Research into algae for the mass-production of oil focuses mainly on microalgae (organisms capable of photosynthesis that are less than 0.4 mm in diameter, including the diatoms and cyanobacteria) as opposed to macroalgae, such as seaweed. The preference for microalgae has come about due largely to their less complex structure, fast growth rates, and high oil-content (for some species). However, some research is being done into using seaweeds for biofuels, probably due to the high availability of this resource.
 researchers across various locations worldwide have started investigating the following species for their suitability as a mass oil-producers:
* Botryococcus braunii
* Chlorella
* Dunaliella tertiolecta
* Gracilaria
* Pleurochrysis carterae (also called CCMP647).
* Sargassum, with 10 times the output volume of Gracilaria.
The amount of oil each strain of algae produces varies widely. Note the following microalgae and their various oil yields:
*Ankistrodesmus TR-87: 28–40% dry weight
*Botryococcus braunii: 29–75% dw
*Chlorella sp.: 29%dw
*Chlorella protothecoides(autotrophic/heterotrophic): 15–55% dw
*Crypthecodinium cohnii: 20%dw
*Cyclotella DI- 35: 42%dw
*Dunaliella tertiolecta : 36–42%dw
*Hantzschia DI-160: 66%dw
*Nannochloris: 31(6–63)%dw
*Nannochloropsis : 46(31–68)%dw
** Nannochloropsis and biofuels
*Neochloris oleoabundans: 35–54%dw
*Nitzschia TR-114: 28–50%dw
*Phaeodactylum tricornutum: 31%dw
*Scenedesmus TR-84: 45%dw
*Schizochytrium 50–77%dw
*Stichococcus: 33(9–59)%dw
*Tetraselmis suecica: 15–32%dw
*Thalassiosira pseudonana: (21–31)%dw
In addition, due to its high growth-rate, Ulva has been investigated as a fuel for use in the SOFT cycle, (SOFT stands for Solar Oxygen Fuel Turbine), a closed-cycle power-generation system suitable for use in arid, subtropical regions.
Other species used include Clostridium saccharoperbutylacetonicum, Sargassum, Gracilaria, Prymnesium parvum, and Euglena gracilis.