Over the last 10 years years we have shared the information on the figure to the left to algae companies who wanted to produce biofuels. Here it was explained that, even if Spirulina (Arthrospira, probably the cheapest algae to produce) accumulated lipids at 30% of dry weight (it does not), algae biofuel might cost a minimum of $17 per kg (they hired me anyway!). Thus, most algae products today are high value.
A paper published in 2011 (you can read it here) gave us a lot to think about. The author calculated that, under certain conditions, algal biomass gets produced for pennies per kg. Those conditions may not be what most of us envision when we think about algal biotechnology. However, if we consider low cost inputs perhaps we can approach the cost structure of green water.
Here we have shown that costs related to CO2 supply can be greatly reduced. Others have shown that it is possible to produce algal biomass on waste waters (e.g., back in the 1980's algae biomass was produced on farm animal waste at Oceanic Institute). Both of these strategies result in lowering the cost of algal biomass.
Maintaining a clean laboratory, seed cultures, inoculum train, scale-up, etc. may represent 10-30% of the total cost of algal biomass production. What if you did not need this whole infrastructure? By the way, this is one reason why Spirulina production is relatively inexpensive.
In 2015, while at Heliae, we proposed to test this approach. We inoculated 4 outdoor (uncovered) raceway ponds with a wild population of algae. The results (presented at ABO 2016) showed that the population that developed was able to produce biomass rich in lipids and protein continuously without the need for further inoculation. The cultures survived (and thrived) even during contamination events (rotifers, ciliates, amoebae, etc). As of this writing, June 2017, the four ponds are still running! Much cost has been saved by not having to maintain an inoculation train or carry out full culture harvests (including the necessary cleaning between runs).