Danish agriculture has to be greener, and right now research is looking intensively into extracting protein from grass fields. This will not only benefit the agricultural sector, but also the environment. Birgit Bonefeld, a postdoc at the Department of Biological and Chemical Engineering at Aarhus University, is working on utilising fibre residues from the grass to produce textiles. This will not solve the fundamental challenge of pollution in the textile industry, but it could have a significant impact for the green transition, the climate and Danish agriculture.
By Jesper Bruun, March 2021.
Imagine a pasta machine in which the dough is inserted at one end of the machine and comes out as fine, thin spaghetti through holes in a round plate at the other end. In more or less the same way, Birgit Bonefeld, postdoc from the Department of Biological and Chemical Engineering, produces fibres for textile production made of cellulose from grass. Purified and dissolved cellulose extracted from grass from Danish fields enters one end, and very thin and fine fibres, which can be spun into yarn, come out of the other end.
"Today we use biomass for energy production or as cattle feed, but we can also separate the components in biomass and use them as building blocks in other production – for example textiles. We have to face the fact, that agricultural products can, and should, be used for other things than food and fodder. There is a need and potential to use residual products from the crops that grow in the lush soil, and we have to get used to the idea that what comes from the field should also be used as raw materials for non-food products. I can easily imagine manufacturing many more raw materials, even in Denmark," says Birgit Bonefeld.
Birgit Bonefeld is one of Denmark's only technical researchers in the sustainability aspects of textiles; an area of great significance for the green transition.
It is also an important part of the conversion of agricultural to grass production to replace imports of soy protein, because even though clothes and agriculture are not usually mentioned in the same sentence, the coupling is fairly obvious in Danish contexts, and it has great potentials.
Grass contains protein that Danish agriculture can use instead of importing soy protein. During the conversion process from grass to protein powder, part of the grass is separated as a fibre residue, and this residue can be used for cattle feed, biogas and now textiles too.
"Agriculture is a major industry in Denmark, and bi-products from many of the crops are not being used optimally. I want to exploit the sidestreams from the fields, and textile production is an opportunity that will not only benefit agriculture and the environment, but also the textile industry. My dream is to raise the level of knowledge about the technical and environmental aspects of textile production – not only in industry and among researchers, but also very much among consumers and politicians. This will be a huge advantage," says Birgit Bonefeld.
Today, cellulose is used to produce textile fibres, typically from wood or bamboo harvested abroad. This is problematic for several reasons. Among other things, the price is the loss of ever larger areas of virgin and endangered forests, with consequences for the climate and species diversity.
Birgit Bonefeld is focusing on producing Next Generation Cellulose. These are textile fibres made from residual products from agriculture from Danish fields. She does this by boiling and purifying cellulose from grass, for example. When the cellulose has been purified, it becomes a white powder that can be dissolved into cellulose pulp (also called spinning solution).
The cellulose pulp is exactly what goes into the "pasta machine", and out of the other end comes the fine fibres that can be spun into yarn for textiles or used for non-wovens such as wet-wipes, hygiene products (sanitary towels, tampons, nappies), filter material or as reinforcing fibres for tyres or composites.
There are many possibilities, and it is also important in the green transition, where we need to find bio-based alternatives for all the products we produce and use that today mostly consist of fossil carbon. In other words, a win-win solution for agriculture, the climate and the textile industry.
"A little simplistically, this means that the residues I get to make textiles come from areas that are already being used to grow grass protein, so no extra land has to be taken over to obtain the source material to produce these textiles," says Birgit Bonefeld.
The textile industry is one of the world's most polluting industries. More than half of the total volume of textiles produced annually consist of synthetic polymers such as polyester, nylon and acrylic, and the vast majority of the carbon atoms in these materials are of fossil origin. Moreover, an enormous amount of energy is used in manufacturing and processing, and this predominantly comes from fossil sources.
Cotton, which makes up more than a quarter of the total volume of manufactured textiles, is also a significant factor in global challenges. Even though cotton is a natural fibre, it accounts for approximately a quarter of the total global consumption of insecticides and takes up 2-3 per cent of the total agricultural area.
There is still some way to go before we see industrial production of clothes from locally farmed grass, says Birgit Bonefeld, but smaller production can also make a difference.
Actual production of textile products, such as clothes, requires a complete value chain, with large parts outsourced to Asia. However, there is great potential in building a Danish industry that can refine surplus biomass for bio-based building blocks for use in production of bio-based materials, including textile fibres.
Cellulose is precisely such a building block, and when it has been purified and processed, it can be directly marketed to existing fibre makers for further processing.
"Development of modern, responsible fibre and textile production, in which fossil resources are not being exploited, is racing ahead, including in countries neighbouring Denmark. At the moment, Denmark is virtually invisible in this area, despite our strong position within both agriculture and textiles, and even though it actually seems fairly obvious. But things are moving. There is increasing focus on exploiting residual products from agriculture to manufacture materials. So perhaps we don’t have to look too far into the future to see us wearing clothes made of grass from Danish fields," says Birgit Bonefeld and continues:
"But there is a need for commitment and the right investments. We are well on the way with the transformation of agriculture into grass production, and it’s not at all unrealistic to develop an industry to exploit the sidestreams of this production. We don’t have to re-establish the entire textile value chain in Denmark, because we can make do with extracting the bio-based building blocks and then selling them to existing foreign fibre-production companies. It’d be an exciting new export venture for Denmark, and with automated manufacturing technologies, it’s not at all unrealistic. With the right interest, knowledge and investment, we could come a very long way."
