Fermentation of syngas to CO2-neutral chemicals

This project aims to combine syngas fermentation and bioelectrochemical systems as a source of electrons in a novel configuration to capture and valorize all the CO2 present in syngas.

The urgent need of substituting our fossil fuel-based industry requires the development of a renewable chemical platform.

Gasification, followed by syngas fermentation (SF) processes, has the potential of turning 100% of the carbon in residual biomasses into fuels and commodity chemicals when enriched with additional reducing power in the form of electrons.

Lignin accounts for 15-30% of lignocellulosic material and is usually discarded as residual biomass from fermentation processes because of its low biodegradability.

On the other hand, gasification allows for the conversion of 100% of residual biomasses, including lignocellulosic material, into syngas, which consists mainly of CO2, CO, and H2.

Syngas can then be fermented by homoacetogenic bacteria, producing mainly acetate and ethanol through the Wood-Ljundgdahl pathway.

Ethanol and acetate, however, hold low market prices and many studies currently focus on chain-elongation, to improve the cost-effectiveness of the process by targeting higher market price products, such as butyric or caproic acids.

One of the challenges to overcome is the need for additional electron sources, such as externally added electron donors like ethanol or lactate.

In this project, the use of a bioelectrochemical system (BES) is proposed as the electron donor, which would be integrated as a secondary step in an SF-BES strategy.

Therefore, syngas will be fermented in a high-rate reactor and the effluent will be fed into a BES to capture the remaining CO2 and elongate the acetate to produce butyrate and caproate.

These acids act as our proof-of-concept; however, the production could be re-directed to the many different commodity chemicals and fuels currently produced from fossil fuels.

Main supervisor:
Hariklia Gavala

Co- supervisors:
Ioannis V. Skiadas (KT-PROSYS)
Lisbeth Olsson (Chalmers University of Technology)
Yvonne Nygård (Chalmers University of Technology)


Cesar Quintela Garcia
DTU Chemical Engineering


Ioannis V. Skiadas
Associate Professor
DTU Chemical Engineering
+45 45 25 27 29


Hariklia N. Gavala
Associate Professor
DTU Chemical Engineering
+45 45 25 61 96