Construction Parts from the Greenhouse: Renewable Raw Materials for Industrial Production


What is the TEPHA project?

A balance bike, a stool, and small dishes are on the table – an unsual backdrop for a project meeting with mechanical engineers, biologists, architects, and ecologists. However, these items are at the heart of the interdisciplinary project TEPHA or TEchnical Product HArvesting. It's less important what the objects are than what they are made of. "Naturally grown semi-finished products" is the keyword design engineer Anna-Lena Beger uses to summarize the project idea. What sounds complicated, means in actuality that pre-produced objects like tiles or poles are already in their final form as a result of natural growth instead of subsequent forming. The advantages of this idea are clear: less steps in the production process save both material and financial resources. Not to mention that new or better material properties can be targeted. This approach also takes a big step foward in efforts for environmentally friendly disposal.

  Balance bike and gourd Copyright: © Julia Arndt Image 1: balance bike made of bamboo and a gourd

Bamboo Designs – Stable Lightweights

The small balance bike is a handy example: the frame is completely made out of bamboo, a renewable raw material. The curved bars for a product like this are manufactured through thermal shaping. That works – but takes a toll on the stability. If the bamboo is allowed to grow naturally "around the corner," the stability is compromised less, as was investigated in the project. This is particularly interesting because bamboo naturally has a breaking stress similar to steel, explains Dr. Julia Reimer from the Chair of Botany and Molecular Genetics. As a result, numerous applications in the field of design and architecture are conceivable – from a children's balance bike to scaffolding. The prototypes are grown in the Chair's own greenhouse and neighboring open air grounds. The cultivated bamboo grass grow into an angle and from then away from light. "We especially wanted to see if we could produce a right angle, as this is the most common shape used in design," states Dr. Alexandra Wormit, describing the prototypes. Because this works impeccably, it is also possible to produce more obtuse angles.

  Snake-like figure made out of mycelium Copyright: © Julia Arndt Image 2: Complex geometric figure made out of mycelium

Lightweight Building Materials Made of Mycelium

In contrast, the small stool can be made without any additional angled constructions. It looks as if it's been made from one piece. The light material is made out of dried mycelium, which has grown into a mold filled with soil. After the growth process the web of mycelium-soil is removed from the mold and heated to both dry it out and kill the mushroom. Mycelium also grows in complex geometric shapes, which leads to a potentially broad spectrum of application. The mushrooms have good insulating properties and can thus be grown in panels used to construct walls in buildings. It is extremely important to explain the product properties to potential customers, emphasizes Dr. Thomas-Benjamin Seiler from the Department of Ecosystem Analysis. "When people think of fungus in a house, they think of the damaging mildew, which has nothing to do with the product. Everything is dead once it is heated."

Squash as an Ecological Hard Foam

The third sub-section of the research project is an example of how things don't always go according to plan in research. This section focuses on using bottle gourds. Originally, the researchers planned to use the unusual shape of the plant, but this proved to be more difficult than thought during attempts to apply it in the field of vessels and containers. But as has often occurred in the history of science, the researchers stumbled upon a new discovery in the failure. The material properties of the gourds are similar to hard foam in a variety of ways. This plastic is currently primarily produced from petrochemical raw materials. There have been no big commercial alternatives until now. This was reason enough for the TEPHA researchers to take a closer look at this innovative idea. Proposals for multiple subsequent projects have already been submitted. Who knows, what ideas will spring up out of RWTH's greenhouses in the future!


Project Participants

Group photo of project participants Copyright: © Julia Arndt Image 3: The TEPHA team: A total of four chairs and institutes at RWTH Aachen in biology, architecture, and mechanical engineering are involved in the TEPHA project.

Faculty 1 – Biology

Institute of Biology I, Chair of Botany and Molecular Genetics

  • Prof. Dr. Björn Usadel
  • Dr. Alexandra Wormit (junior research group leader)
  • Dr. Julia Jessica Reimer

Institute of Environmental Research, Biology 5

Department of Ecosystem Analysis

  • Prof. Dr. Henner Hollert
  • Dr. Thomas-Benjamin Seiler (junior research group leader)
  • Christoph Kämpfer

Faculty 2 - Architecture

Chair of Structures and Structural Design, Trako

  • Prof. Dr.-Ing. Martin Trautz
  • Franziska Moser

Faculty 4 - Mechanical Engineering

Chair and Institute for Engineering Design, ikt

  • Prof. Dr.-Ing. Jörg Feldhusen
  • Dr.-Ing. Manuel Löwer (senior engineer)
  • Anna-Lena Beger (senior engineer)