Chalmers and partners spin textile fibre from grass and clover press cake

The result makes two claims, and the experiment tested one of them. The tested claim is purity. Press cake contains cellulose, the same substance used to make textile fibre from wood ^[2]. "We have produced pulp from the press cake, which is initially brown and green, and shown that it meets the requirements for dissolving pulp, including purity," said Diana Bernin, an associate professor in Chalmers' Department of Chemistry and Chemical Engineering ^[4]. I think this is the solid finding. A residue that starts out green can be brought to dissolving-pulp grade, and the spun fibre and knitted sample show the pulp went through the next two steps of the chain ^[3].

The comparison with wood is a different kind of claim. It rests on plant structure. Trees are built to withstand the elements for many years, and that toughness makes their cellulose harder to extract. In grass the fibres are more accessible ^[7]. "The cellulose is the same whether it comes from a tree or from grass. The difference is how easily we can extract it," Bernin said ^[6]. From there she makes a process claim: "We can use simpler chemistry and smaller amounts of chemicals to extract the fibers. This also saves energy" ^[16].

She also said the size of that advantage is unknown. "The environmental and resource benefits need further investigation. We have worked with a process on a laboratory scale, and it is difficult to compare that with an industrial-scale process," Bernin said ^[8]. The control this claim needs is a large-scale industrial process. Testing at pilot scale and comparing against one is the group's stated next step ^[9]. The release does not report yields, chemical quantities, energy use or fibre strength, so any difference from wood cannot be sized from it ^[8].

The first users would be green biorefineries that already extract protein from grass. In the Swedish-Danish Green Valleys project, researchers and farmers worked through the chain from cultivation to protein extraction and biogas, with demonstration facilities at Sötåsen Agricultural College in Sweden and Aarhus University in Denmark ^[11]. Bernin explained why the group aimed at clothing and not boxes. "Our aim has been to produce something of high value, and that is where textile fibers come in. Packaging could also be an option, but it would be much better to make a product that can be used for a long time and potentially recycled," she said ^[14].