The defossilisation of the chemical sector is essential for achieving the net-zero targets of Switzerland and the EU. As the demand for renewable carbon from biomass, recycled materials and regionally captured CO2 increases, the cosmetic industry faces particular challenges: ingredients cannot be recovered for recycling and ultimately degrade into CO2 or biomass. While process optimisation and renewable energy reduce carbon footprints at the process gate, they do not mitigate end-of-life emissions from fossil-based embedded carbon. Using biogenic carbon in non-collectable products can support carbon neutrality, but the overall balance depends strongly on upstream processes, including sourcing and conversion of raw materials. Process development in chemicals is time-intensive, often requiring up to a decade due to safety evaluations, impurity profiling, toxicological studies and regulatory registration. Therefore, value-chain transformation must start well before 2045. Although biomass-derived bulk chemicals may not soon be cost-competitive, bio-based alternatives are viable for higher-value sectors such as cosmetics. Several solvents are already available at scale, yet many required solvents and additives remain fossil-based, and their recovery generates residual fossil emissions. This WP will focus on biomass-derived chemicals and materials for the cosmetics sector, including chemical key building blocks and auxiliaries. As biomass availability and composition vary by region, processing and conversion technologies must be adapted, requiring dynamic modelling of sourcing and technology scenarios. This implementation project will establish the foundation for renewable carbon sourcing by developing a prospective system-dynamics model assessing future availability, environmental impacts and upstream risks. Complementary Life-Cycle Assessment (LCA) will evaluate the net-zero potential of bio-based chemicals versus fossil and CCU alternatives.