Polyhydroxyalkanoates are synthesized by microorganisms, similar to synthetic polymers, and completely biodegradable. Polyhydroxyalkanoates or PHAs can be processed in a similar way to synthetic polymers and are considered substitutes for petroleum-based plastics. In the culture media, bacteria and large amounts of organic carbon sources are responsible for 50% of the total cost of production of commercial PHAs. It is only possible for the PHA to have a greater commercial application in a reduction in the cost of production. The potential for microalgae to provide PHAs at a lower cost has been suggested by several studies, they require relatively little nutrients as well as deriving energy from light and CO2, i.e., being photoautotrophs. The purpose of this paper is to examine biopolymer composition and properties, to determine whether petroleum-based plastics can be replaced by PHAs. Microalgal studies that stimulate PHA synthesis are still in the early stages. However, it remains evidentthat microalgae are capable of producing biopolymers at a low cost and can be used to contribute to the environment.