About This Project

Gigaton-scale CO2 removal can be achieved by developing carbon-negative sources for everyday plastics. To scale, these plastics must be chemically identical to oil-derived plastics and produced at a comparable price to oil-derived plastics. We propose enzyme engineering experiments to develop a new biosynthetic route for plastic biosynthesis. This novel pathway will enable direct production of carbon-negative plastics from sugars made by plant photosynthesis of atmospheric CO2.

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Motivating Factor

Greenhouse gas emissions (GHG) have led to increasing global temperatures in the last century. If emissions continue unabated there will be destabilizing and irreversible damage to the environment, including extreme storms and flooding, heat waves, and crop failures [1]. To combat this, many governments and companies have pledged to become carbon neutral by 2050 as part of the Paris Agreement [2]. Part of realizing these commitments will require decarbonization of plastics which account for over 5% of GHG today [3]. Given their amazing utility, plastic consumption is growing faster than population growth driven rising wealth in the developing world [4]. Incremental improvements will not be enough to decarbonize plastics. Renewable energy for plastics production can’t zero out the processes emissions chemically released when converting petroleum into plastics. A fundamentally different paradigm for plastic manufacturing is needed.

Specific Bottleneck

To meaningfully reduce greenhouse gas emissions from plastic manufacturing, new technologies producing low-cost, drop-in replacements from CO2 are needed. Such technology would capture and sequester hundreds of millions of tons of existing atmospheric carbon that would otherwise originate from fossil fuels. Fermentations of renewable sugars into plastics precursors have the potential to be used at large scales needed to address this challenge. The two main historically limiting factors for biosynthetic approaches are 1) most have not been sufficiently low cost to match existing plastic prices and 2) most do not manufacture chemically-identical replacements but rather different compounds which ultimately have somewhat different properties. As a result, there are significant time and cost barriers to adoption of new biobased plastics and materials including investments in product validation and retooling existing infrastructure [5].

Actionable Goals

Novel biosynthetic routes are needed that produce chemically identical plastic replacements which are price competitive and scalable. These routes must use plant-derived commodity substrates to be scalable and cheap. Furthermore, the pathways must be high yield, thermodynamically favorable, and redox balanced. Pathways meeting these requirements will enable low-cost, anaerobic fermentations when engineered into microbes like Saccharomyces, Lactobacillus, or E. coli. Building metabolic pathways meeting these requirements will require novel enzymes to be developed, otherwise the pathways would already exist in nature. The main actionable goal is to discover/engineer these missing enzymes to enable novel biosynthetic pathways. Once a pathway has been demonstrated, it will unlock strain engineering and fermentation optimization to build a high productivity and high yield biochemical manufacturing technology to produce GHG-sequestering plastics at industrial scales.