Why microalgal biofuel is (potentially) the most impactful energy technology you’ve never heard of
author's footnotes
1 Welcome to the footnotes! I enjoy using footnotes to communicate further/clarify certain thoughts that run through my mind whilst I write, so this is usually where you’ll find the goodies. My third year literature review was on the engineering of microalgae for biofuel specific applications, so ask me more! Find me at alexander_khor@hotmail.com!
2 This estimation is probably wrong, depending on who you ask. This is because the term ‘microalgae’ is largely a blanket word used to describe a vast network of photosynthetic eukaryotic organisms, meaning that the classification of the group is often grey at best.
3 An engineering term adopted by biologists to explain the notion of a general platform on which various types of additions/changes may be made to produce different biomolecules, as in chassis of an automobile.
4 Hydrogen production is also an emerging energy application, but let’s just stick to liquid fuels here.
5 Whilst bio-ethanols aren’t strictly produced this way (they’re usually produced from residual biomass), I’m happy to concede some scientific accuracy for the sake of simplicity. Learn more about fuel generation from microalgae here:
https://www.frontiersin.org/articles/10.3389/fbioe.2014.00090/full
6 By this, I intend to mean the increasing ease and robustness by which we are able to engineer organisms. In microalgae specifically, the rise of computational and ‘omics’ strategies have greatly accelerated the field by increasing our knowledge of complex metabolic pathways, and subsequently informing target selection. CRISPR enables more specific/direct alterations. Read more about microalgae engineering tech here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6026345/
7 Note ‘conceptually’, there are still MANY difficulties associated with designing organisms this way. Where exactly the limitation lies is up for debate. Recent reports using CRISPR has enabled the transgene expression of external genes into C. reinhardtii. See more in reference 5.
8 As you may know, there are other sources of biofuels. A large percentage of the biofuel that is currently on the market is produced by sugar/lignocellulose based crops such as maize and oil palm. They have been shown to be much less productive than even the lowest oil content microalgae.
9 First generation being sugar based crops, and second generation being lignocellulose based crops. Both of which were deemed to be energetically non-feasible.
Exxon Mobil recently reported a goal to produce 10,000 barrels per day by 2025: https://corporate.exxonmobil.com/researchand-innovation/advanced-biofuels/advanced-biofuels-and-algae-research#biofuelsResearchPortfolio).
11 British Algoil is funded by the UK government and has largely been a failure. The Bill and Melinda Gates Foundation is partnered with Sapphire Energy.
12 Dewatering is the process of removing water from the microalgal biomass. This usually requires multiple processes, most commonly repeated sedimentation and centrifugation.
13 Though this is a slightly dated estimation, recent estimations have not changed much.
14 Different types of fuel will naturally have a variable energy content, but biodiesel is currently the highest density hydrocarbon that we can produce — so most calculations are based on this.
15 Compounds such as astaxanthin and collagen fetch high prices from the pharmaceutical/cosmetic companies. Consider this: a biomolecule such as astaxanthin could demand up to $100 per kg vs. biofuels, which need to compete with oil prices of $0.45 USD per litre.
16 There are also worries about Algenol’s strain of GE (genetically engineered) cyanobacteria and the threat they may pose should they be released into the wild.
17 Famously, the commercialisation of these in 2014 saw the reintroduction of blue M and M’s, which were previously removed from their product line up because of food safety concerns.