Brazil. Evaluating and addressing the environmental impacts of beef tallow biodiesel are of great importance for its life cycle impact assessment (LCIA).

Methods

Inventory data on tallow and biodiesel production were collected from the literature and from a primary data source provided by a Brazilian biodiesel plant. The modeled system represents the Brazilian reality for the 2005–2015 decade. Subsequently, the environmental impacts of beef tallow biodiesel production were characterized for a selection of environmental impact indicators: global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), and water footprint (assessed based on blue water use (BWU) and blue water consumption (BWC) indicators). From the characterization of these environmental burdens, the main sources of environmental impact were evaluated. Sensitivity analysis was conducted to verify the influence of key parameters (emission factor, energy consumption, and prices) on changes in the environmental load of beef tallow biodiesel.

Results and discussion

Carbon flux results indicate that beef tallow biodiesel production acts as a carbon source. Namely, pasture carbon uptake (91% of all carbon input) is lower than combined biogenic and fossil CO₂ emissions, which are controlled by cattle enteric fermentation as methane (72%) and by thermal energy processes (25%). Otherwise, thermal energy production accounts for 80% of total AP emissions, and cattle urine and manure are responsible for 70% of total EP emissions. The BWC and BWU water footprints of the whole process are controlled by electricity usage, which was greater than 90% for each indicator due to the high proportion of total energy (70%) derived from hydropower in Brazil. The environmental burden from transportation is minimal compared to other processes. Tallow biodiesel GWP can be improved if the carbon uptake potential from grass and low fertilizer utilization are accurately considered, as observed in the sensitivity analysis. For each MJ of beef tallow biodiesel produced, 4.6 g of CO₂ is released to the atmosphere.

Conclusions

Methane emissions, mainly due to cattle enteric fermentation, and thermal energy processes at the industrial units were the main sources of environmental GWP, AP, and EP impacts. Otherwise, water footprint indicators were associated with the high proportion of total energy derived from hydropower in Brazil.

     

Life cycle assessment of commodity chemical production from forest residue via fast pyrolysis

Purpose

This life cycle assessment evaluates and quantifies the environmental impacts of renewable chemical production from forest residue via fast pyrolysis with hydrotreating/fluidized catalytic cracking (FCC) pathway.

Methods

The assessment input data are taken from Aspen Plus and greenhouse gases, regulated emissions, and energy use in transportation (GREET) model. The SimaPro 7.3 software is employed to evaluate the environmental impacts.

Results and discussion

The results indicate that the net fossil energy input is 34.8 MJ to produce 1 kg of chemicals, and the net global warming potential (GWP) is ?0.53 kg CO₂ eq. per kg chemicals produced under the proposed chemical production pathway. Sensitivity analysis indicates that bio-oil yields and chemical yields play the most important roles in the greenhouse gas footprints.

Conclusions

Fossil energy consumption and greenhouse gas (GHG) emissions can be reduced if commodity chemicals are produced via forest residue fast pyrolysis with hydrotreating/FCC pathway in place of conventional petroleum-based production pathways.     

LCA case study. Part 2: environmental footprint and carbon tax of cradle-to-gate for composite and stainless steel I-beams

Purpose

Part 1 of this research investigated environmental footprint for the cradle-to-grave of a linear metre I-beam made from traditional and alternative materials which are stainless steel (316) and glass reinforced plastics (GRP). Results revealed that GRP generally produced less environmental footprint than stainless steel. The main contribution found in the cradle-to-gate caused by raw materials (90 %) and associated transportation (10 %). Certain impact categories of GRP were either equalled or higher than stainless steel I-beam including the climate change impact category. Therefore, part 2 of this research further investigates the ecological and economic hot spots of the cradle-to-gate of GRP I-beam and alternative supply chain scenarios. The potential carbon tax was also estimated under two different situations.

Methods

GRP and stainless steel (316) are used to assess the environmental footprint and the economic impact of 6,098 m I-beams as a production volume in practice. The World ReCiPe midpoint and endpoint methods generated the life cycle inventory, characteristic and single score results for the environmental footprint. The economic impact estimated based on a simple cost calculation associated with the cradle-to-gate including material, production and transportation costs. The ecological and economic hot spots were identified and formed 12 supply chain scenarios.

Results and discussion

Both identified hot spots came from raw materials that used in large quantities, consumed higher electricity and delivered by road and water transportation over long travel distances. The climate change impact category and the potential carbon tax values are improved under the scenarios that use a supplier from countries that generate electricity from less coal-based energy source and involve less transportation in delivering the raw materials.

Conclusions

Win–win and trade-off scenarios were revealed when comparing both impacts. The former scenario reduces material costs, the travel distances and using lower freight rate transportation that consumes less fuel such as shipping. The latter scenarios are often occurred by either attempting to reduce the environmental footprint from using less transportation but the raw material costs are suffered. Manufacturers may select the scenario based on their production constrains. Cradle-to-grave was discussed and shown the benefits in including steel recycling into the assessment which can equate the potential carbon tax of the stainless steel with some GRP I-beam scenarios. Future work can be enhanced by considering other factors in the practice of manufacturing system such as insurance cost and lead time.     

Life cycle environmental impacts of decommissioning Magnox nuclear power plants in the UK

Purpose

Full life cycle assessment (LCA) impacts from decommissioning have rarely been assessed, largely because few sites have been decommissioned so that the impacts of decommissioning are currently uncertain. This paper presents the results of an LCA study of the ongoing decommissioning of the Magnox power plant at Trawsfynydd in the UK. These results have been used to estimate the potential environmental impacts for the whole UK Magnox fleet of 11 reactors that will have to be decommissioned during this century.

Methods

The functional unit is defined as ‘decommissioning one Magnox power plant’. The system boundary considers all stages in the life cycle of decommissioning, including site management, waste retrieval, plant deconstruction, packaging and storage of intermediate- and low-level wastes (ILW and LLW). High-level waste, i.e. waste fuel is excluded as it was being removed from the site to be reprocessed at Sellafield. The environmental impacts have been estimated using the CML 2001 methodology. Primary data have been sourced from the Trawsfynydd site and the background from Ecoinvent.

Results and discussion

Most impacts from decommissioning are due to the plant deconstruction (25–75 %) and ILW storage and disposal (25–70 %). For the example of global warming potential (GWP), estimated at 241 kt CO₂ eq./functional unit, or 3.5 g CO₂ eq./kWh of electricity generated during the lifetime of the plant, 55 % of the impact is from plant deconstruction and 30 % from ILW disposal. The results for the whole UK Magnox fleet indicate that the impacts vary greatly for different sites. For example, the GWP ranges from 0.89 to 7.14 g CO₂ eq./kWh. If the impacts from storage of waste fuel at Sellafield are included in the estimates, the GWP increases on average by four times. Overall, decommissioning of the UK Magnox reactors would generate 2 Mt of CO₂ eq. without and 11 Mt of CO₂ eq. with the waste from Sellafield. This represents 0.4 and 2 % of the total UK annual emissions, respectively.

Conclusions

The impacts of decommissioning can vary greatly at different sites depending on the amount of waste and electricity generated by the plants. Delaying decommissioning to allow the energy system to decarbonise could reduce the environmental impacts, e.g. GWP could be reduced by 50 %. The impacts could also be reduced by reducing the volume of waste and increasing recycling of materials. For example, recycling 70 % of steel would reduce the impacts on average by 34 %.     

LCA case study. Part 1: cradle-to-grave environmental footprint analysis of composites and stainless steel I-beams

Purpose

I-beams for outdoor structures are traditionally made from conventional materials such as stainless steel due to its high strength and corrosive resistant properties. Alternatively, the I-beam can also be made from composite materials such as glass-reinforced plastics (GRP), which provide similar properties under a lighter weight and a lower cost condition. Nonetheless, their environmental footprint performance depends largely on activities involved during their life cycle. Therefore, the findings are presented in two parts: Part 1 and 2. This paper is about Part 1, which presents the environmental footprint for the cradle-to-grave of one linear metre I-beam that is made from two materials namely stainless steel (316) and GRP. Part 2, which will be submitted as a separate paper, has specifically analysed their environmental and economic impacts for the different cradle-to-gate scenarios and the potential carbon tax.

Materials and methods

Materials that were used to compare the environmental footprint of an I-beam are GRP and stainless steel (316). Their cradle-to-grave activities included raw material extraction, supplier transportation, manufacturing process, distribution, disposal transportation and process. Input data were based on data provided by a composites company in Australia, the Ecoinvent 2.2 and Australian data 2007 databases. The World ReCiPe midpoint and endpoint methods were used to assess the environmental footprint.

Results and discussion

The environmental footprint results for the cradle-to-grave of the I-beams are presented as a contribution percentage of the single score unit in the total and damage category levels which produced by the endpoint method. The characteristic and normalisation results were also generated for all impact categories by the midpoint method.

Conclusions

Overall, the cradle-to-grave results show that the composite I-beam produces 20 % less environmental footprint than that of the stainless steel I-beam. The human health damage category is affected the most due to the main contribution from the material stage. The cradle-to-gate results are contributed by 90 % from raw material extraction, 7 % from the manufacturing process and 3 % from the supplier transportation. In terms of the characteristic results, the composite I-beam produces less environmental impact in most of the impact categories except for the climate change, photochemical oxidant formation, terrestrial acidification, marine eutrophication, natural land transformation and fossil depletion. Therefore, the influential parameters of these impact categories are investigated further in Part 2 where the environmental footprint and economic impact are estimated for different cradle-to-gate scenarios of the I-beams.     

Life cycle assessment of a large,thin ceramic tile with advantageous technological properties

Purpose

Ceramic tiles play a strategic role in the Italian market; currently, the Italian production is of 367.2 million m² (Confindustria Ceramica 2012). In 2009, Italy was positioned as the world’s fourth largest producer of ceramic tiles, producing 368 million m² of the world’s total production of 1,735 million m² Giacomini (Ceram World Rev 88:52–68, 2010). Therefore, there is an ongoing effort to create innovations in the products offered and their manufacturing processes, in order to better compete on the market and to create eco-friendly products. Recently, the Italian Ceramic District has increased its focus on environmental issues with the aim of protecting natural resources and reducing the energy and material consumption. For this reason, a new product was born in the Italian Ceramic District, namely, a large thin ceramic tile (dimensions 1,000 mm?×?3,000 mm?×?3.5 mm) reinforced with a fibreglass backing, which gives the product excellent resistance and flexibility properties. The aim was to manufacture a new product with lower environmental impact than the traditional one. The production of a large thin ceramic tile requires, in fact, a lower quantity of materials, transports and energy consumptions comparing to the same metres square of traditional ceramic tile. At the present, no comparative life cycle assessment (LCA) studies have been performed between traditional and innovative ceramic stoneware tiles. This study analyses, for the first time, a life cycle of the innovative ceramic product (porcelain stoneware) developed by a company of the Italian Ceramic District.

Methods

The analysis is performed using the LCA methodology, in order to identify environmental impacts, energy consumption and CO₂ equivalent emissions that occur during extraction of raw materials, transportation, production, material handling, distribution and end-of-life stages within a cradle to grave perspective.

Results and conclusions

LCA analysis indicates that the highest environmental impact mainly affects the respiratory inorganics impact category due to base slip production (27.62 %), caused by the transport of the raw materials and by non-renewable impact category due to both the pasting phase (21.31 %) and the two-component adhesive manufacture. The major greenhouse gas (GHG) emissions are related to the production of polyurethane, a component of the adhesive used in the pasting stage, and to the natural gas consumption in the firing process.     

Assessing environmental impacts associated with freshwater consumption along the life cycle of animal products: the case of Dutch milk production in Noord-Brabant

Purpose

The assessment of water footprints of a wide range of products has increased awareness on preserving freshwater as a resource. The water footprint of a product was originally defined by Hoekstra and Hung (2002) as the sum of the volumetric water use in terms of green, blue and grey water along the entire life cycle of a product and, as such, does not determine the environmental impact associated with freshwater use. Recently, several papers were published that describe building blocks that enable assessment of the site-specific environmental impact associated with freshwater use along the life cycle of a global food chain, such as the impact on human health (HH), ecosystem quality (EQ) or resource depletion (RD). We integrated this knowledge to enable an assessment of the environmental impact associated with freshwater use along the life cycle of milk production, as a case for a global food chain.

Material and methods

Our approach innovatively combined knowledge about the main impact pathways of freshwater use in life cycle assessment (LCA), knowledge about site-specific freshwater impacts and knowledge about modelling of irrigation requirements of global feed crops to assess freshwater impacts along the life cycle of milk production. We evaluated a Dutch model farm situated on loamy sand in the province of Noord-Brabant, where grass and maize land is commonly irrigated.

Results and discussion

Production of 1 kg of fat-and-protein corrected milk (FPCM) on the model farm in Noord-Brabant required 66 L of consumptive water. About 76 % of this water was used for irrigation during roughage cultivation, 15 % for production of concentrates and 8 % for drinking and cleaning services. Consumptive water use related to production of purchased diesel, gas, electricity and fertiliser was negligible (i.e. total 1 %). Production of 1 kg of FPCM resulted in an impact on HH of 0.8?×?10^?9 disability adjusted life years, on EQ of 12.9?×?10^?3 m²?×?year and on RD of 6.7 kJ. The impact of producing this kilogram of FPCM on RD, for example, was caused mainly by cultivation of concentrate ingredients, and appeared lower than the average impact on RD of production of 1 kg of broccoli in Spain.

Conclusions

Integration of existing knowledge from diverse science fields enabled an assessment of freshwater impacts along the life cycle of a global food chain, such as Dutch milk production, and appeared useful to determine its environmental hotspots. Results from this case study support earlier findings that LCA needs to go beyond simple water volume accounting when the focus is on freshwater scarcity. The approach used, however, required high-resolution inventory global data (i.e. especially regarding crop yield, soil type and root depth), and demonstrated a trade-off between scientific quality of results and applicability of the assessment method.     

Environmental impacts of German food consumption and food losses

Purpose

The objective was to assess the environmental burden of food consumption and food losses in Germany with the aim to define measures to reduce environmentally relevant food losses. To support the finding of measurements, the study provides differentiated information on life phases (agriculture, processing, retailer, and consumption), consumption places (in-house and out-of-home), and the average German food basket consisting of eight food categories.

Methods

In order to obtain information on the environmental impacts of German food consumption, the study analyzed the material flows of the food products in the German food basket starting from consumption phase and going backwards until agricultural production. The analysis includes all relevant impact categories such as GWP, freshwater and marine eutrophication, particular matter formation, and agricultural land and water use. The life stages consumers, retail, wholesale, food production, and agriculture have been taken into account. Furthermore, transports to and within Germany have been considered. Consumption and production data have been taken from the German income and consumption sample, German production and trade statistics, and studies recently carried out on food losses. In order to model German food consumption, some simplifications had to be done.

Results and discussion

Results show that German food consumption is responsible for 2.7 t of greenhouse gases per person and year. Fourteen cubic meters of blue water is used for agricultural food production per person, and 2673 m² of agricultural land is occupied each year per German for food consumption. Between 14 and 20 % of the environmental burdens (depending on the impact category) result from food losses along the value chain. Out-of-home consumption is responsible for 8 to 28 % of the total environmental impacts (depending on the impact category). In particular, animal products cause high environmental burdens. Regarding life cycle phases, agriculture and consumption cause the highest impacts: together, they are responsible for more than 87 % of the total environmental burdens.

Conclusions

The study shows that food production and consumption as well as food losses along the value chain are of high relevance regarding Germany’s environmental impacts. In particular, animal products are responsible for high environmental burdens. Thus, with respect to reducing environmentally relevant food losses, measures should focus in particular on the reduction of food waste of animal origin. The most relevant life cycle phases to reduce environmental impacts are agricultural production and consumption in households and out-of-home.

     

Effects of nano-sized zero-valent iron on DDT degradation and residual toxicity in soil: a column experiment

Background and aims

Nanoscale zero-valent iron (nZVI) application is a promising technology for degradation of chlorinated contaminants in soil. Plants also play an important role in soil remediation and nZVI should not adversely affect plants growing on treated soils. Large amounts of DDT are still found in certain soils and means to remediate these soils are limited. Our aims were to investigate the effect of nZVI on DDT degradation and evaluate possible negative effects of nZVI on plants.

Methods

Columns with spiked (20 mg DDT kg^?1) soil were percolated with nZVI (1 g nZVI L^?1) and leached with five pore volumes of water to assess leaching of nZVI and residual toxicity of leachates and soil to plants using seed germination and plant growth tests (barley, flax).

Results

Addition of nZVI led to degradation of 45 % of the added DDT. Percolation with water significantly oxidized and transported iron through the columns. The first leachates had negative effects on plant development, but after leaching with 4 pore volumes, neither soil nor leachates affected plant negatively.

Conclusions

nZVI is efficient for degradation of DDT and adverse effects of nZVI on plants seem ephemeral and are alleviated after oxidation mediated by percolating water.