iGEM SORBONNE

As suggested by Alex Pudney, CSO of Algenuity, we also tried to estimate the costs of growing Chlamydomonas reinhardtii, by developing a techno-economic model of our business and going further with our Implementation of FITI.

We found a very pertinent article describing the costs of growing C.reinhardtii for renewable diesel production through hydrothermal liquefaction and pyrolysis [1]. The article starts by describing Chlamydomonas culture at a large scale, in raceways, and harvested by coagulation-flocculation-decantation. This would be a more cost-effective solution, but closed systems, while being variable in design, provide a more productive environment while protecting the culture from contamination.

Another paper [2] describes the culture of Chlamydomonas in bioreactors, using TAP media. It was shown that cell growth reaches a maximal concentration of 1.8E7 cells/mL, with a doubling time of 9.35 hours. The lag phase lasted for around 2 days, before the exponential growth phase, which lasted 4 days and saw the culture reach its maximum concentration in cells. After thirty days of culture, the cells reach a concentration of 1.2E7 to 1.4E7 cells/mL, but are depleted in thylakoid membranes and enriched in both starch granules and lipid bodies. This might have positive effects on nutritional value, without increasing medium costs, but will decrease turnover by increasing culture and labor costs.

Another paper |4] showed that using mixotrophic batch culture for 168 hours, an average biomass productivity of 181.01 mg/L/h was attainable, a 10-fold increase in comparison to traditional batch cultures. Cultures were started using 800mL of a modified TAP medium, whose costs can be assimilated to those of normal TAP media. TAP was found available for as little as 1 dollar per liter, and could be sterilized at the production facility. The feed used was 80 times more concentrated than the modified TAP medium, so based on that its cost could be estimated at 80 dollars per liter. Costs could most likely be reduced even further by bulk ordering and in-house media optimisation and mixing. Little information is available on personnel and photobioreactor upkeep costs, and companies tend to keep their costs by biomass under a tight lock. An article by PowerPlantCCS read in 2022 estimates costs for a 1 ton per day bioreactor using the microalgae Nannochloropsis, whose growth curves somewhat resemble those of Chlamydomonas reinhardtii [5], despite a much higher biomass productivity. A study sponsored by the National Renewable Energy Laboratory estimates minimum biomass selling price between 500 and 1800 $₂₀₁₄/ton_US AFDW depending on production method and infrastructure [6], representing media costs as only a tiny fraction of the costs, dwarfed by infrastructure upkeep, personnel costs, energy and plastics renewal.

Chinese Spirulina tablets sell for 0.25 €/kg, and powder can be purchased for as low as 0.14 €/kg. These prices, if the companies made no profit off their sales, would mean that the minimum biomass selling price in China could be estimated to 127.01 €₂₀₂₂/ton_US AFDW or 98.78 $₂₀₁₄/ton_US AFDW. It must be noted though that because Spirulina is grown in high-pH media, it suffers little to no competition from « classic » contaminations, allowing it to be cultivated in open air, or under sheds for human consumption. This is enough to explain the greatly reduced costs compared to the NREL’s study.

If we were to trust the NREL’s data on closed PBRs and use the Dongoutchi farm’s spirulina candy recipe, we could produce spirulina for 274 904 batches of candies for 625 to 2251 USD when accounting for inflation. When accounting for other materials, infrastructure and labor costs (little information was found concerning the production costs, we fictitiously outsourced production and packaging to Jiangsu Handian Biotechnology Co., Ltd.), we can produce a batch of candies for 63.1 US cents, or 1 kilogram of candies for 8.34 USD (table 1 and 2). For comparison, the cheapest price for standard gummy bears on American Amazon is 7.34 USD/kg.

Costs could be reduced by reducing content in lime juice and/or using artificial flavouring, as well as investing in factories after derisking and showing proof of market.

Table 1. Raw material price breakdown

Table 2. Production cost price breakdown (without shipping and marketing)

Figure 1. Diagram of FITI (From Idea To Innovation) thought process and techno-economic model price point

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Sources

Acronyms:NAWI: Nutritive Algae for World Improvement; GMO: Genetically Modified Organism; R&D: Research and Development; CSO: Chief Scientific Officer; TAP: Tris-Agar-Phosphate; AFDW: Ash Free Dry Weight; NREL: National Renewable Energy Laboratory; PBRs: Photobioreactors; USD: United States Dollars (2022);

1- Céline Hognon, Florian Delrue, Guillaume Boissonnet, Energetic and economic evaluation of Chlamydomonas reinhardtii hydrothermal liquefaction and pyrolysis through thermochemical models, Energy, 2015
2-Darwish, Randa. (2020). Chlamydomonas reinhardtii Is a Potential Food Supplement with the Capacity to Outperform Chlorella and Spirulina. Applied Sciences.
3-D1.2. COST AND ECONOMIC FEASIBILITY GUIDE FOR LARGE SCALE MICROALGAL BIOREFINERIES, Sabana Project Report, 2018,
4-Francis J. Fields, Joseph T. Ostrand, Stephen P. Mayfield, Fed-batch mixotrophic cultivation of Chlamydomonas reinhardtii for high-density cultures, Algal Research, 2018.
5-Ryu, A.J., Kang, N.K., Jeon, S. et al. Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production. Biotechnol Biofuels 13, 46 (2020). https://doi.org/10.1186/s13068-020-01681-4
6-Jennifer Clippinger and Ryan Davis, Techno-Economic Analysis for the Production of Algal Biomass via Closed Photobioreactors: Future Cost Potential Evaluated Across a Range of Cultivation System Designs, National Renewable Energy Laboratory, 2019