Soon roads in bio-bitumen based on micro-algae?

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DAlready used to produce biofuel, plastic or cosmetics, microalgae are presented as a serious alternative to petroleum. In this perspective, microalgae were used for the first time to make bitumen.

This biobitum was created as part of the Algoroute project, led by researchers from the University of Nantes and the French Institute for Transport, Planning and Network Sciences and Technologies (Ifsttar). To achieve this, they mixed algae and pressurized water, until they obtained a black and viscous liquid close to conventional petroleum. And the similarities are not limited to its appearance, since biobitume has the same properties as petroleum: “Liquid above 100 ° C, it allows to coat mineral aggregates viscoelastic from -20 ° C to 60 ° C , it ensures the cohesion of the granular structure, supports loads and relaxes mechanical stresses ”.
Tests must now be conducted to study the behavior of this biobitum over time, and the profitability of the process before seeing it, perhaps, cover our roads. Microalgae have long been known for their applications as colorants in cosmetics or as food supplements. Refining them to produce, for example, biofuels, is an idea that has emerged in recent years. Today, microalgae are among the promising alternatives to petroleum. With the development of efficient and profitable processes, many products from the refining industry would become accessible.

As part of the Algoroute program, funded by the Pays de la Loire region, researchers from Nantes and Orleans laboratories have produced bio-bitumen by upgrading residues of microalgae, resulting for example from the extraction of water-soluble proteins from algae for cosmetics industry. They used a hydrothermal liquefaction process, more simply pressurized water (in the subcritical state): This transforms this microalgae waste into a hydrophobic black viscous phase (bio-bitumen) having a similar appearance. that of a petroleum bitumen. This process is carried out with a current conversion efficiency of 55%. While the chemical composition of bio-bitumen is completely different from that of bitumen from petroleum, they have similarities: black color and rheological properties. Liquid above 100 ° C, bio-bitumen makes it possible to coat viscoelastic mineral aggregates from -20 ° C to 60 ° C, it ensures the cohesion of the granular structure, supports loads and relaxes mechanical stresses. Durability analyzes have started, as well as studies to assess the profitability of the process with a view to large-scale production. This innovation brings a potential new option for the road industry, currently entirely dependent on petroleum. Until now, the bio-bitumens developed incorporated oils of agricultural origin (with the disadvantage of competing with human nutrition) or from the paper industry, mixed with resins to improve their viscoelastic properties. Using microalgae, the cultivation of which does not require the mobilization of arable land, therefore presents an attractive solution.