Abstract

The two most common biofuels are biodiesel and bioethanol, which can potentially replace conventional liquid fuel such as diesel and petrol, respectively. Particularly, bioethanol can be produced from abundant supplies of starch/cellulose biomass. Although growth of feedstock crops for ethanol is feasible (i.e., sugarcane in Brazil, corn and wheat in the United States and sugar beet in Europe, its production has raised doubts about possible impacts on food supply and security. The fuels versus food debate is aggravated by the large-scale cultivation demands and the high levels of resources required. Accordingly, there is an urgent demand for alternative, sustainable fuels, and feedstocks in order to replace food-based feedstocks. In comparison to other feedstocks, seaweeds are a promising source for renewable energy production since they use solar energy and fix carbon dioxide from the atmosphere for assimilation, mainly in the form of carbohydrates and lipids, which can be exploited for biofuel production. In addition, the use of seaweed may also reduce the use of freshwater that is necessary for crop production and transformation processes. Furthermore, macroalgae have high productivity and photosynthetic efficiency, great potential for carbon dioxide fixation, low percentage of lignin, and high content of carbohydrates that are all advantageous for biofuel production. Macroalgae are a source for a variety of chemical compounds that are of commercial interest, which could be separated from the polysaccharides used for bioethanol prior to using the remaining biomass for biofuel production, allowing the inclusion of the biorefinery concept.