Anne-Marie Tillman

Significance of decision-making for LCA methodology

Abstract Decision-making is central to life cycle assessment (LCA), both in the sense that LCA may be used as decision support and in the sense that different methodological choices in LCA are relevant to different applications. This latter issue is pursued in this paper: i.e., how the decision-making context, and thus goal definition, may be used to guide methodological choices in LCA. A distinction is made between a retrospective or accounting perspective and a prospective perspective, where the consequences of alternative actions are investigated. This has significant implications for LCA guidelines, including the standard on LCA compiled by the International Standardization Organization (ISO).

Open-loop recycling: Criteria for allocation procedures

If the aim of an LCA is to support decisions or to generate and evaluate ideas for future decisions, the allocation procedure should generally be effect-oriented rather than cause-oriented. It is important that the procedure be acceptable to decision makers expected to use the LCA results. It is also an advantage if the procedure is easy to apply. Applicability appears to be in conflict with accurate reflection of effect-oriented causalities. To make LCA a more efficient tool for decision support, a range of feasible allocation procedures that reflect the consequences of inflows and outflows of cascade materials is required.

Choice of system boundaries in life cycle assessment

System boundaries in life cycle assessments (LCA) must be specified in several dimensions: boundaries between the technological system and nature, delimitations of the geographical area and time horizon considered, boundaries between production and production of capital goods and boundaries between the life cycle of the product studied and related life cycles of other products. Principles for choice of system boundaries are discussed, especially concerning the last dimension. Three methods for defining the contents of the analysed system in this respect are described: process tree, technological whole system and socio-economic whole system. The methods are described in the applications multi-output processes and cascade recycling, and examples are discussed. It is concluded that system boundaries must be relevant in relation to the purpose of an LCA, that processes outside the process tree in many cases have more influence on the result than details within the process tree, and that the different methods need to be further compared in practice and evaluated with respect to both relevance, feasibility and uncertainty.

A simplified procedure for the acetylation of hardwood and softwood flakes for flakeboard production.

Abstract Southern pine and aspen flakes were acetylated with acetic anhydride alone without cosolvent or catalyst by a simple dip procedure. The new procedure greatly shortens reaction time and simplifies chemical recovery. Acetylation weight gains of 15% to 20% can be achieved in 1 to 3 hours with southern pine flakes and in 2 to 4 hours with aspen flakes. Flakeboards made from acetylated southern pine or aspen flakes absorbed much less water, both in water-soaking tests and when subjected to humid air, and swelled at a lower rate and to a lower extent than did control boards. Hygroscopicity of the resulting flakeboards decreased with increased level of wood acetylation. The equilibrium moisture content (EMC) for flakeboards made from acetylated flakes was lower at each relative humidity tested than that of control boards.

Life cycle assessment of municipal waste water systems

Life Cycle Assessment was applied to municipal planning in a study of waste water systems in Bergsjön, a Göteborg suburb, and Hamburgsund, a coastal village. Existing waste water treatment consists of mechanical, biological and chemical treatment. The heat in the waste water from Bergsjön is recovered for the district heating system. One alternative studied encompassed pretreatment, anaerobic digestion or drying of the solid fraction and treatment of the liquid fraction in sand filter beds. In another alternative, urine, faeces and grey water would separately be conducted out of the buildings. The urine would be used as fertilizer, whereas faeces would be digested or dried, before used in agriculture. The grey water would be treated in filter beds. Changes in the waste water system would affect surrounding technical systems (drinking water production, district heating and fertilizer production). This was approached through system enlargement. For Hamburgsund, both alternatives showed lower environmental impact than the existing system, and the urine separation system the lowest. Bergsjön results were more difficult to interpret. Energy consumption was lowest for the existing system, whereas air emissions were lower for the alternatives. Water emissions increased for some parameters and decreased for others. Phosphorous recovery was high for all three alternatives, whereas there was virtually no nitrogen recovery until urine separation was introduced.

Environmental impacts of hybrid, plug-in hybrid, and battery electric vehicles—what can we learn from life cycle assessment?

PurposeThe purpose of this review article is to investigate the usefulness of different types of life cycle assessment (LCA) studies of electrified vehicles to provide robust and relevant stakeholder information. It presents synthesized conclusions based on 79 papers. Another objective is to search for explanations to divergence and “complexity” of results found by other overviewing papers in the research field, and to compile methodological learnings. The hypothesis was that such divergence could be explained by differences in goal and scope definitions of the reviewed LCA studies.MethodsThe review has set special attention to the goal and scope formulation of all included studies. First, completeness and clarity have been assessed in view of the ISO standard’s (ISO 2006a, b) recommendation for goal definition. Secondly, studies have been categorized based on technical and methodological scope, and searched for coherent conclusions.Results and discussionComprehensive goal formulation according to the ISO standard (ISO 2006a, b) is absent in most reviewed studies. Few give any account of the time scope, indicating the temporal validity of results and conclusions. Furthermore, most studies focus on today’s electric vehicle technology, which is under strong development. Consequently, there is a lack of future time perspective, e.g., to advances in material processing, manufacturing of parts, and changes in electricity production. Nevertheless, robust assessment conclusions may still be identified. Most obvious is that electricity production is the main cause of environmental impact for externally chargeable vehicles. If, and only if, the charging electricity has very low emissions of fossil carbon, electric vehicles can reach their full potential in mitigating global warming. Consequently, it is surprising that almost no studies make this stipulation a main conclusion and try to convey it as a clear message to relevant stakeholders. Also, obtaining resources can be observed as a key area for future research. In mining, leakage of toxic substances from mine tailings has been highlighted. Efficient recycling, which is often assumed in LCA studies of electrified vehicles, may reduce demand for virgin resources and production energy. However, its realization remains a future challenge.ConclusionsLCA studies with clearly stated purposes and time scope are key to stakeholder lessons and guidance. It is also necessary for quality assurance. LCA practitioners studying hybrid and electric vehicles are strongly recommended to provide comprehensive and clear goal and scope formulation in line with the ISO standard (ISO 2006a, b).

Life cycle assessment of flooring materials: Case study

The environmental impact of the three flooring materials linoleum, vinyl flooring and solid wood flooring during their life cycles was assessed and compared through life cycle assessment (LCA). The scenarios used describe a Swedish situation. Only impacts on the natural environment were studied The quantitative results of the inventory analysis were evaluated by using three different assessment methods. According to the results, solid wood flooring proved to be clearly the most environmentally sound flooring. Linoleum was ranked as more environmentally sound than vinyl flooring, although this was less evident in comparison with ranking the solid wood flooring.

LCA of concrete and steel building frames

The effects on the external environment of seven concrete and steel building frames representative of present-day building technology in Sweden were analysed using LCA methodology. Objects of the study included frame construction and supplementary materials. Several-storey offices and dwellings were studied. The functional unit was defined as one average m2 of floor area during the lifetime of the building. Inventory data were elaborated for concrete and steel production, the building site, service life, demolition and final disposal. Parameters included were raw material use, energy use, emissions to air, emissions to water and waste generation. The inventory results were presented and evaluated as such, in addition to an interpretation by using three quantitative impact assessment methods. Parameters that weighed heavily were use of fossil fuels, CO2, electricity, SOx2 NOx2 alloy materials and waste, depending on what assessment method was used. Over the life cycle, building production from cradle to gate accounted for about the same contribution to total environmental loads as maintenance and replacement of heat losses through external walls during service life, whereas demolition and final disposal accounted for a considerably lower contribution.

Product Chain Actors' Potential for Greening the Product Life Cycle

The challenge in working with environmental improvements is to select the action offering the most substantial progress. However, not all actions are open to all actors in a product chain. This study demonstrates how life cycle assessment (LCA) may be used with an actor perspective in the Swedish postfarm milk chain. The potential measures were identified, applied by the dairy, retailer, and household, that gave the most environmental improvement in a life cycle perspective. Improved energy efficiency, more efficient transport patterns, reduced milk and product losses, and organic labeling were investigated. Milk, yogurt and cheese were considered. After LCAs of the products were established, improvement potentials of the actors were identified and quantified. The quantification was based mostly on literature studies but also on assumptions. Then the LCAs were recalculated to include the estimated improvement potential. To find the action with the greatest potential, the environmental impacts of the modified and original LCAs were compared for each actor. No action was superior to any other from the dairy perspective, but reduced wastage lowered most impacts for all three products. For retailers, using less energy is the most efficient improvement. From the household perspective, reducing wastage gives unambiguously positive results. When households choose organic products, reductions in energy use and greenhouse gases are even larger, but eutrophication increases. Overall, households have greatest potential for improvement while yogurt is the product offering the most improvement potential.

Dimensional stabilization of flakeboard by chemical modification

SummarySouthern pine, aspen, and Douglas-fir flakes were reacted with either butylene oxide/triethylamine or acetic anhydride for various reaction times to give levels of bonded chemicals up to 25 weight percent gain. Flakes modified to 20 weight percent gain with bytylene oxide gave a flakeboard which absorbed 25% less water and had reduced thickness swelling up to 50% as compared to an untreated flakeboard. With acetic anhydride, modification, water absorption was 50% less and thickness swelling was reduced 85%. There was a 60% reduction in thickness swelling in flakeboard made from butylene oxide-modified flakes and 85% reduction from acetic anhydride-modified flakes when the boards were subjected to 90% relative humidity over a period of 20 days. The mechanism of effectiveness to reduce moisture uptake and thickness swelling is based on chemical bulking of, and a reduction in the hydrophilic nature of the cell wall polymers.