From: Prospects for Biofuels: A Review Date of download: 10/20/2017 Copyright © ASME. All rights reserved. From: Prospects for Biofuels: A Review J. Thermal Sci. Eng. Appl. 2013;5(2):021006-021006-9. doi:10.1115/1.4023602 Figure Legend: Biofuel production by region for 2001–2011 [4]. For comparison, in 2011 petroleum oil production was 83.6 × 106 barrels per day worldwide and 14.3 × 106 barrels per day in North America.

From: Prospects for Biofuels: A Review Date of download: 10/20/2017 Copyright © ASME. All rights reserved. From: Prospects for Biofuels: A Review J. Thermal Sci. Eng. Appl. 2013;5(2):021006-021006-9. doi:10.1115/1.4023602 Figure Legend: Past and projected United States biofuel production for 2001–2022 [4]. Projection to 2022 based on Energy Independence and Security Act target [5]. For comparison, U.S. petroleum oil production and consumption in 2011 was 7.8 × 106 and 18.8 × 106 barrels per day, respectively.

From: Prospects for Biofuels: A Review Date of download: 10/20/2017 Copyright © ASME. All rights reserved. From: Prospects for Biofuels: A Review J. Thermal Sci. Eng. Appl. 2013;5(2):021006-021006-9. doi:10.1115/1.4023602 Figure Legend: Pathways for biofuel synthesis from various feedstocks

From: Prospects for Biofuels: A Review Date of download: 10/20/2017 Copyright © ASME. All rights reserved. From: Prospects for Biofuels: A Review J. Thermal Sci. Eng. Appl. 2013;5(2):021006-021006-9. doi:10.1115/1.4023602 Figure Legend: Lifecycle GHG emissions as a percentage of those produced by conventional petroleum gasoline or diesel, data from Ref. [35]. The negative result for switchgrass ethanol from a biochemical (fermentation) process indicates that this fuel results in negative net GHG emissions (i.e., carbon capture is greater than GHG emissions).

From: Prospects for Biofuels: A Review Date of download: 10/20/2017 Copyright © ASME. All rights reserved. From: Prospects for Biofuels: A Review J. Thermal Sci. Eng. Appl. 2013;5(2):021006-021006-9. doi:10.1115/1.4023602 Figure Legend: The carbon debt incurred by the replacement of an ecosystem with a biofuel crop (in years of biofuel production required to repay the GHG emissions resulting from displacing a natural ecosystem), adapted from Ref. [36]

From: Prospects for Biofuels: A Review Date of download: 10/20/2017 Copyright © ASME. All rights reserved. From: Prospects for Biofuels: A Review J. Thermal Sci. Eng. Appl. 2013;5(2):021006-021006-9. doi:10.1115/1.4023602 Figure Legend: Ethanol and biodiesel yields for different feedstocks, ethanol yields [42], and biodiesel yields [43,44]

From: Prospects for Biofuels: A Review Date of download: 10/20/2017 Copyright © ASME. All rights reserved. From: Prospects for Biofuels: A Review J. Thermal Sci. Eng. Appl. 2013;5(2):021006-021006-9. doi:10.1115/1.4023602 Figure Legend: The energy return on investment (EROI) for selected biofuels and fossil resources; sources of EROI data: oil, natural gas, shale oil, and bitumen from tar sands [47], sugarcane ethanol [51], cellulosic ethanol [52], corn ethanol [31], and soybean biodiesel [53]

From: Prospects for Biofuels: A Review Date of download: 10/20/2017 Copyright © ASME. All rights reserved. From: Prospects for Biofuels: A Review J. Thermal Sci. Eng. Appl. 2013;5(2):021006-021006-9. doi:10.1115/1.4023602 Figure Legend: The energy supplied to society (gray area) and the energy use to procure that energy (white) as a function of EROI, adapted from Murphy and Hall [47]

From: Prospects for Biofuels: A Review Date of download: 10/20/2017 Copyright © ASME. All rights reserved. From: Prospects for Biofuels: A Review J. Thermal Sci. Eng. Appl. 2013;5(2):021006-021006-9. doi:10.1115/1.4023602 Figure Legend: Total water requirements for biofuels [63] with comparison to petroleum [65]

From: Prospects for Biofuels: A Review Date of download: 10/20/2017 Copyright © ASME. All rights reserved. From: Prospects for Biofuels: A Review J. Thermal Sci. Eng. Appl. 2013;5(2):021006-021006-9. doi:10.1115/1.4023602 Figure Legend: Tailpipe emissions for biofuels, data for B100 and B20 from the U.S. EPA [67] and E85 from Yanowitz and McCormick [68]