This course defines biofuels, and explains why we should make them. It presents the challenges and opportunities of sustainable biofuels, addressing issues of land use, and competition with food production. It describes production processes of first generation, and cellulosic ethanol. It covers microbial engineering to improve production, or make new advanced biofuels. It describes the use of photosynthetic organisms such as algae, which fix carbon directly from the atmosphere to make biofuels. It addresses the environmental, economic and societal impact of biofuels, and how they can fulfill their promise as a renewable source of energy.