The paper focused on the co-production of high-value-added product thermostable C-phycocyanin (C-PC) and biomass, further utilized in pyrolysis. The photobiosynthesis of CPC was carried out by the thermophilic cyanobacteria Synechococcus PCC6715 cultivated in the helical and flat panel photobioreactors (PBR). Despite the application of different inorganic carbon sources, both PBRs were characterized by the same growth efficiency and similar C-PC concentration in biomass. To release the intracellular C-PC the biomass was concentrated and disintegrated by the freeze-thaw method. The crude C-PC was then further purified by foam fractionation (FF), aqueous two-phase extraction (ATPE), membrane techniques (UF) and fast protein liquid chromatography (FPLC). Each of the tested methods can be used separately; however, from a practical and economic point of view, a three-stage purification system (FF, FPLC and UF) was proposed. The purity ratio of the final C-PC was about 3.9, which allows it to be classified as a reactive grade. To improve the profitability of 3G biorefinery, the solid biomass residue was used as a substrate to pyrolysis process, which leads to production of additional chemicals in the form of oils, gas (containing e.g. H ₂) and biochar.

Efforts were made to demonstrate that in biorefineries it is possible to manufacture all the commodities required for maintaining human civilisation on the current level. Biorefineries are based on processing biomass resulting from photosynthesis. From sugars, oils and proteins, a variety of food, feed, nutrients, pharmaceuticals, polymers, chemicals and fuels can further be produced. Production in biorefineries must be based on a few rules to fulfil sustainable development: all raw materials are derived from biomass, all products are biodegradable and production methods are in accordance with the principles of Green Chemistry and Clean Technology. The paper presents a summary of state-of-the-art concerning biorefineries, production methods and product range of leading companies in the world that are already implemented. Potential risks caused by the development of biorefineries, such as: insecurities of food and feed production, uncontrolled changes in global production profiles, monocultures, eutrophication, etc., were also highlighted in this paper. It was stressed that the sustainable development is not only an alternative point of view but is our condition to survive.