VALORISATION OF CARBON DIOXIDE THROUGH BIOTECHNOLOGICAL PROCESSES. To bring a halt to climate change, we need several strategies. One of those strategies is Carbon Capture and Utilisation (CCU): Turning carbon dioxide from point sources and possibly even air into commercially-valuable chemicals. Biotechnological processes such as fermentation and bio-electric conversion have already proven to be technically feasible.

“Our research on fermentation for the valorisation of waste streams has been running for five years, but only in the last couple of years did we start using carbon dioxide in our processes,” Linsey Garcia-Gonzalez, researcher at VITO, explains. “By feeding carbon dioxide to specifi c bacteria under specifi c circumstances, polyhydroxyalkanoate (PHA) is created: a polymer with plenty of application possibilities.”

Unique infrastructure

The production of PHA occurs in the presence of oxygen and hydrogen. To use this potentially explosive gas mixture safely, VITO developed a unique setup: a bioreactor attached to a special gas analysis and dosage system. “Our system complies with the European ATEX guidelines (ATmosphères EXplosibles),” says Garcia-Gonzalez. “By using an online gas chromatograph we always know the exact composition of the gas phase in the reactor and can ensure safety, even for processes that require oxygen. Moreover, this system allows us to adjust the gas composition continuously based on usage. Our very own software system controls the adjustments.”

First tests with real waste gas

After tests with synthetic gas mixtures, the first step was taken towards the use of real carbon dioxide-rich waste gases from the industry. “The experiments showed similar PHA yields under analogous working conditions,” Garcia- Gonzalez adds. In 2015, a doctoral study on the subject was completed. In cooperation with the UGent, Salatul Mozumder studied how PHA can be produced from industrial organic bypass flows and carbon dioxide.

3D printing

In the next years, VITO aims to adapt the properties of PHA out of carbon dioxide to the different applications on the one hand and study enzymatic processes for carbon dioxide conversion to monomers on the other, all within the framework of the MIP(1)-project CO2MPASS (2015-2017). Garcia-Gonzalez: “For example, the copolymer polyhydroxybutyrate-valerate (PHBV) is required for 3D printing. Combined with polylactic acid, it creates a sustainable fi lament that can serve as raw material for 3D printing. We can acquire PHBV through fermentation. We can create lactic acid, the monomer of polylactic acid, out of carbon dioxide via the enzymatic process.”

Patented electrodes

Carbon dioxide can be converted through bio-electric conversion. In that case, bacteria turn carbon dioxide into useful chemical products such as acetate or ethanol through the presence of electric currents. VITO has two patented electrodes on the market: VITO CoRETM and VITO CaSETM. These electrodes are gas porous and coated with bioactive layers that contain bacteria. Instead of bacteria, enzymes are also capable of driving the reaction. In a post-doctoral research project (Marie Curie ELECTROENZEQUEST, 2013-2015), the enzymatic conversion of carbon dioxide into formic acid was optimised. The technology can now be used to create more high-quality components.

Green energy

“We need a lot of energy to convert carbon dioxide into new substances. A bio-electrochemical system has the advantage of being able to use electric current as a direct source of energy,” researcher Deepak Pant of VITO explains. “Moreover, the electric current for this process can be provided by green energy sources, such as wind energy or photovoltaic cells. The surplus of green energy could be used to power electrosynthesis modules on a large scale.” Connecting renewable energy and electric conversion was one of the central themes of VITO’s participating projects in the innovation competition Climate Launchpad 2015. VITO researchers got a place in the top 10 and will now develop their concept into a start-up within the framework of the Climate-KIC Accelerator Programme.

Pilot installation in India

In India, VITO is also working on the development of carbon dioxide conversion. The Indian petrochemistry company Indian Oil founded a Centre of Excellence for CO2 Conversion in 2013 along with 10 partners, including VITO. Their aim is to build a large-scale pilot installation in five years.