What this work is about, in plain words
A theoretical estimate of the limiting productivity of open-air microalgae near Isfahan (Iran): how much biomass sunlight can give at different photosynthetic efficiencies.
Sunlight is a free source of energy for growing algae, but its amount is limited and changes from day to day and season to season. The authors set out to estimate theoretically the largest microalgae yield that can be obtained in the open air near Isfahan.
The calculation rests on simple assumptions: the daily distribution of solar radiation at the Earth's surface, the average calorific value of a gram of dry biomass, and different photosynthetic efficiencies. Different orientations of the installation relative to the sun were considered, including a rotating one that tracks the sun.
By the authors' calculation, at a photosynthetic efficiency of 5 % the limit is about 38 g of dry biomass per square meter per day, and at 15 % about 114 g. If a curve is drawn through the spring and autumn equinoxes and the summer solstice, the limiting yield for this period at 15 % efficiency is about 18.5 kg per square meter.
The estimate is useful when choosing a site and type of installation for growing algae under sunlight.
Limitations. This is an ideal calculated limit, not the yield of a real installation. In content, the work is close to a Russian-language article by the same authors in Biotechnologia Acta (2014).