Theory of materials and energy flow analysis in ecology and economics

Systematic data-driven exploration of Austrian wastewater and sludge treatment - implications for phosphorus governance, costs and environment

Within the new policy framework shaped by the EU Green Deal and the Circular Economy Action Plans, the field of wastewater and sludge treatment in Europe is subject to high expectations and new challenges related to mitigation of greenhouse gas emissions, micropollutant removal and resource recovery. With respect to phosphorus recovery, several technologies and processes have been thoroughly investigated. Nevertheless, a systemic and detailed understanding of the existing infrastructure and of the related environmental and economic implications is missing. Such basis is essential to avoid unwanted consequences in designing new strategies, given the long lifespan of any infrastructural change. This study couples a newly collected and highly detailed database for all wastewater treatment plants in Austria bigger than 2000 population equivalent with a combination of analyses, namely Substance Flow Analysis with focus on nutrient and metal distribution in different environmental and anthropogenic compartments, Energy Flow Analysis, Life Cycle Assessment and cost estimation. The case study of Austria is of special interest, given its highly autonomous administration in federal states and its contrasting traits, ranging from flat metropolitan areas like Vienna to low-populated alpine areas. The significant impact of electricity demand of wastewater treatment on the overall Cumulative Energy Demand (CED) shows the importance of optimization measures. Further, the current system of wastewater and sludge disposal have a low efficiency in recovering nutrients and in directing pollutants as heavy metals into final sinks. Sludge composting with subsequent use in landscaping does not only show an unfavorable environmental balance, but it is the only relevant route leading to additional CED and Global Warming Potential emissions and to the highest transport volume. Altogether, the outcomes of this study provide a sound basis to further develop national strategies for resource recovery aimed to optimize trade-offs between different economic and environmental objectives.

Macro Sustainability across Countries: Key Sector Environmentally Extended Input-Output Analysis

When formulating economic development strategies, the environment and society must be considered to preserve well-being. This paper proposes a comparative sustainability assessment method using environmentally extended input-output analysis and multi-criteria decision aid. Using symmetric input-output tables and sectoral CO2 emissions and employment data for six countries, linkage coefficients are calculated for 163 sectors in each country. Multi-criteria decision aid tool, ELECTRE III, is used to derive outranking relationships among each country’s sectors using these coefficients as criteria, resulting in a hierarchy of sectors ordered by sustainability. Sectors that frequently appear at the top of the six hierarchies included education, health care, construction, and financial intermediation. China’s results differ significantly because of its concentration of economic activity on the primary/secondary sectors. The results can enable identification of key intervention pathways along which sustainable development could be stimulated. Country-specific recommendations and reflections on economic and sustainability policy initiatives are discussed.

Energy Management System Application for Sustainable Development in Wood Industry Enterprises

This study analyzes the energy management approach as one of the driving factors for sustainable development, not only in enterprises, but also countries. Sustainability of an enterprise is defined as its tendency to meet the need of customers and stakeholders through creative and innovative business strategies as well as activities that have a positive influence on society and environment. In this study, sustainability is measured through the application of an energy management system, but in the wood industry, which has an increasingly significant impact on the economic development in one country. The aim of this research is to determine the current situation regarding the application of energy management practices in production and service systems. The ISO 50001 standard for energy management systems considers the energy performance achieved by an enterprise. The connections between critical factors and the level of application requirements for the energy management system were statistically analyzed in this research. It was found that in enterprises that have a certified system of quality and environmental management, a higher level of energy management system implementation is evident. The research results provide data on the scientific level for the national policy improvement, as well as a developed model based on the Plan Do Check Act (PDCA) cycle for energy management system application.

An Integrative Dynamic Model of Colombian Population Distribution, Based on the Maximum Entropy Principle and Matter, Energy, and Information Flow

Human society has increased its capacity to exploit natural resources thanks to new technologies, which are one of the results of information exchange in the knowledge society. Many approaches to understanding the interactions between human society and natural systems have been developed in the last decades, and some have included considerations about information. However, none of them has considered information as an active variable or flowing entity in the human–natural/social-ecological system, or, moreover, even as a driving force of their interactions. This paper explores these interactions in socio-ecological systems by briefly introducing a conceptual frame focused on the exchange of information, matter, and energy. The human population is presented as a convergence variable of these three physical entities, and a population distribution model for Colombia is developed based on the maximum entropy principle to integrate the balances of related variables as macro-state restrictions. The selected variables were electrical consumption, water demand, and higher education rates (energy, matter, and information). The final model includes statistical moments for previous population distributions. It is shown how population distribution can be predicted yearly by combining these variables, allowing future dynamics exploration. The implications of this model can contribute to bridging information sciences and sustainability studies.

Structuring an integrated water-energy-food nexus assessment of a local wind energy desalination system for irrigation

Desalination is increasingly put forward as a sustainable local solution to water scarcity in combination with the exploitation of renewable energy sources. However, the complexity of the resource nexus entails the unavoidable existence of pros and cons across its various dimensions that can only be assessed at different scales of analysis. In turn, these pros and cons entail different winners and losers among the different social actors linked through the nexus. To address these challenges, a novel approach to resource nexus assessment is put forward, based on multi-scale integrated analysis of societal and ecosystem metabolism (MuSIASEM) and recognizing the resource nexus as a wicked problem. The integrated representation identifies the existence of biophysical constraints determined by processes both under human control (in the technosphere) and beyond human control (in the biosphere). The approach is illustrated with a local case study of desalination in the Canary Islands, Spain. The material presented has been generated in the context of the project "Moving towards adaptive governance in complexity: Informing nexus security" (MAGIC) for use in participatory processes of co-production of knowledge claims about desalination, a prerequisite for informed policy deliberation.

CO2 Emissions Embodied in Interprovincial Electricity Transmissions in China

Existing studies on the evaluation of CO₂ emissions due to electricity consumption in China are inaccurate and incomplete. This study uses a network approach to calculate CO₂ emissions of purchased electricity in Chinese provinces. The CO₂ emission factors of purchased electricity range from 265 g/kWh in Sichuan to 947 g/kWh in Inner Mongolia. We find that emission factors of purchased electricity in many provinces are quite different from the emission factors of electricity generation. This indicates the importance of the network approach in accurately reflecting embodied emissions. We also observe substantial variations of emissions factors of purchased electricity within subnational grids: the provincial emission factors deviate from the corresponding subnational-grid averages from -58% to 44%. This implies that using subnational-grid averages as required by Chinese government agencies can be quite inaccurate for reporting indirect CO₂ emissions of enterprises' purchased electricity. The network approach can improve the accuracy of the quantification of embodied emissions in purchased electricity and emission flows embodied in electricity transmission.

Designing Industrial Networks Using Ecological Food Web Metrics

Biologically Inspired Design (biomimicry) and Industrial Ecology both look to natural systems to enhance the sustainability and performance of engineered products, systems and industries. Bioinspired design (BID) traditionally has focused on a unit operation and single product level. In contrast, this paper describes how principles of network organization derived from analysis of ecosystem properties can be applied to industrial system networks. Specifically, this paper examines the applicability of particular food web matrix properties as design rules for economically and biologically sustainable industrial networks, using an optimization model developed for a carpet recycling network. Carpet recycling network designs based on traditional cost and emissions based optimization are compared to designs obtained using optimizations based solely on ecological food web metrics. The analysis suggests that networks optimized using food web metrics also were superior from a traditional cost and emissions perspective; correlations between optimization using ecological metrics and traditional optimization ranged generally from 0.70 to 0.96, with flow-based metrics being superior to structural parameters. Four structural food parameters provided correlations nearly the same as that obtained using all structural parameters, but individual structural parameters provided much less satisfactory correlations. The analysis indicates that bioinspired design principles from ecosystems can lead to both environmentally and economically sustainable industrial resource networks, and represent guidelines for designing sustainable industry networks.

Re-evaluating Primary Biotic Resource Use for Marine Biomass Production: A New Calculation Framework

The environmental impacts of biomass harvesting can be quantified through the amount of net primary production required to produce one unit of harvested biomass (SPPR-specific primary production required). This paper presents a new calculation framework that explicitly takes into account full food web complexity and shows that the resulting SPPR for toothed whales in the Icelandic marine ecosystem is 2.8 times higher than the existing approach based on food web simplification. In addition, we show that our new framework can be coupled to food web modeling to examine how uncertainty on ecological data and processes can be accounted for while estimating SPPR. This approach reveals that an increase in the degree of heterotrophy by flagellates from 0% to 100% results in a two-fold increase in SPPR estimates in the Barents Sea. It also shows that the estimated SPPR is between 3.9 (herring) and 5.0 (capelin) times higher than that estimated when adopting food chain theory. SPPR resulting from our new approach is only valid for the given time period for which the food web is modeled and cannot be used to infer changes in SPPR when the food web is altered by changes in human exploitation or environmental changes.

Quantifying the environmental impact of an integrated human/industrial-natural system using life cycle assessment; a case study on a forest and wood processing chain

Life Cycle Assessment (LCA) is a tool to assess the environmental sustainability of a product; it quantifies the environmental impact of a product's life cycle. In conventional LCAs, the boundaries of a product's life cycle are limited to the human/industrial system, the technosphere. Ecosystems, which provide resources to and take up emissions from the technosphere, are not included in those boundaries. However, similar to the technosphere, ecosystems also have an impact on their (surrounding) environment through their resource usage (e.g., nutrients) and emissions (e.g., CH4). We therefore propose a LCA framework to assess the impact of integrated Techno-Ecological Systems (TES), comprising relevant ecosystems and the technosphere. In our framework, ecosystems are accounted for in the same manner as technosphere compartments. Also, the remediating effect of uptake of pollutants, an ecosystem service, is considered. A case study was performed on a TES of sawn timber production encompassing wood growth in an intensively managed forest ecosystem and further industrial processing. Results show that the managed forest accounted for almost all resource usage and biodiversity loss through land occupation but also for a remediating effect on human health, mostly via capture of airborne fine particles. These findings illustrate the potential relevance of including ecosystems in the product's life cycle of a LCA, though further research is needed to better quantify the environmental impact of TES.

Urban metabolism: a review of research methodologies

Urban metabolism analysis has become an important tool for the study of urban ecosystems. The problems of large metabolic throughput, low metabolic efficiency, and disordered metabolic processes are a major cause of unhealthy urban systems. In this paper, I summarize the international research on urban metabolism, and describe the progress that has been made in terms of research methodologies. I also review the methods used in accounting for and evaluating material and energy flows in urban metabolic processes, simulation of these flows using a network model, and practical applications of these methods. Based on this review of the literature, I propose directions for future research, and particularly the need to study the urban carbon metabolism because of the modern context of global climate change. Moreover, I recommend more research on the optimal regulation of urban metabolic systems.

Phosphorus use-efficiency of agriculture and food system in the US

The rapid increase in human mobilization of phosphorus has raised concerns on both its supply security and its impact on the environment. Increasing the efficiency of phosphorus use is an approach to mitigate the adverse impacts associated with phosphorus consumption. This study estimates the life-cycle phosphorus use-efficiency of the US food system. A framework for accounting phosphorus stocks and flows is developed, and the account was populated with data. A map of phosphorus stocks and flows around the US food system is drawn and phosphorus use-efficiency was calculated. The results show that only 15% of the total phosphorus extracted from nature for the provision of food is eventually ingested by humans and the rest is lost to the environment. Major losses occur during the livestock, meat and dairy production and crop cultivation stage, where about 66% of the total phosphorus extracted is lost to the environment. The results also show that other losses of phosphorus including household food waste, mining waste, and fertilizer manufacturing waste are not negligible, which constitute about 19% of the total phosphorus extracted for food purpose. A data quality assessment and sensitivity analysis was performed to identify data quality hotspots and to envisage effective measures to improving phosphorus use-efficiency. Improving yields of livestock and crop cultivation without additional phosphorus input and reducing household food waste are shown to be effective measures to improve life-cycle phosphorus use-efficiency. The results highlight the need of a concerted effort by all entities along the life-cycle for efficient use of phosphorus.

Accounting for ecosystem services in life cycle assessment, Part I: a critical review

If life cycle oriented methods are to encourage sustainable development, they must account for the role of ecosystem goods and services, since these form the basis of planetary activities and human well-being. This article reviews methods that are relevant to accounting for the role of nature and that could be integrated into life cycle oriented approaches. These include methods developed by ecologists for quantifying ecosystem services, by ecological economists for monetary valuation, and life cycle methods such as conventional life cycle assessment, thermodynamic methods for resource accounting such as exergy and emergy analysis, variations of the ecological footprint approach, and human appropriation of net primary productivity. Each approach has its strengths: economic methods are able to quantify the value of cultural services; LCA considers emissions and assesses their impact; emergy accounts for supporting services in terms of cumulative exergy; and ecological footprint is intuitively appealing and considers biocapacity. However, no method is able to consider all the ecosystem services, often due to the desire to aggregate all resources in terms of a single unit. This review shows that comprehensive accounting for ecosystem services in LCA requires greater integration among existing methods, hierarchical schemes for interpreting results via multiple levels of aggregation, and greater understanding of the role of ecosystems in supporting human activities. These present many research opportunities that must be addressed to meet the challenges of sustainability.