Tubular Photobioreactors

Tubular Photobioreactors are one of the most used technologies for microalgae production in closed systems.

  • Ideal for the production of high-value and high-quality products and the production of strains that require a strict control of temperature, or that produce volatile compounds.
  • The tubes arrangement versatility is an asset for optimal cost-effective production. For instance, it can be designed to act as a solar collector (Unilayer Horizontal Tubular PBR) or provide the highest amount of photosynthetic area using the minimum implantation surface (Multilayer Horizontal Tubular PBR).
  • A4F has a large experience optimizing this production technology, for different algae species, location, environmental characteristics and type of product / applications of our Customers.


  • Fluid flow dynamics: reduction of the reactor zero velocity areas/dead volumes.
  • Fluid flow dynamics: constant velocity along all the PBR piping extension (> 100 m long).
  • Optimized global mass and energy balance: O2, CO2, nutrients mixing, thermoregulation through internal coils.
  • Energetic optimization for cost-effective production: efficient circulation pumps.
  • Improved culture management via parameter control, analysis and fast response: adjust culture circulation velocity, pH, temperature.


  • This configuration comprises several layers of tubes disposed horizontally and parallel to the ground, which means that it has a higher volume to area ratio. This configuration is the most common in the microalgae sector, and has been used for several years in A4F. This configuration allows more flexibility to vary the ratio light/cell and decrease the photo-inhibition effect.
  • Ideal for applications with artificial illumination as only or additional energy source, since the area available for artificial light exposure is high, compared to an unilayer configuration.
  • Higher ratio volume/area
       o More flexibility to vary the ratio light/cell.
       o Temperature is more easily controlled, which might represent an advantage in extreme heat environments.
       o Degassing less critical =>higher volume for oxygen build-up



A PBR system developed as an optimization of the multilayer for most applications. Its special configuration comprises one sole layer of tubes disposed horizontally and parallel to the ground, which maximizes the available radiation per cell, enabling a very high photosynthetic efficiency; this configuration allows a maximization of the volumetric productivity and consequently higher culture concentrations and a more robust culture; another direct impact of its higher volumetric productivity is the decrease in harvesting costs due to the lower total volume of the culture

  • Ideal for cultures growing exclusively with solar radiation
  • Lower ratio volume/area
       o Lower amount of water and inorganic nutrients required =>reduction of CAPEX and OPEX
       o Higher concentration of the biomass => Better culture conditions and quality =>higher annual productivity