GREEN-B2B will pave the way towards the sustainable production of a bulk chemical product such as butadiene (BD) from waste biomass, simultaneously avoiding CO₂ emissions. By a smart integration of functionalities, CO₂ inherently produced during fermentation will be consumed within the process itself. Thanks to innovations in genetic engineering, catalyst design and synthesis, and kinetic and process modeling by a diverse, yet complementary team of ambitious scientists, major leaps forward will be realized in the microbial production of butanediols (BDOs) from paper and cardboard hydrolysate (and CO₂) followed by acid catalyzed conversion into BD.