Although open systems have many advantages, they also have many problems in the mass cultivation of microalgae. Thus, closed systems have become the choice for biofuels production. The volumetric productivity in closed photobioreactors is more than 30 times higher than that in open pond raceways [62]. Owing to the higher mass productivity, harvesting costs can be significantly reduced. Numerous types of closed photobioreactors have been designed to best control the conditions in mass cultivation. These can be divided into three main categories: tubular, column, and flat plate photobioreactors. Table 2 lists some closed photobioreactors with solar and artificial radiation that have overcome some shortcomings in open photobioreactors. However, these closed photobioreactors are still not very suitable to use for mass cultivation and need more design work.