Enzymes convert CO2 into green chemicals

Tuesday 02 Jun 20

by Peter Aagaard Brixen

Contact

Anne Merete Boye Strunge Meyer

Professor

DTU Bioengineering

+45 45 25 25 98
asme@dtu.dk

Capturing CO2 with enzymes

Using microbial enzymes to convert CO₂ into useful chemicals such as formic acid, formaldehyde, and methanol has been a key research focus at DTU Bioengineering for several years.

The researchers have identified a number of microbial enzymes that can be used in microbial production systems, such as E. coli bacteria. The enzymes can in principle be produced cheaply on a large scale, but they need to be stabilized.

Developing the technology requires new research into how enzymes can be produced on a large scale and at a higher yield. Another field of research is testing the methodology on different CO₂ sources which may have different compositions, depending on whether they originate from, e.g., a steel mill stack or a bioethanol plant or come directly from the air.

The researchers estimate that approximately 200 tons of enzymes can convert 1 megaton CO₂ a day under ideal conditions.

Scientists activate enzymes’ ability to absorb CO₂ from the air and convert and store it as eco-friendly chemicals.

Using enzymes to convert CO₂ from the air has the potential to become a new sustainable method of producing chemicals in the future. This is the view of researchers at DTU who have identified enzymes that are extremely effective at converting CO₂ into formic acid, which can then be further converted into, e.g., methanol by using other enzymes.

“Particularly two of the enzymes we have categorized in the formate dehydrogenase group show great potential of being able to capture CO₂. In experimental studies, CO₂ combined with electrons have proven to effectively convert CO₂ into liquid chemicals,” says Christian Førgaard Nielsen, PhD student at DTU Bioengineering.

Sustainable fuel

Using enzymes to convert CO₂ requires power, and Christian Førgaard Nielsen believes that a production unit with enzymes in combination with electricity from wind turbines is a potential candidate for a new source of sustainable chemicals.

“Bioelectrochemistry is, in my opinion, the best bet for sustainable production, because we avoid retrieving fossils from underground deposits and burning them. Instead, we can exploit the fact that it’s technically possible to electrify the enzymes and thus activate their ability to absorb CO₂ from the air,” says Christian Førgaard Nielsen.

Developing production unit

Researchers have been working for decades to develop a technology that can effectively convert carbon from CO₂ into fuel. A number of materials have been created in laboratories which can convert CO₂ into, e.g., methanol when combined with electrons from an electrical source. However, it has still not been possible to develop a technology that is sufficiently effective, but the next step is to improve the existing technology, including the enzymes that catalyze the conversion of formic acid into methanol.

According to Christian Førgaard Nielsen, the identification of the CO₂-transformingenzymes is also still at a basic scientific level. The next step will be to create and scale up an efficient production of the selected enzymes and to construct a production unit that can be tested in combination with wind turbines, for example, to create formic acid.

Scientific breakthrough

Anne S. Meyer, Professor at DTU Bioengineering, believes that discovering the CO₂-transforming enzymes and producing them in a production organism is a genuine breakthrough.

“It opens up exciting possibilities. We don’t have a finished production technology yet, but we do have some important components that can be included in experiments where the enzymes in production units are connected to solar panels or wind farms. And it’s even a technology where Denmark has the potential to become a market leader, considering its strong enzyme industry,” says Anne S. Meyer.