Feature
Written by Sabrina Deparine
Monday, 05 July 2010 12:58
A research team from the Biodesign Institute of the Arizona State University has achieved another milestone for the biofuel industry.
In the past week, news broke out that the team has made a new discovery: optimizing the growth conditions of blue-green algae (also known as cyanobacteria) to make these grow abundantly for biofuel production.
The blue-green algae is one of the most attractive feedstock options for biofuels because of its capability to produce 100 times the amount of clean fuel per acre as compared to other types of feedstock. Also, blue-green algae do not have any special requirements. It only requires sunlight, water and carbon dioxide. A few nutrients may be needed for it to survive and to grow exponentially and abundantly. Blue-green algae also eliminate the concerns over requiring vast lands for biofuel production. It can be grown on any location where there is sufficient supply of sunlight and carbon dioxide.
According to Raveender Vannela, a member of the research team, they had discovered the use of a photobioreactor in optimizing the growth of blue-green algae. The said photobioreactor utilizes solar photons as an energy source to convert carbon dioxide in reduced forms. This is epitomizes the cliché that goes “shooting two birds with one stone”. The bioreactor makes use of solar energy for it to run and its output benefits biofuel production. However, the process requires a more delicate and complex interplay of carbon dioxide, phosphorous and light radiation within the photobioreactor for it to optimize the growth of the algae.
For this experiment, Vannela and another researcher, Hyun Woo Kim made use of the Synechocystis PC6803 type of blue-green algae. These were cultivated in a benchtop photobioreactor and were supplied with BG-11, a customary growth medium. The carbon dioxide was manipulated along with the light irradiance and phosphorus content in the plant to boost its growth.
Based on the output of their experiment, it was concluded that blue-green algae are not able to maximize carbon dioxide in their growth cycle so they added phosphorous to the BG-11 medium. This resulted to higher biomass productivity. When the phosphorous has been consumed, the abundant growth of the algae is hampered by the light irradiation and carbon dioxide. What happens is the additional growth results to the crowding of biomass in the photobioreactor vessel so that it blocks the light. This issue can be resolved by more frequent harvesting of the reactor.
If this will be implemented on a large scale, the blue-green algae can get nutrients from other sources like waste streams or harvested biomass. This will form a close-loop, self-sustaining system that harness and produce energy from contaminants and carbon emissions.
Aside from biofuels, blue-green algae can also be used in the manufacturing of chemical-based materials like biopolymers and isoprenes which are used for industrial applications.
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