Dr.-Ing.

Albrecht, Stefan

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  • Publication
    Bringing light into the dark - Overview of environmental impacts of carbon fiber production and potential levers for reduction
    ( 2024)
    Prenzel, Tobias Manuel orcid-logo
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    Hohmann, Andrea
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    Prescher, Tim
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    Angerer, Kerstin
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    Wehner, Daniel orcid-logo
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    Ilg, Robert
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    Reden, Tjark von
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    Drechsler, Klaus
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    Albrecht, Stefan orcid-logo
    Carbon fibers (CFs) are a crucial material for lightweight structures with advanced mechanical performance. However, there is still a paucity of detailed understanding regarding the environmental impacts of production. Previously, mostly singled-out scenarios for CF production have been assessed, often based on scarce transparent inventory data. To expand the current knowledge and create a robust database for future evaluation, a life cycle assessment (LCA) was carried out. To this end, a detailed industry-approved LCI is published, which also proved plausible against the literature. Subsequently, based on a global scenario representing the market averages for precursor and CF production, the most relevant contributors to climate change (EF3.1 climate change, total) and the depletion of fossil energy carriers (EF3.1 resource use, fossil) were identified. The energy consumption in CF manufacturing was found to be responsible for 59% of the climate change and 48% of the fossil resource use. To enable a differentiated discussion of manufacturing locations and process energy consumption, 24 distinct scenarios were assessed. The findings demonstrate the significant dependence of the results on the scenarios’ boundary conditions: climate change ranges from 13.0 to 34.1 kg CO2 eq./kg CF and resource use from 262.3 to 497.9 MJ/kg CF. Through the investigated scenarios, the relevant reduction potentials were identified. The presented results help close an existing data gap for high-quality, regionalized, and technology-specific LCA results for the production of CF.
  • Publication
    Sustainable Pultruded Sandwich Profiles with Mycelium Core
    ( 2023-07-28)
    Früchtl, Marion
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    Senz, Andreas
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    Sydow, Steffen
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    Frank, Jonas Benjamin
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    Hohmann, Andrea
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    Albrecht, Stefan orcid-logo
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    Fischer, Matthias orcid-logo
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    Holland, Maximilian
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    Wilhelm, Frederik
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    Christ, Henrik-Alexander
    This research focuses on exploring the potential of mycelium as a sustainable alternative to wood or solid foam in pultruded glass fiber-reinforced plastic (GFRP) sandwich profiles. The study evaluates the performance and the environmental sustainability potential of this composite by mechanical tests and life cycle assessment (LCA). Analysis and comparison of pultruded sandwich profiles with mycelium, polyurethane (PUR) foam and chipboard demonstrate that mycelium is competitive in terms of its performance and environmental impact. The LCA indicates that 88% of greenhouse gas emissions are attributed to mycelium production, with the heat pressing (laboratory scale) being the main culprit. When pultruded profiles with mycelium cores of densities 350 and 550 kg/m 3 are produced using an oil-heated lab press, a global warming potential (GWP) of 5.74 and 9.10 kg CO 2-eq. per functional unit was calculated, respectively. When using an electrically heated press, the GWP decreases to 1.50 and 1.78 kg CO 2-eq. Compared to PUR foam, a reduction of 23% in GWP is possible. In order to leverage this potential, the material performance and the reproducibility of the properties must be further increased. Additionally, an adjustment of the manufacturing process with in situ mycelium deactivation during pultrusion could further reduce the energy consumption.
  • Publication
    Resource efficiency and environmental impact of fiber reinforced plastic processing technologies
    ( 2018)
    Hohmann, Andrea
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    Albrecht, Stefan orcid-logo
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    Lindner, Jan Paul orcid-logo
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    Voringer, Bernhard
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    Wehner, Daniel
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    Drechsler, Klaus
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    Leistner, Philip
    The process energy demand and the environmental indicators of two carbon fiber reinforced plastic process chains have been investigated. More precisely, the impact of different production set-ups fora standard textile preforming process using bindered non-crimp fabric (NCF) and a material efficient 2D dry-fiber-placement (DFP) process are analyzed. Both 2D preforms are activated by an infrared heating system and formed in a press. The resin-transfer-molding (RTM) technologyis selected for subsequent processing. Within a defined process window, the main parameters influencing the process energy demand are identified. Varying all parameters, a reduction of 77% or an increase of 700% of the electric energy consumption compared to a reference production set-up is possible, mainly depending on part size, thickness, and curing time. For a reference production set-up, carbon fiber production dominates the environmental indicators in the product manufacturing phase with a share of around 72-80% of the total global warming potential (GWP). Thus, the reduction of production waste, energy efficient carbon fiber production, and the use of renewable energy resources are the key environmental improvement levers. For the production of small and thin parts in combination with long curing cycles, the influence of the processing technologies is more pronounced. Whereas for a reference production set-up, only 10% (NCF-RTM) and 15% (DFP-RTM) of the total GWP are caused by the processing technologies, a production set-up leading to a high process energy demand results in a share of 40% (NCF-RTM) and 49% (DFP-RTM), respectively.
  • Publication
    Recommendations for resource efficient and environmentally responsible manufacturing of CFRP products
    (Carbon Composites, 2017)
    Hohmann, Andrea
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    Albrecht, Stefan orcid-logo
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    Lindner, Jan Paul orcid-logo
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    Wehner, Daniel orcid-logo
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    Kugler, Martin
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    Prenzel, Tobias orcid-logo
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    Pitschke, Thorsten
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    Seitz, Matthias
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    Schüppel, Denny
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    Kreibe, Siegfried
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    Reden, Tjark von