Modelling the economic and environmental performance of engineering products: a materials selection case study

Purpose

Life cycle assessment (LCA) studies allow understanding all relevant processes and environmental impacts involved in the life cycle of products. However, in order to fully assess their sustainability, these studies should be complemented by economic (LCC) and societal analyses. In this context, the present work aims at assessing all costs (internal and external) and the environmental performance associated to the full life cycle of specific engineering products. These products are lighting columns for roadway illumination made with three different materials: a glass fibre reinforced polymer composite, steel and aluminium.

Methods

The LCA/LCC integrated methodology used was based in a ??cradle-to-grave?? assessment which considers the raw materials production, manufacture, on-site installation, use and maintenance, dismantlement and end-of-life (EoL) of the lighting columns. The fossil fuels environmental impact category was selected as the key environmental impact indicator to perform the integrated environmental and cost analysis.

Results

The potential total costs obtained for the full life cycle of the lighting columns demonstrated that the one made in steel performs globally worse than those made in composite or aluminium. Although the three systems present very similar internal costs, the steel column has higher external costs in the use phase that contribute for its higher total cost. This column has very high costs associated to safety features, since it constitutes a significant risk to the life of individuals. The raw material and column production stages are the main contributors for the total internal life cycle costs. The EoL treatment is a revenue source in all systems because it generates energy (in the case of the composite incineration) or materials (in the case of metal recycling). The composite and aluminium lighting columns present similar ??cradle-to-grave?? life cycle total cost. However, until the dismantlement phase, the aluminium column presents the highest environmental impact, whereas in the EoL treatment phase this scenario is reversed. The ??cradle-to-grave?? life cycle potential total cost and the environmental impact (fossil fuels) indicator of the steel lighting column are higher than those of the other columns.

Conclusions

Even though the uncertainties in the LCC are larger if external costs are included, their consideration when modelling the economic performance of engineering products increases the probability of developing a more sustainable solution from a societal perspective.     

Life cycle optimization of energy-intensive processes using eco-costs

Purpose

This study provides a general methodology to integrate LCA into a single- or multi-objective process design optimization context. It uses specific weightings for foreground emissions, for preventable background emissions and for unpreventable background emissions, for each impact category. It is illustrated for a natural gas combined cycle power plant with three scenarios to reduce its carbon dioxide emissions: CO₂ capture and sequestration, fuel substitution with biogas or fuel substitution with synthetic gas from wood.

Methods

Assuming that the opportunity to prevent emissions elsewhere is an implicit part of the process design decision space, the optimal solution cannot waste such opportunities and is shown to minimize total life cycle costs, including emission avoidance costs based on the optimal combination of prevention and compensation measures in the background system. In the case study, background emissions are inventoried from the ecoinvent database, their compensation costs are derived from the Ecocosts 2007 impact assessment method and their prevention costs are estimated from the literature. The calculated avoidance costs (weightings) then show how the background system affects the final choice of CO₂ reduction scenario.

Results and discussion

In the case study, all three options partially shift environmental burdens to the background system, which can be prevented or compensated. The corresponding minimum avoidance cost is highest overall for the biogas option, thus putting it at a disadvantage. For a vast majority of ecoinvent processes, energy efficiency is important to minimize total avoidance costs because they are dominated by background CO₂. Furthermore, prevention cost data gathering can be simplified in some cases, without distorting design decisions, using a CO₂-only background inventory. The non-CO₂ background inventory is more useful after process design, for procurement decisions.

Conclusions

Over-investing in design modifications cannot achieve the same background impact reductions as a sensible green procurement policy. Thus, the proposed weighting methodology ensures that all types of design decisions integrate LCA without incorrectly assuming that emissions are necessarily unavoidable when in the background. Within a context of future emission taxes or tradable permits, the weightings can also anticipate the after-tax cost passed on by suppliers—a marketable benefit of LCA.

Recommendations

Since many LCA studies are equivalent to design optimization problems, the proposed weighting methodology provides a single-score impact method relevant to decision-making as well as a straightforward approach to LCA interpretation in terms of detailing the optimal combination of applicable design modifications, prevention measures and compensation measures.     

Towards life cycle sustainability assessment: drawing on the NEEDS project’s total cost and multi-criteria decision analysis ranking methods

Purpose

In the European Union project New Energy Externalities Development for Sustainability (NEEDS), power generation technologies were ranked by means of two sustainability assessment approaches. The total costs approach, adding private and external costs, and a multi-criteria decision analysis (MCDA) were used, integrating social, economic and environmental criteria. Both approaches relied on environmental indicators based on life cycle assessment. This study aims to analyse the extent to which the development of life cycle sustainability assessment (LCSA) can draw on these ranking methods.

Methods

The approaches to rank technologies in the NEEDS project are reviewed in terms of similarities and differences in concept, quantification and scope. Identified issues are discussed and set into perspective for the development of a potential future LCSA framework.

Results and discussion

The NEEDS MCDA and total costs considerably overlap regarding issues covered, except for several social aspects. Beyond total costs being limited to private and external costs, most notable conceptual differences concern the coverage of pecuniary (i.e. price change-induced) external effects, and potential double-counting for instance of resource depletion or specific cost components. External costs take account of the specific utility changes of those affected, requiring a rather high level of spatial and temporal detail. This allows addressing intra- and inter-generational aspects. Differences between both ranking methods and current LCSA methods concern the way weighting is performed, the social aspects covered and the classification of indicators according to the three sustainability dimensions. The methods differ in the way waste, accidents or intended impacts are taken into account. An issue regarding the definition of truly comparable products has also been identified (e.g. power plants).

Conclusions

For the development of LCSA, the study suggests that taking a consequential approach allows assessing pecuniary effects and repercussions of adaptation measures, relevant for a sustainability context, and that developing a life cycle impact assessment for life cycle costing would provide valuable information. The study concludes with raising a few questions and providing some suggestions regarding the development of a consistent framework for LCSA: whether the analyses in LCSA shall be distinguished into the three dimensions of sustainable development at the inventory or the impact level also with the aim to avoid double-counting, whether or not LCSA will address exceptional events, whether or not benefits shall be accounted for and how to deal with methodological and value choices (e.g. through sensitivity analyses).     

Fouling release coating application as an environmentally efficient retrofit: a case study of a ferry-type ship

Purpose and methods

The paper introduces a simple retrofit performed on a case study vessel, with the aim of assessing the retrofit’s potential environmental impacts via doing a life cycle assessment. Additionally, the case presented herein strives to evidence the applicability of life cycle assessment (LCA) appraisals within shipyard representatives or managers.

Results and discussion

The environmental results shown in this paper are related to cost calculations presented for the selected retrofit, underlining the potential environmental impacts from the retrofit, while appraising its economic performance.

Conclusions

The paper strives to evidence that significant savings with regard to fuel costs can be achieved by the application of this retrofit to ships with a similar operational profile, but more importantly, the improved operational efficiency and the emission reductions can be noteworthy. Lastly, the results summarised intend to offer an optimistic context towards the implementation of the retrofit at a larger scale, i.e. a section of the existing fleet.     

Life cycle cost analysis of the UK housing stock

Purpose

The aim of the paper is to estimate life cycle costs (LCC) of the current housing stock in the UK as part of sustainability assessment of the residential construction sector. This is carried out by first estimating the life cycle costs of individual houses considering detached, semi-detached and terraced homes. These results are then extrapolated to the UK housing stock consisting of seven million each of semi-detached and terraced houses and four million of detached houses. A brief discussion of life cycle environmental impacts is also included to help identify improvement opportunities for both costs and impacts.

Methods

The life cycle costing methodology followed in the study is congruent with the life cycle assessment methodology. The system boundary for the study is from ‘cradle to grave’, including all activities from extraction and manufacture of construction materials to construction and use of the house to its demolition. The functional unit is defined as the construction and occupation of a house in the UK over the lifetime of 50 years.

Results and discussion

The total life cycle costs are estimated at £247,000 for the detached house, £192,000 for the semi-detached and £142,000 for the terraced house. The running costs in the use stage contribute 52 % to the total life cycle costs of which half is from energy use. The construction costs contribute 35 % to the total LCC with the walls and the roof being the most expensive items. The remaining 13 % of the costs are incurred at the end of life of the house which are largely (85 %) due to the cost of labour for demolition. Recovery of end-of-life materials has a limited potential to reduce the overall life cycle costs of a house. The life cycle costs of the whole housing stock are estimated at £67 billion per year or £3,360 billion over the 50-year lifetime.

Conclusions

The existing housing stock in the UK is facing a number of challenges that will need to be addressed in the near future. These include improving energy efficiency and reducing the dependency on fossil fuels to reduce energy demand, fuel poverty and environmental impacts. Furthermore, the disparity between the construction costs and house market prices will need to be addressed to ensure that access to housing and house ownership do not become the privilege of a few.     

A life cycle assessment case study of ground rubber production from scrap tires

Purpose

The number of scrap tires generated in China has grown dramatically every year. Generation of ground rubber from scrap tires is the dominant management option in China. It is necessary to assess the environmental impacts of ground rubber production from scrap tires to provide technical advices on a cleaner production.

Methods

Production of ground rubber from recycled scrap tires consist of three steps: rubber powder preparation, devulcanization, and refining. A process life cycle assessment (LCA) of ground rubber production from scrap tires is carried out, and Eco-indicator 99 method coupled with ecoinvent database is applied to evaluate the environmental impacts of this process.

Results and discussion

During the ground rubber production stage, the impact factor of respiratory inorganic is the most serious one. Devulcanization has the highest environmental load of about 66.2 %. Moreover, improvement on the flue gas treatment contributes to a cleaner production and a more environmental-friendly process. Applying clean energy can largely reduce environmental load by about 21.5 %.

Conclusions

The results can be a guidance to reduce environmental load when producing ground rubber from scrap tires. Meanwhile, increasing energy efficiency, improving environmental protection equipment, and applying clean energy are the effective measures to achieve this goal.     

Life cycle assessment evaluation of green product labeling systems for residential construction

Purpose

Life cycle assessment (LCA) is a tool that can be utilized to holistically evaluate novel trends in the construction industry and the associated environmental impacts. Green labels are awarded by several organizations based on single or multiple attributes. The use of multi-criteria labels is a good start to the labeling process as opposed to single criteria labels that ignore a majority of impacts from products. Life cycle thinking, in theory, has the potential to improve the environmental impacts of labeling systems. However, LCA databases currently are lacking in detailed information about products or sometimes provide conflicting information.

Method

This study compares generic and green-labeled carpets, paints, and linoleum flooring using the Building for Environmental and Economic Sustainability (BEES) LCA database. The results from these comparisons are not intuitive and are contradictory in several impact categories with respect to the greenness of the product. Other data sources such as environmental product declarations and ecoinvent are also compared with the BEES data to compare the results and display the disparity in the databases.

Results

This study shows that partial LCAs focused on the production and transportation phase help in identifying improvements in the product itself and improving the manufacturing process but the results are uncertain and dependent upon the source or database. Inconsistencies in the data and missing categories add to the ambiguity in LCA results.

Conclusions

While life cycle thinking in concept can improve the green labeling systems available, LCA data is lacking. Therefore, LCA data and tools need to improve to support and enable market trends.     

Life cycle assessment and life cycle costing of road infrastructure in residential neighbourhoods

Purpose

The built environment consists of a huge amount of infrastructure, such as roads and utilities. The objective of this paper is to assess the life cycle financial and environmental impact of road infrastructure in residential neighbourhoods and to analyse the relative contribution of road infrastructure in the total impact of neighbourhoods.

Methods

Various road sections are analysed based on an integrated life cycle approach, combining life cycle costing and life cycle assessment. To deal with complexity, a hierarchic assessment structure, using the principles of the “element method for cost control”, is implemented. Four neighbourhood models with diverse built densities are compared to gain insight in the relative impact of road infrastructure in neighbourhoods.

Results and discussion

The results reveal important financial and environmental impact differences between the road sections analysed. Main contributors to the life cycle financial and environmental impact are the surface layer and electrical and piped services. The contribution of road infrastructure to the total neighbourhood impact, ranging from 2 to 9 % of the total cost, is relatively limited, compared to buildings, but not negligible in low built density neighbourhoods.

Conclusions

Good spatial planning of the neighbourhood is recommended to reduce the amount of road infrastructure and the related financial and environmental impact. The priority should be to design denser neighbourhood layouts, before decreasing the financial and environmental impact of the road sections.

     

Integrating environmental and economic life cycle analysis in product development: a material selection case study

Purpose

Achieving sustainability by rethinking products, services and strategies is an enormous challenge currently laid upon the economic sector, in which materials selection plays a critical role. In this context, the present work describes an environmental and economic life cycle analysis of a structural product, comparing two possible material alternatives. The product chosen is a storage tank, presently manufactured in stainless steel (SST) or in a glass fibre reinforced polymer composite (CST). The overall goal of the study is to identify environmental and economic strong and weak points related to the life cycle of the two material alternatives. The consequential win–win or trade-off situations will be identified via a life cycle assessment/life cycle costing (LCA/LCC) integrated model.

Methods

The LCA/LCC integrated model used consists in applying the LCA methodology to the product system, incorporating, in parallel, its results into the LCC study, namely those of the life cycle inventory and the life cycle impact assessment.

Results and discussion

In both the SST and CST systems, the most significant life cycle phase is the raw materials production, in which the most significant environmental burdens correspond to the Fossil fuels and Respiratory inorganics categories. The LCA/LCC integrated analysis shows that the CST has globally a preferable environmental and economic profile, as its impacts are lower than those of the SST in all life cycle stages. Both the internal and external costs are lower, the former resulting mainly from the composite material being significantly less expensive than stainless steel. This therefore represents a full win–win situation. As a consequence, the study clearly indicates that using a thermoset composite material to manufacture storage tanks is environmentally and economically desirable. However, it was also evident that the environmental performance of the CST could be improved by altering its end-of-life stage.

Conclusions

The results of the present work provide enlightening insights into the synergies between the environmental and the economic performance of a structural product made with alternative materials. Furthermore, they provide conclusive evidence to support the integration of environmental and economic life cycle analysis in the product development processes of a manufacturing company or, in some cases, even in its procurement practices.     

Life cycle assessment of the Peruvian industrial anchoveta fleet: boundary setting in life cycle inventory analyses of complex and plural means of production

Purpose

This work has two major objectives: (1) to perform an attributional life cycle assessment (LCA) of a complex mean of production, the main Peruvian fishery targeting anchoveta (anchovy) and (2) to assess common assumptions regarding the exclusion of items from the life cycle inventory (LCI).

Methods

Data were compiled for 136 vessels of the 661 units in the fleet. The functional unit was 1 t of fresh fish delivered by a steel vessel. Our approach consisted of four steps: (1) a stratified sampling scheme based on a typology of the fleet, (2) a large and very detailed inventory on small representative samples with very limited exclusion based on conventional LCI approaches, (3) an impact assessment on this detailed LCI, followed by a boundary-refining process consisting of retention of items that contributed to the first 95 % of total impacts and (4) increasing the initial sample with a limited number of items, according to the results of (3). The life cycle impact assessment (LCIA) method mostly used was ReCiPe v1.07 associated to the ecoinvent database.

Results and discussion

Some items that are usually ignored in an LCI’s means of production have a significant impact. The use phase is the most important in terms of impacts (66 %), and within that phase, fuel consumption is the leading inventory item contributing to impacts (99 %). Provision of metals (with special attention to electric wiring which is often overlooked) during construction and maintenance, and of nylon for fishing nets, follows. The anchoveta fishery is shown to display the lowest fuel use intensity worldwide.

Conclusions

Boundary setting is crucial to avoid underestimation of environmental impacts of complex means of production. The construction, maintenance and EOL stages of the life cycle of fishing vessels have here a substantial environmental impact. Recommendations can be made to decrease the environmental impact of the fleet.     

The Quebec Life Cycle Inventory Database Project

Purpose

Life cycle assessment (LCA) in Quebec (Canada) is increasingly important. Yet, studies often still need to rely on foreign life cycle inventory (LCI) data. The Quebec government invested in the creation of a Quebec LCI database. The approach is to work as an ecoinvent “National Database Initiative” (NDI), whereby the Quebec database initiative uses and contributes to the ecoinvent database. The paper clarifies the relationship between ecoinvent and the Quebec NDI and provides details on prioritization and data collection.

Methods

The first steps were to select a partner database provider and to work out the modalities of the partnership. The main criterion for partner selection was database transparency, i.e., availability of unit process data (gate-to-gate), necessary for database adaptation. This and other criteria, such as free access to external reviewers, conservation of dataset copyright, seamless embedding of datasets, and overall database sophistication, pointed to ecoinvent. Once started, the NDI project proceeded as follows: (1) data collection was prioritized based on several criteria; (2) some datasets were “recontextualized,” i.e., existing datasets were duplicated and relocated in Quebec and linked to datasets representing regional suppliers, where relevant; (3) new datasets were created; and (4) Canadian environmentally extended supply-use tables were created for the ecoinvent IO repository.

Results and discussion

Prioritization identified 500 candidate datasets for recontextualization, based on the relative importance of relative contribution of direct electricity consumption to cradle-to-gate impacts, and 12 key sectors from which about 450 data adaptation or collection projects were singled out. Data collection and private sector solicitation are underway. Private sector participation is highly variable. A number of communication tools have been elaborated and a solicitation team formed to palliate this obstacle. The new ecoinvent database protocol (Weidema et al. 2011) increases the amount of information that is required to create a dataset, which can lengthen or, in extreme cases, impede dataset creation. However, this new information is required for the new database functionalities (e.g., providing multiple system models based on the same unit process data and regionalized LCA).

Conclusions

Being an NDI is advantageous for the Quebec LCI database project on multiple levels. By conserving dataset copyright, the NDI remains free to spawn or support other LCI databases. Embedding datasets in ecoinvent enables the generation of LCI results from “day 1.” The costs of IT infrastructure and data review are null. For these reasons, and because every NDI improves the global representativity of ecoinvent, we recommend other regional or national database projects work as NDIs.

     

When consumer behavior dictates life cycle performance beyond the use phase: case study of inkjet cartridge end-of-life management

Purpose

Conventional wisdom suggests that product reuse can provide environmental savings. The purpose of this study is to first compare the environmental impacts of retail refilling and remanufactured inkjet cartridge alternatives to production of new inkjet cartridges, and then determine the extent to which consumer behavior can influence life cycle outcomes.

Methods

A life cycle inventory was developed for an inkjet cartridge with an integral print head using material composition data collected from cartridge disassembly and material processing, product manufacturing, and transportation inputs estimated from market data and the ecoinvent database in SimaPro 7.3. Although previous comparative life cycle assessment (LCA) studies for printer cartridges typically use “pages printed” or a variation thereof for the functional unit, “cartridge use cycles” is more suitable for examining reused inkjet cartridge alternatives that depend on the inkjet cartridge end-of-life (EOL) route chosen by the consumer. Since multiple reuse cycles achieved from refilling by a retailer was of specific interest, a functional unit defined in the form of “five use cycles” included the mode and manner in which consumers purchased inkjet cartridge use cycles.

Results and discussion

Cartridge refills present the lowest environmental impact, offering a 76 % savings in global warming potential (GWP) impact compared to production and purchase of a new inkjet cartridge alternative, followed by the remanufacturing case, which provided a 36 % savings in GWP impact compared to the new inkjet cartridge. However, results varied widely, even switching to favor new cartridge purchase, depending on how consumer transport was modeled, specifically the mode of travel, travel patterns (number of trips), and method of allocating impact to each trip.

Conclusions

Refilling an original equipment manufacturer (OEM) cartridge four consecutive times provides the best alternative for reducing environmental impact for those consumers that purchase inkjet cartridges one at a time. On the other hand, consumers that purchase multiple cartridges in a single trip to a retailer reduce environmental impact more by transport minimization than by refilling. Results reinforce the need for more comprehensive inclusion of consumer behavior when modeling life cycle environmental impact of product alternatives.     

A methodological improvement for assessing petrochemical projects through life cycle assessment and eco-costs

Purpose

As the debate on how to effectively link life cycle analysis (LCA) and negative externalities of the products or processes is still unsolved, an improved methodology that involves the private and social (environment) profitability to petrochemical projects in Mexico is presented. We incorporate both environmental impacts, identified through the LCA, using the eco-costs model, within a project appraisal analysis. The eco-costs are a single LCA-based indicator of environmental burden, based on the concept of marginal prevention costs, i.e. costs required to bring back the environmental degradation to a sustainable level.

Methods

The methodology was carried out in four steps. First, the potential environmental impacts (in physical units) were assessed through life-cycle assessment. Second, the marginal prevention costs of pollution (eco-costs) of impact categories were estimated. Third, since these monetary values are given for a European income level, eco-costs were adjusted to Mexican income levels (i.e., benefit transfer). Fourth, these adjusted values were used for assessing the financial viability of two petrochemical projects at two stages of installed capacity.

Results and discussion

The costs of marginal prevention (eco-costs) changed from 1.62 USD/kg of acrylonitrile in the old design to 0.926 USD/kg in the redesign. In case of vinyl chloride monomer (VCM), the eco-costs were from 16.08 USD/kg of VCM for the stage design to 1.62 USD/kg for the operational stage (ex post). The sensitivity analysis identified that only 15 % of these eco-costs, in the case of acrylonitrile, and 1.5 % for the VCM, could be incorporated to the costs of the project without affecting the profit on the investment.

Conclusions

The developed methodology was helpful to express potential environmental impacts in monetary units as financial indicators in a project appraisal. Thus, the methodology can be used to internalize the eco-costs into product prices, shifting the financial burden to firms and consumers, in order to offset the high costs of the green net national product.     

Emission payback periods for increased residential insulation using marginal electricity modeling: a life cycle approach

Purpose

Increases in residential insulation can reduce energy consumption and corresponding life cycle emissions, but with increased manufacturing and transportation of insulation and the associated impacts. In this study, we conducted life cycle analyses of residential insulation and estimated payback periods for carbon dioxide (CO₂), nitrogen oxides (NOx), and sulfur dioxide (SO₂) emissions, using modeling techniques that account for regional variability in climate, fuel utilization, and marginal power plant emissions.

Methods

We simulated the increased production of insulation and energy savings if all single-family homes in the USA increased insulation levels to the 2012 International Energy Conservation Code, using an energy simulation model (EnergyPlus) applied to a representative set of home templates. We estimated hourly marginal changes in electricity production and emissions using the Avoided Emissions and Generation Tool (AVERT), and we estimated emissions related to direct residential combustion. We determined changes in upstream emissions for both insulation and energy using openLCA and ecoinvent. Payback periods were estimated by pollutant and region. In sensitivity analyses, we considered the importance of marginal versus average power plant emissions, transportation emissions, emission factors for fiberglass insulation, and sensitivity of emission factors to the magnitude of electricity reduction.

Results and discussion

Combining the life cycle emissions associated with both increased insulation manufacturing and decreased energy consumption, the payback period for increased residential insulation is 1.9 years for CO₂ (regional range 1.4–2.9), 2.5 years for NOx (regional range 1.8–3.9), and 2.7 years for SO₂ (regional range 1.9–4.8). For insulation, transportation emissions are limited in comparison with manufacturing emissions. Emission benefits displayed strong regional patterns consistent with relative demands for heating versus cooling and the dominant fuels used. Payback periods were generally longer using average instead of marginal emissions and were insensitive to the magnitude of electricity savings, which reflects the structure of the intermediate complexity electricity dispatch model.

Conclusions

The life cycle benefits of increased residential insulation greatly exceed the adverse impacts related to increased production across all regions, given insulation lifetimes of multiple decades. The strong regionality in benefits and the influence of a marginal modeling approach reinforce the importance of site-specific attributes and time-dynamic modeling within LCA.

     

Life cycle energy and environmental benefits of a US industrial symbiosis

Purpose

The industrial ecosystem identified in and around the Campbell Industrial Park in Honolulu County, Hawai’i involves 11 facilities exchanging water, materials, and energy across an industrial cluster. This paper highlights the advantages of this arrangement using life cycle assessment to determine the energy and environmental costs and benefits of the existing pattern of exchanges.

Methods

A consequential approach was used to evaluate each material substitution for four environmental impact categories: primary energy use, greenhouse gas (GHG) emissions, acidification, and eutrophication. Each material exchange included avoided production and reduced use of virgin materials, any necessary pre-processing or transportation of local by-products, and avoided treatment or disposal of these by-products.

Results and discussion

All exchanges exhibited positive net savings across all environmental impact categories, with the exceptions of waste oil and tire-derived fuel burned as substitutes for coal. The greatest savings occur as a result of sharing steam between a combined cycle fuel oil-fired cogeneration plant and a nearby refinery. In total, the environmental savings realized by this industrial cluster are significant, equivalent to 25 % of the state’s policy goal for reducing the industrial component of GHG emissions over the next decade. The role of policy in supporting material and energy exchanges is also discussed as the central cluster of two power plants and two refineries share steam and water in part under regulatory requirements.

Conclusions

The results show environmental benefits of the sharing of by-product resources accrued on a life cycle basis, while for the local context, the reduction of imported fuels and materials helps to reduce the external dependency of Oahu’s remote island economy. The environmental benefits of materials exchanges are often ignored in energy policy, though, as in this case, they can represent considerable savings.     

A trade-based method for modelling supply markets in consequential LCA exemplified with Portland cement and bananas

Purpose

This study proposes a method based on the analysis of trade networks over time for modelling the marginal supply of products in consequential life cycle assessment (LCA). It aims at increasing the geographical granularity of markets, accuracy of transport distances and modes and material losses during transit by creating country-specific markets, instead of region-based supply-origin markets as currently proposed by ecoinvent. It leads to a better consideration of the environmental weight of trade following a change in demand on a local market and may serve as an inspirational basis for future releases of consequential life cycle inventory (LCI) databases.

Methods

The method uses ecoinvent v.3.3 as a support LCI database and two distinct traded products: bananas and grey Portland cement. Each country involved in the trade of a said product has a corresponding market created in the LCI database. The behavior of market to a marginal change in internal demand is modelled after its marginal trading preferences: it can either affect local production, imports, exports or a mix of the first two. Markets are linked to one another based on the linear regression analysis of their historical trade relations. The inventories that follow an increase in demand of 1000 kg of bananas and grey Portland cement are calculated for each market involved in their trade and are environmentally characterized and compared to the generic region-based market datasets provided by ecoinvent to assess the gains in accuracy through a higher geographical granularity. Furthermore, the characterized inventories of the markets for bananas are compared to a parallel scenario where transport distances are kept to a minimum using the shortest path method. It isolates the environmental burden associated to the utility maximization of the demand.

Results and discussion

When comparing the characterized impacts of country-specific markets with the generic ecoinvent market datasets, disparities in results appear. They highlight the importance of transport induced by demand displacement and losses of material during transport, both being the consequences of the extent a given market decides to be supplied directly from producing markets at the margin. These are aspects that may go unaccounted for when using generic regional markets. Second, optimizing transport distances for each market decreases the environmental impacts for most categories by more than 70%.

Conclusions

This study shows there is a need for modelling and understanding market relations to more accurately define the role of trade, supply chain efficiency and import policies in LCA.

     

Calculating the influence of alternative allocation scenarios in fossil fuel chains

Goal, Scope and Background

As part of an LCA study comparing an average Dutch passenger car running on petrol with a similar car running on bio-ethanol and comparing an average Dutch passenger car running on diesel with a similar car running on biodiesel, the question raised to get more insight into the allocations made in fossil fuel chains in existing data bases such as ecoinvent. Both biofuel and fossil fuel chains contain various allocation situations that have been approached differently by various authors leading to differing and incomparable results. For biofuel chains, stakeholders had obtained insight into the allocations in earlier studies, but for the allocations made for the fossil chains, this was not the case. Therefore, one part of the study, which is reported in this paper, focused on a quick scan of different allocation scenarios for fossil fuels chains using the Swiss ecoinvent v1.1 database.

Methods

The quick scan focused on three different allocation scenarios for fossil fuel chains: economic allocation, physical allocation and the ecoinvent default allocation. There appeared to be 54 multi-output (MO) processes linked to both the passenger car and the diesel system in the ecoinvent v1.1 database. Based on contribution analyses identifying which multi-output processes contribute most to one of the environmental impact categories of the characterisation, seven multi-output processes were selected that have been further analysed with the three allocation scenarios mentioned.

Results

The results show that although at the process level allocation factors may differ significantly (up to almost 250), the total results only differ modestly (1–1.5), at least for the present case.

Discussion

There is no general rule between these two. They depend on the scaling factor and the environmental impact related to the resource extractions and emissions of a particular multi-output process and its upstream processes in the total system analysed.

Conclusions

The results of this quick scan are mainly intended for illustrating and learning purposes focusing on the possible influence of different allocation scenarios for fossil fuel chains. Bearing these limitations in mind, it can be concluded that different allocation methods can generate large differences in allocation factors and thus also at the level of environmental impacts allocated to the derived single-output processes. Nevertheless, the aggregated results for the present case only differ modestly.     

Integrating life cycle assessment and material flow cost accounting to account for resource productivity and economic-environmental performance

Purpose

This study contributes to measuring the interactions between human technological activities and the natural environment in an integrative approach to support organisations and supply chain partners in their efforts to increase the resource productivity and economic-environmental performance of their product systems. We expand existing knowledge on the underlying methodological facets of the integrative use of two standardised instruments. We further guide the discussion with a case study and depict areas for future research.

Methods

We discuss the integration of life cycle assessment and material flow cost accounting to examine resource inputs and product and non-product outputs alongside environmental impacts and costs. Life cycle assessment is a non-financial instrument to identify hotspots of resource use and associated environmental burdens, while material flow cost accounting is a powerful financial instrument used to monetise resource use (in)efficiencies and demonstrate the resources bound in product and non-product output. Both are valuable life cycle management instruments to measure and control strategic themes related to improvement measures and investment decisions and support communication between the different decision-makers involved. We highlight the methodological facets of this integrative assessment based on a holistic single case study in order to share the lessons learned.

Results and discussion

Our case study illustrates a typical case where manufacturing costs and environmental burdens are primarily borne by the product, whereas a substantial portion of the resources also flows into by-products and non-products. We highlight the relevance of a shared set of rules and assumptions for systems, functions, system boundaries, inventories, and allocation rules which avoid an undesired interfusion of the physical and monetary dimensions to support a more systematic, consistent, and comparable modelling of integrated life cycle assessment and material flow cost accounting. However, researchers and practitioners should bear in mind the benefits and limitations of such integrated assessments, such as methodological choice, which also affect the decisive direction of the results.

Conclusions

The present study expands existing knowledge on the methodological facets of combining life cycle assessment and material flow cost accounting. By contrasting the hotspots of resource use as well as associated costs and environmental burdens, the instruments jointly provide valuable insights to identify integrated resource saving as well as economic and environmental improvement potentials for present and future business operations. Future research is needed in the following arenas: further development of the environmental impact indicators to capture the temporal and geographical occurrence of impacts; updating allocation criteria for integrated assessments in standards and guidelines; improving the visualisation of revenues in Sankey diagrams, the flow-based classification in the modelling software, as well as cost accounting and information systems; formalisation of indicators in management processes to generate resource efficiency strategies and goals; and finally, assessment of circular economy strategies and negative effects.

     

Tackling environmental impacts in simple trigeneration systems operating under variable conditions

Purpose

Environmental concerns have been a growing issue when planning energy supply systems for buildings, as the energy demands (presenting seasonal and daily variations) represent one of the most energy-intensive consumptions in industrialized societies. The optimal operation corresponding to different energy demands of a trigeneration system was analyzed by an integrated methodology combining Thermoeconomic analysis and life cycle assessment, in order to adequately allocate the energy resources and the generated environmental loads to the different energy services produced.

Methods

Thermoeconomic analysis, which is usually used to allocate energy and economic costs, is herein applied to the evaluation of environmental costs and distribution of resources throughout the trigeneration system. Attention is focused on the correct allocation of energy resources and environmental loads to internal flows and final products. Appropriate rules were established to calculate energy and environmental costs.

Results and discussion

Operation of the system considered the possibilities that surplus electricity could be exported to the national grid and part of the cogenerated heat could be wasted if this resulted in a decrease of operation costs and/or environmental loads. The results obtained show a low-cost and low-emission production with respect to the separate production in different operation modes. It was observed that, in specific periods, the trigeneration system operates wasting part of the cogenerated heat, and, in other periods, part of the electricity produced is exported to the electric grid. The trigeneration system operates in these modes because it results beneficial from environmental or economic viewpoints, achieving a lower economic cost or fewer CO₂ emissions.

Conclusions

The methodology presented as well as the allocation method proposal were congruent with the objectives of installing trigeneration systems that supplied energy services with fewer emissions than those of separate production and of equally benefitting the consumers of heat, coolth (“coolth” is used as the noun form of “cool”; opposite of warmth. Not to be confused with cooling, which is the opposite of heating.) (alias cooling energy), and electricity.