NOVELTY - Producing biomass and products derived from it by culturing unicellular algae in aqueous medium fed with a stream of carbon dioxide (CO2) in one set of bioreactors, comprises: (a) injecting inside the photobioreactor a stream of seawater, brackish or fresh culture medium as algae enriched with nutrients; (b) inject into the photobioreactor at least one strain of a species of unicellular algae, and contacting the strain with the stream enriched in light conditions for crop growth through photosynthesis; (c) injecting inside the photobioreactor, gas stream containing CO2.    USE - The process is useful for producing biomass and products derived from it by culturing unicellular algae in aqueous medium fed with stream of CO2 in one set of bioreactors (claimed).    ADVANTAGE - Energy efficient process is provided that prevents the emission of gaseous and liquid contaminants to the environment.    DETAILED DESCRIPTION - Producing biomass and products derived from it by culturing unicellular algae in aqueous medium fed with a stream of carbon dioxide (CO2) in one set of bioreactors, comprises: (a) injecting inside the photobioreactor a stream of seawater, brackish or fresh culture medium as algae enriched with nutrients, microfiltered and previously disinfected; (b) inject into the photobioreactor at least one strain of a species of unicellular algae, and contacting the strain with the stream enriched in light conditions for crop growth through photosynthesis; (c) injecting inside the photobioreactor, gas stream containing CO2; and further comprises: (d) extracting the algal culture from the photobioreactor, stored in a storage tank and sent to a separate biomass removed by mechanical and/or chemical separation unit so that the biomass obtained has a moisture content between 50% and 90%; (e) submitting wet biomass in a separate settling and/or cavitation to remove part of lipids and/or fatty acids and other value added products along with a first rejection unit, passing the rest of the biomass to the next stage; (f) subjecting the rest of the biomass from the stage prior to direct thermal liquefaction in a separate low temperature to produce bio-crude and a second rejection unit, all at a temperature between 250 degrees C and 350 degrees C and a pressure between 150 and 210 bar, both limits included, for a time comprised between 1 and 120 minutes; and (g) recovering rejects from the extraction stage of lipids, fatty acids and other value-added products and the later stage of thermochemical treatment in subcritical conditions, store in separate chambers. An INDEPENDENT CLAIM is a plant for producing plant biomass and products derived from it by culturing at least one species of unicellular algae in aqueous medium fed with a gas stream containing CO2, comprising at least one sweet and/or salty pickup unit, storage and injection of seawater stream connected to unit injection of nutrients to the stream before entering the photobioreactor as a unit and microfiltration disinfection; at least a scanning unit; a set of two or more upstanding annular photobioreactor; unit for extracting a part of the culture inside the photobioreactor and a collection tank of the same; unit of extraction of lipids and/or fatty acids and/or other value added by cavitation, decanting and/or dissolution of biomass; thermochemical treatment unit for the production of bio-crude by direct thermal liquefaction of low temperature from the remaining biomass unit extraction of lipids and/or fatty acids and/or other value-added products; a storage chamber of the first rejection; and a storage chamber of the second rejection.