Like plants, algae use the sunlight for the process of photosynthesis. Photosynthesis is an important biochemical process in which plants, algae, and some bacteria convert the energy of sunlight to chemical energy. Algae capture light energy through photosynthesis and convert inorganic substances into simple sugars using the captured energy.
There are two main methods of cultivation
- Ponds
- Photobioreactors
Ponds
Since algae need sunlight, carbon-di-oxide and water for their growth, they can be cultivated in open ponds & lakes. More about open ponds are discussed here - Cultivation in open pond
Photobioreactors
A Photobioreactor is a controlled system that incorporates some type of light source. The term photobioreactor is more commonly used to define a closed system, as opposed to an open pond. A pond covered with a greenhouse could also be considered an unsophisticated form of photobioreactor. Because these systems are closed, everything that the algae need to grow, (carbon dioxide, water and light) need to be introduced into the system. More about photobioreactors are discussed here - Cultivation in photobioreactors
There are several factors to determine the growth rate of algae. The following are the important factors that determine the growth rate of algae
- Light - Light is needed for the photosynthesis process
- Temperature: There is an ideal temperature range that is required for algae to grow
- Medium/Nutrients - Composition of the water is an important consideration (including salinity)
- pH - Algae typically need a pH between 7 and 9 to have an optimum growth rate
- Algae Type - Different types of algae have different growth rates
- Aeration - The algae need to have contact with air, for its CO2 requirements
- Mixing - Mixing prevents sedimentation of algae and makes sure all cells are equally exposed to light
- Photoperiod: Light & dark cycles
A Generalized Set of Conditions for Culturing Micro-Algae
| Parameters | Range | Optima |
| Temperature (°C) | 16-27 | 18-24 |
| Salinity (g.l-1) | 12-40 | 20-24 |
| Light intensity (lux) | 1,000-10,000 (depends on volume and density) | 2,500-5,000 |
| Photoperiod (light: dark, hours) | 16:8 (minimum) 24:0 (maximum) | |
| pH | 7-9 | 8.2-8.7 |
Source: http://www.fao.org/docrep/003/w3732e/w3732e06.htm
Algae cultivation can be done in a variety of environments. Algae cultivation in various environments are discussed in the following pages.






