Algae used to convert CO2 into carbon fibres

Chemists from the Technical University of Munich (TUM) have developed a process that, according to initial calculations, provides an economic way of removing carbon dioxide from the atmosphere — and creates valuable new materials at the same time.

Opening an option for a net carbon sink, the technology tackles the problem of atmospheric warming at the root, using algae to convert carbon dioxide from the atmosphere, power plants or steel processing exhaust into algae oil. This is subsequently used to produce lightweight and high-strength carbon fibres.

Important technical groundwork was done by Professor Thomas Brück and his team at TUM’s Algae Cultivation Center. The algae investigated at the centre not only produces biofuel, but can also be used to efficiently produce polyacrylonitrile (PAN) fibres. The energy of parabolic solar reflectors then chars the PAN fibres to yield carbon fibres in a CO₂-neutral manner.

Carbon fibres from algae are no different from conventional fibres and can therefore be used in all existing processes; for example, as a substitute for structural steel in construction materials. Thanks to their strength they save on cement, and granite reinforced with carbon fibre can even be used to produce beams that have the same load-bearing capacity as steel but are as lightweight as aluminium. At the end of their life cycle, the carbon fibres can be stockpiled in empty coal seams, permanently removing the associated carbon dioxide equivalents from the atmosphere.

“When you make plastics from carbon dioxide, it is quickly returned to the atmosphere through waste incineration plants following a few years of use,” said TUM’s Kolja Kuse. “With the final safe storage, we remove the carbon dioxide from the atmosphere for millennia. This also makes the process clearly superior to carbon capture and storage (CCS) in the underground.”

A beam made of carbon fibre-reinforced granite is load-bearing like steel, as light as aluminium and extremely durable. Image credit: Kolja Kuse/TechnoCarbonTechnologies.

Prof Brück now plans to further improve the algae technology, suggesting large-scale plants in southern Europe and North Africa.

“The system is easily scalable to large areas,” said Prof Brück. “Plants which together would cover the size of Algeria would offset all CO₂ emissions from air transport.”

He also rejects any suggestion that the technology would compete with the agricultural use of land, as is the case with biogas. “Saltwater algae thrive in sunny areas,” he said. “In North Africa, for example, there are ample stretches of land where agriculture makes no sense.”

The technology has been described in two studies in the journal Industrial & Engineering Chemistry Research.

Top image caption: Carbon fibre reinforcement gives the granite plate an extremely high strength, enabling efficient construction. Image credit: A Battenberg/TUM.