This is the simplest and oldest form of algae farming. Open Ponds are large, shallow basins filled with microalgae and nutrient-rich water. Sunlight provides the energy for photosynthesis, and the ponds are usually mixed to keep the microalgae suspended in the water.

The construction and operating costs of the Open Pond systems are relatively low, which enables cost-effective production on a large scale. They also use natural sunlight, which reduces energy costs.

The open nature of these systems makes them vulnerable to contamination by competing algal species, pests and pathogens. In addition, environmental parameters such as temperature, light and nutrient concentration are difficult to control, which can affect the growth and productivity of the algae. Evaporation and the resulting high water consumption can also be a major problem in dry regions.

This is a variant of the Open Pond system with long, narrow channels in which microalgae circulate in a loop.

The basins are relatively inexpensive to build and operate. The circulation ensures that the algae are evenly supplied with sunlight and nutrients, which increases productivity compared to Open Ponds systems.

Similar to Open Ponds systems, Raceway Ponds are at risk of contamination and offer limited control over environmental parameters. They still require a lot of land area, a lot of water and are not suitable for growing algal strains that are sensitive to environmental changes.

Tubular photobioreactors consisting of transparent plastic or glass tubes. These are closed systems in which microalgae are cultivated. Nutrient-rich water is pumped through the tubes and sunlight or indoor lighting systems provide the energy for photosynthesis.

Tubular photobioreactors provide a controlled environment that reduces the risk of contamination. Compared to open systems, they can achieve high algal density and productivity. They also allow the cultivation of a variety of algal strains.

These systems involve higher investment and operating costs compared to open systems. The tubes can suffer from biofouling and overheating due to solar radiation. In addition, there are difficulties in cleaning the tubes and the risk of clogging. Last but not least, the light distribution can also be uneven, leading to suboptimal growing conditions.

These systems use flat, transparent plastic panels for algae culture. Nutrient-rich water flows through the panels, and sunlight or indoor lighting systems provide the energy for photosynthesis.

Flat-panel photobioreactors offer efficient light utilisation due to their large surface-to-volume ratio. They offer a high degree of control over cultivation parameters and have a lower risk of contamination.

Despite their advantages, these systems can be more expensive to build and operate. They can also face problems with temperature control and biofouling.

These systems are a variant of the flat-panel design and use airlift technology to circulate the culture medium.

In addition to the benefits offered by standard flat panel photobioreactors, the airlift mechanism promotes a homogeneous cultivation environment, increasing growth rates and biomass yield. It also improves the efficiency of gas transfer, resulting in higher photosynthetic efficiency, without the stressful shear effects of mechanical systems on the algae.

These systems are complex and can be more costly to set up and maintain. However, their high productivity and efficiency often justify the initial investment.

In these closed systems, algae are grown in vertical or horizontal columns. The air bubbles supply oxygen and mix the microalgae, while light is supplied from the top of the column.

Column photobioreactors provide a controlled environment and can achieve satisfactory algal densities. They are also more efficient in terms of space utilisation compared to open systems.

Building and operating these systems can be expensive. High energy consumption and the difficulty of controlling the size of the air bubbles are among the problems with this technology. They also have problems with uneven light distribution, similar to tubular photobioreactors.

These systems use large, transparent plastic bags filled with the culture medium.

Bag photobioreactors are relatively inexpensive and easy to set up. They offer a satisfactory surface-to-volume ratio, allowing reasonably satisfactory light penetration. They also provide a controlled environment that reduces the risk of contamination.

While these systems are cost effective, they can have durability issues due to the risk of leaks and cracks. There is also no uniform penetration of CO2 and control of culture parameters such as temperature and pH can be more challenging compared to other closed systems.