While polymers have become an indispensable part of our daily lives, the vast majority of current commercial polymers are still derived from fossil-based resources and thus contribute to climate change and global warming. Furthermore, their recalcitrant nature hinders biodegradation and leads to their accumulation in the environment. Biopolymers, which are biodegradable and derived from renewable and sustainable resources, could offer a solution. However, to be able to cover the broad range of applications of fossil-derived plastics, new types of biopolymers have to be investigated. Even more, the associated production cost should be kept at a minimum to be able to compete with traditional products. With respect to this, the use of industrial gas streams rich in CO2 offers a promising route forward. Yet, in order to capture this CO2 through microbial processes, a significant amount of hydrogen gas is needed, increasing the costs of the process. This project aims to solve this issue by engineering a microbial strain to improve its hydrogen efficiency, thereby significantly lowering production costs. This engineered strain will then be tweaked to produce 2-pyrone-4,6-dicarboxylic acid from CO2 as a new and vastly promising building block for the production of biodegradable biopolymers. Overall, the ECHO project paves the way towards the sustainable and cost-efficient production of bio-based building blocks for novel polymers with a wide variety of applications.