Oleaginous algae are economically important algae, that have a potential to produce more than 20% of oils (mainly Triacylglycerol) per dry cell weight. Many oleaginous strains of algae for bio diesel production are now known by scientists. These strains can produce large quantities of oils. Algae has a potential to produce the highest yield of biofuel than all the other major feed stocks. Yearly yield potential of algae range from 5,000 gallons per acre to 20,000 gallons per acre, which is the greatest yield potential than even the best yielding vegetable oil producer plants, such as soy beans and palm oils. All algae species produce eleven types of oils, from this oils the one which is used as a feed stock for biofuel is Triacylglycerol. This type of oil is produced by algae mainly as a response to stress situations, for its use as storage of starch or energy. In alga farms stress situations are created by nutrients starvation, high temperature and high light intensity as the algae are aging normally. Naturally most oleaginous strains produce more Triacylglycerol while aging.
Nutrient starvation: is done by depleting the nitrogen, silicon and phosphate supply of the algae. This will cause the algae to produce more Triacylglycerol.
Temperature increase: As the temperature increase the production of Triacylglycerol also increases.
Light intensity increase: Higher light intensity increases Triacylglycerol. Light intensity is increased by exposing the algae to direct scorching sunlight.
Algae species that produces more amount of Triacylglycerol in response to stress situations are:
- All of: Green algae species
- Many of: Diatom Species
- Some of: Haptophytes, Eustigmatophytes, Chrysophytes and Xanthophytes species
- None of: Cyanobacteria or Blue Green algae species
Naturally under no stress environmental conditions Green algae, Diatoms, Haptophytes, Eustigmatophytes and Chrysophytes have an average of 26% of oil, but under stress conditions their average oil content increases significantly to 45% per dry cell weight.
The yield from oleaginous algae is much more in hundreds of fold as compaired to the yield produced from the best oil producer crops. The reason for this is due to the ability of each and every algae cells to perform a range of various physiological functions starting from CO2 fixation to Triacylglycerol production and accumulations by it self. But in crops such as soy beans this physiological functions took place in separate and specific parts of the plant such as in seeds.
These days production of biofuel is gaining increasing popularity because of different reasons.
- Algae are easy to grow. Algae needs little attention to grow, it can grow easily in sewages, farm outlets, barren and unproductive lands, salt water and in hot dry desert climate.
- Algae reproduce very rapidly, this will make algae production for biofuel a lot sustainable, continual and unseasonal.
- Algae produces 7 to 30 times more yield of oils than all of the oil crops combined. In other words it has high potential of yield per hectare.
- Ease of the use of coal power plants as CO2 source for alga culture.
- Its use to purify seawages and drainage canals from toxic chemicals and excess fertilizers.
- Its huge ability to reduce green house gases such as carbon dioxide.
- For its other economically important byproduct such as pigments, cosmetic products, animal feed, food products such as proteins, carbohydrates, vitamins and omega-3.
- Increasing new discoveries and techniques to grow algae in open ponds and phobiotoreactors.
But there are also some serious impediments for the applicability of producing biofuel from algae. The estimated production cost is very high and most of this cost involves in setting up the centrifugal system to extract the oils and in running the system, the estimated cost could reach hundreds of millions of USD. Other minor problems include unavailability of reliable carbondioxide source, high evaporation losses, contamination and enough water source.
Taking all the high production costs in to consideration now days, it is much more advisable to grow algae for food companies than for biofuel purpose, but biofuel production from algae have a very huge potential for the future and a lot of research are underway to slash the paralyzing cost of production. As for me the future looks greener.
