Carbon Capture is fine on paper. But it needs Microalgae to become truly great.
We can produce actually valuable chemicals from CO2, instead of just storing it in the ground. Why aren't we doing that?
Living things that photosynthesize remove excess carbon dioxide from the atmosphere (i.e. atmospheric carbon), but it isn’t very efficient.
So naturally we ask, could engineered biology - specifically engineered microalgae - be harnessed to remove atmospheric carbon more efficiently and create high-value products/profitable businesses at the same time? Through engineering their capacity to remove carbon dioxide (CO2) and create value-added products at the same time, microalgae might prove both an efficient and profitable method to combat climate challenges.
As a brief to get everyone up to speed; microalgae are single-celled microorganisms that photosynthesis to get energy like plants. They’re also incredibly genetically diverse, with species living in extreme conditions like snowbanks.
(Note: you might have also seen the terms red, green, & brown algae, which refer to more complex single & multicellular algae species that we’re not going to cover here).
Many microalgal species naturally use CO2 as part of photosynthesis - using light & CO2 to create energy. Compared to Escherichia coli & other autotrophic bacteria which grow on expensive sugar-rich media, the ability to photosynthesize is a major advantage for biomanufacturing - as less inputs are needed for growth. Microalgae can also be used for remediating some heavy metals.
Microalgae-derived products & applications include beauty product ingredients, cooking oil, protein, biofuels - and even biocement(!). Notable members of the family already in use are Spirulina and coccolithophores; tiny microalgae that create limestone shells around themselves and are used in chalk today! In fact, some believe future cities may be built with limestone grown from coccolithophores.
What are some pros and cons then to engineered microalgae over other options like plants? Seeing as we already have enormous amounts of the global bioeconomy dedicated to agriculture; swapping to microalgae would represent a significant upheaval. From a high-level overview:
Pros:
Microalgae are more efficient photosynthetically than plants.
Microalgae convert around 10~20% of the solar energy they receive into biomass, in comparison to the paltry average 2~3% for plants.
They grow rapidly!
Just these two points alone are enough to consider microalgae as a viable alternative to agricultural-based biomanufacturing - and don’t even account for the added facts that microalgae can be more readily engineered to produce commodity products and value-added chemicals, as well as help with heavy metal remediation. Yet there are major considerations & challenges to overcome:
Scale up cost; potentially resource intensive.
Profitability - potential high-cost facilities & production systems.
Less engineering tools and knowledge compared to other organisms.
Plants have been the subject of decades, centuries even, of molecular biological research. Microalgae in contrast are much newer to the scene.
Microalgae facilities also need a system not open to the environment - i.e. the system must be entirely closed off to both prevent cells escaping into surrounding areas (which would be classed as a biological hazard), as well as prevent invasive organisms from coming in and infecting the biocontainer. Plants, on the other hand, are generally more robust, and can be grown in fields without specialized containerization.
Profitability has also been a concern for commercial adoption. With the right products, however, the balance of these scales could tip. Nathan Paumier, in his article on circular biomanufacturing with a case study on the fall of algal biofuels, mentions:
“[Algal biofuels] relied on turning 80% of the biomass into commodity products to drive 80% of the revenue. The nascent technology couldn’t compete with fossil fuels receiving trillions in subsidies.”
When phrased simply like this, it becomes obvious why previous attempts to commercializing algae and build companies around the technology struggled and ultimately failed. Following this, he proposes a different angle in regard to commoditizing the biochemicals we can produce with algae:
“The business model ignored the presence of high-value compounds like antioxidants, carotenoids, and other nutraceuticals in microalgae – some of which can fetch price points above $1,000/kg. In an integrated biorefinery model, 10% of the biomass could generate 90% of the revenue, which could then fund the transformation of the rest into biofuels.”
By incorporating a system that produces commodity & valuable products at the same time engineered microalgae farming may, eventually, be made profitable.
Microalgae may not be a great solution for CO2 removal right now, but enhancing its capabilities through engineering may lead it to become an efficient and profitable option. Perhaps, one day, like NASA suggests, microalgae may even be used off-planet, converting CO2 into nutrients in one of the most remote locations known to man - space.
References:
He Dahai, Yin Zhihong, Qin Lin, Li Yuhong, Tian Lei, Li Jiang, Zhu Liandong, The application of magical microalgae in carbon sequestration and emission reduction: Removal mechanisms and potential analysis, Renewable and Sustainable Energy Reviews, Volume 197, 2024, 114417, ISSN 1364-0321, https://doi.org/10.1016/j.rser.2024.114417.
Emerging Trends in Genetic Engineering of Microalgae for Commercial Applications - PMC (nih.gov)
Grama, S. B., Liu, Z., & Li, J. (2022). Emerging Trends in Genetic Engineering of Microalgae for Commercial Applications. Marine drugs, 20(5), 285. https://doi.org/10.3390/md20050285
Microalgae: A Promising Source of Valuable Bioproducts - PMC (nih.gov)
Dolganyuk, V., Belova, D., Babich, O., Prosekov, A., Ivanova, S., Katserov, D., Patyukov, N., & Sukhikh, S. (2020). Microalgae: A Promising Source of Valuable Bioproducts. Biomolecules, 10(8), 1153. https://doi.org/10.3390/biom10081153