Towards a dynamic assessment of raw materials criticality: linking agent-based demand--with material flow supply modelling approaches

Criticality and Life-Cycle Assessment of Materials Used in Fuel-Cell and Hydrogen Technologies

The purpose of this paper is to obtain relevant data on materials that are the most commonly used in fuel-cell and hydrogen technologies. The focus is on polymer-electrolyte-membrane fuel cells, solid-oxide fuel cells, polymer-electrolyte-membrane water electrolysers and alkaline water electrolysers. An innovative, methodological approach was developed for a preliminary material assessment of the four technologies. This methodological approach leads to a more rapid identification of the most influential or critical materials that substantially increase the environmental impact of fuel-cell and hydrogen technologies. The approach also assisted in amassing the life-cycle inventories—the emphasis here is on the solid-oxide fuel-cell technology because it is still in its early development stage and thus has a deficient materials’ database—that were used in a life-cycle assessment for an in-depth material-criticality analysis. All the listed materials—that either are or could potentially be used in these technologies—were analysed to give important information for the fuel-cell and hydrogen industries, the recycling industry, the hydrogen economy, as well as policymakers. The main conclusion from the life-cycle assessment is that the polymer-electrolyte-membrane water electrolysers have the highest environmental impacts; lower impacts are seen in polymer-electrolyte-membrane fuel cells and solid-oxide fuel cells, while the lowest impacts are observed in alkaline water electrolysers. The results of the material assessment are presented together for all the considered materials, but also separately for each observed technology.

Addressing temporal considerations in life cycle assessment

In life cycle assessment (LCA), temporal considerations are usually lost during the life cycle inventory calculation, resulting in an aggregated "snapshot" of potential impacts. Disregarding such temporal considerations has previously been underlined as an important source of uncertainty, but a growing number of approaches have been developed to tackle this issue. Nevertheless, their adoption by LCA practitioners is still uncommon, which raises concerns about the representativeness of current LCA results. Furthermore, a lack of consistency can be observed in the used terms for discussions on temporal considerations. The purpose of this review is thus to search for common ground and to identify the current implementation challenges while also proposing development pathways. This paper introduces a glossary of the most frequently used terms related to temporal considerations in LCA to build a common understanding of key concepts and to facilitate discussions. A review is also performed on current solutions for temporal considerations in different LCA phases (goal and scope definition, life cycle inventory analysis and life cycle impact assessment), analysing each temporal consideration for its relevant conceptual developments in LCA and its level of operationalisation. We then present a potential stepwise approach and development pathways to address the current challenges of implementation for dynamic LCA (DLCA). Three key focal areas for integrating temporal considerations within the LCA framework are discussed: i) define the temporal scope over which temporal distributions of emissions are occurring, ii) use calendar-specific information to model systems and associated impacts, and iii) select the appropriate level of temporal resolution to describe the variations of flows and characterisation factors. Addressing more temporal considerations within a DLCA framework is expected to reduce uncertainties and increase the representativeness of results, but possible trade-offs between additional data collection efforts and the increased value of results from DLCAs should be kept in mind.

Forecasting the temporal stock generation and recycling potential of metals towards a sustainable future: The case of gallium in China

Gallium is one such co-product mineral, being used for consumer electronics and contemporary renewable energy applications. China is the top producer of gallium and supplies over 70% of global demand. However, supply uncertainty of primary gallium is increasing due to a shortage of reserves. Thus, development of recycling technologies to complement primary production should be prioritized, with more country-specific attention due to its low investment cost and short-term feasibility. In this study, possible end-of-life (EoL) gallium waste generation in China until 2050 was forecasted using linear regression and constructed a scenario analysis based on population and annual demand growth parameters. Similarly, cumulative domestic demand was estimated using 1%, 5%, 10%, 15%, 20%, and 30% recycling rates to investigate the effect of recycling on sustainability of gallium resources. Based on the used method, study results were different; however, continuous demand growth and resource use are expected in most cases. The annual total gallium stock generation in 2050 will reach to 368 t under linear regression forecasting while it will likely fall between 59 t and 148 t according to scenario analysis. Linear projections show that cumulative demand will surpass even reserve base in 2047 whilst scenario analyses demonstrate that cumulative demand will exceed reserve between 2037 and 2047, if there would be unable to implement necessary recycling routes in the short term. The linear regression cumulative demand prediction urges the need of substitution, while the scenario analysis demonstrates the importance of increasing EoL recycling rates. The latter should also be supported with improved EoL collection rates, technological transfer from high-tech countries to China and appropriate policy advancement. The output of the study also convinces the importance of moving towards a circular economic model in the anthropogenic flow of gallium utilization.

Bibliometric and Systemic Analysis on Material Flow Mapping and Industrial Ecosystems

Global instability can be seen as a reflection of the increasing demand for natural resources and the reduction of personnel expenditures. Yet, this is often associated with industrial systems, whose main objectives are to increase productive capacity and reduce costs. This scenario identifies the need for changes in strategy establishment in the organization’s operation mode focusing on sustainable development. Industrial ecosystems, through the symbiotic relationship of industries, aim to achieve sustainability goals. Material flow mapping is essential for the construction of these industrial ecosystems. Hence, the present paper carries out a structured literature review process in order to identify the state of the art and the research opportunities on material flow mapping and industrial ecosystems. For the accomplishment of this research, the methodological procedure called Knowledge Development Process — Constructivist (ProKnow-C) was adopted. The bibliographic portfolio is represented by 35 articles of the research theme. Throughout the bibliometric analysis, a statistical analysis of the articles that compose the portfolio is presented. In the systemic analysis, the main research problems, the means of solving them and the detected opportunities about this research theme are identified. Finally, conclusions and recommendations for future research are presented.

Criticality of Water: Aligning Water and Mineral Resources Assessment

The concept of criticality has been used to assess whether a resource may become a limiting factor to economic activities. It has been primarily applied to nonrenewable resources, in particular to metals. However, renewable resources such as water may also be overused and become a limiting factor. In this paper, we therefore developed a water criticality method that allows for a new, user-oriented assessment of water availability and accessibility. Comparability of criticality across resources is desirable, which is why the presented adaptation of the criticality approach to water is based on a metal criticality method, whose basic structure is maintained. With respect to the necessary adaptations to the water context, a transparent water criticality framework is proposed that may pave the way for future integrated criticality assessment of metals, water, and other resources. Water criticality scores were calculated for 159 countries subdivided into 512 geographic units for the year 2000. Results allow for a detailed analysis of criticality profiles, revealing locally specific characteristics of water criticality. This is useful for the screening of sites and their related water criticality, for indication of water related problems and possible mitigation options and water policies, and for future water scenario analysis.