Review of Biojet Fuel Conversion Technologies

Abstract

Biomass-derived jet (biojet) fuel has become a key element in the aviation industry's strategy to reduce operating costs and environmental impacts. Researchers from the oil-refining industry, the aviation industry, government, biofuel companies, agricultural organizations, and academia are working toward developing commercially viable and sustainable processes that produce long-lasting renewable jet fuels with low production costs and low greenhouse gas emissions. Additionally, jet fuels must meet ASTM International specifications and potentially be a 100% drop-in replacement for the current petroleum jet fuel. The combustion characteristics and engine tests demonstrate the benefits of running the aviation gas turbine with biojet fuels. In this study, the current technologies for producing renewable jet fuels, categorized by alcoholsto-jet, oil-to-jet, syngas-to-jet, and sugar-to-jet pathways, are reviewed. The main challenges for each technology pathway, including feedstock availability, conceptual process design, process economics, life-cycle assessment of greenhouse gas emissions, and commercial readiness, are discussed. Although the feedstock price and availability and energy intensity of the process are significant barriers, biomass-derived jet fuel has the potential to replace a significant portion of conventional jet fuel required to meet commercial and military demand. 3 Conclusion .

Conceptual Design of Operation Strategies for Hybrid Electric Aircraft

“…In this calculation, electricity is assumed to be generated from renewable energy plants that do not cause emissions. Hence, the emissions are directly proportional to the fuel burn of the aircraft, which causes 3.14 kg CO 2 per kg fuel [43]. The analysis in Section 4 refers to this perspective only.…”

“…A holistic investigation of the CO 2 emissions of aviation in Section 5 considers additional environmental impacts for the well-to-tank process. Whereas 0.61 kg CO 2 /kg fuel [43] has to be added for the conventional route, the electricity generation is characterized by an average OECD (Organisation for Economic Co-operation and Development) measure of 0.42 kg CO 2 /kWh electricity [44]. Second aspect of the overall target is to provide a cost competitive HEA configuration.…”

The Alcohol‐to‐Jet Conversion Pathway for Drop‐In Biofuels: Techno‐Economic Evaluation

“…Ethanold ehydration has been explored extensively with av ariety of catalysts including zeolites, silicoaluminum phosphates, and heteropolyacids. [31,32] Specialized ethanol-to-ethylene heterogeneous catalysts such as Syndol have become commercially available with high selectivity and conversion. [32,33] Dehydration of higher alcohols has been less explored, although isobutanol dehydration has been reportedt ob ea chievable with av arietyo fh eterogeneousc atalysts including zeolites, alumina, and acids, also with relatively high conversion.…”

“…[31,32] Specialized ethanol-to-ethylene heterogeneous catalysts such as Syndol have become commercially available with high selectivity and conversion. [32,33] Dehydration of higher alcohols has been less explored, although isobutanol dehydration has been reportedt ob ea chievable with av arietyo fh eterogeneousc atalysts including zeolites, alumina, and acids, also with relatively high conversion. [14b, 25, 32, 34] Dehydration of isobutanol can produce am ixture of butene isomers ande ven initiate oligomerization reactions, butahigh selectivity to isobutene in the dehydration step is reportedlyp referred for isobutanol conversion.…”

“…[6c, 30, 32, 35] Iso-and n-buteneo ligomerization has been extensively explored, but is less developed commercially than its ethylene counterpart. [25,32,36] The formation of C 12 trimers and C 16 tetramersi sp referred for the jet-fuel range with or withoutt he use of recycle or as econdary reactor to further drive the growth of C 8 hydrocarbons. Am olar selectivity of 20 %C 8 ,7 0% C 12 ,a nd 10 %C 16 has been described for isobutene oligomerization with an Amberlyst-35 catalyst.…”