The enhanced use of biomass for the production of energy, fuels, and materials is one of the key strategies towards sustainable production and consumption. Various life cycle assessment (LCA) studies demonstrate the great potential of bio-based products to reduce both the consumption of non-renewable energy resources and greenhouse gas emissions. However, the production of biomass requires agricultural land and is often associated with adverse environmental effects such as eutrophication of surface and ground water. Decision making in favor of or against bio-based and conventional fossil product alternatives therefore often requires weighing of environmental impacts. In this article, we apply distance-to-target weighing methodology to aggregate LCA results obtained in four different environmental impact categories (i.e., non-renewable energy consumption, global warming potential, eutrophication potential, and acidification potential) to one environmental index. We include 45 bio- and fossil-based product pairs in our analysis, which we conduct for Germany. The resulting environmental indices for all product pairs analyzed range from -19.7 to +0.2 with negative values indicating overall environmental benefits of bio-based products. Except for three options of packaging materials made from wheat and cornstarch, all bio-based products (including energy, fuels, and materials) score better than their fossil counterparts. Comparing the median values for the three options of biomass utilization reveals that bio-energy (-1.2) and bio-materials (-1.0) offer significantly higher environmental benefits than bio-fuels (-0.3). The results of this study reflect, however, subjective value judgments due to the weighing methodology applied. Given the uncertainties and controversies associated not only with distance-to-target methodologies in particular but also with weighing approaches in general, the authors strongly recommend using weighing for decision finding only as a supplementary tool separately from standardized LCA methodology.
Resource flows constitute the materials basis of the economy. At the same time, they carry and induce an environmental burden associated with resource extraction and the subsequent material flows and stocks, which finally end up as waste and emissions. A reduction of this material throughput and the related impacts would require a reduction of resource inputs. And breaking the link between resource consumption and economicgrowth would require an increase in resource productivity. Material flow analysis (MFA) can be used to quantify resource flows and indicate resource productivity. In this article, we study the available empirical evidence on the actual (de-)linkage of material resource use and economic growth. We compare resource use with respect to total material requirement (TMR) and direct material input (DMI) for 11 and 26 countries, respectively, and the European Union (EU-15). The dynamics of TMR, as well as of the main components are analysed in relation to economic growth in order to show whether there is a decoupling (relative or absolute) from GDP and a change of the metabolic structure in the course of economicdevelopment. DMI/cap so far only decoupled from GDP/cap in relative terms; that is, in most countries, it reached a rather constant level but - with the exception of Czech Republic - showed no absolute decline yet. TMR/cap was reduced in two high-income countries and one low-income country due to political influence. Changes in TMR were more influenced by hidden flows (HF) than by DMI. We analyse the dynamics of the structure and composition of TMR in the course of economic development. In general, the economic development of industrial countries was accompanied by a shift from domestic to foreign resource extraction. Different relations can be discovered for the share of biomass, fossil fuel resources, construction resources and metals and industrial minerals.
Der vorliegende Artikel vergleicht die Nutzung nachwachsender Rohstoffe zur Erzeugung von Energie (Wärme und Elektrizität), Kraftstoffen und Gebrauchsprodukten anhand von vier ausgewählten Umweltbelastungskategorien. Dazu wurden Ökobilanzdaten aus 11 verschiedenen Publikationen für insgesamt 45 Produktpaare auf Basis nachwachsender und fossiler Rohstoffe analysiert und bezogen auf Einwohneräquivalente pro Hektar landwirtschaftliche Fläche miteinander verglichen. Die Ergebnisse zeigen im Allgemeinen Vorteile für die nachwachsenden Produktalternativen in den Kategorien Nichterneuerbarer Energieverbrauch und Treibhauspotenzial, während Produkte aus fossilen Ausgangsstoffen beim Eutrophierungspotenzial günstiger abschneiden und sich in der Kategorie Versauerungspotenzial uneinheitliche Resultate ergeben. Durch die Nutzung nachwachsender Rohstoffe zur Erzeugung von Gebrauchsgütern und Energie lassen sich durch Substitution der fossilen Produktalternativen größere ökologische Entlastungen realisieren als durch die Herstellung von Biokraftstoffen, die als Vollsubstitute für Diesel eingesetzt werden. Wesentliche Nachteile der Biomassenutzung sind mit dem Pflanzenanbau im Rahmen der konventionellen Landwirtschaft verbunden. Durch andere Bewirtschaftungsformen (z. B. Extensivierung) und eine besser an die jeweiligen Verwendungszwecke angepasste Auswahl bzw. Verarbeitung der nachwachsenden Rohstoffe könnten die Umweltbelastungen durch Energie, Kraftstoffe und Gebrauchsprodukte aus nachwachsenden Rohstoffen deutlich verringert werden.
Rationale for and interpretation of economy-wide materials flow analysis and derived indicators
(2003)
Economy-wide material flow analysis (MFA) and derived indicators have been developed to monitor and assess the metabolic performance of economies, that is, with respect to the internal economic flows and the exchange of materials with the environment and with other economies. Indicators such as direct material input (DMI) and direct material consumption (DMC) measure material use related to either production or consumption. Domestic hidden flows (HF) account for unused domestic extraction, and foreign HF represent the upstream primary resource requirements of the imports. DMI and domestic and foreign HF account for the total material requirement (TMR) of an economy. Subtracting the exports and their HF provides the total material consumption (TMC). DMI and TMR are used to measure the (de-) coupling of resource use and economic growth, providing the basis for resource efficiency indicators. Accounting for TMR allows detection of shifts from domestic to foreign resource requirements. Net addition to stock (NAS) measures the physical growth of an economy. It indicates the distance from flow equilibrium of inputs and outputs that may be regarded as a necessary condition of a sustainable mature metabolism. We discuss the extent to which MFA-based indicators can also be used to assess the environmental performance. For that purpose we consider different impacts of material flows, and different scales and perspectives of the analysis, and distinguish between turnover-based indicators of generic environmental pressure and impact-based indicators of specific environmental pressure. Indicators such as TMR and TMC are regarded as generic pressure indicators that may not be used to indicate specific environmental impacts. The TMR of industrial countries is discussed with respect to the question of whether volume and composition may be regarded as unsustainable.