Biofuel is generally defined as energy obtained from biomass, through direct combustion, alcohol fermentation, and methane fermentation. Biomass, the raw material of biofuel, especially for bioalcohol, can be classified into sugar-based (sugar cane, sugar beet, etc), starch-based (corn, potato, sweet potato, etc) and wood-based (wastewood, rice straw, wastepaper, etc).
Today, most of the liquid biofuels are sugar or starch based and are obtained from crops of sugar beet, sugar cane, potatoes or corn. A problem in the future could be the lack of agricultural lands. These crops use good lands on which food can grow instead. An idea to decrease use of proper agricultural lands would be to use the unproductive areas to obtain biofuels.
Korea Institute of Technology in South Korea patented the use of freshwater algae to obtain biofuel. The scientists developed a method to use marine algae or seaweed to produce bioethanol and avoid using productive lands.
The seaweed has a lot of advantages in comparison with land biomass: grows much faster allowing up to six harvests per year, it does not contain lignin and so requires no pre-treatment before it can be turned into fuel, decreasing in this way the costs with this extra process, and it absorbs up to seven times as much carbon dioxide from the atmosphere as wood.
The patent suggests to break all kind of algae with a hydrolytic enzyme and/or a hydrolytic catalyst into mono sugars which can be then fermented into ethanol. The seaweeds can be produced in outdoor ponds or tanks and the biofuel made from them is cheaper than crop or wood based fuels.