There is an urgent need to reduce greenhouse gas emissions by transitioning to a sustainable bioeconomy, with industrial biotechnology playing a key role through the production of bio-based chemicals, bioplastics, and microbial proteins. This research focuses on using diverse second- and third-generation feedstocks, such as food waste and macroalgae, with the bacterium Cupriavidus necator to produce high-purity bioplastics (polyhydroxyalkanoates) and microbial protein via advanced multi-stage fermentation processes. These processes will be scaled up and evaluated for techno-economic feasibility, aiming to identify optimal strategies for sustainable and industrially viable production that outperform current fossil-based and first-generation bio-based alternatives.