Assessing the Environmental Impact of Silk Protein Production for Bio-Based Materials: A Life Cycle Assessment Study.

Replacing oil-based materials with renewable alternatives is an important step towards decarbonization. The wood product market is one of the larger consumers of synthetic polymers, with over 65% of synthetic adhesives consumption worldwide. Natural resources such as proteins have been proposed as building blocks for wood resins. While the use of renewable substances is suitable for ecological change, other factors must also be considered. For example, among the main protein sources soya production has shown less environmental impacts than chemical compounds of synthetic resins, but it requires high water and land consumption. Furthermore, its use in wood adhesives competes with its use in food. A promising alternative of soya for bio adhesive formulations is cocoons silk. In order for a new technology to be environmentally friendly, it is necessary to evaluate the environmental impact of its production. Therefore, a LCA study was performed on silk protein productions. Both primary and secondary data have been used in this study. Primary data have been collected in an Italian company to assess the environmental impacts of all stages involved in silk cocoon supply chain, from mulberry harvesting to the silk protein production. Secondary data have been used for emission factors provided by Ecoinvent database. Environmental impacts have been calculated using CML 2001 method and impact categories associated with air, soil and water pollution have been selected. As far as possible, the results were compared with scientific literature data on the production of chemical compounds used for wood adhesives and bioplastics production.