Theoretical investigation of biomass productivities achievable in solar rectangular photobioreactors for the cyanobacterium Arthrospira platensis

Abstract

Modeling was done to simulate whole‐year running of solar rectangular photobioreactors (PBRs). Introducing the concept of ideal reactor, the maximal biomass productivity that could be achieved on Earth on nitrate as N‐source was calculated. Two additional factors were also analyzed with respect to dynamic calculations over the whole year: the effect of PBR location and the effects of given operating conditions on the resulting decrease in productivity compared with the ideal one. Simulations were conducted for the cyanobacterium Arthospira platensis, giving an ideal productivity (upper limit) in the range 55–60 tX ha−1 year−1 for a sun tracking system (and around 35–40 tX ha−1 year−1 for a fixed horizontal PBR). For an implantation in France (Nantes, west coast), the modification in irradiation conditions resulted in a decrease in biomass productivity of 40%. Various parameters were investigated, with special emphasis on the influence of the incident angle of solar illumination on resulting productivities, affecting both light capture and light transfer inside the bulk culture. It was also found that with appropriate optimization of the residence time as permitted by the model, productivities close to maximal could be achieved for a given location. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012

Investigation and modeling of the effects of light spectrum and incident angle on the growth of Chlorella vulgaris in photobioreactors

“…All the PBRs used in this study present light attenuation along only one main direction (i.e., the depth of culture z ) so we can apply the two‐flux model already shown to be efficient in several studies . A complete description can be found in Pottier et al and in Pruvost et al The two‐flux model was expressed in this study as a function of the wavelength and the incident angle θ , to take into account the general case of oblique irradiation with any incident light spectrum. For all the PBRs and conditions tested, the irradiance field was then given by the general formula (collimated incident light): …”

How Mixing and Light Heterogeneity Impact the Overall Growth Rate in Photobioreactors

“…Absorption (Beer‐Lambert), scattering phase function (Henyey‐Greenstein) , reflection on surfaces (Fresnel), and refraction (Descartes) through the transparent walls of the PBR were taken into account in a MATLAB 2016a homemade code. The absorption and scattering coefficients of Spirulina are given by Pruvost , E a =162 m 2 kg −1 and E s = 640 m 2 kg −1 . The anisotropy of the scattering phase function is taken from Dauchet , g = 0.97.…”

Site selection for microalgae farming on an industrial scale in Chile

“…On a lineal projection, considering the conservative surface biodiesel productivity rate of 15 m 3 /ha/year of a mixed microalgae farming plant (hybrid system, PBR as inoculum for RWP) [8,[23][24][25], discussed in the Introduction, the potential 103,600 ha identified (see Table 3) could produce 1,554,000 m 3 /year of biodiesel. With this volumetric flux it would be possible to replace 17.14% of the annual Chilean diesel consumption and reduce energy imports by 5% [2].…”

“…For the use of RWP, extensive land surfaces are required that comply with numerous environmental standards and design constraints, in order to optimize industrial production. For a microalgae farm of regular conditions, capable of yielding 15 m 3 /ha/year of biodiesel [8,[23][24][25], the necessary surface areas required that have been documented [26] are listed in Table 1.…”