Life cycle assessment of composite packaging waste management—a Chinese case study on aseptic packaging

Purpose

Approximately 46,000 t/day of packaging waste was generated in China in 2010, of which, 2,500 t was composite packaging waste. Due to the lack of recycling technology and an imperfect recovery system, most of this waste is processed in sanitary landfills. An effective packaging waste management system is needed since this waste not only uses up valuable resources, but also increases environmental pollution. The purpose of this study is to estimate the environmental impact of the treatment scenarios in composite packaging waste which are commonly used in China, to determine the optimum composite packaging waste management strategy, and to design new separating and recycling technology for composite packaging, based on the life cycle assessment (LCA) results.

Methods

To identify the best treatment for composite packaging waste, the LCA software SimaPro 7.1.6 was used to assist in the analysis of the environmental impacts, coupled with the impact assessment method Eco-Indicator 99. LCA for composite packaging waste management was carried out by estimating the environmental impacts of the four scenarios most often used in China: landfill, incineration, paper recycling, and separation of polyethylene and aluminum. One ton of post-consumption Tetra Pak waste was selected as the functional unit. The data on the mass, energy fluxes, and environmental emissions were obtained from literature and site investigations.

Results and discussion

Landfill—scenario 1—was the worst waste management option. Paper recycling—scenario 3—was more environmentally friendly than incineration, scenario 2. Scenario 4, separating out polyethylene and aluminum, was established based on the LCA result, and inventory data were obtained from the demonstration project built by this research. In scenario 4, the demonstration project for the separation of polyethylene and aluminum was built based on the optimum conditions from single-factor and orthogonal experiments. Adding this flow process into the life cycle of composite packaging waste treatment decreased the environmental impacts significantly.

Conclusions

The research results can provide useful scientific information for policymakers in China to make decisions regarding composite packaging waste. Incineration could reduce more environmental impacts in the respiratory inorganics category, and separation of polyethylene and aluminum, in the fossil fuel category. If energy saving is the primary governmental goal, the separation of polyethylene and aluminum would be the better choice, while incineration would be the better choice for emission reduction.     

Environmental impacts of end-of-life vehicles’ management: recovery versus elimination

Purpose

In Portugal, the management of end-of-life vehicles (ELV) is set out in targets of the European Union policy for the year 2015, including 85 % recycling, 95 % recovery, and maximum of 5 % landfilling. These goals will be attained only through more efficient technologies for waste separation and recycling of shredder residues or higher rates of dismantling components. Focusing on this last alternative, a field experiment was carried out. There is potential for additional recycling/recovery of 10 %.

Methods

Three scenarios were proposed for the management of ELV wastes: (1) scenario 1 corresponds to the baseline and refers to the current management, i.e., the 10 % of ELV wastes are shredded whereby some ferrous and non-ferrous metals are recovered and the remaining fraction, called automotive shredder residues (ASR), is landfilled, (2) scenario 2 wherein the ASR fraction is incinerated with energy recovery, and (3) scenario 3 includes the additional dismantling of components for recycling and for energy recovery through solid recovered fuel, to be used as a fuel substitute in the cement industry. The environmental performance of these scenarios was quantified by using the life cycle assessment methodology. Five impact categories were assessed: abiotic resource depletion, climate change, photochemical oxidant creation, acidification, and eutrophication.

Results and discussion

Compared to the other scenarios, in scenario 1 no benefits for the impact categories of climate change and eutrophication were observed. Scenario 2 has environmental credits due to the recycling of ferrous and non-ferrous metals and benefits from energy recovery. However, this scenario has a significant impact on climate change due to emissions from thermal oxidation of polymeric materials present in the ASR fraction. A net environmental performance upgrading seems to be ensured by scenario 3, mainly due to replacing fossil fuel by solid recovered fuel.

Conclusions

The proposed additional dismantling of ELV (scenario 3) not only brings environmental benefits but also meets the European recovery and recycling targets. The associated increase of dismantling costs can be compensated by the additional recycling material revenues as well as social benefits by a rise in employment.     

Environmental impact and cost assessment of incineration and ethanol production as municipal solid waste management strategies

Purpose

Municipal solid waste (MSW) can be handled with several traditional management strategies, including landfilling, incineration, and recycling. Ethanol production from MSW is a novel strategy that has been proposed and researched for practical use; however, MSW ethanol plants are not widely applied in practice. Thus, this study has been conducted to analyze and compare the environmental and economic performance of incineration and ethanol production as alternatives to landfilling MSW.

Methods

The ISO 14040 life cycle assessment framework is employed to conduct the environmental impact assessment of three different scenarios for the two MSW management strategies based on processing 1 ton of MSW as the functional unit. The first scenario models the process of incinerating MSW and recovering energy in the form of process heat; the second scenario also includes the process of incinerating MSW but yields in the recovery of energy in the form of electricity; and the third scenario models the process of converting MSW into ethanol. The economic impacts of each scenario are then assessed by performing benefit-to-cost ratio (BCR) and net present value (NPV) analyses.

Results and discussion

The results from the environmental impact assessment of each scenario reveal that scenario 2 has the highest benefits for resource availability while scenario 3 is shown to be the best alternative to avoid human health and ecosystems diversity impacts. Scenario 1 has the worst environmental performance with respect to each of these environmental endpoint indicators and has net environmental impacts. The results of the economic analysis indicate that the third scenario is the best option with respect to BCR and NPV, followed by scenarios 2 and 1, respectively. Furthermore, environmental and economic analysis results are shown to be sensitive to MSW composition.

Conclusions

It appears municipalities should prefer MSW incineration with electricity generation or MSW-to-ethanol conversion over MSW incineration with heat recovery as an alternative to landfilling. The contradiction between the environmental impact assessment results and economic analysis results demonstrates that the decision-making process is sensitive to a broad set of variables. Decisions for a specific MSW management system are subject to facility location and size, MSW composition, energy prices, and governmental policies.     

Life cycle assessment of a steam thermolysis process to recover carbon fibers from carbon fiber-reinforced polymer waste

Purpose

Carbon fibers have been widely used in composite materials, such as carbon fiber-reinforced polymer (CFRP). Therefore, a considerable amount of CFRP waste has been generated. Different recycling technologies have been proposed to treat the CFRP waste and recover carbon fibers for reuse in other applications. This study aims to perform a life cycle assessment (LCA) to evaluate the environmental impacts of recycling carbon fibers from CFRP waste by steam thermolysis, which is a recycling process developed in France.

Methods

The LCA is performed by comparing a scenario where the CFRP waste is recycled by steam-thermolysis with other where the CFRP waste is directly disposed in landfill and incineration. The functional unit set for this study is 2 kg of composite. The inventory analysis is established for the different phases of the two scenarios considered in the study, such as the manufacturing phase, the recycling phase, and the end-of-life phase. The input and output flows associated with each elementary process are standardized to the functional unit. The life cycle impact assessment (LCIA) is performed using the SimaPro software and the Ecoinvent 3 database by the implementation of the CML-IA baseline LCIA method and the ILCD 2011 midpoint LCIA method.

Results and discussion

Despite that the addition of recycling phase produces non-negligible environmental impacts, the impact assessment shows that, overall, the scenario with recycling is less impactful on the environment than the scenario without recycling. The recycling of CFRP waste reduces between 25 and 30% of the impacts and requires about 25% less energy. The two LCIA methods used, CML-IA baseline and ILCD 2011 midpoint, lead to similar results, allowing the verification of the robustness and reliability of the LCIA results.

Conclusions

The recycling of composite materials with recovery of carbon fibers brings evident advantages from an environmental point of view. Although this study presents some limitations, the LCA conducted allows the evaluation of potential environmental impacts of steam thermolysis recycling process in comparison with a scenario where the composites are directly sent to final disposal. The proposed approach can be scaled up to be used in other life cycle assessments, such as in industrial scales, and furthermore to compare the steam thermolysis to other recycling processes.

     

Discussion on methods to include prevention activities in waste management LCA

Purpose

Waste prevention has been assigned increasing attention worldwide during recent years, and it is expected to become one of the core elements of waste management planning in the near future. In this framework, this paper presents and discusses two possible LCA approaches for the evaluation of the environmental and energetic performance of municipal solid waste (MSW) management systems which include the effects of waste prevention activities.

Methods

The two approaches are conceived for the comparison of waste management scenarios including waste prevention activities with baseline scenarios without waste prevention. For both of them, the functional unit is defined and the system boundaries are described with reference to different typologies of waste prevention activities identified in an extensive review. The procedure for the calculation of the LCA impacts of scenarios is also reported and an example illustrating the processes to be included in system boundaries for a specific waste prevention activity is provided.

Results and discussion

The presented approaches lead to the same result in terms of difference between the LCA impacts of a waste prevention scenario and of a baseline one. However, because of the partially different upstream system boundaries, different values of the impacts of single scenarios are obtained and the application of the two approaches is more suitable in different situations and in analyses with different purposes. The methodological aspects that can complicate the applicability of the two approaches are discussed lastly.

Conclusions

The environmental and energetic performance of MSW management scenarios including waste prevention activities can be evaluated with the two LCA approaches presented in this paper. They can be used for many purposes such as, among the most general, evaluating the upstream and downstream environmental consequences of implementing particular waste prevention activities in a given waste management system, complementing waste reduction indicators with LCA-based indicators and supporting with quantitative evidence the strategic and policy relevance of waste prevention.     

A life cycle assessment of residential waste management and prevention

Purpose

The oft-cited waste hierarchy is considered an important rule of thumb to identify preferential waste management options and places waste prevention at the top. Nevertheless, it has been claimed that waste prevention can sometimes be less favorable than recycling because (1) recycling decreases only the primary production of materials, whereas waste prevention may reduce a combination of both primary and low-impact secondary production, and (2) waste prevention decreases the quantity of material recycled downstream and the avoided impacts associated with recycling. In response to this claim, this study evaluates the life cycle effects of waste prevention activities (WPAs) on a residential waste management system.

Methods

This life cycle assessment (LCA) contrasts the net impacts of a large residential solid waste management system (including sanitary landfilling, anaerobic digestion, composting, and recycling) with a system that incorporates five WPAs, implemented at plausible levels (preventing a total of 3.6 % of waste generation tonnage) without diminishing product service consumption. WPAs addressed in this LCA reduce the collected tonnage of addressed advertising mail, disposable plastic shopping bags, newspapers, wine and spirit packaging, and yard waste (grass).

Results and discussion

In all cases, the WPAs reduce the net midpoint and endpoint level impacts of the residential waste management system. If WPAs are incorporated, the lower impacts from waste collection, transportation, sorting, and disposal as well as from the avoided upstream production of goods, more than compensate for the diminished net benefits associated with recycling and the displaced electricity from landfill gas utilization.

Conclusions

The results substantiate the uppermost placement of waste prevention within the waste hierarchy. Moreover, further environmental benefits from waste prevention can be realized by targeting WPAs at goods that will be landfilled and at those with low recycled content.     

Conventional and exergetic life cycle assessment of organic rankine cycle implementation to municipal waste management: the case study of Mae Hong Son (Thailand)

Purpose

The critical issue of waste management in Thailand has been rapidly increasing in almost all of the cities due to the economic growth and rising population that could double the amount of solid waste in landfill area. The alternative ways of waste treatment that have more efficiency and effectiveness in terms of energy, ecology, and resources become the key issue for each municipality to replace the old fashioned technology and be able to enhance the ability of solid waste problem management. Waste to energy is one of the favorable approaches to diminish the amount of waste to landfill and utilize waste for electricity. The aim of this study is to identify and quantify the life cycle impacts of the municipal solid waste (MSW) of Mae Hong Son municipality (MHSM), and the case study is the selected waste treatment technology of the Refuse-Derived Fuel (RDF) hybrid with 20 kW of Organic Rankine Cycle (ORC).

Methods

The functional unit is defined as 1 t of MSW. The energy, environment, and resource impacts were evaluated by using Life Cycle Assessment (LCA); ReCipe and Net Energy Consumption were referred to calculate the environmental impacts and the benefits of energy recovery of WtE technology. Exergetic LCA was used to analyze the resource consumption, especially land use change.

Results and discussion

The results indicated that the environmental impacts were comparatively high at the operation stage of RDF combustion. On the other hand, the production stage of RDF illustrated the highest energy consumption. The ORC power generation mainly consumed resources from material and energy used. The ORC system demonstrated better results in terms of energy and resource consumption when applied to waste management, especially the land required for landfill. Substitution of electricity production from ORC system was the contributor to the reduction of both energy and resource consumption. Installation of spray dry and fabric filter unit to RDF burner can reduce heavy metals and some pollutants leading to the reduction of most of the impacts such as climate change, human toxicity, and fossil depletion which are much lower than the conventional landfill.

Conclusions

LCA results revealed that the environmental impacts and energy consumption can be reduced by applying the RDF and ORC systems. The exergetic LCA is one of the appropriate tools used to evaluate the resource consumption of MSW. It is obviously proven that landfill contributed to higher impacts than WtE for waste management.

     

Life-cycle greenhouse gas inventory analysis of household waste management and food waste reduction activities in Kyoto, Japan

Purpose

Source-separated collection of food waste has been reported to reduce the amount of household waste in several cities including Kyoto, Japan. Food waste can be reduced by various activities including preventing edible food loss, draining moisture, and home composting. These activities have different potentials for greenhouse gas (GHG) reduction. Therefore, we conducted a life-cycle inventory analysis of household waste management scenarios for Kyoto with a special emphasis on food waste reduction activities.

Methods

The primary functional unit of our study was ??annual management of household combustible waste in Kyoto, Japan.?? Although some life-cycle assessment scenarios included food waste reduction measures, all of the scenarios had an identical secondary functional unit, ??annual food ingestion (mass and composition) by the residents of Kyoto, Japan.?? We analyzed a typical incineration scenario (Inc) and two anaerobic digestion (dry thermophilic facilities) scenarios involving either source-separated collection (SepBio) or nonseparated collection followed by mechanical sorting (MecBio). We assumed that the biogas from anaerobic digestion was used for power generation. In addition, to evaluate the effects of waste reduction combined with separate collection, three food waste reduction cases were considered in the SepBio scenario: (1) preventing loss of edible food (PrevLoss); (2) draining moisture contents (ReducDrain); and (3) home composting (ReducHcom). In these three cases, we assumed that the household waste was reduced by 5%.

Results and discussion

The GHG emissions from the Inc, MecBio, and SepBio scenarios were 123.3, 119.5, and 118.6 Gg CO₂-eq/year, respectively. Compared with the SepBio scenario without food waste reduction, the PrevLoss and ReducDrain cases reduced the GHG emissions by 17.1 and 0.5 Gg CO₂-eq/year. In contrast, the ReducHcom case increased the GHG emissions by 2.1 Gg CO₂-eq/year. This is because the biogas power production decreased due to the reduction in food waste, while the electricity consumption increased in response to home composting. Sensitivity analyses revealed that a reduction of only 1% of the household waste by food loss prevention has the same GHG reduction effect as a 31-point increase (from 50% to 81%) in the food waste separation rate.

Conclusions

We found that prevention of food losses enhanced by separate collection led to a significant reduction in GHG emissions. These findings will be useful in future studies designed to develop strategies for further reductions in GHG emissions.     

The Application of the Environmental Product Declaration to Waste Disposal in a Sanitary Landfill - Four Case Studies (10 pp)

Goal, Scope and Background

The aim of the present study is to evaluate, through LCA, the potential environmental impact associated to urban waste dumping in a sanitary landfill for four case studies and to compare different technologies for waste treatment and leachate or biogas management in the framework of the EPD® system. Specific data were collected on the four Italian landfills during a five-year campaign from 2000 to 2004. This work also analyses the comparability of EPD results for different products in the same product category. For this purpose, a critical review of PSR 2003:3, for preparing an EPD on ‘Collection, transfer and disposal service for urban waste in sanitary landfills', is performed.

Methods

PSR 2003:3 defines the requirements, based on environmental parameters, that should be considered in an LCA study for collecting and disposal service of Municipal Solid Waste (MSW) in a sanitary landfill. It defines functional unit, system boundaries towards nature, other technical systems and boundaries in time, cut-off rules, allocation rules and parameters to be declared in the EPD. This PSR is tested on four case studies representing the major landfills located from the farthest west to the farthest east side of the Ligurian Region. Those landfills are managed with different technologies as concerns waste pre-treatment and leachate or biogas treatment. For each landfill, a life cycle assessment study is performed.

Results and Discussion

The comparison of the LCA results is performed separately for the following phases: Transport, Landfill, Leachate and Biogas. The following parameters are considered: Resource use (Use of non-renewable resources with and without energy content, Use of renewable resources with and without energy content, Water consumption); Pollutant emissions expressed as potential environmental impact (Global Warming Potential from biological and fossil sources, Acidification, Ozone depletion, Photochemical oxidant formation, Eutrophication, Land use, Hazardous and other Waste production). The comparison of the LCA results obtained for alternative landfill and biogas management techniques in the case studies investigated shows that the best practicable option that benefits the environment as a whole must be identified and chosen in the LCA context. For example, a strong waste pre-treatment causes a high biological GWP in the Landfill phase, but a low GWP contribution in the Biogas phase, due to the consequent low biogas production, evaluated for 30 years since landfill closure.

Conclusion

The analysis of four case studies showed that, through the EPD tool, it is possible to make a comparison among different declarations for the same product category only with some modification and integration to existent PSR 2003:3. Results showed that different products have different performances for phases and impact categories. It is not possible to identify the \best product\ from an environmental point of view, but it is possible to identify the product (or service) with the lowest impact on the environment for each impact category and resource use.

Recommendation and Perspective

In consequences of the verification of the comprehensiveness of existent PSR 2003:3 for the comparability of EPD, some modifications and integration to existent rules are suggested.

     

Comparative life cycle assessment and social life cycle assessment of used polyethylene terephthalate (PET) bottles in Mauritius

Purpose

Improper disposal of used polyethylene terephthalate (PET) bottles constitute an eyesore to the environmental landscape and is a threat to the flourishing tourism industry in Mauritius. It is therefore imperative to determine a suitable disposal method of used PET bottles which not only has the least environmental load but at the same time has minimum harmful impacts on peoples employed in waste disposal companies. In this respect, the present study investigated and compared the environmental and social impacts of four selected disposal alternatives of used PET bottles.

Methods

Environmental impacts of the four disposal alternatives, namely: 100 % landfilling, 75 % incineration with energy recovery and 25 % landfilling, 40 % flake production (partial recycling) and 60 % landfilling and 75 % flake production and 25 % landfilling, were determined using ISO standardized life cycle assessment (ISO 14040:2006) and with the support of SimaPro 7.1 software. Social life cycle assessments were performed based on the UNEP/SETAC Guidelines for Social Life Cycle Assessment of products. Three stakeholder categories (worker, society and local community) and eight sub-category indicators (child labour, fair salary, forced labour, health and safety, social benefit/social security, discrimination, contribution to economic development and community engagement) were identified to be relevant to the study. A new method for aggregating and analysing the social inventory data is proposed and used to draw conclusions.

Results and discussion

Environmental life cycle assessment results indicated that highest environmental impacts occurred when used PET bottles were disposed by 100 % landfilling while disposal by 75 % flake production and 25 % landfilling gave the least environmental load. Social life cycle assessment results indicated that least social impacts occurred with 75 % flake production and 25 % landfilling. Thus both E-LCA and S-LCA rated 75 % flake production and 25 % landfilling to be the best disposal option.

Conclusions

Two dimensions of sustainability (environmental and social) when investigated using the Life Cycle Management tool, favoured scenario 4 (75 %?% flake production and 25 % landfilling) which is a partial recycling disposal route. One hundred percent landfilling was found out to be the worst scenario. The next step will be to explore the third pillar of sustainability, economic, and devise a method to integrate the three dimensions with a view to determine the sustainable disposal option of used PET bottles in Mauritius.     

A triple bottom line evaluation of solid waste management strategies: a case study for an arid Gulf State,Kuwait

Purpose

We extend a life cycle assessment (LCA) embracing both economic and social perspectives to develop an integrated solid waste management system for Kuwait. This study considers the domestic waste generated by households and waste generated commercially. Six municipal solid waste (MSW) scenarios (SR₁, SR₂, …, SR₆) are evaluated using a triple bottom line (TBL) approach that incorporates environmental, financial, and social bottom lines (social BLs).

Methods

Within the TBL framework, the environmental BL employs LCA in accordance with ISO 14044. The financial BL is calculated using capital and operational costs as well as the associated recycling revenues. The social BL applies macro-economic indicators that examine the effects of a given MSW scenario (SR) on the inhabitants. To integrate the TBLs, we apply an analytic hierarchy process (AHP) because of its advantage of pairwise unit-free rescaling. The relative importance of each BL is determined by considering the political, legal, socio-cultural, and economic climates of the country. The relative weights are cross-multiplied with indicators from each BL to calculate a composite sustainability index (CSI) for the proposed MSW SR.

Results and discussion

The environmental BL (LCA) indicates that global warming, acidification, and human toxicity are the most adversely affected impact categories, considering the local conditions and waste composition. Environmentally, SR₁ (landfilling) scored the worst in almost all impact categories and, thus, was labeled the worst-case scenario environmentally. SR₆ (composting, recycling, and incineration) performed the best from an environmental perspective. Financially, landfilling (SR₁) is the most economical scenario. Any SR that focused on incineration (SR₂ and SR₅) was financially unfavorable. The scenarios that involved composting were scored as financially reasonable (SR₃, SR₄, and SR₆). From a social acceptability perspective, SR₂ (incineration) scored the highest, while SR₁ (landfills) scored the lowest. Finally, across the TBL framework, SR₄ (composting and incineration) had the highest CSI based on the relative importance scheme adopted for each BL.

Conclusions

Although they are often overlooked in most LCA studies, the financial and social aspects are indispensable to proving feasibility and credibility at a strategic level. The complexity of financial and social formulations in LCA is inherited from the difficulty in quantifying emissions and other impacts. In addition, from a social perspective, the contingent risks and associated uncertainty vary widely across cultures, ideologies, and degrees of development and are further complicated because of the scarcity and uncertainty of the data.

     

Inclusion of uncertainty in the LCA comparison of different cherry tomato production scenarios

Purpose

Knowledge regarding environmental impacts of agricultural systems is required. Consideration of uncertainty in life cycle assessment (LCA) provides additional scientific information for decision making. The aims of this study were to compare the environmental impacts of different growing cherry tomato cultivation scenarios under Mediterranean conditions and to assess the uncertainty associated to the different agricultural production scenarios.

Materials and methods

The burdens associated to cherry tomato production were calculated and evaluated by the LCA methodology. The functional unit (FU) chosen for this study was the mass unit of 1 t of commercial loose cherry tomatoes. This study included the quantitative uncertainty analysis through Monte Carlo simulation. Three scenarios were considered: greenhouse (GH), screenhouse (SH), and open field (OF). The flows and processes of the product scenario were structured in several sections: structure, auxiliary equipment, fertilizers, crop management, pesticides, and waste management. Six midpoint impact categories were selected for their relevance: climate change, terrestrial acidification, marine eutrophication, metal depletion, and fossil depletion using the impact evaluation method Recipe Midpoint and ecotoxicity using USEtox.

Results and discussion

The structure, auxiliary equipment, and fertilizers produced the largest environmental impacts in cherry tomato production. The greatest impact in these stages was found in the manufacture and drawing of the steel structures, manufacture of perlite, the amount of HDPE plastics used, and the electricity consumed by the irrigation system and the manufacture and application of fertilizers. GH was the cropping scenario with the largest environmental impact in most categories (varying from 18 and 37% higher than SH and OF, respectively, in metal depletion, to 96% higher than SH and OF, in eutrophication). OF showed the highest uncertainty in ecotoxicity, with a bandwidth of 60 CTUe and a probability of 100 and 99.4% to be higher than GH and SH, respectively.

Conclusions

The LCA was used to improve the identification and evaluation of the environmental burdens for cherry tomato production in the Mediterranean area. This study demonstrates the significance of conducting uncertainty analyses for comparative LCAs used in comparative relative product environmental impacts.

     

A preliminary LCA case study: comparison of different pathways to produce purified terephthalic acid suitable for synthesis of 100 % bio-based PET

Purpose

This study provides a preliminary comparison of the environmental burdens of three different pathways for production of bio-based purified terephthalic acid (PTA), suitable for the production of 100 % bio-based poly(ethylene terephthalate), PET. These pathways are through (1) muconic acid originating in wheat stover; (2) isobutanol originating in corn; and (3) benzene, toluene, and xylene (BTX) originating in poplar. The goal is to point out what areas of these processes are the largest environmental contributors and hence are the most critical for development of accurate primary data, as well as to indicate which of these pathways looks most promising, from an environmental viewpoint, for production of 100 % bio-based PET.

Methods

Because much of the needed life cycle information to produce PTA is currently not available, inventory data for each scenario for the production of PTA were estimated based on the chemistry involved. In the impact analysis stage, the inventory data were classified and characterized with a focus on several environmental midpoint categories. SimaPro 7.3.3 software was used as the main computational software and Impact 2002+ v2.1 was used as the life cycle impact assessment methodology in this attributional life cycle assessment.

Results and discussion

Valuable preliminary environmental impact data including identification of critical steps in the process were obtained. The global warming value of PET synthesized through the muconic acid scenario was 1.6 times larger than that of the scenario of PET synthesized through BTX even after a limited Monte Carlo simulation of 1,000 runs.

Conclusions

Among the three scenarios for producing PET, PET synthesized through BTX looked the most promising to pursue for production of bio-based PET with lower environmental burdens. This work also indicated that the first production steps of producing PET through any of the evaluated scenarios (from biomass to the first intermediate) are responsible for the largest environmental burden and should be further characterized since they were the dominant processes in many impact categories.     

Life cycle assessment of construction materials: the influence of assumptions in end-of-life modelling

Purpose

The nature of end-of-life (EoL) processes is highly uncertain for constructions built today. This uncertainty is often neglected in life cycle assessments (LCAs) of construction materials. This paper tests how EoL assumptions influence LCA comparisons of two alternative roof construction elements: glue-laminated wooden beams and steel frames. The assumptions tested include the type of technology and the use of attributional or consequential modelling approaches.

Methods

The study covers impact categories often considered in the construction industry: total and non-renewable primary energy demand, water depletion, global warming, eutrophication and photo-chemical oxidant creation. The following elements of the EoL processes are tested: energy source used in demolition, fuel type used for transportation to the disposal site, means of disposal and method for handling allocation problems of the EoL modelling. Two assumptions regarding technology development are tested: no development from today’s technologies and that today’s low-impact technologies have become representative for the average future technologies. For allocating environmental impacts of the waste handling to by-products (heat or recycled material), an attributional cut-off approach is compared with a consequential substitution approach. A scenario excluding all EoL processes is also considered.

Results and discussion

In all comparable scenarios, glulam beams have clear environmental benefits compared to steel frames, except for in a scenario in which steel frames are recycled and today’s average steel production is substituted, in which impacts are similar. The choice of methodological approach (attributional, consequential or fully disregarding EoL processes) does not seem to influence the relative performance of the compared construction elements. In absolute terms, four factors are shown to be critical for the results: whether EoL phases are considered at all, whether recycling or incineration is assumed in the disposal of glulam beams, whether a consequential or attributional approach is used in modelling the disposal processes and whether today’s average technology or a low-impact technology is assumed for the substituted technology.

Conclusions

The results suggest that EoL assumptions can be highly important for LCA comparisons of construction materials, particularly in absolute terms. Therefore, we recommend that EoL uncertainties are taken into consideration in any LCA of long-lived products. For the studied product type, LCA practitioners should particularly consider EoL assumptions regarding the means of disposal, the expected technology development of disposal processes and any substituted technology and the choice between attributional and consequential approaches.     

Life cycle assessment of an offshore grid interconnecting wind farms and customers across the North Sea

Purpose

This study aims to contribute to an improved understanding of the environmental implications of offshore power grid and wind power development pathways. To achieve this aim, we present two assessments. First, we investigate the impacts of a North Sea power grid enabling enhanced trade and integration of offshore wind power. Second, we assess the benefit of the North Sea grid and wind power through a comparison of scenarios for power generation in affected countries.

Methods

The grid scenario explored in the first assessment is the most ambitious scenario of the Windspeed project and is the result of cost minimization analysis using a transmission-expansion-planning model. We develop a hybrid life cycle inventory for array cables; high voltage, direct current (HVDC) links; and substations. The functional unit is 1 kWh of electricity transmitted. The second assessment compares two different energy scenarios of Windspeed for the North Sea and surrounding countries. Here, we utilize a life cycle inventory for offshore grid components together with an inventory for a catalog of power generation technologies from Ecoinvent and couple these inventories with grid configurations and electricity mixes determined by the optimization procedure in Windspeed.

Results and discussion

Developing, operating, and dismantling the grid cause emissions of 2.5 g CO₂-Eq per kWh electricity transmission or 36 Mt CO₂-Eq in total. HVDC cables are the major cause of environmental damage, causing, for example, half of total climate change effects. The next most important contributors are substations and array cabling used in offshore wind parks. Toxicity and eutrophication effects stem largely from leakages from disposed copper and iron mine tailings and overburden. Results from the comparison of two scenarios demonstrate a substantial environmental benefit from the North Sea grid extension and the associated wind power development compared with an alternative generation of electricity from fossil fuels. Offshore grid and wind power, however, entail an increased use of metals and, hence, a higher metal depletion indicator.

Conclusions

We present the first life cycle assessment of a large offshore power grid, using the results of an energy planning model as input. HVDC links are the major cause of environmental damage. There are differences across impact categories with respect to which components or types of activities that are responsible for damage. The North Sea grid and wind power are environmentally beneficial by an array of criteria if displacing fossil fuels, but cause substantial metal use.     

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.     

Design of recycling system for poly(methyl methacrylate) (PMMA). Part 1: recycling scenario analysis

Introduction

In this series of papers, we present a poly(methyl methacrylate) (PMMA) recycling system design based on environmental impacts, chemical hazards, and resource availability. We evaluated the recycling system by life cycle assessment, environment, health, and safety method, and material flow analysis.

Purpose

Previous recycling systems have not focused on highly functional plastics such as PMMA, partly because of lower available volumes of waste PMMA compared with other commodity plastics such as polyethylene or polypropylene. However, with the popularization of PMMA-containing products such as liquid crystal displays, the use of PMMA is increasing and this will result in an increase in waste PMMA in the future. The design and testing of recycling systems and technologies for treating waste PMMA is therefore a high research priority. In this study, we analyze recycling of PMMA monomers under a range of scenarios.

Methods

Based on the differences between PMMA grades and their life cycles, we developed a life cycle model and designed a range of scenarios for PMMA recycling. We obtained monomer recycling process inventory data based on the operational results of a pilot plant. Using this process inventory data, we quantified life cycle greenhouse gas (LC-GHG) emissions and fossil resource consumption, and we calculated the LIME single index.

Results and discussion

PMMA produces more than twice the amount of GHG emissions than other commodity resins. Through scenario and sensitivity analyses, we demonstrated that monomer recycling is more effective than mechanical recycling. Operational modifications in the monomer recycling process can potentially decrease LC-GHG emissions.

Conclusions

Highly functional plastics should be recycled while maintaining their key functions, such as the high transparency of PMMA. Monomer recycling has the potential to achieve a closed-loop recycling of PMMA.     

End of life of buildings: three alternatives, two scenarios. A case study

Purpose

The objective of this case study is to identify the relevant processes needed in the environmental assessment of the end of life of a building and to identify the demolition process variables that significantly affect energy consumption and emissions of greenhouse gases. Different scenarios of demolition, based on three alternatives for managing construction and demolition waste (C&DW) generated during demolition works, are analyzed. This study is based upon typical construction and demolition practices and waste management in Spain.

Methods

Life cycle assessment (LCA) methodology is applied to assess objectively and quantitatively different C&DW management plans during the design phase and to identify the significant environmental aspects. The impact categories considered are global warming potential and human toxicity potential. Furthermore, the indicator primary energy (non renewable energy from fossil fuels) is also studied.

Results

Design of C&DW management plans to enhance the recovery of waste, reducing significantly the selected environmental indicators, was assessed in this study. Waste transport from the demolition work to the treatment plant and the transport of the non-recyclable fraction to the final disposal, as well as the fuel consumption in hydraulic demolition equipment and in the loading/unloading equipment of the treatment plants, are the most significant environmental aspects associated with the management plan based on a selective demolition, whereas in a conventional demolition process, the main environmental aspect is waste transport from the demolition work to final disposal.

Conclusions

LCA studies allow an assessment of different demolition processes. A tool for recording environmental data has been developed. This tool provides in a systematic manner life cycle inventory and life cycle impact assessment of the end of life of a building, facilitating the study of management plans in the design phase.     

LCA of a newsprint paper machine: a case study of capital equipment

Purpose

The environmental aspects of paper as a consumer good have been extensively studied. However, the paper machine has been mostly neglected in the literature. The purpose of this article is to present a LCA case study that explicitly focuses on the system of a newsprint paper machine and its environmental impacts and not on the system of the consumer good paper. The relevance of the paper machine as capital equipment is analyzed, and conclusions for the environmental improvement of paper machines are drawn based on identified hotspots. The article hereby answers the more general research questions of whether capital equipment has rightly been neglected in other studies regarding pulp and paper and which impact categories are important for analyzing the environmental burdens of a paper machine.

Methods

The study has been executed in collaboration with Voith Paper, an original equipment manufacturer. Hence, in distinction to literature-based studies, primary data on the paper machine was available resulting in a high overall data quality. Based on the ISO 14040 (2006) and 14044 (2006) standards, this article pursues a cradle-to-grave approach for the paper machine. It assesses the environmental impacts in the impact categories defined by the ReCiPe impact assessment methodology. Different types of energy generation are examined in a scenario analysis with combined heat and power generation (CHP) as the baseline case. For interpretation, a normalization and a sectoral analysis are performed.

Results and discussion

The normalized results indicate fossil resource depletion and global warming as the most important impact categories. Global warming impacts are highly dependent on the energy processes and result to 432.7 kg CO2e per production of 1 t of paper for CHP and to 701.7 kg CO2e for EU25 grid mix. The sectoral analysis shows that the machinery's operations/use phase is clearly dominating most impact categories due to its long lifetime. An exception is the metal depletion, for which the materials and manufacturing processes are most important.

Conclusions

These findings prove that for most categories, the operations/use phase of the paper machine is the most important life cycle stage. In systems focusing on the consumer good paper, it is therefore sufficient to model the operation of the paper machine, whereas the manufacturing, transport, and end-of-life processes regarding the paper machine equipment can be neglected, unless metal depletion is important to the study.     

Environmental evaluation and comparison of selected industrial scale biomethane production facilities across Europe

Purpose

The two main reasons for producing biomethane as renewable fuel are reduction of climate impacts and depletion of fossil resources. Biomethane is expected to be sustainable, but how sustainable is it actually? This article contributes to the clarification. Therefore, the environmental impacts of several biomethane facilities all over Europe were assessed. A special focus is put on the differences between the facilities as they follow different production routes.

Methods

The method used for evaluation is life cycle assessment (LCA) applied in a well-to-wheel approach. This enables to show the overall performance in terms of global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), photochemical ozone creation potential (POCP) and PE fossil. The system boundary includes the entire chain from biogas production to upgrading, distribution and use. For evaluating the different production routes several years of measuring data, calculating and improving the LCA models in close cooperation with the plant operators were carried out.

Results and discussion

The evaluation of the production routes shows a high reduction potential compared to fossil fuels. Regarding the depletion of fossil resources, the amounts vary between the sites, but the reduction is at least 50 % and reaches almost 100 % reductions at some sites. The reduction of GWP is at least 65 %, because waste flows free of environmental burdens are used almost exclusively as substrate. Other dominant factors are power and heat demand, methane losses to the environment and the use of by-products, e.g. fertilizer.

Conclusions

Despite this caveat, the evaluated systems demonstrate the possible positive results of renewable fuel production if done properly.