Utilization of algae for bioethanol production

In today, countries must to produce and use biofuels due to the increasing energy demand, some enacted laws and signed protocols for eliminating environmental problems and global warming. Bioethanol, an alternative for gasoline is obtained via fermentation of various biomass resources in the presence of microorganisms. Besides using as a biofuel, bioethanol is also a valuable product for usage in medicine, chemistry and pharmaceutical areas. Because of common use first generation bioethanol feedstocks such as wheat, corn and sugar beet as a food supply, especially usage of lignocellulosic materials which are considered as a second generation bioethanol feedstock gets attention for bioethanol production. However, difficulties in pre-treatment process of lignocellulosic materials and high production cost cause in researches of new technologies on pre-treatment methods and low cost feedstock. Algal biomass, which is very popular in biodiesel production as a third generation feedstock, has an important potential for also bioethanol production because of their high amounts of cellulose and starch. In this study macroalgae in coastal regions of Marmara Sea were collected and utilized for bioethanol production and effects of the pre-treatment type (acid or alkaline), concentration of treatment chemicals, pre-treatment temperature, pre-treatment and fermentation time on bioethanol yields were investigated. Comparisons were made for performing two different chemical pre-treatment, and deformations of algal structure were investigated. Highest bioethanol yields for acid and alkaline pre-treatments were obtained as 24.48% and 11.47%, under condition of 2 N H2SO4 and 0.75% (w/v) KOH concentrations, pre-treatment temperature of 100 °C, 60 minutes of pre-treatment time, respectively. This thesis study have shown that macroalgae, which have high carbohydrate content, can be effectively used for bioethanol production.