Process for producing a biocrude employing microalgae

Procedure for obtaining a biocrude from a gas comprising CO2, procedure which comprises the steps of:

• a. supply of the gas which comprises CO2 to a reactor containing a culture which comprises at least one species of microalga which is capable of photosynthesis;
• b. photosynthesis carried out by the species of microalga using the CO2 supplied to produce a biomass;
• c. anaerobic fermentation of the biomass obtained;
• d. thermochemical decomposition of the biomass fermented at a pressure between 0 and 20 MPa and a temperature between 200 and 420° C. in order to obtain a biocrude mixed with water and gases, and
• e. separation of the biocrude obtained,
• characterised in that following the photosynthesis stage, between 5 and 100% of the culture is removed from the reactor which is subsequently separated into a solid fraction which contains biomass, which solid fraction will subsequently be subjected to the stage of anaerobic fermentation, and a liquid fraction containing carbonates and/or bicarbonates, which are separated from the liquid fraction, and which liquid fraction is returned at least partially to the reactor substantially devoid of carbonates and bicarbonates.