Fraunhofer Institute for Wood Research Lightweight-construction materials made from renewable raw resources are of prime importance at the Fraunhofer WKI
Lightweight construction is considered a key technology of the future. It provides an important contribution towards increasing competitiveness and achieving climate and sustainability goals. Lightweight materials, components and products require less transportation energy and often also smaller amounts of raw resources. Lightweight products made from renewable raw materials can be particularly sustainable. Even renewable raw materials will, however, become scarce if they are used to create an ever-increasing number of products and the world’s population continues to grow. Researchers at the Fraunhofer WKI are developing resource-efficient lightweight-construction solutions using renewable raw materials: from the development of alternative raw materials from climate-adapted ecosystems and plant residues, through material and process development, component design and quality control, and on to cascade utilization and recycling.
The employees at the Fraunhofer WKI are pursuing the goal of replacing fossil and other finite raw materials with renewable raw materials. Wood is, by nature, a meaningful and established lightweight-construction material. It has a low bulk density with simultaneous high stability. The scientists at the Fraunhofer WKI are, however, not only searching for new application possibilities for wood, but also for other renewable raw materials such as hemp and flax fibers or lignin.
Furthermore, the researchers are combining natural or wood fibers with other materials such as bio-based plastics or metals. These hybrid lightweight-construction materials containing renewable raw resources are increasingly gaining in importance on the market. They can be used to manufacture resource- and climate-friendly products that fulfill several functions - for example, load-bearing construction products with integrated thermal and sound insulation as well as durable (upholstered) furniture and packaging.
Further fields of application for the lightweight-construction materials developed at the Fraunhofer WKI can be found in the mobility sector. Lightweight cars, trucks and trains made from renewable raw materials can provide a contribution towards resource conservation and climate protection. The lighter a vehicle is, the lower the energy consumption during the journey. Lightweight-construction solutions therefore play an important role in the mobility of the future. As a joining technology for the production of lightweight-construction components, bonding in particular offers numerous advantages and is therefore gaining increasing significance as a key technology of the future - particularly with regard to hybrid materials.
Project “Ligninschaum”:
Sustainable bio-foams for car bumpers on the basis of lignosulfonate
The wood constituent lignin accrues in large quantities as a by-product of pulp and paper production. In collaboration with industrial partners, researchers at the Fraunhofer WKI are developing a high-performance, lightweight bio-foam from lignin. In order to demonstrate its market potential, the lignin foam is being processed into molded parts for the automotive industry within the scope of the project. These parts are to be utilized as the core in car bumpers. Petrochemical foam materials could also be replaced by climate-friendly lignin foams in numerous other applications - for example in packaging, insulation materials or as a core material in wind-turbine rotor blades. Previously developed “lignin foams” are polyurethane foams that contain a maximum proportion of 40 percent lignin. The aim is to develop a solely lignin-based foam. In order to be economically competitive with petrochemical foams, cost-intensive purification of the lignin should furthermore be avoided. Residual materials from the plant-pulping process, such as non-digested fiber bundles and rejects, are to be specifically used to strengthen the foam.
Project “LignoLight”:
Modular, recyclable lightweight furniture made from lignin-based foams and imitation leather
Small city apartments, house moves, and changes in living and working circumstances: These days, furniture has to fulfill demanding requirements in terms of functionality and flexibility. In collaboration with research partners and companies, researchers at the Fraunhofer WKI are developing furniture that meets these requirements and is furthermore sustainable. The starting point is the new and further development of compounds, foams and imitation leather made from lignin - a plant-based residual material from industry. The aim is the creation of modular, lightweight furniture that can be easily disassembled, transported, repaired and repurposed. In other words, the service life of the material should be as long as possible. A further focus of the project is the recyclability of the furniture - from entire assemblies through to the single-type separation and preparation of the individual materials. Possibilities for the transfer of materials to other areas of application – such as the fashion industry and the motorhome sector – are also being considered.
Scientific consulting:
World’s tallest wooden tower for wind turbines - Fraunhofer WKI provides support with bonding
Modvion AB in Gothenburg received assistance from the Fraunhofer WKI during the bonding of the first wooden tower for commercial wind turbines. The WKI researchers were on site and provided the company with advice and support regarding complex bonding processes. Including a V90-2.0MW turbine from the Vestas Group, the tower attains an overall height of 150 meters (actual tower height 105 meters), making it the tallest wooden wind-turbine tower in the world. It consists of prefabricated modules that are bonded to one another at the construction site. Compared to conventional wind turbines made from concrete or steel, the timber construction method enables CO2 savings of up to 90 percent. The wooden tower is not only more sustainable, but also offers advantages in terms of lightweight construction: In relation to its own weight, wood has a higher specific strength than steel, as a result of which lighter constructions are possible. This, together with the modular design, enables savings in transportation energy.
Project “Holztafel 2.0”:
How can prefabricated wooden panels be made recyclable?
Timber frame construction is a very resource-efficient and technically mature construction method and is therefore by far the most common method in timber construction. However, the material mix of metallic, organic and mineral components makes it difficult to separate the individual components by type. Researchers at the Fraunhofer WKI, in collaboration with the Technische Universität Braunschweig, the Ruhr-Universität Bochum and four industrial partners (Otto Baukmeier Holzbau-Fertigbau GmbH & Co. KG, Sto SE & Co. KGaA, Fermacell - James Hardie Europe GmbH, and ALBA Braunschweig GmbH), want to change this. By the end of 2026, the project team wants to have developed wood panels that are significantly easier to recycle by type. The raw materials recovered during the recycling process can be used as starting materials for new products. At the end of the project, a number of demonstrators are intended to demonstrate the feasibility of the “Design for Recycling” of the wooden panel, the recycling processes and the reutilization of the recovered raw materials in new products.
Project “Plachs”:
Method for the development of recyclable products made from bio-fiber-reinforced plastic
Fiber-reinforced plastics are suitable for resource-conserving and climate-friendly lightweight-construction solutions. They can make cars, construction elements, furniture, containers and many other products more sustainable - particularly if renewable or recycled raw materials are thereby utilized. However, can the products also be easily recycled? Product design, technology, waste streams, economic efficiency: The influencing factors are extremely diverse. So how can marketable products made from fiber-reinforced plastics be conceptualized for a sustainable circular economy? In this project, researchers from the Fraunhofer WKI are working in collaboration with designer Jonathan Radetz on the development of an interdisciplinary method for this purpose. The development of a piece of seating furniture will enable the team to test whether the method works in practice. Based on this, sustainable development methods could be developed in a similar way for other (composite) materials.
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