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Oil from algae

One of the newest and most innovative forms of alternative fuels in development today is algae based biofuel. Algae are one of the fastest growing and most adaptive organisms on the planet and researchers are developing ways of using algae to capture CO2 from the atmosphere and to output fuels that can meet our energy needs. Proponents hope that large scale production of algae based fuel can dramatically lessen our dependence on crude oil as well as capture immense quantities of CO2 in the process. Obviously this CO2 will be released again once the fuel is burned, but the system represents a cycle that is much more sustainable than the one currently practiced.

The process of producing algae is really quite simple. Algae are grown in either open-pond or closed-pond systems. Once the algae have been harvested, the lipids (oils) are extracted from the walls of the algae cells. There are different ways to extract oil from algae. The oil press is the simplest, most popular method because it extracts up to 75% of the oil from the algae being pressed.

Another process is called the hexane solvent method. In this method, the hexane solvent is combined with combined with the pressed algae, which then extracts up to 95% of oil from algae. First, the press squeezes the oil. Then, the leftover algae is mixed with hexane, filtered, and cleaned so as to ensure that no chemical is left in the oil.

A third process is known as the supercritical fluids method. This method extracts up to 100% of the oil from algae. Carbon dioxide behaves as the supercritical fluid—when a substance is pressurized and heated to change its composition into a liquid as well as a gas. The carbon dioxide is then mixed with the algae. Once combined, the carbon dioxide turns the algae into oil. The additional equipment and work needed in this method makes it a less popular option.

by S. C.
25 december 2010, Food & Fun > Nature

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