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Plant pots made of natural fibres – "bio", no ifs or buts

Plastic plant pots are not good for the environment; strictly speaking, they should not even be disposed of in recycling bins. Alternatives such as coconut fibre pots are compostable, but not pollutant-free and therefore not "bio" at all. The Karlsruhe-based company Fiber Engineering has developed a truly ecofriendly way to grow plants: pots made of hemp or grass, which are only preserved with biological components and decompose completely within a few weeks.

It is almost impossible to imagine our daily life without plastics - whether as packaging material, thermal insulation and in adhesives or cosmetics. Many areas of everyday life cannot do without them or would be much less comfortable for us. However, once they are no longer needed, most plastic products are not recycled. Most plastic parts end up in landfills, many of their components accumulate in the environment and, depending on the material, take several hundred years to decompose. This is why researchers around the world are looking hard for alternatives to plastic products of all kinds. In theory, nature offers a variety of raw materials for this purpose. However, in the majority of cases, these products are not as good as the original plastic one.

Natural fibres of all kinds can be used to produce many everyday products

Light brown hexagonal pots made of grass and reed
Fiber Engineering’s novel plant pots are made entirely of natural materials, including organic wax and organic glue and decompose in soil within 6 weeks without leaving pollutants behind. © Fiber Engineering

Fiber Engineering, founded in 2003 in Karlsruhe, is a specialist in novel fibre processing approaches. The company uses a specially developed fibre injection molding (FIM) technology to manufacture products of all kinds with natural fibres such as grass, flax, coconut and even camel hair. "Our new technology enables us to produce 3D moulded parts in a highly efficient way – i. e. with the lowest possible energy and material consumption", explains Egon Förster, company founder and managing director. "We can do this because we are making the products without having to go via semi-finished products, which means that we process the fibre mixtures directly. This does away with a complete production step. We are specialised in adjusting the densities of products locally. Product areas that require lower density use less material; this cuts costs and makes the products lighter.” Förster's core technology has already been patented in more than 30 countries worldwide. There are a wide variety of applications, he says, and this could open up many interesting markets.

Biodegradable pots decompose completely after a few weeks

Two plastic bags filled with plant fibres and binder, a ruler for size estimation, and a plant pot
Figure showing the amount of fibres and binders needed to make a plant pot. © Fiber Engineering

In fact, with its new technology, Fiber Engineering has already developed a whole range of innovations for the automotive, aviation and packaging industries as well as the agricultural sector. The company's latest product is fully biodegradable plant pots. "Previous alternatives to the standard black or brown plastic flowerpots that we all know, 20 million of which are produced in Europe every single day, have been around for some time. Some of them also contain organic fibres such as coconut," says Förster. "But these coconut fibre products have to be stabilised with plastic glue. In addition, considering that the raw materials from Sri Lanka have to be transported a long way to their final destination, the final product cannot under any circumstances be referred to as “bio”." Förster points out that approaches involving PLA (polylactide), which can be produced from lactic acid or corn starch, are anything but organic. He comments: "Although these PLA-based products use a different raw material source, the final product is still made of plastic.”

Fiber Engineering therefore began looking for an alternative to plastic plant pots over two years ago. They were successful: the product developed by Förster and his staff can be produced very efficiently. In addition, it is "bio", no ifs or buts, as Förster says, because it can be composted in private compost heaps or buried without leaving behind harmful pollutants. The experts had set themselves the ambitious goal to process as many different natural materials as cheaply as possible.

Starting material: natural residues

Two small heaps of straw-like yellow fibres
A broad range of different natural materials can be used to produce bio plant pots - here: Miscanthus and maize leaves. © Fiber Engineering

"After a few initial hurdles, we are now able to use quite a broad range of residual materials, including hemp, grass and reeds. All these materials work quite well,” reports Förster. "There is only one problem, namely all plant stems are different, whether they come from the same plant species or not. Durability and decomposition can therefore vary greatly depending on the composition of the starting material. We have solved this by adding two extra components to the fibres, i.e. organic wax and organic glue. We can use these two parameters to make the product in such a way that it decomposes during the desired timespan.
During the development phase, we tested a large number of different fibre mixtures for their suitability for plant pots.”

The result of the company’s efforts is now a plant pot that is as light as possible, but also as strong as possible. In addition, it consists entirely of natural residues. Fiber Engineering obtains the residual materials from various organisations. Hemp residues, for example, come from a company called BAFA Neu GmbH in Malsch which produces diverse hemp products; grasses come from areas close to Karlsruhe and maize leaves come from Hof University of Applied Sciences.

Development work continues

Green mould made of metal with cavities for four pots
Prototype tools for producing biodegradable plant pots © Fiber Engineering

The product has already been successfully tested by other organisations, including the University of Hohenheim and the Hohenstein Institute. Amongst other things, these two institutions carried out weathering tests that showed that the pots decomposed within six weeks. "We are now in a position to start discussions with various interested parties, large companies and retail chains, who might want to market the pots. We do not have the distribution infrastructure for commercialising the plant pots ourselves,” says Förster, who hopes to be able to place the bio plant pots on the market in 2020. “However, if it turns out that no distributor is interested in selling the pots for us, then we will market them directly.”

The project is still in the prototype stage. At present, the pots are hexagonal but the company is in principle also able to produce round and square ones. However, before Fiber Engineering decides on the future pot design, it wants to wait and see what customers want. General development of the innovative biodegradable plant pot has not yet been completed. Förster comments: “We are in the process of improving them further. We are working with another company from Karlsruhe that produces biofuel in an attempt to produce organic wax using the carbon dioxide that accumulates during this process. This means that we are removing carbon dioxide where it is harmful and unwanted, and taking it to where it is needed, namely to the growing plants.”

Fiber Engineering is currently also working on some entirely different projects. Amongst other things, the company is seeking a solution for replacing polystyrene in exterior wall facades and polyurethane foam used in the automotive sector with biogenic materials. “We have many ideas, but unfortunately not enough money for rapid implementation,” says Förster. “The world never stands still, you can always do things better.”

Website address: https://www.biooekonomie-bw.de/en/articles/news/pflanztoepfe-aus-naturfasern-bio-ohne-wenn-und-aber