Going Green...Literally

by:  Natasha Hochlowski
Institution:  Princeton University
Date:  March 2010

In the December 22, 2008 special energy issue of Optics Express, the Optical Society of America's open-access journal, Professor Anastasios Melis and graduate student Mautusi Mitra of the University of California, Berkeley, described a new method for using microalgae to make biofuel. Such a method may make it possible to produce fuel at a rate of 30 times that of other biofuels, greatly reducing production costs and ultimately providing a cheaper, renewable source of fuel.

In the paper, the scientists explained tla, a process used to truncate, or shorten, the size of the chlorophyll arrays without compromising the photosynthesis process in the cells. Chlorophyll, the molecule that gives algae their green color, absorbs energy from sunlight to begin the process of photosynthesis, through which carbon dioxide in the air is converted into sugars the organisms need to survive. Once modified, the microalgae could produce hydrogen or hydrocarbons instead of sugar, which would then be used in fuel production. According to Mitra and Melis, "the truncated light-harvesting chlorophyll antenna size (tla) property may find application in the commercial exploitation of microalgae for the generation of biomass, biofuel, chemical feedstock, as well as nutraceutical and pharmaceutical products." The modified microalgae may not only run cars or heat houses but may be used in medicine and food as well, incorporated into nutraceutical products, foods that provide health benefits.

Biofuel,gas fuel derived from a biological source that has died relatively recently,is not a new concept. Biodiesel, fuel made from oils such as peanut or vegetable oil, has been around for over one hundred years. These types of fuel are becoming increasingly important as new methods appear to combat the rising price of fuel, which makes up about two-thirds of the world's energy market.

Unlike land plants such as sugar cane and corn, both of which have been frequently discussed for use as biofuel, microalgae have an extremely high rate of photosynthesis, about ten times that of other biofuel sources. They can produce fuel much more efficiently and cost-effectively,algae have been found to produce approximately 30 times more fuel per acre than traditional land plants.

The Berkeley researchers have identified genetic instructions in the algae genome responsible for deploying about 600 chlorophyll molecules in the light-gathering antennae, a number that can be reduced by about four-fifths without harming the algae's functioning. They hope to be able to divert the normal function of photosynthesis, causing many of the chlorophyll molecules to produce products such as lipids, hydrocarbons, and hydrogen.

Although the use of algae as a source of fuel has been discussed for several years, more time is required to put these developments into practical use. Says Melis, "Progress is substantial to date, but not enough to make the process commercially competitive with fossil fuels. Further improvement in the performance of photosynthesis under mass culture conditions, and in the yield of biofuels' by the microalgae are needed before a cost parity with traditional fuels can be achieved."