Vast amounts of straw left over from wheat harvesting are treated as waste and left to rot on European farms or used as bedding for livestock. Researchers with the EU-funded OPTISOCHEM project see these wheat stalks as a feedstock for the production of bio-based chemicals and fuels.
Fermentation of wheat straw sugars yields a gas from which bio-isobutene can be extracted and refined into replacements for fossil fuel-based chemicals used in turn to produce plastics, sealants and other products.
“We are facing a challenge—we need more produce for a growing population but we have limited resources," said Bernard Chaud, the coordinator of OPTISOCHEM. "At the same time we want to protect the environment and reduce fossil fuel use. With bio-isobutene from wheat straw, we can use a feedstock already available (for biochemicals).”
If just 48 million of the 144 million tonnes of wheat straw waste produced in the EU was collected, it could produce 21 million tonnes of sugar to supply 100 commercial biorefinery plants. The result would be a steady supply of biochemicals for use by different industries, including biofuels, which could displace the equivalent of 35 million barrels of fossil fuel per year.
Some of the straw residue should remain in the field to reduce erosion and protect the organic carbon and nutrients in the soil, say the researchers, who also note that 30-60 percent of the material can be exported off farms without endangering soil quality.
Another EU-funded initiative, the REHAP project, is also focused on transforming wheat straw waste into new products: eco-friendly resins for wood and biochemicals for greener cement.
"We are extracting sugars and lignin from wheat straw waste," said Dr. Miriam García, a materials scientist at Tecnalia Research and Innovation centre in Gipuzkoa, Spain, and REHAP coordinator. Bio-resins are being formulated, which reduce the amount of fossil fuels used to develop artificial chemicals consumed in wooden plank and board manufacturing. The biochemicals could serve as a binding agent in concrete, helping to reduce the amount of water needed during construction.
Sugars and tannins extracted from forestry waste will be used to develop wooden boards as well as sustainable polyurethanes, a type of polymer used in home insulation, furniture and bedding.