ALBERT

Description: Purpose The goal of this study is to analyze the environmental improvement brought about by an alternative system for waste management proposed by the Integral-b project, funded by the European Union (EU). Its aim is to treat both used cooking oil (UCO) and organic waste from the restaurant and catering sector in Spain, by biodiesel production and anaerobic digestion, respectively. A cogeneration engine adapted to use glycerin as a fuel is implemented. Methods The functional unit (FU) is the management of the UCO and organic waste from restaurants and catering produced per person and year in Spain. The system proposed (scenario A) is compared to a system consisting of the prevailing management options for the same kind of waste (scenario B). Apart from including biodiesel production from the UCO, this reference scenario assumes that the organic waste is allocated to different streams, according to Spanish statistics. The systems under study generate different coproducts and as such are complex; therefore, system expansion is performed. Different scenario formulations are set to analyze the influence of assumptions regarding coproduct credits in the results. Finally, Monte Carlo simulations are carried out to analyze parameter uncertainty. Results and discussion The environmental benefits caused by scenario A are conditional on the choices regarding coproduct credits. Scenario A causes a reduction of the impact (43–655 %) in most of the scenario formulations when the current levels of UCO collection are considered. However, when higher levels of UCO collection are taken into account for the definition of the FU, scenario B performs better for half of the scenario formulations, due to the increase in the environmental credits from glycerin production. The only impact categories for which scenario A performs unconditionally better than scenario B are global warming and photochemical ozone creation. Parameter uncertainty appears to influence the comparative results to a lesser extent, mainly caused by the parameters involved in avoided processes. Conclusions Although system expansion appears as an option for dealing with the multifunctionality of waste management processes, uncertainty caused by choices must be assessed. Under our scenario assumptions, re-using the glycerol in the system proposed by Integral-b can be detrimental, and the reference scenario results in higher avoided burdens in some scenario formulations. Including glycerin valorization in scenario B should be considered if the biodiesel production keeps increasing in Spain. Analyzing parameter uncertainty helps to provide reliable results.

Description: Purpose Phase change materials (PCMs) hold considerable promise for thermal energy storage and reduction of temperature swings in building space, and can reduce reliance on fossil fuel sources for both heating and cooling. Previous studies have evaluated the use of PCMs for energy storage and provided some limited information on the embodied energy of the PCM; however, an important factor that has not fully been addressed until now is the environmental impact of preparation of organic PCMs. This study presents life cycle assessments (LCAs) of two organic, biosourced PCMs for their applications, focusing on embodied energy and CO 2 emissions. Methods Dodecanoic acid produced from palm kernel oil was considered as a PCM for use in a solar thermal water heating application, and ethyl hexadecanoate produced from algae was considered for thermal buffering. The functional units were defined as 1 t of dodecanoic acid PCM and 1 kg of encapsulated ethyl hexadecanoate PCM, respectively. The LCA encompasses all phases in the PCM production: growth and harvesting of the feedstocks, extraction of the oil, treatment of the oil, and separation of singular components. The two PCMs were evaluated in terms of the payback times for their embodied energies and embodied CO 2 under a modeled use phase. Results and discussion The energy payback time for dodecanoic acid in a solar thermal application was found to be less than 2 years. Although production of dodecanoic acid is a net CO 2 emitter, use of this PCM in a solar thermal system can recoup the CO 2 of production in less than a year. Ethyl hexadecanoate produced from algae, considered for use in a thermal buffering wallboard product, would require at least 30 years of use before its energy savings would match its embodied energy, mostly due to the drying step in the production of the PCM. However, ethyl hexadecanoate is a strong sequester of CO 2 at 7.6 t per ton of ethyl hexadecanoate. Conclusions Dodecanoic acid produced from palm kernel oil for use in a solar thermal hot water system appears to be a viable PCM. Its payback time, both for energy and carbon emissions, is under 3 years. On the other hand, the high embodied energy of ethyl hexadecanoate produced from algae gives a prohibitively long payback time for use in domestic thermal buffering applications.

Description: Purpose Current comparative life cycle assessment (LCA) studies claim to answer whether it is better or worse for the environment to change from old to new systems. Most commonly, the attributional LCA (ALCA) is practised despite its limitations to describe market effects. Hence, an attempt is done here to include market effects in the ALCA practice for comparisons in order to improve ALCA. The purpose is neither to investigate which LCA concept, ALCA, consequential LCA or decisional LCA, is the best for comparisons nor which is the best for decision-making. Methods Here, for the first time, a method based on marked changes which can be used for sensitivity checks of comparative ALCAs, advanced ALCA (AALCA) is presented. The new concept of global change mix factors (GCMF) is introduced. The method, based on accessible market data, is applied to previous comparative ALCAs of conductive adhesives, cooling modules used in radio base stations, office computing systems, as well as personal devices usage, here represented by multifunctional smartphones replacing other devices such as digital cameras. Results and discussion The results show that AALCA based on market data improves the understanding and can act as a sensitivity check of comparative ALCA results. For declining markets of products, with relatively high eco-environmental impacts, the difference between comparative AALCA and ALCA can be significant. As AALCA is founded in marginal electricity thinking and uses market data, there are similarities between AALCA and simplistic consequential LCA (CLCA). However, AALCA is not intended to replace CLCA or decisional LCA (DLCA). Conclusions By applying allocation factors, GCMF, based on real or future market changes, the interdependence of global markets and micro-level LCA shifts can be taken into account in comparative micro-level ALCA studies and make them more robust. Further, the sensitivity of using price units instead of physical units, as the basis for the GCMF, should be investigated. The degree to which AALCA and CLCA can complement each other should be examined. Also, the degree to which the GCMF used in AALCA-H address rebound effects should be further explored. The annual eco-environmental impacts of mobile devices towards 2020 are also of interest, and more LCA case studies are welcome.

Description: Purpose Previous estimates of carbon payback time (CPT) of corn ethanol expansion assumed that marginal yields of newly converted lands are the same as the average corn yield, whereas reported marginal yields are generally lower than the average yield (47–83 % of average yield). Furthermore, these estimates assumed that the productivity of corn ethanol system and climate change impacts per unit greenhouse gas (GHG) emissions remain the same over decades to a century. The objective of this study is to re-examine CPT of corn ethanol expansion considering three aspects: (1) yields of newly converted lands (i.e., marginal yield), (2) technology improvements over time within the corn ethanol system, and (3) temporal sensitivity of climate change impacts. Methods A new approach to CPT calculation is proposed, where changes in productivity of ethanol conversion process and corn yield are taken into account. The approach also allows the use of dynamic characterization approach to GHGs emitted in different times, as an option. Data are collected to derive historical trends of bioethanol conversion efficiency and corn yield, which inform the development of the scenarios for future biofuel conversion efficiency and corn yield. Corn ethanol’s CPTs are estimated and compared for various marginal-to-average (MtA) yield ratios with and without considering technology improvements and time-dependent climate change impacts. Results and discussion The results show that CPT estimates are highly sensitive to both MtA yield ratio and productivity of ethanol system. Without technological advances, our CPT estimates for corn ethanol from newly converted Conservation Reserve Program (CRP) land exceed 100 years for all MtA yield ratios tested except for the case where MtA yield ratio is 100 %. When the productivity improvements within corn ethanol systems since previous CPT estimates and their future projections are considered, our CPT estimates fall into the range of 15 years (100 % MtA yield ratio) to 56 years (50 % MtA yield ratio), assuming land conversion takes place in early 2000s. Incorporating diminishing sensitivity of GHG emissions to future emissions year by year, however, increases the CPT estimates by 57 to 13 % (from 17 years for 100 % MtA yield ratio to 88 years for 50 % MtA yield ratio). For 60 MtA yield ratio, CPT is estimated to be 43 years, which is relatively close to previous CPT estimates (i.e., 40 to 48 years) but with very different underlying reasons. Conclusions This study highlights the importance of considering technological advances in understanding the climate change implications of land conversion for corn ethanol. Without the productivity improvements in corn ethanol system, the prospect of paying off carbon debts from land conversion within 100 years becomes unlikely. Even with the ongoing productivity improvements, the yield of newly converted land can significantly affect the CPT. The results reinforce the importance of considering marginal technologies and technology change in prospective life cycle assessment.

Description: Purpose The security of the supply of resources is a key policy and business concern. This concern has been increasingly addressed by bodies such as the European Commission to help identify materials of potential concern in terms of economic importance and supply risks. Equally, tools such as life cycle assessment (LCA) systematically compile inventories of the resources attributable to the supply of goods and services. Such well-established tools, hence, provide an important opportunity for business and governments for strategic management and for identifying improvement options that reduce reliance on so-called critical raw materials (CRMs). This paper explores current practice and the potential of LCA to help business and governments more systematically assess their supply chains. Methods Raw materials of concern to business and governments in relation to security of supply are denoted as critical . This paper highlights how such CRMs are identified in the existing methodologies. It then focuses on LCA methodology and explores its potential in providing information on CRMs at different levels: considering the flows of CRMs at inventory level, including criticality criteria in the impact assessment, and analyzing the flows of CRMs associated with the consumption of goods and services at macroeconomic scale. Results and discussion Consideration of resource security can be specifically addressed in LCA starting from the goal and scope definition. These CRMs may otherwise be neglected due to cut-off criteria based, e.g., on quantity. If systematically addressed, LCA can provide such CRM information routinely at inventory level. Inclusion of further indicators under the Area of Protection (AoP) “Resources” in LCA may also ensure such assessments more systematically address issues such as criticality. In strategic analysis, as those at macroeconomic scale, LCA results at the inventory (e.g., amounts of CRMs domestically extracted and those used for producing imported and exported intermediate products) and at impact assessment level can better support decision making. Conclusions At both microscale and macroscale, LCA might have more potential in capturing hot spots and improvement opportunities of raw materials of concern, not only in terms of scarcity. This paper highlights that LCA is well positioned for providing information on resource-related issues of concern to business and governments such as the criticality of raw materials used in the supply chains. The paper outlines the methodological developments that could enhance LCA potential to further support resource assessments to help more systematically meet such business and governmental interests.

Description: Purpose USEtox is a scientific consensus model for assessing human toxicological and ecotoxicological impacts that is widely used in life cycle assessment (LCA) and other comparative assessments. However, how user requirements are met has never been investigated. To guide future model developments, we analyzed user expectations and experiences and compared them with the developers’ visions. Methods We applied qualitative and quantitative data collection methods including an online questionnaire, semi-structured user and developer interviews, and review of scientific literature. Questionnaire and interview results were analyzed in an actor-network perspective in order to understand user needs and to compare these with the developers’ visions. Requirement engineering methods, more specifically function tree, system context, and activity diagrams, were iteratively applied and structured to develop specific user requirements-driven recommendations for setting priorities in future USEtox development and for discussing general implications for developing scientific models. Results and discussion The vision behind USEtox was to harmonize available data and models for assessing toxicological impacts in LCA and to provide global guidance for practitioners. Model developers show different perceptions of some underlying aspects including model transparency and expected user expertise. Users from various sectors and geographic regions apply USEtox mostly in research and for consulting. Questionnaire and interview results uncover various user requests regarding USEtox usability. Results were systematically analyzed to translate user requests into recommendations to improve USEtox from a user perspective and were afterwards applied in the further USEtox development process. Conclusions We demonstrate that understanding interactions between USEtox and its users helps guiding model development and dissemination. USEtox-specific recommendations are to (1) respect the application context for different user types, (2) provide detailed guidance for interpreting model and factors, (3) facilitate consistent integration into LCA software and methods, (4) improve update/testing procedures, (5) strengthen communication between developers and users, and (6) extend model scope. By generalizing our recommendations to guide scientific model development in a broader context, we emphasize to acknowledge different levels of user expertise to integrate sound revision and update procedures and to facilitate modularity, data import/export, and incorporation into relevant software and databases during model design and development. Our fully documented approach can inspire performing similar surveys on other LCA-related tools to consistently analyze user requirements and provide improvement recommendations based on scientific user analysis methods.

Description: Purpose Numerous publications in the last years stressed the growing importance of nanotechnology in our society, highlighting both positive as well as in the negative topics. Life cycle assessment (LCA) is amongst the most established and best-developed tool in the area of product-related assessment. In order to use this tool in the area of nanotechnology, clear rules of how emissions of nanomaterials should be taken into account on the level of life cycle inventory (LCI) modelling are required—i.e. what elements and properties need to be reported for an emission of a nanomaterial. The objective of this paper is to describe such a framework for an adequate and comprehensive integration of releases of nanomaterials. Methods With a three-step method, additional properties are identified that are necessary for an adequate integration of releases of nanomaterials into LCA studies. Result and discussion In the first step, a comprehensive characterisation of the release of a nanomaterial is compiled—based on reviewing scientific publications, results from expert workshops and publications from public authorities and international organisations. In the second step, this comprehensive overview is refined to a list containing only those properties that are effectively relevant for LCA studies—i.e. properties that influence the impacts in the areas of human toxicity and ecotoxicity, respectively. For this, an academic approach is combined with a second, more practical, view point, resulting together in a prioritisation of this list of properties. Finally, in a third step, these findings are translated into the LCA language—by showing how such additional properties could be integrated into the current LCA data formats for a broader use by the LCA community. Conclusions As a compromise between scholarly knowledge and the (toxicological) reality, this paper presents a clear proposal of an LCI modelling framework for the integration of releases of nanomaterials in LCA studies. However, only the broad testing of this framework in various situations will show if the suggested simplifications and reductions keep the characterisation of releases of nanomaterials specific enough and/or if assessment is accurate enough. Therefore, a next step has to come from the impact assessment, by the development of characterisation factors as a function of size and shape of such releases.

Description: Purpose This study aims to compare the life cycle greenhouse gas (GHG) emissions of two cellulosic bioenergy pathways (i.e., bioethanol and bioelectricity) using different references and functional units. It also aims to address uncertainties associated with a comparative life cycle analysis (LCA) for the two bioenergy pathways. Methods We develop a stochastic, comparative life cycle GHG analysis model for a switchgrass-based bioenergy system. Life cycle GHG offsets of the biofuel and bioelectricity pathways for cellulosic bioenergy are compared. The reference system for bioethanol is the equivalent amount of gasoline to provide the same transportation utility (e.g., vehicle driving for certain distance) as bioethanol does. We use multiple reference systems for bioelectricity, including the average US grid, regional grid in the USA according to the North American Electric Reliability Corporation (NERC), and average coal-fired power generation, on the basis of providing the same transportation utility. The functional unit is one unit of energy content (MJ). GHG offsets of bioethanol and bioelectricity relative to reference systems are compared in both grams carbon dioxide equivalents per hectare of land per year (g CO 2 -eq/ha-yr) and grams carbon dioxide equivalents per vehicle kilometer traveled (g CO 2 -eq/km). For the latter, we include vehicle cycle to make the comparison meaningful. To address uncertainty and variability, we derive life cycle GHG emissions based on probability distributions of individual parameters representing various unit processes in the life cycle of bioenergy pathways. Results and discussion Our results show the choice of reference system and functional unit significantly changes the competition between switchgrass-based bioethanol and bioelectricity. In particular, our results show that the bioethanol pathway produces more life cycle GHG emissions than the bioelectricity pathway on a per unit energy content or a per unit area of crop land basis. However, the bioethanol pathway can offer more GHG offsets than the bioelectricity pathway on a per vehicle kilometer traveled basis when using bioethanol and bioelectricity for vehicle operation. Given the current energy mix of regional grids, bioethanol can potentially offset more GHG emissions than bioelectricity in all grid regions of the USA. Conclusions The reference and functional unit can change bioenergy pathway choices. The comparative LCA of bioenergy systems is most useful for decision support only when it is spatially explicit to address regional specifics and differences. The difference of GHG offsets from bioethanol and bioelectricity will change as the grid evolves. When the grids get cleaner over time, the favorability of bioethanol for GHG offsets increases.