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Project TitleContinuous Production of Medium-Chain Carboxylates from Biowaste-derived Ethanol
Track Code5473
Short Description

A highly efficient reactor process to generate energy-dense, medium-chain carboxylates (MCCs) from lignocellulose, with almost total recovery of all input carbon molecules with minimal loss as CO2.



In 2015, 14.8 billion gallons of ethanol was produced in the U.S., mainly derived from corn. It is the most used alcohol in the biofuel industry. Ethanol is, however, miscible in water and additional steps and energy are necessary for its extraction.  Alternatives are production of higher added value chemicals that are hydrophobic and derived from organic wastes (industrial or agricultural).


Cornell researchers have developed a carboxylate platform that consists of at least one anaerobic fermentation system with an open microbial culture (reactor microbiome) that relies on the reverse β-oxidation pathway to produce MCCs by chain elongation from ethanol used as the electron donor. 


The following step of purification of the carboxylates is passive using an organic phase separation, preventing the carboxylate concentration from reaching critical levels in the reactor. 


Proof-of-concept: The method has been validated using biomass in the presence of excess ethanol derived from non-distilled ethanol in fermented mash.  This excess of ethanol into the reactor further drove chain elongation from acetate and butyrate (short-chain carboxylates, SCCs) to longer chain C6-carboxylates (n-caproic acid or n-hexanoic acid) and C8-carboxylates (n-caprylic acid or n-octanoic acid).  It has also been showed that nearly all carbon input molecules are recovered as a potential energy source when methane step is not inhibited.  This process makes highly efficient use of carbon, without any appreciable loss of carbon by carbon dioxide.


Potential Applications

  • Conversion of biowaste to a potential source of 6-chain or 8-chain carboxyl acid
  • Highly efficient commercial production of medium-chain carboxylates, which can be converted to many chemical products such as alkanes, esters, alcohols, and aldehydes.



  • This process uses very little energy to extract carboxylates and saves on energetic cost of distilling ethanol
  • Can be integrated into already-established ethanol production lines
  • Unlike existing technologies, which normally inhibit methanogenesis, this process allows methane formation, thus avoiding loss of carbon by carbon dioxide, which can otherwise be a carbon loss as high as 33%
  • Offer better carbon emissions reduction
  • Closed system thus requires low maintenance
  • Ethanol-fed bioreactors have demonstrated superior n-caproic acid productivity.


Tagsbiofuel, energy, alternative & green energy, life science, physical science
Posted DateMay 17, 2012 4:03 PM


Largus Angenent
Matthew Agler

Additional Information

Licensing Contact

Jeff Fearn


File Name Description
Technology Brief D5473 Production of Medium-Chain Carboxylates Download