Hydrotreated Renewable Jet Research Articles

Emissions characterization tests for hydrotreated renewable jet fuel from used cooking oil and its blends

Experimental trials have been conducted using an optical swirl burner to compare the heat release and emission profiles from the application of four different aviation fuel blends with changing inlet conditions. The mixtures comprised fossil Jet A-1 and a HRJ (Hydrotreated Renewable Jet fuel) batch produced from used cooking oil processing, and blended in discrete ratios. Changes in the produced emissions were quantified with varying combustor pressure and equivalence ratio, in addition to analysing the distribution of combustion heat release using OH∗ chemiluminescence, and monitoring operational rig temperatures. Results suggest the presence of HRJ can reduce emissions and lead to a more compacted and homogenous heat release zone, beneficial as localised hot-spots can lead to the generation of soot and thermal NOx. An increase in pressure was also shown to compact the flame brush at constant thermal power, due to density changes in the combustion air, and reduced bulk flow. The presented heat release distributions and experimental data are useful for the validation of numerical simulations, particularly for the use of alternative fuels. The work also highlights the correlation of flow/acoustic perturbations with heat release, crucial in characterising global combustion behaviour.

Development of Dryland Oilseed Production Systems in Northwestern Region of the USA

This report addresses the development of dryland oilseed crops to provide feedstock for production of biofuels in semi-arid portions of the northwestern USA. Bioenergy feedstocks derived from Brassica oilseed crops have been considered for production of hydrotreated renewable jet fuel, but crop growth and yields in the northwestern region are limited by a lack of plant available water. Based on a review of the scientific literature, several areas were identified where research could be directed to provide improvements. The current agronomic limitations for oilseed production are mainly due to seedling establishment under extreme heat, dry seedbeds at optimum planting times, survival under extreme cold, and interspecific competition with weeds. To improve emergence and stand establishment, future work should focus on developing soil management and seeding techniques that optimize plant available water, reduce heat stress, and provide a competitive advantage against weeds that are customized for specific crops, soil types, and soil and environmental conditions. Spring and winter cultivars are needed that offer increased seedling vigor, drought resistance, and cold tolerance.

Development of near-infrared spectroscopy calibrations to measure quality characteristics in intact Brassicaceae germplasm

Determining seed quality parameters is an integral part of cultivar improvement and germplasm screening. However, quality tests are often time consuming, seed destructive, and can require large seed samples. This study describes the development of near-infrared spectroscopy (NIRS) calibrations to measure moisture, oil, fatty acid profile, nitrogen, glucosinolate, and chlorophyll content in six species from the Brassicaceae family. Rapeseed and similar oilseeds are potential feedstocks for producing hydrotreated renewable jet fuel. Screening samples with NIRS would allow cultivars with desirable characteristics to be quickly identified. A total of 367 samples of six species (Brassica napus, Brassica carinata, Brassica juncea, Brassica rapa, Sinapis alba, and Camelina sativa) were scanned with NIRS. Global calibrations for all six species were developed using modified partial least squares regression with reference values obtained through wet chemistry techniques. Comparing predicted values to reference data, the coefficients of determination (r2) and ratios of performance to deviation (RPD) varied, with some calibrations performing better than others. The calibration equations for seed oil content (r2=0.98, RPD=7.3) and nitrogen (r2=0.98, RPD=5.3) performed very well while the equations for seed moisture (r2=0.93, RPD=3.8) and total glucosinolate content (r2=0.92, RPD=2.3) were more qualitative. Large variation was observed for chlorophyll content (0–390mg/kg) so two calibration equations were developed, one for the higher and one for the lower range of values. When combined, these calibrations also showed very good performance (r2=0.99, RPD=14). The performance of the calibrations for the fatty acids was more varied, with some performing very well, such as the calibration for C18:3 (r2=0.99, RPD=9.9), and others, such as C22:0 (r2=0.69, RPD=1.9), showing poor correlation.

Bio-Hydrocarbons through Catalytic Pyrolysis of Used Cooking Oils: Towards Sustainable Jet and Road Fuels

Vegetable Oil (VO) is today the most used feedstock for transport biofuel production by transesterification to biodiesel. Other commercial technologies for renewable fuels production are mainly based either on Fischer-Tropsch (FT) synthesis from coal, natural gas and possibly biomass, or hydro treating of vegetable oil (Hydrotreated Vegetable Oil, HVO): this also includes Hydrotreated Renewable Jet fuel, HRJ, Used Cooking Oil (UCO) is a highly sustainable feedstock (based on EC-RED scheme): it is therefore considered as a possible alternative to VOs for greening of air transport and, under proper circumstances, for reducing the feedstock cost component. However, the use of UCO is not trivial in reactors, as catalysts are sensitive to impurities and contaminations, which are typical of waste oils. Moreover, the chemical composition of UCO is variable regionally as well as seasonally, because the type of base-vegetable oils vary with Country and period of the year. In the framework of the ITAKA EU FP7 project, (catalytic) thermochemical conversion of UCO has been considered to obtain an intermediate biofuel suitable for upgrading by hydrotreating. The catalytic conversion of UCO and Fatty Acids were investigated in a 1.5kg/h pilot unit. UCO, properly filtered and conditioned, was characterized, and then converted in bio-oil by means of thermal and catalytic reactionsunder controlled conditions. The type of catalyst and the reaction conditions, including several parameters such as temperature, reactor geometry, heating rate and residence time, were evaluated, and selected combinations were tested. The bio-oil was characterized in terms of main constituents and hydrocarbons content, and GC-MS and GC-FID analyses were used to qualitatively and quantitatively assess the composition of the fuel.

Conventional and Bio-Derived Jet Fuel Surrogate Modeling in Low Temperature and Lean Combustion

Recently published chemical kinetic mechanisms are used to evaluate autoignition characteristics for conventional and alternative hydrotreated renewable jet (HRJ) fuels at low temperature and under...

Estimation of soil carbon change from rotation cropping of rapeseed with wheat in the hydrotreated renewable jet life cycle

Rapeseed is being considered as a potential feedstock for hydrotreated renewable jet (HRJ) fuel in the USA through its cultivation in rotation with wheat. The goal of this research was to determine the impact of soil C changes, induced through replacing the fallow period with rapeseed in rotation with wheat, and the effects it would have on emission of greenhouse gases (GHG) of rapeseed HRJ. The Intergovernmental Panel on Climate Change (IPCC) (Tier 1) method was used with modifications to determine the changes in soil C of wheat–wheat–rapeseed (WWR) relative to the reference wheat–wheat–fallow (WWF) rotation for 20 years of cultivation. The 27 case scenarios were conducted to study the impacts of changes in management practices (tillage practice and residue input) on changes in soil C for WWR rotation in multiple locations in 10 US states. The CO2 emissions resulting from soil C changes were incorporated into the rapeseed HRJ pathway in order to evaluate the GHG emissions. Introducing rapeseed to replace the fallow period with wheat could either increase or decrease changes in soil C, depending on management practices. Soil C is predicted to increase with increased residue input and reduced tillage. The greatest gain of soil C was found when using high residue input for wheat and rapeseed under no tillage, resulting in the best management practice. Conversely, adding low residue input to both crops with full tillage created the highest loss of soil C, referring to as the worst management practice. Soil C changes varied across locations from −0.22 to 0.32 Mg C ha−1 year−1. Consequently, the GHG emissions of rapeseed HRJ ranged from 4 to 70 g CO2 eq./MJ, comparing to 46 g CO2 eq./MJ for excluding soil C change. The rapeseed HRJ exhibited the GHG savings of 65–96 % for the best practice and 20–42 % for the worst practice when compared to petroleum jet fuel. Based on results using the modified IPCC method, adoption of high residue input with no tillage for the rotation cropping of rapeseed with wheat had the potential to increase soil C. However, the method has limitations for predicting soil C changes regarding crop management practices. Biogeochemical-based models that have a potential to capture processes of C and N dynamics in soil and yield may be better suited to quantify regional variations in soil C changes for the rotation cropping of rapeseed with wheat.

Comparison of reforming performance of JP-8 and HRJ-5 for fuel cell applications

A comparative study of fuel reformation using petroleum-based aviation jet fuel (JP-8) versus hydro-treated renewable jet fuel (HRJ-5) in an oxidative steam reforming process was performed in a single-tube reformer using a Precision Combustion, Inc. (PCI) Microlith® catalyst. The primary parameters compared during the study were reformate composition, carbon concentration in the effluent, and reforming efficiency versus catalyst temperature. This report illustrates an initial contrast between the reformation results for JP-8, a fossil fuel, as compared to HRJ-5, which is a plant-based fuel derivative. HRJ-5 showed improved fuel conversion with less carbon formation, higher reforming efficiency, and a lower catalyst operating temperature, as compared to 100% JP-8, and a 50%:50% blend of JP-8 and HRJ-5.

Application of the roundtable on sustainable biofuels method to regional differences in nitrous oxide emissions for the rapeseed hydrotreated renewable jet life cycle

Abstract Hydrotreated Renewable Jet (HRJ) fuel has increasingly become important for the aviation sector to address energy security and climate change mitigation. Rapeseed ( Brassica Napus ) is a favored candidate feedstock for HRJ because of its high quality oil content and agroeconomic benefit to replace the fallow period in wheat/fallow rotations. We conducted research to evaluate regional differences in nitrous oxide (N 2 O) emissions for rapeseed cultivation in several counties in 10 states in the United States (U.S.). The Roundtable on Sustainable Biofuels (RSB) methodology was applied, and results were compared to the Intergovernmental Panel on Climate Change (IPCC) guidelines. In this study, yield, nitrogen fertilizer rate, and types were held constant for all locations in order to understand the similarities and differences in the RSB and IPCC methods for estimating N 2 O emissions. From the results, the RSB-calculated N 2 O emissions varied for different U.S. states, though regional differences were very small, 0.72–0.73 kg N 2 O Mg −1 seed, while N 2 O emissions from IPCC method were the same for all sites, 0.87 kg N 2 O Mg −1 seed. The difference between the RSB and IPCC methods is caused by the indirect N 2 O emissions from ammonia emissions and nitrate leaching. However, the influence of indirect effect is relatively small compared to overall N 2 O emissions. The utilization of the RSB method may not be justified for estimating regional variations in N 2 O emissions. As a consequence, the preliminary greenhouse gas (GHG) of rapeseed HRJ fuel using the RSB method in several locations had small differences in result, 42.7–43.0 g CO 2 eq/MJ compared to 45.9 g CO 2 eq/MJ using the IPCC method.

Density, Viscosity, Speed of Sound, Bulk Modulus, Surface Tension, and Flash Point of Binary Mixtures of n-Dodecane with 2,2,4,6,6-Pentamethylheptane or 2,2,4,4,6,8,8-Heptamethylnonane

In this work, the physical properties of binary mixtures of n-dodecane with 2,2,4,6,6-pentamethylheptane or 2,2,4,4,6,8,8-heptamethylnonane were measured and compared to properties of four hydrotreated renewable jet (HRJ) and hydrotreated renewable diesel (HRD) fuels. Density and viscosity were measured at temperatures ranging from (293.15 to 393.15) K, and the speed of sound was measured at temperatures ranging from (293.15 to 333.15) K. For the mixtures, the speed of sound at 293.15 K decreased (1297.6 to 1285.7) m·s–1 as the mole fraction of 2,2,4,4,6,8,8-heptamethylnonane increased and decreased (1297.6 to 1203.6) m·s–1 as the mole fraction of 2,2,4,6,6-pentamethylheptane increased. The bulk modulus was calculated from density and speed of sound data. Flash points for the mixtures ranged from (318 to 367) K, and surface tension values ranged from (21.8 to 25.3) mN·m–1. When comparing to alternative fuels, two-component mixtures could be found to match the density and viscosity of HRJs and HRDs. The mixtures matched the speed of sound, bulk modulus, surface tension, and flash point of some of these hydrotreated fuels. These data suggest that binary mixtures of n-dodecane with branched alkanes may be suitable surrogates for renewable fuels.

JP-5 and HRJ-5 Autoignition Characteristics and Surrogate Modeling

A heated rapid compression machine has been used to investigate the autoignition behavior of JP-5 and camelina-based hydrotreated renewable jet (HRJ-5) fuels. Testing was conducted at low temperatures (Tc = 627–733 K), low-to-moderate pressures (pc = 5, 10, and 20 bar), and lean (ϕ = 0.25 and 0.50) and stoichiometric mixtures in air. The HRJ-5 fuel, which is 99% paraffinic, exhibited greater reactivity than the JP-5 fuel in the form of shorter ignition delays. The HRJ-5 fuel also exhibited transition into the negative temperature coefficient region at a lower compressed temperature (Tc = 675 K) than the JP-5 fuel (Tc = 700 K). Two surrogate fuel blends and kinetic models intended for Jet-A and kerosene-type fuels are evaluated for their ability to predict JP-5 ignition delay times because JP-5 and Jet-A ignition delay times showed close resemblance. The models reproduced the qualitative trend in the data, including an accurate representation of when the negative temperature coefficient behavior appears. The best agreement between the data and predictions was obtained at pc = 5 bar and ϕ = 1.0, but outside of this region, the disparity was often 2-fold or greater.

Effect of Soot Structure Evolution from Commercial Jet Engine Burning Petroleum Based JP-8 and Synthetic HRJ and FT Fuels

Soot from jet engines is relevant to environmental and health concerns. In this study, JP-8, HRJ (hydro-treated renewable jet), and FT (Fischer–Tropsch) fuels were tested in a CFM56-2C1 engine on a DC-9 aircraft. Comparisons of PM physical structure at length scales spanning aggregate to primary particle to nanostructure, all by TEM, are reported. Petroleum based JP-8 derived soot shows the nanostructure progression from amorphous to graphitic-like as a function of increasing engine power. Soots from the renewable HRJ and FT fuels exhibit significant nanostructure at each power level. Results are interpreted in terms of different soot formation regions with associated variations in temperature and local equivalence ratio. The driver for such differences is the nascent fuel composition, more specifically the different classes of components therein.

Extinction Studies of Flames of Heavy Neat Hydrocarbons and Practical Fuels

Extinction strain rates of premixed and non-premixed flames of , , a petroleum-derived JP-5 jet fuel, a camelina-derived hydrotreated renewable JP-5 jet fuel, a petroleum-derived F-76 diesel fuel, and an algae-derived hydrotreated renewable F-76 diesel fuel were measured in the counterflow configuration at atmospheric pressure and a fuel-containing stream temperature of 443 K. Recently developed kinetic models were used to simulate the experimental data for and flames. The computed results are in close agreement with the data for premixed flames, whereas the data are over-predicted for non-premixed flames. Furthermore, the extinction strain rates of premixed and flames are similar, while compared to , non-premixed flames exhibit greater extinction resistance. Regarding the practical fuels, the extinction propensity of flames of petroleum-derived fuels is higher compared to bio-derived fuels. The extinction strain rates of flames of 80% toluene mixtures were computed also to evaluate the effects of addition of aromatics on extinction. The results confirmed that the addition of toluene increases the extinction propensity compared to neat flames under both premixed and non-premixed conditions, which explains partially the experimental results for petroleum- and bio-derived practical fuels.

Ignition behavior and surrogate modeling of JP-8 and of camelina and tallow hydrotreated renewable jet fuels at low temperatures

The autoignition characteristics of the conventional jet fuel, JP-8, and the alternative jet fuels, camelina and tallow hydrotreated renewable jet (HRJ) fuels, are investigated using a rapid compression machine and the direct test chamber charge preparation approach. Ignition delay measurements are made at low compressed temperatures (625K⩽Tc⩽730K), compressed pressures of pc=5, 10, and 20bar, and equivalence ratios of ϕ=0.25, 0.5 and 1.0 in air. The HRJ fuels ignite more readily than JP-8 for all tested conditions, consistent with derived cetane number data in the literature. The camelina and tallow HRJ fuels exhibit similar autoignition characteristics, but the two fuels can be distinguished under stoichiometric conditions. Kinetic modeling is conducted with a 2-component surrogate (10% n-dodecane/90% 2-methylundecane) and a single component surrogate (2-methylnonane) to evaluate the potential to predict ignition behavior of the HRJ fuels. Modeling results indicate that the surrogate fuels can only provide useful predictions at a limited set of conditions (pc=5bar and ϕ=1.0), and that the agreement of the model and experimental data improves with decreasing compressed pressure. Under most conditions, the 2-component surrogate provides better prediction of ignition behavior, but the single component surrogate is superior at low pressures near the negative temperature coefficient region.

Flame propagation of mixtures of air with high molecular weight neat hydrocarbons and practical jet and diesel fuels

Laminar flame speeds of mixtures of air with n-C14H30, n-C16H34, a petroleum-derived JP-5 jet fuel, a camelina-derived hydrotreated renewable JP-5 jet fuel, a petroleum-derived F-76 diesel fuel, and an algae-derived hydrotreated renewable F-76 diesel fuel, were measured in the counterflow configuration at atmospheric pressure and elevated unburned mixture temperatures. Digital particle image velocimetry was used to measure the axial flow velocities along the stagnation streamline. The experiments for n-C14H30/air and n-C16H34/air mixtures were modeled using recently developed kinetic models, and the experimental data were predicted satisfactorily. Both experiments and simulations revealed that the laminar flame speeds of n-C14H30/air and n-C16H34/air mixtures are very close to each other, as expected. On the other hand, the laminar flame speeds for the four practical fuels were found to be lower than n-C14H30 and n-C16H34, due to the presence of aromatics and branched hydrocarbons. Similarly, the laminar flame speeds for the alternative fuels were found to be higher than the petroleum-derived ones, again due to the presence of aromatic compounds in the latter. Further insight into the effects of kinetics and molecular transport was obtained through sensitivity analysis.

Comprehensive chemical kinetic modeling of the oxidation of 2-methylalkanes from C 7 to C 20

Conventional petroleum jet and diesel fuels, as well as alternative Fischer–Tropsch (FT) fuels and hydrotreated renewable jet (HRJ) fuels, contain high molecular weight lightly branched alkanes (i.e., methylalkanes) and straight chain alkanes ( n-alkanes). Improving the combustion of these fuels in practical applications requires a fundamental understanding of large hydrocarbon combustion chemistry. This research project presents a detailed and reduced chemical kinetic mechanism for singly methylated iso-alkanes (i.e., 2-methylalkanes) ranging from C 7 to C 20. The mechanism also includes an updated version of our previously published C 8–C 16 n-alkanes model. The complete detailed mechanism contains approximately 7200 species 31400 reactions. The proposed model is validated against new experimental data from a variety of fundamental combustion devices including premixed and non-premixed flames, perfectly stirred reactors and shock tubes. This new model is used to show how the presence of a methyl branch affects important combustion properties such as laminar flame propagation, ignition, and species formation.

Camelina‐derived jet fuel and diesel: Sustainable advanced biofuels

AbstractRecently, an isoparaffin‐rich jet fuel derived from camelina, a low‐input nonfood oilseed crop, was flight‐tested by a commercial airline. To date, all test results indicate that this hydrotreated renewable jet fuel (HRJ) not only meets stringent engine fuel and performance specifications but also reduces environmental emissions. Several scenarios are now being considered for camelina as a sustainable feedstock for advanced biofuel production. For example, growth of camelina in the Northern Plains of the United States on either marginal lands or as a rotation crop during fallow periods on existing lands already in food crop production can avoid the conflict with food cultivation and concerns with indirect land use change impacts. Updated estimates of camelina cultivation requirements and commercial scale oil recovery and refining were used to calculate life cycle greenhouse gas (GHG) emissions and energy demand for both HRJ and renewable diesel (green diesel, GD). GHG life cycle emissions for GD and HRJ are 18.0 and 22.4 g CO2 equiv/MJ fuel, which represent savings relative to petroleum counterparts of 80% and 75%, respectively. Scenario analyses were conducted to determine response to model assumptions and data uncertainty, including allocation methodology, N fertilizer application rate, N2O emission factor, source of H2, and farm diesel consumption. © 2010 American Institute of Chemical Engineers Environ Prog, 2010