Heterotrophic vs autotrophic production of microalgae: Bringing some light into the everlasting cost controversy

Heterotrophic or autotrophic? This is the continuous question the industry faces when microalgae production is the endeavor. Surprisingly, nowadays specialists have not reached a consensus on which is the most economical option. The current work analyses costs for heterotrophic and autotrophic cultivation of microalgae at an industrial scale. Heterotrophic cultivation of microalgae results in a production cost of 4.00 €·kg⁻¹ of dry weight as a centrifuged paste. This is within the range of autotrophic costs, but still above the production cost in some photobioreactors. The study also identifies the current limitations on the technology and studies the effect on the cost of overcoming these. Once achieved, the advances in the process could result in a heterotrophic production cost reduced to 1.08 €·kg⁻¹. Autotrophic cultivation seems competitive with heterotrophic production. It is time to leap forward in the autotrophic production scale to achieve the critical reduction in production cost.