Biodiesel, bioethanol, and biobutanol production from microalgae

Abstract

Due to depletion of fossil fuel supplies and hazardous impacts on the global climate, clean renewable and sustainable energy production is being critically demanded. First-generation biofuels are mainly produced from edible crops and oilseeds. Because of competition with human food, first-generation biofuels are restricted in their ability to accomplish the global biofuel need, climate change amendment, and economic growth. Consequently, second-generation and thirdgeneration biofuels were developed from nonedible feedstocks including lignocellulosic biomasses and microalgae, respectively, to overcome these challenges. However, algae are considered as a superior feedstock for biofuel production because of their diversity. Some of the major benefits of algae are their extremely fast growth rate and the ability of sequestration of carbon dioxide with high oil and carbohydrate contents that can be easily transformed into biodiesel or other gasoline components such as butanol. Biodiesel has been receiving globally growing consideration due to the liquid fuel needs and its potential as a biodegradable nontoxic substitute to petroleum diesel. In addition, butanol has become an attractive biofuel as a by-product of algal biomass processing after lipid extraction for biodiesel, due to its higher energy content, lower vapor pressure, and less hygroscopy than ethanol. This chapter reviews the current status of microalgae for biodiesel and butanol production as eco-friendly alternatives for liquid fossil fuels.