After the carbon-hydrogen bonds in the feedstock are "cracked" using gasification and converted into syngas, bacterial fermentation (biofermentation) of the syngas into ethanol occurs using proprietary Coskata microorganisms.

Coskata microorganisms are extremely efficient, utilizing the entire energy value of available input material to produce ethanol. This is a significant advantage over other approaches that only use a fraction of this energy due to their inability to utilize all portions of biomass input material and/or result in non-ethanol byproducts hurting efficiencies.

                                         

Chemical Catalysis v. Biofermentation
Some ethanol conversion processes use a gasification front-end and chemical catalysis for conversion, producing a mix of alcohols from methanol to pentanol and beyond, resulting in considerable separations and/or recycling costs as well as decreased yield.

Ethanol conversion using chemical catalysts requires extremely pure syngas streams, as impurities readily degrade the catalysts. Not only are these catalysts expensive, but the high purity requirements of the syngas stream results in greater capital intensity. Additionally, chemical catalysis approaches require syngas compression in preparation for the high-pressure alcohol synthesis operation.

Chemical catalysis is also inefficient with regard to energy and carbon dioxide. It requires a specific ratio of CO:H2 to make ethanol.  These ratios are not found in nature, and require an energy consuming "water shift" reaction to make ethanol.

                                                        

Coskata's biofermentation step avoids these higher-cost complexities:

• During biofermentation, Coskata's naturally occurring microorganisms - some of the oldest biological mechanisms in existence - use the chemical energy of syngas (CO and/or H2) to exclusively produce ethanol.
  
• Coskata microorganisms have demonstrated a level of tolerance to typical syngas impurities that poison a chemical conversion approach

Together, Coskata's proprietary microorganisms and bioreactor designs lead to the highest conversion rates of feedstock to ethanol in the industry, as well as greater resistance to phage infections and bacterial contaminants.