Characterizing IT asset disposition flows for the circular economy: A case study on export for reuse from Ireland

Understanding flows of resource-rich electrical and electronic equipment throughout its life cycle is increasingly important in the development of global circular economies, reflected by heavy legislative focuses on waste prevention and resource use efficiency. This research facilitates broader material flow analysis by characterizing flows of professional IT equipment within the Republic of Ireland, emphasizing the flow of legal exports for the purposes of refurbishment and reuse. The analysis of transboundary movement of non-waste used equipment contributes to a less often measured, but influential, facet of material flows. Eight key exporters of used equipment, comprising original equipment manufacturers, information technology asset disposition companies, and waste treatment facilities, were interviewed to characterize the sector, map the flow of materials, and identify gaps in existing reporting. Interviewed organizations declared exports of used equipment by category using a voluntary declaration form. Two key flows were identified representing currently unreported and unmeasured flows of non-waste professional equipment. A total of 441,261 units of equipment were declared to be exported for reuse from the Republic of Ireland through these previously unmeasured flows in 2019. Product keys developed by United Nations University were used to estimate the weight of total units exported as approximately 576 metric tons, amounting to an additional approximately 9% of the weight of IT equipment collected in the Republic of Ireland in 2018, or 0.1 kg per inhabitant. These quantifications of IT equipment exported for reuse will be a key component of future material flow analyses in the development of a circular economy.     

A review of methods to trace material flows into final products in dynamic material flow analysis: Comparative application of six methods to the United States and EXIOBASE3 regions,Part 2

Modeling pathways toward sustainable production and consumption requires improved spatio-temporal and material coverage of end-use product stocks. Momentarily, studies on inflow-driven, dynamic material flow analysis (dMFA) extrapolate scarce information on material end-use shares (i.e., ratios that split economy-wide material consumption to different end-use products) for single countries and years across longer time periods and global regions. Therefore, in part 1 of this work, we reviewed five methods to derive material end-use shares which use industry shipment data in physical units and monetary input–output tables (MIOTs). Herein, we comparatively apply these methods to the United States, drawing on detailed national data, as well as the multi-regional input–output model EXIOBASE3. To better match MIOT and dMFA system definitions, we propose the end-use transfer method, which re-routes specific intermediate outputs to final demand in MIOTs. In closing, we conclude on 12 points for improved end-use shares. We find mixed results regarding the fit between end-use shares derived from industry shipments and MIOTs: for detailed national data, we find good fit for some materials (e.g., aluminum), while others deviate strongly (e.g., steel). In many cases, the temporal trend of MIOT-derived end-use shares roughly agrees with industry shipments. For EXIOBASE3, we find good fit for some countries and materials, but substantial mismatches for others. Despite mixed results, combining MIOT-based end-use shares with industry shipments and auxiliary country-level data could enable improved temporal, geographical, and end-use resolution. However, the scarcity, documentation, and quality of input data are key limitations for more accurate and detailed end-use shares. This article met the requirements for a gold-gold data openness badge described at http://jie.click/badges .      

Use of Physical Supply and Use Tables for Calculation of Economy‐Wide Material Flow Indicators

The study described in this article presents the first‐ever physical supply and use tables (PSUTs) based on the recently published methodological standard for the System of Environmental‐Economic Accounting (SEEA). The tables were compiled for the Czech Republic for 2014. The compilation procedure followed was described in detail so that it can serve as a source of inspiration and a benchmark for other researchers and/or statisticians. The major shortcoming of the PSUTs is that not all needed data were readily available in physical units and required estimations based on proxies. Some parts of the tables are therefore burdened with a degree of uncertainty. In order to address the price inhomogeneity of sectoral prices for commodity outputs, imports, and exports, which tends to be typical for monetary supply and use tables (MSUTs), the PSUTs and MSUTs were further used for the calculation of raw material equivalents of import, exports, and raw material input (RMI) and raw material consumption (RMC) indicators. A comparison of results showed that the total indicators do not differ that much: the largest difference of 5% was recorded for raw material equivalents of exports, while RMC, for instance, remained nearly the same. However, we still argue for the use of PSUTs for the calculation of raw material equivalents, as changes in total volume of the indicators were accompanied with changes in their material structure. This can have significant consequences for the assessment of environmental impacts related to material consumption, as environmental impacts are very material specific.     

The highly efficient holding function of the mollusc ‘catch’ muscle is not based on decelerated myosin head cross-bridge cycles

Certain smooth muscles are able to reduce energy consumption greatly when holding without shortening. For instance, this is the case with muscles surrounding blood vessels used for regulating blood flow and pressure. The phenomenon is most conspicuous in ‘catch’ muscles of molluscs, which have been used as models for investigating this important physiological property of smooth muscle. When the shells of mussels are held closed, the responsible muscles enter the highly energy-efficient state of catch. According to the traditional view, the state of catch is caused by the slowing down of the force-generating cycles of the molecular motors, the myosin heads. Here, we show that catch can still be induced and maintained when the myosin heads are prevented from generating force. This new evidence proves that the long-held explanation of the state of catch being due to the slowing down of force producing myosin head cycles is not valid and that the highly economic holding state is caused by the formation of a rigid network of inter-myofilament connections based on passive molecular structures.     

Evaluating the cascading-use of wood furniture: How value-retention processes can contribute to material efficiency and circularity

As utilized technical products, durable wood furniture plays an important role in a future circular economy (CE). However, contemporary CE literature predominantly focuses on wood's biochemical properties and its potential as a consumable material within the bio-cycle. This perspective prevents meaningful consideration of CE strategies for the wood products sector, particularly for value-retention processes (VRPs), including reuse, repair, and refurbishment. We adapt and apply the VRP model introduced by the UN International Resource Panel (IRP) to wood furniture products to quantify select environmental benefits made possible through cascading-use, via VRPs (vs. new manufacturing). Unlike traditional life cycle assessment (LCA), this model accounts for impacts incurred and avoided through product life-extension and VRPs, relative to conventional systems of new manufacturing, disposal, and replacement. Three case studies of wood-based chairs are conducted to demonstrate this new application of the VRP model to compare the relative environmental impacts associated with wood furniture that is diverted to cascading-use, prior to recycling. In collaboration with industry partners, new material requirements (kg/unit), energy requirements (kWh/unit), emissions (kg CO2-e./unit), and waste generation (kg/unit) were calculated for newly manufactured chairs (OEM new) and subsequent cascading-use via reuse, repair, and refurbishment. The differing degrees of environmental impact avoidance and material efficiency are presented for each case study product and VRP, to provoke discussion and future research regarding the effective and optimal utilization of technical, durable wooden furniture within a CE.     

More than energy cost: multiple benefits of the long Achilles tendon in human walking and running

Elastic strain energy that is stored and released from long, distal tendons such as the Achilles during locomotion allows for muscle power amplification as well as for reduction of the locomotor energy cost: as distal tendons perform mechanical work during recoil, plantar flexor muscle fibres can work over smaller length ranges, at slower shortening speeds, and at lower activation levels. Scant evidence exists that long distal tendons evolved in humans (or were retained from our more distant Hominoidea ancestors) primarily to allow high muscle–tendon power outputs, and indeed we remain relatively powerless compared to many other species. Instead, the majority of evidence suggests that such tendons evolved to reduce total locomotor energy cost. However, numerous additional, often unrecognised, advantages of long tendons may speculatively be of greater evolutionary advantage, including the reduced limb inertia afforded by shorter and lighter muscles (reducing proximal muscle force requirement), reduced energy dissipation during the foot–ground collisions, capacity to store and reuse the muscle work done to dampen the vibrations triggered by foot–ground collisions, reduced muscle heat production (and thus core temperature), and attenuation of work-induced muscle damage. Cumulatively, these effects should reduce both neuromotor fatigue and sense of locomotor effort, allowing humans to choose to move at faster speeds for longer. As these benefits are greater at faster locomotor speeds, they are consistent with the hypothesis that running gaits used by our ancestors may have exerted substantial evolutionary pressure on Achilles tendon length. The long Achilles tendon may therefore be a singular adaptation that provided numerous physiological, biomechanical, and psychological benefits and thus influenced behaviour across multiple tasks, both including and additional to locomotion. While energy cost may be a variable of interest in locomotor studies, future research should consider the broader range of factors influencing our movement capacity, including our decision to move over given distances at specific speeds, in order to understand more fully the effects of Achilles tendon function as well as changes in this function in response to physical activity, inactivity, disuse and disease, on movement performance.     

Settlement Hierarchies and Political Complexity in Nonmarket Societies: The Formative Period of the Valley of Mexico

Archaeologists have long recognized that increases in political centralization often coincide with the growth of regional settlement hierarchies. Here I develop a theoretical model which explicitly relates certain aspects of political complexity to variation in settlement size. This model applies specifically to hierarchical societies without well-developed market economies—societies which Service would classify as chiefdoms and (perhaps) simple states. Using settlement data from the Formative Period Valley of Mexico, I show how this model is useful in measuring (1) the number of levels in a regional hierarchy, (2) the degree of political centralization, and (3) the relative amount of surplus food mobilized to support the political establishment.     

Society's Metabolism

"Societal metabolism" provides the appropriate conceptual basis for the rapidly growing development and analylical and policy interest in materials flow analysis (MFA). Following the review of the earlier intellectual background of societal metabolism in the first installment of this two-part article, this paper focuses on the current state of the art by examining more recent research referring t o societal metabolism in terms of material and substance flows. An operational classification of the literature according to frame of reference (socioeconomic system, ecosystem), system level (global, national, regional, functional, temporal), and types of flows under consideration (materials, energy, substances) highlights some of its characteristic features. There follows an integrated discussion of some of the major conceptual and methodological properties of MFA, with a particular focus on the field of bulk materials flows on a national level, comparing the major empirical results. Finally, the theoretical stringency research productivity, and political relevance of the MFA-related studies are assessed.