(587g) Techno-Economic Analysis of Alcohol-to-Jet Conversion Pathways

At 2010 consumption on rates, every penny per gallon increase in the jet fuel price translates into about $175 million annually for U.S. passenger and cargo airlines ¹. This means that each added dollar per gallon translates to $17.5 billion in operational costs annually ¹. Biomass derived jet fuel may provide a solution to the economics and energy demands. Lignocellulosic-based technologies to ethanol under deployment represents an important step in the use of renewable energy. However, the maximum possible use of ethanol creates a blend-wall at 10-15% for the majority of gasoline engine on the road today. Under RFS2, the requirement for conventional corn ethanol plateaus at 15 billion gallons in 2015 ³. After 2015, all additional increases in RFS2 are satisfied solely by advanced biofuels which provides a significant long-term policy driver to support advanced aviation biofuels ^{1, 3}. Ethanol conversion to hydrocarbons is well known via a dehydration step to ethylene and followed by ethylene catalytic upgrading. Alcohol oligomerization (OHO), also called alcohols-to-jet (ATJ), is estimated at approximately 183 million gallons per year (11% in 2015 and 7% in 2020 of total projected production) and could expand up to 1.28 billion gallons by 2020 (14% of total projected production)². Although ATJ pathway is still in the early stages of commercialization, there are lot of interests from both industry entities and federal agencies working on getting jet fuels from these alcohol oligomerization processes through the ASTM certification process ². This paper presents a techno-economic analysis study on several ATJ conversion (upgrading) pathways, including ethanol-to-jet and butanol-to-jet, etc. Both corn grain and corn stover are studied as biomass feedstocks for retrofitting existing corn mill to make jet fuel, as well as process design of green-field cellulosic ethanol to jet facilities. There appear to be many performances and cost tradeoffs for these varying technologies.  Unlike production of jet fuel from Fischer-Tropsch or hydroprocessing, in which longer carbon chain molecules must be broken down into jet fuel and lower value naphtha as a by-product, there may not have significant production yield penalty for making jet fuel or diesel fuel. Only through continued R&D will these tradeoffs be more fully understood. Process economics, especially the promising conversion technologies studied are analyzed and compared in details in this work in order to provide valuable guidance to R&D. Many key variables and parameters can have significant impact on the overall process economics, therefore, major cost drivers are discussed.  For instance, overall bio-jet fuel yield, which is largely based on achieved overall alcohol-to-jet yield achieved in the catalytic upgrading process, is one of the single-most important factors in determining projected bio-jet costs for each process. While many are discussed within this talk, continuing R&D will be necessary to improve yields (both lignocellulosic biomass to alcohol and alcohol to jet yields) and generate data that further guide the development of the biomass conversion industry in the application of jet fuel.

Reference:          

1.            SAFN. SUSTAINABLE AVIATION FUELS NORTHWEST: Powering the Next Generation of Flight.  2011.

2.            Lewis K, S. M, Xu S, Tripp L, Lau M, Epstein A, Fleming G and Roof C. Alternative jet fuel scenario analysis report.  2012.

3.            Schnepf R and Yacobucci BD. Renewable Fuel Standard (RFS): Overview and Issues.  2012.