Integrated system of microalgae refinery – ALGORAFFINERIE

ALGORAFFINERIE is a research project with a process engineering approach. It intends to develop the scientific background necessary for the industrial exploitation of microalgal biomass. This project will focus on the so-called 1st generation biorefinery, i.e., the fractionation and the extraction of the main components but not their conversion into products for the end-user. At the end, the technical and economical feasibility will be assessed. And the social and environmental impacts will be evaluated.
The ALGORAFFINERIE project will not cover the modification of strains or the breeding of algae. It will not be involved in the optimization of photobioreactors either. The project will consider these steps as acquired and no research will be done on them.
The raw material is a fresh algae feedstock with 20% of dry matter. Two species were selected:
- Chlorella vulgaris, which has a high lipid content
- Porphyridium cruentum, which has a high polysaccharide content
Most of published papers state the use of microalgae as non-food feedstock for the production of bio-fuels. However, different high value added chemicals such as pigments, antioxidants, polysaccharides and also proteins can also be extracted.
To our knowledge, there is no research on the whole fractionation of microalgae. Known research activity has dealt exclusively with the extraction of a specific compound from biomass for commercial purposes. In most of the cases the target compounds are high value added molecules for cosmetics, pharmaceuticals or chemical intermediates. There is little information on the fate of the extraction residues.
Contrarily, the ALGORAFFINERIE project aims to the development of methodology and technical processes for the global utilization of microalgae. The strategy can be considered as the eco-conception of an integrated production scheme. Such approach has been used by one of the partners on multiple terrestrial biomasses such as corn or sunflower. This is the first time this partner will apply the biorefinery principles to microalgae.
As microalgae is a fresh biomass and it can perish rapidly, an important point of study will be the storage techniques to preserve microalgae prior to refining. This need arises because a buffer volume is necessary between the exit of the bioreactors and the beginning of the biorefining. Let us note that freezing, one of the most common preservation techniques, can induce the breaking of cells walls. Therefore, the influence of storage conditions on the extraction processes must be studied.
There is a lack of information concerning the microalgae treatments including energy considerations and integrated results interpretation for an overall utilization of biomass. In general the known treatments are optimized for the extraction of a compound of interest, without considering their impact on other recoverable molecules. In an “algorefinery” integrated process, one should take into account each type of molecule and implement techniques with no destructive effect on one or other of these categories.
The final expected result will be the detailed definition of the biorefinery process (sequency of unit operations) leading to enriched fractions of the main target molecules without degradation of any of the fractions. The economic and environmental assessments should be as favourable as possible.