FAA Center of Excellence for Alternative Jet Fuels & Environment: Annual Technical Report 2021: For the Period October 1, 2020 - September 30, 2021: Volume 2

FAA Award Number 13-C.This report covers the period October 1, 2020, through September 30, 2021. The Center was established by the authority of FAA solicitation 13-C-AJFE-Solicitation. During that time the ASCENT team launched a new website, which can be viewed at ascent.aero. The next meeting will be held April 5-7, 2022, in Alexandria, VA

FAA Center of Excellence for Alternative Jet Fuels & Environment: Annual Technical Report 2021: For the Period October 1, 2020 - September 30, 2021: Volume 1

FAA Award Number 13-C.This report covers the period October 1, 2020, through September 30, 2021. The Center was established by the authority of FAA solicitation 13-C-AJFE-Solicitation. During that time the ASCENT team launched a new website, which can be viewed at ascent.aero. The next meeting will be held April 5-7, 2022, in Alexandria, VA

Denoising and Fuel Spray Droplet Detection From Light-Scattered Images Using Deep Learning

13-C-AJFF-PU-011This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) license https://creativecommons.org/licenses/by-nc-nd/4.0/. Please cite this article as: Veeraraghava Raju Hasti, Dongyun Shin, Denoising and fuel spray droplet detection from light-scattered images using deep learning, Energy and AI, Volume 7, 2022, 100130, ISSN 2666-5468, https://doi.org/10.1016/j.egyai.2021.100130.A deep learning-based method for denoising and detecting the gas turbine engine spray droplets in the light-scattered image (Mie scattering) is proposed for the first time. A modified U-Net architecture is employed in the proposed method to denoise and regenerate the droplets. We have compared and validated the performance of the modified U-Net architecture with standard conventional neural networks (CNN) and modified ResNet architectures for denoising spray images from the Mie scattering experiment. The modified U-Net architecture performed better than the other two networks with significantly lower Mean Squared Error (MSE) on the validation dataset. The modified U-Net architecture also produced images with the highest Power Signal to Noise Ratio (PSNR) compared to the other two networks. This superior performance of the modified U-Net architecture is attributed to the encoder-decoder structure. During downsampling, as part of the encoder, only the most prominent features of the image are selectively retained by excluding any noise. This reconstruction of the noise-free features has produced a more accurate and better denoised image. The denoised images are then passed through a center predictor CNN to determine the location of the droplets with an average error of 1.4 pixels. The trained deep learning method for denoising and droplet center detection takes about 2.13 s on a single graphics processing unit (GPU). This study shows the promise for real-time processing of the experimental data using the well-optimized network

Oilseed Cover Crops for Sustainable Aviation Fuels Production and Reduction in Greenhouse Gas Emissions Through Land Use Savings

13-C-AJFF-PU-029This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license https://creativecommons.org/licenses/by/4.0/. Please cite this article as: Taheripour F, Sajedinia E and Karami O (2022) Oilseed Cover Crops for Sustainable Aviation Fuels Production and Reduction in Greenhouse Gas Emissions Through Land Use Savings. Front. Energy Res. 9:790421. doi: 10.3389/fenrg.2021.790421Induced Land Use Changes (ILUCs) can decrease the environmental benefits of Sustainable Aviation Fuels (SAFs) if produced from traditional food crops. The development of oilseed cover crops can eliminate the side effect of ILUCs for biofuel production because they come in rotation with the major crops with some savings in demand for new cropland. This study implemented Life Cycle Analysis (LCA) and GTAPBIO to estimate ILUC emissions values, the potentially available area, and total possible emissions savings of producing SAFs from carinata, camelina, and pennycress in the United States. The results suggest that: 1) the meals produced in conjunction with increases in Sustainable Aviation Fuel production from carinata, camelina, and pennycress could reduce land use emissions by 12.9, 15.3, and 18.3 gCO2e/MJ, respectively; 2) the total area of available land for producing these feedstocks could be about 29.3 million ha in 2035; and 3) using this area of land for SAF production, depends on the mix of oilseed cover crops that can be produced in practice, could generate up to 92 million metric tons of savings in GHG emissions per year. The projected emissions savings is about 11% of the current global GHG emissions generated by the aviation industry. Providing incentives to encourage farmers to produce these cover crops and facilitating investment in producing SAF from these cover crops are the most important factors that could help the aviation industry to enhance emissions savings

Regulatory and Policy Analysis of Production, Development and Use of Sustainable Aviation Fuels in the United States

13-C-AJFF-PSU-031This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license https://creativecommons.org/licenses/by/4.0/. Please cite this article as: Korkut E and Fowler LB (2021) Regulatory and Policy Analysis of Production, Development and Use of Sustainable Aviation Fuels in the United States. Front. Energy Res. 9:750514. doi: 10.3389/fenrg.2021.750514The United States, spurred in part by international developments, is expanding its law and policy to incentivize the use of sustainable aviation fuels. While the U.S. has agreed to participate in the International Civil Aviation Organization\u2019s (ICAO\u2019s) Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), it has only recently adopted federal rules that define greenhouse gas emission reduction standards for certain classes of airplanes (effective January 2021). However, such standards focus on engine efficiency rather than the fuel burned. For sustainable aviation fuels, the U.S. continues to rely on voluntary programs at a federal, state, and regional level. The federal Renewable Fuel Standard program allows producers to opt in. In addition, states have started to allow sustainable aviation fuel producers to \u201copt in\u201d to their programs; this includes California\u2019s Low Carbon Fuel Standard, Oregon\u2019s Clean Fuels Program, and Washington\u2019s newly adopted Clean Fuels Program. Other states are also starting to consider such programs. Elsewhere, states like Hawaii are starting to support SAF production in other ways, including through tax mechanisms. In addition, regional and private efforts to adopt and/or promote sustainable aviation fuels are underway. This piecemeal approach\u2014due in part to the lack of cohesive U.S. federal policy\u2014stands in contrast to the European Union\u2019s Renewable Energy Directive and Emissions Trading System, and adoption of policies by European countries. Because of aviation\u2019s international nature, tracking what is happening in Europe matters greatly for U.S. carriers. As the U.S. works to meet its international obligations through CORSIA, finding a way forward with sustainable aviation fuel in the United States may depend on a more defined federal policy. Actions taken by both the EU and European countries offers some guidance for actions that could be taken by the U.S. Even in the absence of more defined measures, better tracking of voluntary measures is a critical step

Secondary Sonic Boom Predictions for U.S. Coastlines

13-C-AJFE-PSU-021055This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license https://creativecommons.org/licenses/by/4.0/. Please cite this article as: The Journal of the Acoustical Society of America 152, 2816 (2022); https://doi.org/10.1121/10.0014860This study examines the behavior of secondary sonic booms on United States (U.S.) coastlines to have a more complete understanding of the impact of supersonic travel on communities. Secondary sonic booms occur when the atmospheric conditions are such that the atmospheric refraction causes the sound that would ordinarily not reach the ground to bend toward the ground. NASA's PCBoom software is a preferred simulation tool to predict the location and pressure signatures of sonic booms. It was expanded to include secondary boom propagation but has not yet been rigorously used for secondary sonic booms in a variety of conditions. This study looks at how secondary sonic booms change throughout the year and how they behave at different U.S. coastline locations

Threshold Sooting Index of Sustainable Aviation Fuel Candidates From Composition Input Alone: Progress Toward Uncertainty Quantification

13-C-AJFF-UD-026, 027This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license https://creativecommons.org/licenses/by/4.0/. Please cite this article as: Energy Fuels 2022, 36, 4, 1916\u20131928 Publication Date: January 31, 2022 https://doi.org/10.1021/acs.energyfuels.1c03794 Copyright \ua9 2022 The Authors. Published by American Chemical SocietyA quantitative structure\u2013property relationship model has been developed to predict the threshold sooting index (TSI) of arbitrary mixtures of aliphatic and aromatic hydrocarbons of known composition. The model employs contributions from eight molecular fragments plus a global shift and a penalty factor for naphthenic compounds. For each coefficient, the contributions were determined by a constrained regression to data from five different experimental campaigns, which were stitched together by setting the TSI of methylcyclohexane to 5 and the TSI of 1-methylnaphthalene to 100. Unique to this study; the TSI of 1,3,5-trimethylbenzene was restricted to the range of 54.7 and 63.1, which significantly constrains uncertainty. Within the composite training dataset, which contained 65 molecules and 124 data points, including simple mixtures, the model was found to match 95% of the data within 8.9 TSI. Validation of the model against n-butylcyclohexane, dimethylcyclooctane, and a six-component surrogate jet fuel shows prediction to be well within the 95-percentile confidence band of the experiment. This model is the first to integrate the linear blending rule for the TSI with a linear quantitative structure\u2013property relationship model for the TSI, and the first time that referee controls have been applied to ensure that all datasets, experimental and modeled, are normalized to the same scale

Comprehensive Characterization of Kukui Nuts as Feedstock for Energy Production in Hawaii

13-C-AJFE-UH-This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license https://creativecommons.org/licenses/by/4.0/. Please cite this article as: Jinxia Fu, Seren Weber, and Scott Q. Turn ACS Omega 2023 8 (25), 22567-22574. https://doi.org/10.1021/acsomega.3c00860Fuel properties of oil-bearing kukui (Aleurites moluccana) nuts, a commonly found crop in Hawaii and tropical Pacific regions, were comprehensively studied to evaluate their potential for bioenergy production. Proximate and ultimate analyses, heating value, and elemental composition of the seed, shell, and de-oiled seed cake were determined across five sampling locations in Hawaii. The aged and freshly harvested kukui seeds were found to have similar oil contents, ranging from 61 to 64%wt. Aged seeds, however, have 2 orders of magnitude greater free fatty acids than those freshly harvested (50% vs 0.4%). The nitrogen content of the de-oiled kukui seed cake was found to be comparable to that of the soybean cake. Aging of kukui seeds can decrease the flashpoint temperature and increase the liquid 12solid phase transition temperatures of kukui oil obtained. Mg and Ca are the major ash-forming elements present in the kukui shells, >80%wt of all metal elements detected, which may reduce deposition problems for thermochemical conversion in comparison with hazelnut, walnut, and almond shells. The study also revealed that kukui oil has similar characteristics to canola, indicating that it is well-suited for biofuel production

Comparing Alternative Jet Fuel Dependencies Between Combustors of Different Size and Mixing Approaches

13-C-AJFF-UD-024This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license https://creativecommons.org/licenses/by/4.0/. Please cite this article as: Boehm RC, Colborn JG and Heyne JS (2021) Comparing Alternative Jet Fuel Dependencies Between Combustors of Different Size and Mixing Approaches. Front. Energy Res. 9:701901. doi: 10.3389/fenrg.2021.701901Analyses used to reveal fuel dependencies on lean blow out and ignition at specific operating conditions in specific combustors show inconsistent trends with each other. Such variety is however consistent with the occurrence of transitions between the governing physical phenomena as the ratios between evaporation, mixing, or chemical time scales with their respective residence times also vary with specific operating conditions and combustor geometry. It is demonstrated here that the fuel dependencies on LBO in a large, single-cup, swirl-stabilized, rich-quench-lean combustor varies with operating conditions such that a feature importance match is attained to fuel dependencies observed in a much smaller combustor at one end of the tested range, while a qualitative match to fuel dependencies observed in a lean, premixed, swirler-stabilized combustor of comparable size at the other end of the tested range. The same reference combustor, when tested at cold conditions, is shown to exhibit similar fuel dependencies on ignition performance as the much smaller combustor, when tested at both cold and warm conditions. The practical significance of these findings is that a reference rig, such as the Referee Rig, can capture fuel performance trends of proprietary industry combustors by tailoring the inlet air and fuel temperatures of the tests. It is, therefore, a trustworthy surrogate for screening and evaluating sustainable aviation fuel candidates, reducing the dependency on proprietary industrial combustors for this purpose, thereby increasing transparency within the evaluation process while also expediting the process and reducing cost and fuel volume

The Economic Impact of a Renewable Biofuels/Energy Industry Supply Chain Using the Renewable Energy Economic Analysis Layers Modeling System

13-C-AJFF-UTenn-13This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license https://creativecommons.org/licenses/by/4.0/. Please cite this article as: English BC, Menard RJ and Wilson B (2022) The Economic Impact of a Renewable Biofuels/Energy Industry Supply Chain Using the Renewable Energy Economic Analysis Layers Modeling System. Front. Energy Res. 10:780795. doi: 10.3389/fenrg.2022.78079The University of Tennessee\u2019s (UT) Department of Agricultural and Resource Economics models supply chains for both liquid and electricity generating technologies currently in use and/or forthcoming for the bio/renewable energy industry using the input\u2013output model IMPLAN\uae. The approach for ethanol, biodiesel, and other liquid fuels includes the establishment and production of the feedstock, transportation of the feedstock to the plant gate, and the one-time investment as well as annual operating of the facility that converts the feedstock to a biofuel. This modeling approach may also include the preprocessing and storage of feedstocks at depots. Labor/salary requirements and renewable identification number (RIN) values and credits attributable to the conversion facility, along with land-use changes for growing the feedstock are also included in the supply chain analyses. The investment and annual operating of renewable energy technologies for electricity generation for wind, solar, and digesters are modeled as well. Recent modeling emphasis has centered on the supply chain for liquid fuels using the Bureau of Economic Analysis\u2019s 179 economic trading areas as modeling regions. These various data layers necessary to estimate the economic impact are contained in UT\u2019s renewable energy economic analysis layers (REEAL) modeling system. This analysis provides an example scenario to demonstrate REEAL\u2019s modeling capabilities. The conversion technology modeled is a gasification Fischer\u2013Tropsch biorefinery with feedstock input of 495,000 metric tons per year of forest residue transported to a logging road that is less than one mile in distance. The biorefinery is expected to produce sustainable aviation fuel (SAF), diesel, and naphtha. An estimated one million tons of forest residue are required at fifty percent moisture content. Based on a technical economic assessment (TEA) developed by the Aviation Sustainability Center (ASCENT) and the quantity of hardwood residues available in the Central Appalachian region, three biorefineries could be sited each utilizing 495,000 dry metric tons per year. Each biorefinery could produce 47.5 million liters of SAF, 40.3 million liters of diesel, and 23.6 million liters of naphtha. Annual gross revenues for fuel required for the biorefineries to break even are estimated at $193.7 million per biorefinery. Break-even plant gate fuel prices when assuming RINs and 12.2 percent return on investment are$1.12 per liter for SAF, $1.15 per liter for diesel, and$0.97 per liter for naphtha. Based on IMPLAN, an input\u2013output model, and an investment of $1.7 billion, the estimated economic annual impact to the Central Appalachian region if the three biorefineries are sited is over a half a billion dollars. Leakages occur as investment dollars leaving the region based on the regions local purchase coefficients (i.e., LPPs), which totals$500 million. This results in an estimated $2.67 billion in economic activity with a multiplier of 1.7, or for every million dollars spent, an additional$0.7 million in economic activity is generated in the regional economy. Gross regional product is estimated at $1.28 billion and employment of nearly 1,200 jobs are created during the construction period of the biorefineries, which results in$700 million in labor income with multiplier effects. Economic activity for the feedstock operations (harvesting and chipping) is estimated at slightly more than $16.8 million resulting in an additional$30 million in the economic impact. The stumpage and additional profit occurring from the harvest of the forest residues result in $40 million directly into the pockets of the resource and logging operation owners. Their subsequent expenditures resulted in a total economic activity increase of$71.4 million. These operations result in creating an estimated 103 direct jobs for a total of 195 with multiplier effects. Direct feedstock transportation expenditures of more than $36.7 million provide an estimated increase in economic activity of almost$68 million accounting for the multiplier effects