Technology Innovation Outlook for Advanced Liquid Biofuels in Transport
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organisms to improve tolerance to contaminants, raise yields, and boost selectivity. Despite the economic and practical promise, investment in advanced biofuel plants has slowed (Figure 3). The trend began even before the recent period of lower oil prices, due largely to weakened government support. A variety of measures to support technology development, markets, and enterprise formation could help restore the investment momentum. These include grants to build pilot plants that can test technical concepts at commercial scale, loan guarantees to reduce the risks of such plants to lenders, incentives and targets to encourage biofuel conversion from lignocellulosic feedstocks, public procurement initiatives in subsectors like aviation and freight shipping, and identification of coproducts like fuel additives, chemicals, plastics, and cosmetics to boost profits. It is not too late to realize the potential.
iquid biofuels provide the only practical alternative to fossil fuel for airplanes, ships, and heavy freight trucks. Advanced biofuels, using lignocellulosic feedstocks, waste, and algae, can vastly expand the range of resources for fuelling light and heavy transport alike. Such advanced biofuels can be refined from agricultural residues (associated with food crops), forest residues (such as sawdust from lumber production), rapidly growing grasses (like switchgrass and miscanthus), and short rotation tree species (such as poplar and eucalyptus). Residues do not compete with food or lumber production but grow along with it. High-yielding grasses and trees can grow more energy per unit of land area than conventional biofuel crops, avoiding carbon-releasing land use change and leaving more land for food crops. IRENA’s study Renewable Energy Innovation Outlook: Advanced Liquid Biof uels provides a comprehensive view of advanced biofuel potential and steps to achieve this potential. It examines the following: • Practical and economic potential for advanced liquid biofuels • Biofuel technology pathways and innovation opportunities • Trends in advanced biofuel technology deployment • Measures to support advanced biofuel commercialization. The analysis indicates that by 2045, the most cost-effective advanced biofuels could be produced for around US$15−$36 per GJ (nonblue colored bars in Figure 1). By comparison, at oil prices of $40 to $140 per barrel, conventional diesel and gasoline would cost around $10 to $36 per GJ (dark gray bars). At oil prices under $80 per barrel ($20/GJ), it would be hard for advanced biofuels to compete with fossil-based gasoline and diesel. However, at oil prices above $100 ($25/GJ), advanced biofuels could compete effectively. The study reviews technology readiness levels across a wide spectrum of advanced biofuel conversion pathways (Figure 2). For each of the pathways, it identifies opportunities for innovation, with specific focus on improvements in process integration and energy system integration: • Hydrolysis and fermentation could be greatly reduced in cost by integrating the two steps to reduce enzyme loading, modifying fermentation organisms, and applying membrane separation. • Pyrolysis has high efficiency and potentially low processing costs with decentralized production, but more effective catalytic upgrading processes are needed. • Gasification needs to prove reliable long-term operation in view of feedstock contaminants. Process optimization is also needed to achieve target syngas composition. • Fischer−Tropsch processes need proof at commercial scale. Small-scale modular units may help. • Alcohol (ethanol and methanol) fermentation from syngas could benefit from modification of fermentation © 2016 American Chemical Society
Jeffrey Skeer* Francisco Boshell Maria Ayuso
International Renewable Energy Agency (IRENA), Abu Dhabi, United Arab Emirates
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RELATED READINGS (1) General: IRENA. Innovation Outlook: Advanced Liquid Biof uels for Transport; IRENA: Abu Dhabi, to be published. Appendices detail the various technology pathways for advanced liquid biofuels. (2) IRENA. REmap: Roadmap for a Renewable Energy Future, 2016 Edition; IRENA: Abu Dhabi, 2016; www.irena.org/remap. (3) Hydrolysis and Fermentation: Chiaramonti, D.; Prussi, M.; Ferrero, S.; Oriani, L.; Ottonello, P.; Torre, P.; Cherchi, F. Review of Pretreatment Processes for Lignocellulosic Ethanol Production and Development of an Innovative Method. Biomass Bioenergy 2012, 46 (1), 25−35. (4) Pyrolysis: Karatzos, S.; McMillan, J. D.; Saddler, J. N. The Potential and Challenges of Drop-in Biof uels; IEA Bioenergy Task 39, 2014; http://task39.sites.olt.ubc.ca/files/2014/01/Task-39Drop-in-Biofuels-Report-FINAL-2-Oct-2014-ecopy.pdf. (5) Gasification: Bain, R. L.; Broer, K. Gasification. In Thermochemical Processing of Biomass: Conversion into Fuels, Chemicals and Power; Brown, R. C., Ed.; Wiley-VCH: Chichester, U.K., 2011; pp 47−77.
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AUTHOR INFORMATION
Notes
The authors declare no competing financial interest. Received: July 21, 2016 Accepted: September 1, 2016 Published: September 9, 2016 724
DOI: 10.1021/acsenergylett.6b00290 ACS Energy Lett. 2016, 1, 724−725
Energy Focus
http://pubs.acs.org/journal/aelccp
Energy Focus
ACS Energy Letters
Figure 1. Current and projected fossil fuel and biofuel production costs. Source: IRENA (2016).
Figure 2. Commercialization status of various advanced biofuel conversion technologies. Source: IRENA (to be published).
Figure 3. Declining global investment in advanced and conventional biofuels. Source: IRENA (2016), Bloomberg New Energy Finance.
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DOI: 10.1021/acsenergylett.6b00290 ACS Energy Lett. 2016, 1, 724−725
