What this work is about, in plain words
What is the highest productivity microalgae can give under sunlight and artificial light? The authors calculated the upper limit and named three parameters without which such an estimate cannot be made.
Artificial light makes it possible to control cultivation and biomass composition, but it is expensive. Sunlight is free, but its amount depends on latitude, season and weather. The authors set out to estimate the limiting productivity of microalgae with different light sources.
The calculation rests on three quantities: the share of light energy that cells convert into biomass (photosynthetic efficiency), the calorific value of the biomass, and the light conditions the cells are in.
By the authors' calculation, under sunlight at a photosynthetic efficiency of 11 % the limit is about 102 g of dry biomass per square meter per day for latitudes 30–40°. For the territory of Ukraine and Russia, the estimate was about 63 g. Under artificial light, productivity is determined by the power and spectrum of the sources and by how the light is delivered to the culture.
The work provides a guide for design: it shows what yield is achievable in principle and what it depends on.
Limitations. This is a calculation of the ideal upper limit. Real installations give less, and photosynthetic efficiency and the calorific value of biomass depend on the species and growth conditions.