Extraction of Valuable Oils from Algae and other Green Plants: Challenges, Opportunities and Commercial Landscape

by Brian Goodall (First Garden City Consulting/Lee Enterprises Consulting/Biofuels Digest) ... (I)n the case of microalgae the oil has to coaxed out of the whole plant (typically single cells) using chemical or physical means to break open the cells and expose the contents to solvent extraction.

Indeed, with very few exceptions, the “oil” extracted from photosynthetic algae ranges from black tar-like viscous materials to black solids once all the extraction solvent has been removed.

Some other oils from green plants such as cannabis and hemp oils are likewise not extracted from a bean or seed but from the entire plant (either the buds, the leaves or “trim” or the whole plant itself) and consequently the levels of chlorophyll and related color bodies are orders of magnitude higher than canola or soybean oils.

In this regard cannabis and hemp resemble photosynthetic (autotrophic) algae, and both families deliver viscous black crude oils which have proven extremely difficult (and in some cases impossible) to efficiently obtain as light colored, low viscosity oils in many cases. Unlike algae, which often require energy intensive cell lysis to open the cells and free the oil, the oil in hemp and cannabis is trivial to extract since the oil resides on the surface of the plant (including the leaves or trim) in the form of trichomes. Simply immersing the plant, bud or leaves (even with short residence times and at low temperatures) in a variety of solvents (e.g. hexane, ethanol, acetone) results in fairly efficient extraction and recovery of the oil. The challenges come in the downstream refining of the crude oil – distillation is expensive, time consuming and causes substantial loss of the desired components (as much as 20%), and can cause partial or even total degradation of some.

There are much more viable technologies (originating from the algae world) in existence that enable the desired end result (in algae, hemp, cannabis and likely all similar oils), the commercialization of which is in the early stages of development and commercialization. READ MORE