There exists about 72,500 algal species in the world and approximately 33% of these algal species have been explored for different purposes to this day . Pakistan holds a distinctive geographical, geological and environmental position in its region which promotes biodiversity. Pakistan possess plentiful algal flora because of rich saline habitats and diverse water .
The first attempt to produce biodiesel from algal biomass in Pakistan was carried out by Khola et al., . He studied Cladophora sp. The study highlighted the biomass after oil extraction, pH and quantitative properties of obtained biodiesel. Khola compared the quality of biodiesel with Oedogonium
sp. and Spirogyra sp. . Obtained results indicated that Cladophora sp. produces more quantity of biodiesel as compared to Oedogonium
sp. and Spirogyra sp. Ahmad et al.,  studied the waste water nutrition for growth of microalgae and its use for biodiesel production. He used mixed algae culture composed of Microspora sp., Diatoms, Lyngbya sp., Caldophora sp., Spirogyra sp. and Rhizoclonium sp. Results showed that the growth of mixed algae culture was promising and the biodiesel produced was in accordance with the ASTM standards.
Musharraf et al.,  performed the Gas Chromatography-Mass Spectrometry (GC-MS/MS) analysis of Fatty Acid Methyl Esters (FAMEs) and biodiesel production study for six microalgae strains (Scenedesmus quadricauda, Scenedesmus acuminatus, Nannochloropsis
sp., Anabaena sp., Chlorella
sp. and Oscillatoria sp.) collected from fresh and marine water resources located in southern region of Pakistan. Results proposed that microalgae found in southern Pakistan has a potentially active growth rate and can be used for biodiesel production. Ahmad et al.,  performed a study to find out the biodiesel efficiency of Chlorella
vulgaris, Rhizoclonium hieroglyphicum and mixed culture algae by transesterification process. It was suggested by the study that raw municipal waste water can be used for the growth of algal species. The biodiesel obtained was compared with ASTM standards.
Ahmad et al.,  studied the treatment of municipal waste water and biodiesel production by employing Chlorella
vulgaris. Results showed that Chlorella vulgaris
produced biodiesel of good quality which conformed to the ASTM standards. Further, the study indicated that the treated waste water can be used for irrigation purpose as it has BOD and COD within the limits of national environmental quality standards. Fatima et al.,  used two freshwater algae species (Chlorella vulgaris
species) for biodiesel production. The Chlorella
species produced 6.26 g oil from 38.23 g of dry weight and the Oedogonium
species produced 8.07 g of oil from 38.23 g of dried weight. Alam et al.,  inspected 17 species from fresh water sources of Khyber Pakhtunkhwa. Chroococcus turgidus, Sirogonium sticticum, Uronema elongatum and Temnogyra reflexa produced the highest amounts of oil amongst all others. Oil percentages of different microalgae species investigated in Pakistan are presented in table 5.In Pakistan, there exists vast potential to produce biodiesel from mircoalgal biomass. It has been observed from this study and highlighted in figure 4 that Chlorella
sp. (fresh water algae) produced the highest amount of oil content percentage followed by Chlorella vulgaris
which grows in waste water. Rhizoclonium hieroglyphicum and mixed algae culture also produced considerable amount of oil content for biodiesel production.Figure 4:
Oil content (%) of microalgal species existing in Pakistan.