Cultivation of Botryococcus Braunii for the Production of Hydrocarbons Suitable for Fuel Use

Author

Bryan C. Carroll, Clemson UniversityFollow

Date of Award

8-2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Engineering and Earth Science

Committee Chair/Advisor

Caye Drapcho

Committee Member

Elizabeth Melvin

Committee Member

Tom Owino

Abstract

Energy security, rural poverty, and climate change are pressing issues of our time. Biofuels provide a solution to these issues, with a focus on sustainable aviation fuel, SAF, due to compatibility with aircraft infrastructure and energy density. This research aims to review and produce knowledge about a specific microalga, Botryococcus braunii, for its potential for SAF. First a literature review on the process was conducted followed by an experimental study on the impact of aqueous media and inorganic carbon its growth and hydrocarbon content. The literature review found the process consists of cultivation followed by lipid extraction or hydrothermal liquefaction followed by catalytic upgrading to SAF. Certain bifunctional transition metal catalysts with clay supports may be best for production of SAF from B. braunii. Gaps with this pathway may be specific to kinetic parameters and specific design of reactors optimized for production. Current research should be dedicated to mechanisms of conversion of B. braunii to SAF with respect to reactor design, harvesting, lipid extraction, feasibility, cost, and implementation of policy along with other pathways to ensure avoidance of emissions and depletion of resources.

The Showa strain of Botyrococcus braunii was cultivated in batch conditions with artificial lighting in modified versions of BG-11 and MChu13 media. BG-11 medium contains approximately 10 times the nitrogen concentration of MChu13 medium and has 2.3 mg/L added inorganic carbon while MChu13 has none. In the first experiment, the specific growth rates for cultivation in BG-11 LN, BG-11, MChu13, and MChu13-HN were 0.30, 0.23, 0.56, and 0.78 d^-1 respectively during exponential growth. In the second experiment an agar isolate derived culture was used as a seed for cultivation in MChu13-HN media with varying inorganic carbon levels supplied as NaHCO₃, at 0, 10, 20, and 40 times the inorganic carbon level specified in BG-11 media which are 0, 22.7, 45.4, and 90.7 mg C/L. This cultivation was carried out for 21 days and found 2 subsequent exponential phases, with the first fitting Monod model with inorganic carbon by nonlinear regression in JMP, with a maximum specific growth rate, µ_max of 1.09 d^-1 (with a standard error of 0.30 d^-1), and a half-saturation constant, K_s, of 38.7 mg C/L (with a standard error of 27.3 mg C/L). Squalene content was found to range from 1.9% for the 20XC treatment to 10.6% for the 10XC treatment.

Recommended Citation

Carroll, Bryan C., "Cultivation of Botryococcus Braunii for the Production of Hydrocarbons Suitable for Fuel Use" (2025). All Theses. 4587.
https://open.clemson.edu/all_theses/4587