So after determining that official Soylent would take, at a minimum, 1/5 of a football field to grow the macro-nutrients, I started looking at different yeast, bacteria, and algae as nutrient sources.
Vitamin B-12 is the hardest to get, in my estimation, since in the normal diet, it depends on meat from ruminants that get the bacteria from food on the ground. I dug in and found that you can grow cultures of bacteria, process and centrifuge the cultures, and extract pure vitamin b-12.
For protein, I found a nice study that goes through the entire process of grinding and centrifuging crushed dry algae in pure water to extract the protein. Chlorella is an excellent source of protein.
Scenedus Dimorphus is a single celled algae that can produce up to 50% of its weight as fat.
I’m using http://www.oilgae.com/algae/comp/comp.html as a basis for algae compositions.
It seems to me that you could grow the algae, dry and crush it, and then use different processing techniques to separate the desired macro-nutrients from the rest of the biomass. The lipid profiles of algaes are generally very good.
I would grow the algae in flat vertical tanks that had growlight LEDs on each side, with the appropriate spectrum to maximize production of the relevant macro-nutrient.
This paper shows chlorella’s growth rate to be 0.6g/L day , which I interpret as .6 grams per liter per day. Assuming an 80% efficiency for extraction of protein, and a need for roughly 90 grams of protein per day, 200 Liters of algae production space is required to grow sufficient amounts. This would be .2 cubic meters (1 liter = .001 cubic meters).
This would be 2 10 cm x 1m x 1m tanks … not very big. Manipulating the water chemistry and lighting spectrum could increase yield.
For lipids, assuming the protein extraction method destroys everything not-protein, then you’d need an additional 65 grams of oils. Chlorella could again be used, and with the same growth rate, with 12% biomass being oils and 80% extraction efficiency, you’d need 65/(.8*(.14*.6)) liters , or 968L, or .968 cubic meters. You could round it up to another 10 10cm x 1m x 1m tanks - so far, 12 of these tanks are needed.
For carbohydrates, under the same formula, 250g of carbs are needed per day. Around 20% of chlorella can be carbohydrates, so 250/(.8*(.2*.6)) liters , or 2605 liters. This could be rounded up to another 27 tanks, bringing us to 39 tanks in total. All in all, we’re looking at roughly 3.9 cubic meters of space to produce the entire range of macro-nutrients, assuming the extraction methods are exclusive to the macro-nutrient being extracted, and efficiency of extraction is 80%.
If all the nutrients could be extracted sequentially, then the carbohydrates would need the most space, or 2.7 cubic meters. If you increased the extraction efficiency to 95%, then you can reduce it further to 2.4 cubic meters.
I’m going to assume a need for 25 of these tanks to produce sufficient macro-nutrients for daily consumption of 1 individual. Assuming a drying, crushing, processing, centrifuge station, nicely manufactured, could take up an additional 1.5 cubic meters, we’re given a bioreactor that’s 4 cubic meters that can produce all the macro-nutrients needed for human nutrition. This is a heck of a lot smaller than 1/5th of a football field.
The extracts would need additional processing to convert the starches into maltodextrin, and to make the protein and oils more palatable. Nonetheless, I think this avenue of research is interesting. If efficiencies and yields could be substantially improved in a controlled environment, you could reduce the entire equation of macronutrient production to a matter of the cost of electricity and fertilizer.
Here’s where my math might be completely off the reservation: With 25 of these tanks each needing the equivalent of solar input, and solar LEDs offering up roughly the same energy to the algae at a target spectrum, you’ll need roughly .6kW/H each day, per panel. If you were doing this commercially, then your electricity cost would be around 12 cents per kW/H , so each tank would cost 7.2 cents. All of them together would come out to $1.80 a day.
I’m thinking this is probably off by an order of magnitude and that the actual cost would be 18 cents per day. I’ll look into correcting this.