Extraction of Valuable Oils from Algae and other Green Plants: Challenges, Opportunities and Commercial Landscape
By Brian Goodall, PhD; First Garden City Consulting, Member Lee Enterprises Consulting
Special to The Digest
This is the first in a 8-part series of articles — the State of the Advanced Bioeconomy 2018 — more on the complete series here.
Extracting vegetable oils is both an art and a science, with some being practiced commercially on huge scale (e.g. canola oil, soy oil, corn oil) while others are specialty oils extracted on a much smaller scale (e.g. almond, flax, grapeseed, essential oils). In many cases these oils contain low levels of both chlorophyll (which must be removed with bleaching clay or similar color removal technology) and waxes (which are removed by degumming technologies) to give the light colored, low viscosity oils demanded by the customer. The four refining process steps are degumming, neutralizing, bleaching and deodorizing and there are two types of refining processes: chemical and physical. The main difference between the two types of refining processes lies in how the low levels of free fatty acids (FFA) are removed (Chemical refining removes the FFA via neutralization whilst physical refining removes the FFA in the deodorizing step (steam stripping)).
However, unlike these huge vegetable oil processes where the oil is extracted from beans or seeds (Mother Nature’s storage devices for the fats and oils) in 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. If the microalgae is grown by fermentation, using sugars and the like (in the dark) then the resulting oil extracted is golden in color rather like canola oil.
When microalgae is grown the way that Mother Nature intended in sunlight then they represent the most efficient photosynthetic machines on Planet Earth – hence the process of extracting the lipids desired for conversion to fuels, or for formulation into nutraceuticals etc., – also extracts enormous levels of chlorophyll and other undesirable components. 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. The level of viscosity of the product depends largely on the choice of algae strain and solvent chosen for the extraction (examples and pictures will be given).
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. These new products and formulations are starting to emerge at medical marijuana dispensaries in many of the states where it has been legalized.
In the US cannabis is considered by the DEA to be a Schedule I drug (defined as “drugs with no currently accepted medical use and a high potential of abuse” – and on the dea.gov website cannabis is listed third after heroin and LSD. It has been repeatedly argued that alcohol and tobacco (nicotine) fit comfortably into this category but medical uses of cannabis go back not decades, not centuries but millennia in China and Ancient Egypt for example. In the 19th century Queen Victoria was prescribed cannabis for menstrual pain and from 1850 until 1937 cannabis was considered the medicine of choice for in excess of 100 different illnesses and diseases in the U.S. Pharmacopoeia, and sold and distributed by companies including Lilly. Advances in the field of medical applications of cannabis in the USA were halted by the Marijuana Tax Act of 1937 which effectively banned its use and sales.
Despite this history and legal challenges there are hundreds if not thousands of patents and patent applications describing the medical applications of cannabis and cannabis extracts (the authors are not aware of any patents on the medical applications of ethanol).
Surely it is just a matter of time before new therapeutic products start appearing at your nearby pharmacy or Walmart for pain management, face and body creams, weight-loss products, asthma, nausea and more And how long before Big Pharma makes their Big Entry for the foregoing, as non-addictive alternates to opioids, cancer treatment, glaucoma and so much more Will the US end up benefitting fiscally from this massive new opportunity – or will the industry continue to be led by major players outside of the US, for example GW Pharmaceuticals (in the UK) or Aurora Cannabis (in Canada) both having market caps in excess of $3 billion (January 2018).
About the Author: Dr. Brian Goodall, First Garden City Consulting, is a member of Lee Enterprises Consulting, the world’s premier bioeconomy consulting group, with more than 100 consultants and experts worldwide who collaborate on interdisciplinary projects, including the types discussed in this article. The opinions expressed herein are those of the author and do not necessarily express the views of Lee Enterprises Consulting. Brian will be a guest speaker at the ABLC 2018 Conference commencing on February 28, 2018.
The next article in this series is John Forcier’s Case Study: 1MW to 3MW Anaerobic Digester Upgrade in Only 6 Months!