Ethylene is the largest petrochemical produced worldwide and serves as a building block for a wide variety of plastics, textiles, and chemicals. It has been demonstrated that ethylene can be produced biologically both with dehydration of bio-ethanol or the direct production in plants, bacteria, and fungi. Researchers at the National Renewable Energy Laboratory (NREL) have developed a cyanobacterium Synechocystis sp. PCC 6803 (referred as Synechocystis) that produces ethylene via photosynthesis. This cyanobacterium utilizes the ethylene forming enzyme (Efe) pathway to catalyze a single-step reaction involving components of the tricarboxylic acid cycle. The recombinant Synechocystis can also use biomass sugars as a supplemental energy source to enhance ethylene productivity when sunlight is not present or sufficient, however this is considered in future work. Finally, Synechocystis can be grown in saline or brackish water. These technology advantages enable potential valuable biotechnological approaches for bioethylene production. Therefore, understanding the economic potential for the process at a commercial scale is critical to guide research and development towards viability of making bioethylene from photosynthesis using Synechocystis. The goal of this work is to perform a techno-economic analysis (TEA) in combination with R&D efforts to assess the economic potential of bioethylene and bioethylene-to-hydrocarbons to meet mid-term (or long-term) cost targets using solar insolation as the energy input, in order to guide research in the most beneficial direction. Use of biomass sugars as a supplemental energy input is possible but is not included in this analysis. Additionally, key drivers and process and economic challenges will be discussed using the sensitivity analysis approach to improve ethylene productivity and energy efficiency of the overall process. Finally, prospective options for R&D are discussed.

Prospective bioethylene production process from photosynthetically-fixed CO2 in recombinant cyanobacteria

249th National Meeting (2015)

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