Recently, biomass has attracted much attention as a renewable energy resource. Microalgae are particularly promising biomass species because of the high growth rate and high CO₂ fixation ability compared to plants. Effective liquid fuel production from microalgae was studied using Botryococcus braunii and Dunaliella tertiolecta, which accumulated terpenoid hydrocarbon and glycerol, respectively. B. braunii could remove nitrogen and phosphorus from secondarily treated sewage (STS) in a batch system and a continuous bioreactor system with hydrocarbon production. The intracellular glycerol content could be controlled by post-translational modifications in D. tertiolecta. B. braunii is more profitable for liquid fuel production than D. tertiolecta based on calculating the energy balance.