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Gesamtökologische Bewertung der Kaskadennutzung von Holz Umweltauswirkungen stofflicher und energetischer Holznutzungssysteme im Vergleich
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... Along with the rising political awareness for the cascading concept in recent years, several studies on the environmental effects of wood cascading have been conducted using Life Cycle Assessment (LCA) to determine the environmental impacts at life cycle level. Gärtner et al. (2013) compared a wood cascading to a reference scenario providing the same functions from non-wood (mineral, metal, fossil) derived counterparts. Höglmeier et al. (2014) compared a cascading system using recovered wood in particle boards with a reference system providing the same functions using primary wood. ...
... Höglmeier et al. (2014) compared a cascading system using recovered wood in particle boards with a reference system providing the same functions using primary wood. Gärtner et al. (2013) and Höglmeier et al. (2014) presented environmental advantages of the cascading system over the reference systems for most considered impact categories: the benefits are less in comparison to the primary wood system and higher in comparison to the non-wood reference systems. They draw the same conclusion as Sathre and Gustavsson (2006) stating that the direct cascade effects obtained from the use of recovered instead of primary wood are little. ...
... They draw the same conclusion as Sathre and Gustavsson (2006) stating that the direct cascade effects obtained from the use of recovered instead of primary wood are little. Gärtner et al. (2013) and Höglmeier et al. (2014) further concluded, that the main benefits of cascading lie in the fact of saving primary natural resources. The combination of LCA and a material flow model to optimize the environmental impacts of wood utilization at a regional level under the consideration of wood cascading indicated that cascading can improve the environmental performance of wood utilization (Höglmeier et al., 2015). ...
Driven by the scarcity of non-renewable resources and a growing environmental awareness in Germany, the demand for wood could likely exceed its sustainable supply within the next decades. In response to this development, cascading, i. e. the sequential use of one unit of material in material applications with energy generation as final step, is expected to enhance the resource efficiency of wood utilization. In this context, the objective of this paper is to determine the resource consumption and resource efficiency of wood cascading compared to the use of primary wood to provide the same multiple functions. To account for resource use and calculate the efficiency, exergy analysis was applied. The exergy of a material is the potential work that can be obtained from the material in the natural environment. By using Exergy Flow Analysis, key drivers of exergy dissipation and thus hotspots for improvement were identified. Exergetic Life Cycle Assessment was applied to determine resource use and the resource efficiency at a life cycle level. The results indicate that cascading leads to less resource consumption compared to the use of primary wood, indicated by higher resource efficiency (46% vs. 21%) at life cycle level. The main resource saving potential through cascading arises from avoiding primary production in forestry systems. In conclusion, cascading reduces the primary resource extraction and makes wood utilization highly efficient. Exergy analysis proved to be a viable method to study the resource use of multifunctional cascading systems, although showing some limitations with respect to land use accounting.
... (1) Production of new bio-based materials may require an increased manufacturing intensity, and expansion of production capacities for these materials may lead to an increased demand for regional fresh wood resources; (2) Rising final energy demands for fossil-based process energy supplies in the wood manufacturing sector [3] and competition for wood-based energy carriers may require more energy-efficient processes or innovations in fuel substitution; (3) Additional capacities may increase the competition between material and energy-related use of available woody biomass resources and thus set strong constraints on the implementation and optimization of waste-wood cascading systems [4]; (4) The varying degrees of industrial symbiosis among value-added industrial networks may have their own trade-offs in impact mitigation and resource substitution [5]. ...
... (1) Production of new bio-based materials may require an increased manufacturing intensity, and expansion of production capacities for these materials may lead to an increased demand for regional fresh wood resources; (2) Rising final energy demands for fossil-based process energy supplies in the wood manufacturing sector [3] and competition for wood-based energy carriers may require more energy-efficient processes or innovations in fuel substitution; (3) Additional capacities may increase the competition between material and energy-related use of available woody biomass resources and thus set strong constraints on the implementation and optimization of waste-wood cascading systems [4]; (4) The varying degrees of industrial symbiosis among value-added industrial networks may have their own trade-offs in impact mitigation and resource substitution [5]. ...
Bioeconomy regions are a young concept representing emerging amalgamation points for the implementation of cross-sectoral value-added chains. When sustainable bioeconomy strategies are rolled out, their proof-of-concept implies that industrial R&D activities should lead to impact decoupling and that the valorization of locally available lignocellulosic biomass has to contribute to an increase in added value. Furthermore, regional co-benefits for society and a positive influence on local environmental and socioeconomic conditions are major factors. The fulfillment of these strategic goals would be a milestone achievement when progressing from the blueprint development and the road-mapping stage towards socially accepted and sustainable wood-based bioeconomy strategies. For regional industrial and science stakeholders who run pilot facilities for process upscaling and for energy and material flow integration, this requires well-orchestrated integrative processes, which go beyond conventional "Life Cycle Management" approaches. It is obvious that assessing and monitoring such integrative systems will have to account for different stakeholder perspectives and for detailed technology deployment and resource conversion scenarios. Applying a sustainability index methodology in a case study region must include an evaluation of the whole supply chain and the process networks associated with the characteristic products of the evaluated region. To date, no such integrative assessment methods exist in the literature. Therefore, the aim of this paper is to lay out, on the basis of a practical example in the case study region of Central Germany, an assessment of the sustainability level of wood-based bioeconomy networks by applying the Sustainability Monitoring Tool-SUMINISTRO"-to examine regional bio-based industry networks.
... Though there are differences in the definitions of cascading between countries and circumstances (Fraanje 1997;Keegan et al. 2012;Gärtner et al. 2013;Carus et al. 2014;Dewulf et al. 2015), the common idea of cascading wood involves the sequential use of solid wood in applications in which the intrinsic quality of the material is retained for as long a time as possible, thereby fully realising the resource potential (Keegan et al. 2012;Gärtner et al. 2013;Dewulf et al. 2015). Several researchers have explored the flows of cascaded wood, including the benefits to be obtained from cascading. ...
... Though there are differences in the definitions of cascading between countries and circumstances (Fraanje 1997;Keegan et al. 2012;Gärtner et al. 2013;Carus et al. 2014;Dewulf et al. 2015), the common idea of cascading wood involves the sequential use of solid wood in applications in which the intrinsic quality of the material is retained for as long a time as possible, thereby fully realising the resource potential (Keegan et al. 2012;Gärtner et al. 2013;Dewulf et al. 2015). Several researchers have explored the flows of cascaded wood, including the benefits to be obtained from cascading. ...
The aim of this study was to explore potential cascading flows and the measures that could be taken to enhance cascading potential. The results reveal that the potential cascading flow needs to be considered in light of the length and condition of the wood recovered from buildings, rather than the cross-section. For instance, wood in the roof structure such as ‘1 × 4’ or ‘1 × 6’ was recovered with most of the original length intact and with minimal damage, which is suitable for direct reuse. In contrast, wood in walls, floors and ceilings such as ‘2 × 2’, ‘2 × 3’ or ‘2 × 8’ was recovered in poor condition in terms of both length and the occurrence of damage. To enhance cascading potential, the development of the jointing systems and considering the reuse of whole elements of the unit parts should be further investigated. © 2017 IWSc, The Wood Technology Society of the Institute of Materials, Minerals and Mining
... ). Diese Herausforderung ist jedoch nicht Untersuchungsgegenstand dieser Studie.Ein Umweltentlastungspotenzial ist durch die stoffliche Verwertung von Sperrmüllbestandteilen nur vorhanden, wenn die Materialien mit vertretbarem Aufwand sortiert und vorbehandelt werden können und die rezyklierten Materialien an anderer Stelle Neumaterial in der Produktion ersetzen können. Dies ist beispielsweise bei der werkstofflichen Verwertung von Kunststoffen möglich, allerdings ist auch hier aufgrund materialtechnischer Probleme der Rezyklateinsatz und somit der Markt begrenzt.Grundsätzlich ist eine möglichst lange Kaskadennutzung von Holz vor der endgültigen energetischen Verwertung mit den geringsten Umweltauswirkungen verbunden(Gärtner et al., 2013;Vis et al., 2016). Dennoch führt eine Aufbereitung von Altholz, für das anschließend kein Bedarf zur weiteren Verwertung besteht, zu einem unnötigen Energieverbrauch.Eine getrennte Abfuhr oder eine Sortierung des heterogenen Sperrmülls ist mit erheblichem finanziellem und energetischem Aufwand verbunden. ...
A comprehensive analysis of end-of-life tire disposal in Germany was carried out. For this purpose, the legal basis, the material flows, their accounting and the companies involved were considered. Various European end-of-life tire disposal systems were compared, the possibilities and limits of recycling were considered, and a wide range of additional information on the subject of end-of-life tire recycling was compiled.
Available for download on the website of the Federal Environment Agency (UBA) in two languages: German and English.
... Die restlichen 80 % werden direkt, ohne vorherige Nachnutzung, thermisch verwertet (Bundesverband der Altholzaufbereiter und -verwerter, 2018). Dabei sollte der Rohstoff Holz grundsätzlich solange wie möglich in Form einer Kaskadennutzung im Kreislauf gehalten werden und erst, wenn keine stoffliche Nachnutzung technisch mehr möglich ist, sollte die, finale, thermische Verwertung vollzogen werden (Gärtner et al., 2013). ...
Aufgrund von Rohstoffknappheit auch bei nachwachsenden Rohstoffen kann das Recyceln von Holz und Holzwerkstoffen auch im Möbelsektor nur an vor-letzter Stelle, vor der thermischen Verwertung, stehen. Davor gilt es, schon bei der Produktion den Materialeinsatz zu reduzieren bzw. Möbel so zu gestalten, dass eine verlängerte Nutzung möglich ist. Insgesamt muss die Produktnutzung intensiviert werden. Dafür sind unter anderem geeignete Businessmodelle er-forderlich. Hiermit beschäftigt sich das Projekt PERMA an der HNEE. Wird Holz dann zum Altholz, muss die Nachnutzungsquote deutlich erhöht werden. Mit der Identifizierung und Indexierung von Altholz befasst sich daher das Kooperati-onsprojekt WIn-Altholz. Sind allerdings Holzspan-und Holzfaserwerkstoffe be-schädigt oder werden nicht mehr benötigt, gibt es bisher keine sinnvollen Nach-nutzungsszenarien. Das Forschungsprojekt "Respan" will nun ein Recyclingver-fahren entwickeln, dass die Nachnutzung möglichst aller Bestandteile der Werk-stoffe realisiert.
... In a subsequent work, Fraanje (1997) linked the implementation of cascade use with wood. Various authors have indicated the reduced environmental impacts achieved by the cascade use of wood (Budzinski et al., 2020;Gärtner et al., 2013;Höglmeier et al., 2015b;Mehr et al., 2018;Risse et al., 2017;Suter et al., 2017) The material use of recovered timber directly competes with energy use (Husgafvel et al., 2018). Currently, wood cascading concepts are still limited to the degradation of the material quality, in particular dimension (Risse et al., 2019). ...
The transition of our economy towards a bioeconomy is likely to increase the demand for wood in the future. Because the roundwood supply is limited, wood cascading is a promising concept for meeting the growing demand. In this context, it is necessary to map the current timber market for analyzing potential options for the cascading of recovered timber, and for quantifying future amounts of recovered timber, differentiated by the type of semi-finished wood product and sectoral origin. Therefore, a material flow analysis (MFA) for Germany during 2019 is performed and a model for the prediction of the recovery of timber volumes (PRecTimber) is developed. This model is based on a distributed decay approach which considers sectoral lifetimes. Historical data for the domestic consumption of timber products are used to calculate the annual decay of various timber products entering consumption. The MFA results in about 62 Mm³ solid wood equivalents (SWE) of various wood raw material assortments being required in the domestic production of wood products. An increasing amount of recovered timber with a minimum of 26.6 Mm³ (13.1 Mt) for 2019 to 29.5 Mm³ (14.2 Mt) in 2050 can be expected. In 2050, the recovered timber is derived from the sectors construction with 52%, furniture with 30%, packaging with 15%, and others with 2% (mainly consisting of sawn wood and particleboard products). The results of the model can be used, to derive estimates of the dimension and quality of the future recovered timber accompanying the potentials for cascading.
... Die Verweildauer hängt von deren Lebensdauer der Holzprodukte und dem Grad des Recyclings ab. So kann durch eine stärkere Kaskadennutzung, also die Mehrfachverwendung des Rohstoffes Holz, die THG-Bilanz der Holzprodukte verbessert werden (Gärtner et al., 2013;Sikkema et al., 2013 Aus der globalen Perspektive wird -neben einer Verringerung des Waldverlustes und der Wiederaufforstung von Wäldern -die naturnahen Bewirtschaftung und Regeneration von Wäldern als eine kosteneffiziente natürliche Minderungsmaßnahme (Natural Climate Solution) gesehen. Ihr Beitrag zur Vermeidung einer gefährlichen Erwärmung und Erreichung des Pariser 2°-Ziels wird auf ein Potenzial von 0,5-1,5 Gt CO 2 /Jahr beziffert (Griscom et al., 2017). ...
... On the other hand, the further waste wood incineration is postponed into the future, the less that is known about future heat and electricity mixes and hence the potential substitution benefits. Most likely, cleaner energy technologies will be available and more widespread in the future, thus reducing or even effacing the potential substitution benefits thereof (Werner et al., 2010;Gärtner et al., 2013;Suter et al., 2016). Nonetheless, results underline the climate mitigation potential of long-lived wood products, which are predominantly found in the construction sector (Neubauer-Letsch et al., 2012). ...
This study assesses the environmentally optimal wood utilisation patterns under varying wood cascading options, using the example of Switzerland. Cascading is the use of the same wood unit in multiple, successive product cycles. To consider aspects relevant at the system level (e.g. stocks/flows, demand/supply constraints) as well as at the product level (e.g. process inventories), we present a model that combines material flow analysis (MFA), life cycle assessment (LCA) and mathematical optimisation to identify environmentally optimal wood use scenarios concerning climate change and particulate matter formation. We separately include the temporal dynamics of biogenic carbon flows, i.e. carbon uptake, storage and subsequent release, which may have a considerable influence on the climate change performance of wood products.
Results indicate that multiple cascading (mC) of wood can decrease environmental impacts: total systemic impact reductions over the modelled 200-year time horizon compared to single cascading (i.e. all waste wood is directly incinerated), are between 35–59 Mt CO2-eq. and 43–63 kt PM10-eq. Driving factors for the environmental impact of future wood use scenarios are: waste wood processing efficiency, wood storage effects (in case of biogenic carbon accounting), and available cascading options. Particularly, high quality wood cascade of wooden beams is a promising recycling path for reducing environmental impacts.
We conclude that by implementing wood cascading, future Swiss wood utilisation can be further improved in terms of environmental impact. The tool combination of dynamic MFA, LCA and optimisation proved to be suitable to identify environmentally optimal scenarios for a complex value chain.
... Such environmental impacts may be different to the ones occurring today. For example, a delay in the energetic utilization of wood may substitute cleaner future energy sources and can lead to less-favorable benefits as when used today (Gärtner et al. 2013). The focus on the status quo does also not account for carbon storage effects in wood products. ...
Sustainable use of wood may contribute to coping with energy and material resource challenges. The goal of this study is to increase knowledge of the environmental effects of wood use by analyzing the complete value chain of all wooden goods produced or consumed in Switzerland. We start from a material flow analysis of current wood use in Switzerland. Environmental impacts related to the material flows are evaluated using life cycle assessment?based environmental indicators. Regarding climate change, we find an overall average benefit of 0.5 tonnes carbon dioxide equivalent per cubic meter of wood used. High environmental benefits are often achieved when replacing conventional heat production and energy-consuming materials in construction and furniture. The environmental performance of wood is, however, highly dependent on its use and environmental indicators. To exploit the mitigation potential of wood, we recommend to (1) apply its use where there are high substitution benefits like the replacement of fossil fuels for energy or energy-intensive building materials, (2) take appropriate measures to minimize negative effects like particulate matter emissions, and (3) keep a systems perspective to weigh effects like substitution and cascading against each other in a comprehensive manner. The results can provide guidance for further in-depth studies and prospective analyses of wood-use scenarios.
This chapter introduces the concept of utilization of wood in cascades, that is, for multiple successive material applications followed by a final incineration for energy production. Cascading is widely mentioned as a measure to tackle possible resource shortages due to increasing resource utilization. To evaluate this concept, a case study comparing the cascading use of one metric ton of recovered wood to direct incineration of this resource by applying environmental life cycle assessment (LCA) is presented. To enable a comparison of the two options, a system expansion approach based on both primary wood products and fossil products is carried out. Additionally highlighted aspects of LCA in this chapter are carbon storage in wood products and the consideration of time in LCA. In the majority of the considered impact categories and variants, cascading proved to be the more environmental-friendly alternative. Yet, especially the efficiency of the recovery of wood between the different steps of the cascade influences the performance of the cascading system, thereby demonstrating the importance of improving process efficiency as well when handling renewable resources such as wood.
