The answer to this question relies on several factors, including the type of pond you will be building and the type of algae you’d like to produce. Open systems—in other words, outdoor algae ponds without a cover—will rely on available natural sunlight, no extra lighting sources required.
If you’re building a closed system, however, you may need supplemental lighting. Most closed systems—bioreactors included—are built indoors so that you’ll have complete control over temperature, plus shelter and easy access for sensitive equipment. Indoor lighting, even through skylights and window walls, may not be quite enough to keep algae growing at the rates that you will need. This can be problematic if you’re building a bioreactor, as the energy usage for supplemental lighting can sometimes be greater than the energy that the reactor produces. While outdoor bioreactors aren’t common yet, most of these systems rely on as much solar energy as possible, minimizing costs for electricity. Most who build closed system algae ponds design their facilities to maximize natural sunlight usage as much as possible, only supplementing with artificial light sources when necessary.
