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Microbiofuels on the Way?

Hydrogen is one of nature’s simplest molecules. Made of two hydrogen atoms (H2), this gas consists of only two protons and two electrons. Scientists have developed car prototypes that run on H2 rather than gasoline and hope this will offer yet another promising avenue in the search for vehicles using alternatives to fossil fuels. Even better news comes from the world of microbes where several major groups of organisms produce H2 as a normal end product of their metabolism. Could these microbes become a major future source of a new biofuel, a microbiofuel?

Among the microbes that emit H2 are bacteria that ferment sugars in anaerobic (no oxygen) environments, cyanobacteria, specialized photosynthetic bacteria called purple nonsulfur bacteria, and many algae. Cyanobacteria and green algae have been studied as the most promising H2-producers because of their ability to make H2 from water.

Microbiologists caution that microbiofuel-powered vehicles powered still have significant hurdles to overcome. The H2-producing reaction must be harnessed inside specially designed bioreactors. In addition, scientists must learn how to manipulate the microbe’s growth to favor H2 production. The water-to-hydrogen reaction inside microbes also produces an oxygen molecule. Despite the abundance of oxygen around us, this element is very toxic to microbial cells. But the good news about microbial H2 production makes it a goal worth achieving. H2-producers are found almost everywhere in soil and water. They need little to keep them going because, except for fermenting microbes, they are photosynthetic. Simply supply light and water and the microbes do the rest.

Most new technologies that radically change industries start out as too expensive for today’s practical purposes. But without continued research in these technologies, society would never invent anything. The temptation to develop microbes that grow readily in the environment (cheap) and naturally convert sunlight (free) to a fuel that would help break our dependence on fossil fuels seems to be too great to ignore.



Cyanobacteria. [Clean Green, NIH Image Gallery, 2010]

Algae Biodiesel

If the job of getting hydrogen fuel from algae still lies decades away, biodiesel from algae may be much closer on the horizon. Diesel fuel is like gasoline in that it comes from crude oil, but diesel is made in refineries by a different process and used in specially designed engines that differ from gasoline combustion engines. In seeking alternatives to fossil fuels, scientists have for a long time investigated the possibility of making diesel out of non-crude oil sources. If these sources are of biological origin, like plants or microbes, we call the fuel “biodiesel.”

Algae may offer one of the most economic ways to produce biodiesel. Algae grow readily in ponds exposed to sunlight and air from which they absorb carbon dioxide. When algae grows, the cells store energy in the form of oils. Is the harvesting of algae for making biodiesel a practical answer to our need for alternative fuels? Is “oilgae” in our future?

Small entrepreneur companies as well as behemoth oil companies have experimented with algae biodiesel. One approach involves growing mats of algae on the surface of large ponds exposed to sunlight. The mat can be skimmed off the top of the pond and then either pressed to express the oils or treated with an industrial solvent that dissolves the oil. A refining process is then used for turning the algae extract into a fuel.

How close are we to adding algae oil to our list of fossil fuel alternatives? A process for getting fuel from algae has already been designed. But even this seemingly inexpensive process has special requirements with high costs. For example, an algae fuel producer must have sufficient land to build the algae ponds and pay for a large volume of water to keep the ponds working. Entrepreneurs have experimented with indoor algae tanks, which take up less space but also require special lighting to keep the algal photosynthesis reactions going. A few companies are designing new types of algae that grow by fermenting sugars rather than use photosynthesis. This innovation cuts down space and lighting costs. At least one company has in the past few years experimented with a way to harvest the oil from algae without killing them. This would reduce the need for growing a new batch of algae after each harvest.

Will the naysayers win out over the dreamers in our quest to investigate every possible new fossil fuel alternative? In 2008, about 15 algae biodiesel companies were trying their hand at producing this fuel. Since then, the oil companies BP, Shell, Exxon, Valero, and Chevron added research projects in this area. Shell has already scrapped the idea and finds no promise in oilgae. The route to success will probably avoid massive algae-growing operations that use enormous amounts of land and water. Perhaps oilgae technology that has yet to be uncovered will come from new ways to engineer algae tanks or bioreactors, a more efficient oil harvesting process, and oil refining compatible with a new generation of vehicles.

Viruses to the Rescue

Viruses are particles of only a few nanometers in width and which infect living cells. (A nanometer is one-billionth of a meter.) Because of their tiny size, scientists have long considered viruses to be a perfect fit for nanotechnology, the science of objects measured on a nanometer scale. University of California scientists have developed a technique for getting certain viruses to self-assemble into thin films, long strands, and other structures that might be useful in nanotechnology and in human health.

The Berkeley scientists have induced viruses to make three different types of films of increasing complexity. These films may eventually be developed as substitutes for natural substances in the body. Viral films might become precursors for making artificial collagen, skin, or components of the eye. In the future, substances assembled by viruses may be useful in helping the body repair damaged tissue or control abnormal tissue growth.

The virus being studied in these experiments is called M13. M13 is a bacteriophage, which is a virus that infects only bacterial cells and not any other living thing. Thus, M13 is safe for study and for any future uses in medicine.

This is how algae are used to make fuel [, Stoel Rives LLP, 2010]