-Hello, I am Clemence Queffelec, and I am an assistant professor at the University of Nantes, in chemistry. -Hello, I'm Emmanuel Chailleux and I am a researcher at the French Institute of Science and Technology for Transport, Development, and Networks. >> The objectives of this video is to present the Algoroute Project. This project aims to find a substitute to petroleum bitumen from algal biomass. First, we will define the background and the objectives. Then we will present microalgae and their potential use as an alternative binder by measuring the rheological properties of the lipidic fraction of the microalgae. Finally, a thermochemical process able to transform this biomass into a bio-binder will be presented: The hydrothermal liquefaction (HTL), and an example Petroleum oil is a fossil resource. There are controversies on the decrease of the production but the facts are that petroleum is a finite resource. Bitumen is an heavy petroleum product coming from refinery. To anticipate the rarefaction of this product, it appears necessary to find renewable substitutes. >> The challenge is to obtain biomaterial that will present the same properties and performances as conventional bitumen. For road applications, three types of properties have to be assessed related to: the manufacturing process of asphalt mix on road design, (aggregate coating and compaction). the mechanical loading, (rheology at field temperature), and ageing, and the durability. Those requirements are mandatory to fit with the actual road construction technics. Biobitumen from renewable resources have already been developed. Biobitumen generally consist of a vegetable oil mixed with natural or modified resin and sometimes a synthetic polymer, in order to tune the rheological properties. However, the presence of edible oil in the composition of these alternative binders is a major drawback from a social acceptability viewpoint. Saying that, it appeared necessary to find an other type of biomass able to give sustainable material that will not compete with feeding. -Microalgae appared to be a potential alternative. They present significant benefits over other biomass sources: their growth is rapid and the diversity is huge. They present high photosynthetic yield and low competition for arable land. A significant amount of work has been reported on the potential use of microalgae to produce biofuel. They are used as well for food, cosmetics and medicine. For example, the lipidic fraction of the microalgae, scenedesmus species, have been extracted. It is a black,pasty oil. The rheological properties of this oil were measured. They are very similar to conventional bitumen as we can see on the graph where the norm of the complex modulus versus temperatures is plotted for the lipidic aglae fraction and compared to two conventional paving grade bitumen. The lipidic fraction has been characterized. It consists of a mixture of an insoluble fraction dispersed in the oil. It looks really similar to petroleum bitumen, where asphaltenes are dispersed in an oily fraction, (Maltenes, as detailed in a previous video). Analysis of the insoluble fraction by FT-IR, spectroscopy and 13 carbon mass NMR suggests that this solid component is a fatty acid biopolymer refered as algaenan. -For the microalgae studied, the lipidic fraction represent 22% of the biomass. In order to valorize more than 22% of the biomass, the idea of the Algoroute project is to test a promising thermochemical process: the hydrothermal liquefaction (HTL) in order to transform the whole wet biomass into a "biocrude oil". -The hydrothermal liquefaction (HTL), mimics the conditions under which petroleum crude was naturally produced, (high pressure and high temperature). Besides, this thermochemical process can convert wet biomass, thus avoiding the drying step, common in other conversion processes. Moreover, in HTL, ion product of water increases, So chemical reactions are facilitated. Water acts as a solvent and a reagent so the microalgae microstructure is degraded with release of chemical building blocks which react with each other under HTL conditions. Finally the hydrophilic fraction can undergo chemical reactions through deoxygenation, thus increasing the biocrude oil yield. HTL performed on microalgae between 260 degrees and 300 degrees gives the following fractions: Gaz, (mainly CO2) an hydrophillic fraction and a hydrophobic fraction composed of an oily fraction and solid residues. The solid residues was again identified as algaenan. The yield for the hydrophobic fractions was consistent whatever the conditions applied and was about 55%, A great improvement compared to the 22% of the lipidic fraction. The rheological properties of the hydrophobic fractions were investigated. This figure shows the viscoelastic data of the hydrophobic fractions compared to a standard bitumen plotted in a Black diagram. ( i.e. ,phase angle versus norm of the complex modulus measured at several temperatures and frequencies). The rheological behavior of fractions obtained at 280 degrees and 300 degrees markedly differs from the one obtained at 260 degree, which is close to a standard bitumen. This means that: the molecular structure of the sample obtained at 260 degrees appears to be stable with temperature, like a standard bitumen. On the contrary, the fraction obtained at 280 degrees and 300 degrees show isotherms that do not overlap in the black diagram, giving evidence of molecular rearrangements occurring as a function of temperature. In conclusion, microalgae are a promising biomass to obtain a biobitumen with properties similar to conventional bitumen. The hydrothermal liquefaction (HTL), has allowed the transformation of 55% of the initial biomass into a hydrophobic fraction. Under certain conditions, this hydrophobic fraction has properties similar to petroleum bitumen. Mixes with aggregates were manufactured with the hydrophobic fraction. Going to industrilization will induce to valorize microalgae residues, following a concept of integrated biorefinery that could mirror the petroleum refinery. -Reminder of the key points presented Microalgae can be a promising biomass. The lipidic fraction of the studied microalgae is rheologically similar to conventional bitumen. Hydrothermal liquefaction transform wet biomass, and increases the hydrophobic yield. Rheological properties is due to the nature of the biomaterial which is a suspension of a biopolymer in the oily fraction. Thank for your attention.
