Recovery Act – Integrated Pilot-Scale Biorefinery for Producing Ethanol from Hybrid Algae

Biomass and pigment production for Arthrospira platensis via semi‐continuous cultivation in photobioreactors: Temperature effects

“…A representative model parameter set for the productivity model is derived from the PE data sets with [, E k , R 0 ] = [0.061 fixed C/photon, 240 µE·m −2 ·s −1 , 0.1 µmol C·mg Chl.a −1 ·min −1 ] at 30°C providing a reasonable representation of the entire database. The R 0 value at the reference 30°C temperature was taken as 0.1 µmol C·mg Chl.a −1 ·min −1 consistent with conclusions for maintenance respiration from outdoor experiments on a carbon basis (Chance & Roessler, 2019; Legere et al, 2017) and recognizing that R 0 ′ determinations from PE curves will show an irradiance‐related enhancement (Falkowski & Raven, 2007) that is quite complicated, in that it depends on sample history (Torzillo & Vonshak, 1994). To model temperature effects, E k is set as a function of temperature (activation energy 60 kJ/mol), and the maintenance respiration rate ( R 0 ) was modeled as a function of temperature (activation energy as 27 kJ/mol), with the activation energy estimates being consistent with previous studies (Legere et al, 2017) and a bit lower than that found by Torzillo and Vonshak (1994).…”

“…The choice of 230 µE·m −2 ·s −1 was based on the average annual irradiance at the exposed culture surfaces of PBR arrays in Fort Myers, Florida with a height‐to‐spacing ratio chosen to maximize productivity (Legere et al, 2017). To convert the quoted biomass productivities from g·L −1 ·d −1 to g·m −2 ·d −1 , multiply by a geometric factor of 95 L/m 2 .…”

“…The Algenol Productivity Model (Chance & Roessler, 2019; Legere et al, 2017) is used to analyze these indoor PBR experiment results, and determine if a set of photosynthetic parameters can be developed to adequately represent all experimental results—in the process confirming the quantitative relevance of the lab scale results to outdoor performance. A representative model parameter set for the productivity model is derived from the PE data sets with [, E k , R 0 ] = [0.061 fixed C/photon, 240 µE·m −2 ·s −1 , 0.1 µmol C·mg Chl.a −1 ·min −1 ] at 30°C providing a reasonable representation of the entire database.…”

“…The oxygen PE (O 2 production [P] vs. irradiance [E]) curves were determined in Algenol's custom‐designed system. The system comprises a white light light‐emitting diode source, photosynthetically active radiation (PAR) light sensor, and an O 2 sensor, all in a temperature‐controlled cassette (Legere et al, 2017). The optical path length, d , is 1 cm.…”

“…Productivity modeling is included here to help understand the general phenomena observed, and confirm relevance of the results to outdoor performance for both PBR and open‐pond cultivations (see Supporting Information Material). Ethanol productivity from genetically modified cyanobacteria has been successfully modeled by Algenol using a Monod modeling approach (Legere et al, 2017). The Algenol Productivity Model has been adapted for biomass‐only production and used in conjunction with PE‐derived photosynthetic parameters to estimate expected outdoor productivities for PBR deployments in Fort Myers (and elsewhere around the world).…”