A number of other initiatives and researches all over the world have been focusing on the use of open systems for biofuel production from micro-algae that require extensive areas. During the last years, various enterprises and research centres are focusing on the industrial production of compact system to produce biodiesel from micro-algae using innovative photobioreactors.

Closed systems are much more expensive than ponds, and present significant operating challenges (overheating, fouling), and due to gas exchange limitations, among others, cannot be scaled-up much beyond about a hundred square meters for an individual growth unit.