Repetitive non-destructive milking of hydrocarbons from Botryococcus braunii

Global warming, the diminishing availability of fossil fuels and increasing expectations of quality of life are driving the move towards renewable fuel sources. The production of biofuel from Botryococcus braunii is a high potential carbon neutral resource which has recently gained increased interest. Botryococcus braunii stores hydrocarbons within a lipid based extracellular matrix (ECM), allowing the continuous non-destructive extraction (milking) of these hydrocarbons without the compromisation of cellular integrity. This provides an alternate pathway to biofuels, with significantly reduced nutrient and energy requirements. The aim of this review is to utilise the current literature on B. braunii and available solvent extraction technologies to make informed recommendations on the required course of action for furthering this source of renewable energy. Solvent extraction with hexane, through a sieve plate column, was found to be the most suited method for repetitive non-destructive hydrocarbon extraction (milking). This method can provide high extraction efficiencies, a simple downstream separation process, relatively low cost, low shear stress and offers the added option of pulsing for further improvement on mass transfer. Considering, this concept is still relatively new to literature, areas such as; race selection, milking frequency/period, hydrocarbon recovery period, extraction system design and nutrient supplementation are still in the early stages of development, leaving much room for improvement. As progression is made in these fields and more data becomes available, a detailed feasibility study for non-destructive solvent extraction from B. braunii can be carried out, demonstrating the potential of B. braunii as a sustainable source of biofuel