Influence of allocation methods on the environmental performance of biorefinery products—A case study

Life Cycle Assessment (LCA) methodology is the prevailing framework for estimating the environmental performances of a product/service. The application of LCA frequently requires practitioners to address allocation issues, especially when a large number of co-products are produced. The choice of an allocation approach for multifunctional processes is among the most debated methodological aspects in the LCA community, given its potentially large influence on final outcomes. Despite numerous efforts, a uniform consensus on the best allocation practice is still lacking and no single method appears as the most suitable for all situations.The aim of this paper is to assess how different allocation methods affect the environmental performances of a lignocellulosic biorefinery. Biorefinery systems represent a good example of a multifunctional process, since they co-produce multiple energy and material products. The following allocation procedures are applied: system expansion (also named substitution method), partitioning method according to different features of co-products (mass, energy, exergy and economic value), and hybrid approach (given by a combination of the previous ones). In order to enhance the clarity of the discussion, a mathematical notation for these allocation procedures is adopted, and analytical interrelations are investigated. Results show the influence of the allocation methods on the environmental impacts assigned to the individual products, both on a unit and annual flow basis.     

An integrated impact assessment and weighting methodology: evaluation of the environmental consequences of computer display technology substitution

Computer display technology is currently in a state of transition, as the traditional technology of cathode ray tubes is being replaced by liquid crystal display flat-panel technology. Technology substitution and process innovation require the evaluation of the trade-offs among environmental impact, cost, and engineering performance attributes. General impact assessment methodologies, decision analysis and management tools, and optimization methods commonly used in engineering cannot efficiently address the issues needed for such evaluation. The conventional Life Cycle Assessment (LCA) process often generates results that can be subject to multiple interpretations, although the advantages of the LCA concept and framework obtain wide recognition. In the present work, the LCA concept is integrated with Quality Function Deployment (QFD), a popular industrial quality management tool, which is used as the framework for the development of our integrated model. The problem of weighting is addressed by using pairwise comparison of stakeholder preferences. Thus, this paper presents a new integrated analytical approach, Integrated Industrial Ecology Function Deployment (I2-EFD), to assess the environmental behavior of alternative technologies in correlation with their performance and economic characteristics. Computer display technology is used as the case study to further develop our methodology through the modification and integration of various quality management tools (e.g., process mapping, prioritization matrix) and statistical methods (e.g., multi-attribute analysis, cluster analysis). Life cycle thinking provides the foundation for our methodology, as we utilize a published LCA report, which stopped at the characterization step, as our starting point. Further, we evaluate the validity and feasibility of our methodology by considering uncertainty and conducting sensitivity analysis.     

Environmental Assessment Framework for Policy Applications: Life Cycle Assessment,External Costs and Multi-criteria Analysis

The paper presents a framework for the analysis of external costs of environmental burdens, namely an impact pathway analysis, often coupled with the inventory stage of life cycle assessment (LCA). The ground rule is: quantify as much as possible in terms of burdens (pollutant emissions, etc.), impacts, and their monetary equivalent, then use multi-criteria analysis (MCA) for any remaining impacts that are considered to be too uncertain or defy quantification through to monetization. Although MCA could be used directly on estimates of burdens or impacts, monetary valuation provides a mechanism for consistent weighting of impacts categories based on assessment of public preference. Further advantages of extending LCA through detailed impact assessment combined with monetary valuation are that it greatly simplifies MCA by combining a large number of different environmental impact categories, thereby avoiding an unmanageably large number of criteria, and also facilitates cost benefit analysis (CBA). The risks are noted of inappropriate use of the tools or interpretation/use of the results, and recommendations are made for improved practice. These points are illustrated with examples. The key messages are: (1) that policies should be targeted correctly to give a clear signal which source of a burden should be reduced by how much; (2) that analysts should take into account the needs of policy makers and the link between the analysis and possible policy applications; and (3) that current LCA practice gives limited guidance in both areas, largely through a lack of consideration of the relative and absolute importance of different types of impact. However, this is precisely the strength of external costs analysis, particularly when used with MCA.     

Alternative scenarios to meet the demands of sustainable waste management

This paper analyses different alternatives for solid waste management that can be implemented to enable the targets required by the European Landfill and Packaging and Packaging Waste Directives to be achieved in the Valencian Community, on the east coast of Spain. The methodology applied to evaluate the environmental performance of each alternative is Life Cycle Assessment (LCA). The analysis has been performed at two levels; first, the emissions accounted for in the inventory stage have been arranged into impact categories to obtain an indicator for each category; and secondly, the weighting of environmental data to a single unit has been applied. Despite quantitative differences between the results obtained with four alternative impact assessment methods, the same preference ranking has been established: scenarios with energy recovery (1v and 2v) achieve major improvements compared to baseline, with scenario 1v being better than 2v for all impact assessment methods except for the EPS'00 method, which obtains better results for scenario 2v. Sensitivity analysis has been used to test some of the assumptions used in the initial life cycle inventory model but none have a significant effect on the overall results. As a result, the best alternative to the existing waste management system can be identified.     

Life cycle assessment of the production and use of polypropylene tree shelters

A detailed Life Cycle Assessment (LCA) has been conducted for the manufacture, use and disposal of polypropylene tree shelters, which are used to protect young seedlings in the first few years of growth. The LCA was conducted using Simapro software, the Ecoinvent database and ReCiPe assessment methodology. Detailed information on materials, manufacturing, packaging and distribution of shelters was obtained from Tubex Ltd. in South Wales, UK. Various scenarios based on different forest establishment methods, with or without tree shelters were derived and analysed using data from published literature and independent sources. The scenarios included commercial forestry in northern temperate conditions, amenity forest establishment in temperate conditions, and forest establishment in semi-arid conditions. For commercial forestry, a reduction in required seedling production and planting as well as additional time-averaged wood production led to significant benefits with tree shelters, both compared to unprotected and fenced cases. For the amenity forest scenarios, tree shelter use had a net environmental impact, while for semi-arid forestry, the benefits of reduction in water use outweighed shelter production impacts. The current practice of in-situ degradation was compared to collection and disposal and it was found that in-situ degradation was slightly preferable in terms of overall environmental impact. Use of biopolymer-based shelters would improve the environmental performance slightly.     

生命周期评价在我国固体废物环境管理中的应用

生命周期评价是评价产品、工艺或活动（服务）整个生命周期阶段有关环境负荷,进而辨识和评价减少环境影响机会的一种非常有用的工具。将生命周期评价应用于固体废物环境管理,无疑对于我国建立科学化的固体废物环境管理模式具有十分重要的作用。本文对生命周期评价的定义、主要阶段、应用工具、特点进行了阐述,并对生命周期评价如何应用于我国固体废物环境管理进行了探讨。     

Environmental impact minimization of a total wastewater treatment network system from a life cycle perspective

Synthesis of distributed wastewater treatment plants (WTPs) has focused on cost reduction, but never on the reduction of environmental impacts. A mathematical optimization model was developed in this study to synthesize existing distributed and terminal WTPs into an environmentally friendly total wastewater treatment network system (TWTNS) from a life cycle perspective. Life cycle assessment (LCA) was performed to evaluate the environmental impacts of principal contributors in a TWTNS. The LCA results were integrated into the objective function of the model. The mass balances were formulated from the superstructure model, and the constraints were formulated to reflect real wastewater treatment situations in industrial plants. A case study validated the model and demonstrated the effect of the objective function on the configuration and environmental performance of a TWTNS. This model can be used to minimize environmental impacts of a TWTNS in retrofitting existing WTPs in line with cleaner production and sustainable development.     

Life-Cycle Impact Assessment of oil drilling mud system in Algerian arid area

The objective of this work is to assess the environmental impacts of the drilling mud system in Algeria's arid region. Water-based mud (WBM) and oil-based mud (OBM) are used during well drilling in Hassi Messaoud petroleum field, and have a considerable pollution potential particularly on the aquifer system which constitutes the single resource of drinking water in the Sahara. The Life-Cycle Assessment (LCA) approach is applied to evaluate the impacts of several drilling mud systems across all stages of their life cycle, e.g. use, treatment and disposal. Environmental impacts of five treatments scenarios corresponding to the drilling waste management applied in Hassi Messaoud are compared: reserve pit without treatment (burial option), secondary high centrifugation (vertical cuttings dryer), stabilisation/solidification online, stabilisation/solidification off line and thermal desorption. The impact assessment is carried on using the LCIA models of Impact 2002+ method in SIMAPRO7 software. This assessment identifies human toxicity and terrestrial eco-toxicity as the major impact categories in this specific arid context and quantifies the emissions contributions. The local environmental impact is the most important of the drilling mud life cycle and is mainly linked to emissions from reserve pits, treated cuttings, and drilling phase 16″ through the Turonian and Albian aquifer. The main contributing substances are aromatic hydrocarbons fraction and metals in particular barium, zinc, antimony, arsenic, and aluminium. Concerning the comparison of the treatment scenarios, it appears that stabilisation/solidification online is the best one; it has the lowest impact score in the two dominating categories because of the waste minimisation: mud storage avoided in the reserve pit. The second best scenario is the thermal desorption which obtains the lowest impact score in carcinogen effects due to hydrocarbons reduction (<1%) and avoided impacts of recovered oil. The toxic substances fate modeling will be improved by taking into account their site-specific impact.     

Comparing Green and Grey Infrastructure Using Life Cycle Cost and Environmental Impact: A Rain Garden Case Study in Cincinnati,OH

Green infrastructure (GI) is quickly gaining ground as a less costly, greener alternative to traditional methods of stormwater management. One popular form of GI is the use of rain gardens to capture and treat stormwater. We used life cycle assessment (LCA) to compare environmental impacts of residential rain gardens constructed in the Shepherd's Creek watershed of Cincinnati, Ohio to those from a typical detain and treat system. LCA is an internationally standardized framework for analyzing the potential environmental performance of a product or service by including all stages in its life cycle, including material extraction, manufacturing, use, and disposal. Complementary to the life cycle environmental impact assessment, the life cycle costing approach was adopted to compare the equivalent annual costs of each of these systems. These analyses were supplemented by modeling alternative scenarios to capture the variability in implementing a GI strategy. Our LCA models suggest rain garden costs and impacts are determined by labor requirement; the traditional alternative's impacts are determined largely by the efficiency of wastewater treatment, while costs are determined by the expense of tunnel construction. Gardens were found to be the favorable option, both financially (~42% cost reduction) and environmentally (62‐98% impact reduction). Wastewater utilities may find significant life cycle cost and environmental impact reductions in implementing a rain garden plan.     

Life cycle modelling of fossil fuel power generation with post-combustion CO2 capture

Due to its compatibility with the current energy infrastructures and the potential to reduce CO₂ emissions significantly, CO₂ capture and geological storage is recognised as one of the main options in the portfolio of greenhouse gas mitigation technologies being developed worldwide. The CO₂ capture technologies offer a number of alternatives, which involve different energy consumption rates and subsequent environmental impacts. While the main objective of this technology is to minimise the atmospheric greenhouse gas emissions, it is also important to ensure that CO₂ capture and storage does not aggravate other environmental concerns. This requires a holistic and system-wide environmental assessment rather than focusing on the greenhouse gases only. Life Cycle Assessment meets this criteria as it not only tracks energy and non-energy-related greenhouse gas releases but also tracks various other environmental releases, such as solid wastes, toxic substances and common air pollutants, as well as the consumption of other resources, such as water, minerals and land use. This paper presents the principles of the CO₂ capture and storage LCA model developed at Imperial College and uses the pulverised coal post-combustion capture example to demonstrate the methodology in detail. At first, the LCA models developed for the coal combustion system and the chemical absorption CO₂ capture system are presented together with examples of relevant model applications. Next, the two models are applied to a plant with post-combustion CO₂ capture, in order to compare the life cycle environmental performance of systems with and without CO₂ capture. The LCA results for the alternative post-combustion CO₂ capture methods (including MEA, K⁺/PZ, and KS-1) have shown that, compared to plants without capture, the alternative CO₂ capture methods can achieve approximately 80% reduction in global warming potential without a significant increase in other life cycle impact categories. The results have also shown that, of all the solvent options modelled, KS-1 performed the best in most impact categories.     

Assessing the “design paradox” with life cycle assessment: A case study of a municipal solid waste incineration plant

One of the most important processes in an integrated waste management system is incineration, which, among the different waste management disposal options still remains a critical waste treatment system. New dynamics and approaches have to be developed to embrace such a wide and complex topic, and better knowledge and assessment of incineration are strategically significant to define future environmental scenarios.Life cycle assessment (LCA), as a tool to optimise process-operating conditions and to support decision-making process, is often applied to investigate processes under design in various sectors, since choices made in the development phases can affect the future environmental profile. However, even if the greatest opportunity to improve a process from an environmental perspective is during the design phase, at the same time the knowledge is limited, in accordance with the so-called “design paradox”.Thus, in this context, this study used LCA methodology to quantitatively assess the extent to which the environmental impact of an incineration line reflects the environmental burdens perceived during the design phase. A comparative LCA was conducted at the design phase and under operating conditions at an Italian municipal solid waste incineration plant.The outcomes of the study indicated that for almost all of the categories analysed, the impacts associated with the process under design overestimated the impacts associated with the operating process, with the exception of climate change and water depletion. The results suggested that after the conduction of an LCA at the design phase of a process, an LCA of the operative conditions should be carried out to verify how much the over- or under-estimations affected the results.     

Environmental life cycle assessment of different types of the municipal wastewater pipeline network

With the onset of social life, humans have considered waste disposal as essential, and they have been able to repel it through brick and clay channels. Checking sewage pipes for energy consumption and a longer lifetime than other sewage system components is important. Climate change and exploitation of industrial resources have made environmental impacts, which are important factors in decision making. The purpose of this study was to introduce the most suitable type of sewage pipe considering environmental protection. Therefore, we applied the environmental life cycle assessment (LCA) method, using Sima Pro 8.2.3 software for the one-kilometer length of concrete pipes (300 mm in diameter), Polyvinyl chloride (PVC), and polyethylene (PE) (315 mm in diameter). Also, the BEES method and sensitivity analysis were used to validate the results. The comparison between three types of municipal wastewater pipes indicated that PE pipes are a more environmentally friendly option than PVC, and concrete pipes in pipe recycling, reducing extraction from untapped resources, and inefficient extraction of resources. Electricity, diesel fuel, and sulfate resistance cement consumption for concrete production are the most pollution elements in the LCA of concrete pipes. Usage of PVC granular, sanitary landfill of PVC pipes, and using hydraulic drill in LCA of PVC pipes are the most elements of generating pollution. The usage of PE granules, PE pipes landfilling, hydraulic excavator, and electricity consumption in the LCA of the PE pipes are the greatest polluting parameters.     

An analysis of the use of life cycle assessment for waste co-incineration in cement kilns

Life cycle assessment, LCA, has become a key methodology to evaluate the environmental performance of products, services and processes and it is considered a powerful tool for decision makers. Waste treatment options are frequently evaluated using LCA methodologies in order to determine the option with the lowest environmental impact. Due to the approximate nature of LCA, where results are highly influenced by the assumptions made in the definition of the system, this methodology has certain non-negligible limitations. Because of that, the use of LCA to assess waste co-incineration in cement kilns is reviewed in this paper, with a special attention to those key inventory results highly dependent on the initial assumptions made. Therefore, the main focus of this paper is the life cycle inventory, LCI, of carbon emissions, primary energy and air emissions. When the focus is made on cement production, a tonne of cement is usually the functional unit. In this case, waste co-incineration has a non-significant role on CO₂ emissions from the cement kiln and an important energy efficiency loss can be deduced from the industry performance data, which is rarely taken into account by LCA practitioners. If cement kilns are considered as another waste treatment option, the functional unit is usually 1 t of waste to be treated. In this case, it has been observed that contradictory results may arise depending on the initial assumptions, generating high uncertainty in the results. Air emissions, as heavy metals, are quite relevant when assessing waste co-incineration, as the amount of pollutants in the input are increased. Constant transfer factors are mainly used for heavy metals, but it may not be the correct approach for mercury emissions.     

Introducing design for the environment at boeing defense and space group through the application of abridged life-cycle analysis

The streamlined, matrix approach to environmental Life-Cycle Analysis (LCA) developed originally at AT&T by Graedel and Allenby can be adapted to manufacturing processes to produce a useful tool for Design for the Environment (DFE). Pollution prevention in manufacturing has typically focused on the environmental impact of processes at a manufacturer's site. However, it is important to recognize that a process has a “life cycle,” albeit not precisely like the life cycle associated with a product. Modification of processes can also have upstream and downstream effects. In this article, the authors show how, by using a streamlined LCA matrix, it is possible to evaluate the environmental impact associated with a process over the process's life cycle. This approach also allows managers to allocate resources to improve processes that have greater environmental impact and to assess process improvements.     

Multi-objective optimization of waste and resource management in industrial networks – Part II: Model application to the treatment of sewage sludge

In the present article, the thermal treatment of digested sewage sludge generated in the Swiss region of Zürich is modeled and optimized from an environmental perspective. The optimization problem is solved using a multi-objective mixed-integer linear program that combines material flow analysis, process models, life cycle assessment (LCA), and mathematical optimization techniques. The treatment options include co-incineration in municipal solid waste incineration, co-processing in cement production, and mono-incineration with the prospect of phosphorus recovery. The model is optimized according to six environmental objectives. Five of the six single-objective optimal solutions involve splits over the treatment options. The results reflect the available treatment capacities and other constraints, aspects rarely considered in conventional LCA studies. Co-processing in cement production is used to the maximum extent possible when minimizing impacts on climate change, human toxicity, fossil resource depletion, and fully aggregated impacts (ReCiPe H/A), whereas mono-incineration with phosphorus recovery receives the bulk of the sludge when optimizing for ecotoxicity and mineral resource depletion. Four of the single-objective optimal solutions (minimization of fossil energy resource depletion and contribution to climate change, human toxicity, and fully aggregated impacts) outperform the reference case over the six impact categories considered, showing that the current situation can be improved in some environmental categories without compromising others. The results of the sensitivity analysis indicate that assumptions regarding the product systems displaced by recovered by-products are critical for the outcome of the optimization. Our approach identifies in all of the cases solutions in which significant environmental improvements can be attained.     

Life cycle assessment of EPS and CPB inserts: design considerations and end of life scenarios

Expanded polystyrene (EPS) and corrugated paperboard (CPB) are used in many industrial applications, such as containers, shock absorbers or simply as inserts. Both materials pose two different types of environmental problems. The first is the pollution and resource consumption that occur during the production of these materials; the second is the growing landfills that arise out of the excessive disposal of these packaging materials. Life cycle assessment or LCA will be introduced in this paper as a useful tool to compare the environmental performance of both EPS and CPB throughout their life cycle stages. This paper is divided into two main parts. The first part investigates the environmental impacts of the production of EPS and CPB from 'cradle-to-gate', comparing two inserts--both the original and proposed new designs. In the second part, LCA is applied to investigate various end-of-life cases for the same materials. The study will evaluate the environmental impacts of the present waste management practices in Singapore. Several 'what-if' cases are also discussed, including various percentages of landfilling and incineration. The SimaPro LCA Version 5.0 software's Eco-indicator 99 method is used to investigate the following five environmental impact categories: climate change, acidification/eutrophication, ecotoxicity, fossil fuels and respiratory inorganics.     

Life‐Cycle Assessment of Construction in a Developing Country

The construction industry plays a great role in a country's or an area's economy. Construction activities also have significant and increasing effects on the environment. Life‐cycle assessment (LCA) is one of the environmental management techniques that can be used to evaluate the environmental burdens of construction. The authors of this study applied the LCA approach and SimaPro 7.1 software within the framework of the International Organization of Standardization's (ISO) 14040 series of standards and analyzed the global warming potential (GWP) and acidification potential (AP) of the materials acquisition and construction phases of the Parand residential apartment complex located in the southwest part of Tehran province, Iran.     

Use of recycled natural fibres in industrial products: A comparative LCA case study on acoustic components in the Brazilian automotive sector

This paper summarizes the results and the lessons learnt from an LCA case study comparing acoustic automotive components. Three alternative acoustic components produced by the Brazilian automotive sector are considered: dual-layer polyurethane (DL-PU) panel, recycled textile absorption-barrier-absorption (ABA-cotton) panel and recycled textile DL (DL-cotton) panel. DL-PU is a “status-quo” alternative, composed mainly of synthetic plastics and the two other alternatives are mainly made of recycled cotton fibres. Using the Life Cycle Assessment (LCA) method, the three following phases of the panels’ life cycle are examined: production, use and end-of-life. For the latter, two end-of-life scenarios are analysed: landfill and incineration with energy recovery. For the LCA model, some Life Cycle Inventory (LCI) datasets have been adapted from the data available in the EcoInvent database in order to adjust to the Brazilian context. LCA results show that, within the entire life cycle, the DL-cotton option, which combines two layers of recycled fibres of different densities, is overall the best alternative from an environmental perspective. This result is therefore independent from the end-of-life scenario. This is mainly due to the lower weight of this component, which is extremely important for the transportation aspects, but also due to its lower consumption of fossil resources, to the energy saving during its production and to the avoidance of textile disposal that would happen otherwise. The obtained results confirm the available literature dealing with the use of renewable fibres in industrial products. The particular behaviour of recycled fibres compared to virgin ones (in terms of shared contribution of agricultural production and of avoidance of landfilling) is highlighted in this paper, thanks to the application of the “50/50” allocation rule. LCA results are discussed in terms of their potential use in an R&D context. Further research needs are also derived from the case study, including the potential benefits of developing multi-objective optimization methods that include environmental impact to be used in the design of such a component.     

Limitations of applying life cycle assessment to complex co-product systems: The case of an integrated precious metals smelter-refinery

Integrated smelter-refineries play an important role in the recovery of multiple metals from complex primary and secondary materials, and hence in closing metals cycles. Processes in these facilities are strongly interconnected, dynamic, and multifunctional, which challenges a typical representation in life cycle assessment (LCA). This is especially true when LCA is applied to calculate the environmental profile of single metals products.This study examines methodological requirements for assessing complex co-product systems using attributional LCA through a static, gate-to-gate inventory model that quantifies the environmental impacts of each of the metal products of an integrated precious metals smelter-refinery. The model is based on a large number of subprocesses and is formulated using detailed industry data, which allows quantification of the sensitivity of the results with respect to allocation rationales and the data collection period.The results within one impact category vary strongly among metals (up to four orders of magnitude for copper compared to rhodium). Moving from mass- to value-based allocation changes the result for a given metal by up to two orders of magnitude. If value-based allocation is used, the selected reference year for metals prices influences the results by up to a factor of two.Allocation rationales are critically analyzed, and it is shown that none reflect the business model or other system drivers. While the model is focused on quantifying environmental impacts of metal outputs, the actual process is economically driven to efficiently treat a continuously changing feed mix. The complexity of a smelter-refinery cannot be captured by static, attributional inventory models, which is why the choice of allocation rationale remains arbitrary. Instead, marginal, parameterized models are needed; however, such models are substantially more time and data intensive and require disclosure of more detailed, process specific data.