Hydroprocessed Esters And Fatty Acids Research Articles

Algae to HEFA: Economics and potential deployment in the United States

AbstractTo reach the goals set by the US Department of Energy's Sustainable Aviation Fuel (SAF) Grand Challenge, currently available feedstocks may be insufficient. Giving priority to developing, prototyping and reducing the cost of algal feedstock before investing and lining up locations is important. As the production of algal feedstocks advances, a simplified conversion approach using more mature technologies can help reduce the investment risk for algae‐based fuels. Reducing process complexity to the steps described here [namely, conversion of lipids to HEFA (hydroprocessed esters and fatty acids) fuels and relegating the remainder of the biomass to anaerobic digestion or food/feed production] enables the near‐term production of algal SAF but presents challenging economics depending on achievable cultivation costs and compositional quality. However, these economics can be improved by present‐day policy incentives. With these incentives, the modeled algae‐to‐HEFA pathway could reach a minimum fuel selling price as low as $4.7 per gasoline gallon equivalent depending on the carbon intensity reduction that can be achieved compared with petroleum. Uncertainty about algal feedstock production maturity in the current state of technology and the future will play a large role in determining the economic feasibility of building algae‐to‐HEFA facilities. For example, if immaturity increases the feedstock price by even 10%, SAF production in 2050 is about 58% of the production which could have been achieved with mature feedstock. Additionally, growth in this conversion pathway can be notably boosted through the inclusion of subsidies, and also through higher‐value coproducts or higher lipid yields beyond the scope of the process considered here.

Evaluating the Impact of Using HEFA Fuel on the Particulate Matter Emissions from a Turbine Engine

The dynamically growing sustainable aviation fuel (SAF) industry and the implemented European policy create the need for conducting research on the actual benefits of using alternative fuels in aviation. The aim of this research was to assess the impact of HEFA (hydroprocessed esters and fatty acids) fuel on the particulate matter emission indicators of an aircraft engine. This article presents the results of the measurements of particle emissions from a jet engine fueled by a blend of aviation kerosene and HEFA fuel (with HEFA content at 5%, 20%, and 30% by volume). A positive effect of HEFA on both the number and mass indices of particles was observed. The use of SAF fuel led to a reduction in the particulate number index by 90% and the particulate mass index by 75%. The Particle Number Emission Index (EIN) for an engine fueled with Jet A-1 exhibited values ranging from 5.23 × 1016 to 1.33 × 1017 particles per kilogram. The use of HEFA fuel (30% content) allowed for a reduction in the EIN to the range of 2.83 × 1015 to 1.04 × 1016 particles per kilogram. A detailed analysis of particle size distribution (PSD) for both the number and volume of particles was conducted. It was noted that neither the fuel composition nor the engine operating parameters significantly affected the shape of the PSD, but the use of HEFA fuel distinctly reduced the values of the number-based PSD. It was observed that the volume-based PSD had a bimodal shape, indicating a significant contribution of particles larger than 100 nm, forming the so-called soot mode. Our findings suggest that even a small amount of HEFA fuel yields satisfactory results in reducing particulate matter emissions.

Corelease of Genotoxic Polycyclic Aromatic Hydrocarbons and Nanoparticles from a Commercial Aircraft Jet Engine - Dependence on Fuel and Thrust.

Jet engines are important contributors to global CO2 emissions and release enormous numbers of ultrafine particles into different layers of the atmosphere. As a result, aviation emissions are affecting atmospheric chemistry and promote contrail and cloud formation with impacts on earth's radiative balance and climate. Furthermore, the corelease of nanoparticles together with carcinogenic polycyclic aromatic hydrocarbons (PAHs) affects air quality at airports. We studied exhausts of a widely used turbofan engine (CFM56-7B26) operated at five static thrust levels (idle, 7, 30, 65, and 85%) with conventional Jet A-1 fuel and a biofuel blend composed of hydro-processed esters and fatty acids (HEFA). The particles released, the chemical composition of condensable material, and the genotoxic potential of these exhausts were studied. At ground operation, particle number emissions of 3.5 and 0.5 × 1014 particles/kg fuel were observed with highest genotoxic potentials of 41300 and 8800 ng toxicity equivalents (TEQ)/kg fuel at idle and 7% thrust, respectively. Blending jet fuel with HEFA lowered PAH and particle emissions by 7-34% and 65-67% at idle and 7% thrust, respectively, indicating that the use of paraffin-rich biofuels is an effective measure to reduce the exposure of airport personnel to nanoparticles coated with genotoxic PAHs (Trojan horse effect).

Technology Route Options of China’s Sustainable Aviation Fuel: Analysis Based on the TOPSIS Method

Developing production technology pathways of sustainable aviation fuel (SAF) that align with China’s national conditions and aviation transportation needs is crucial for promoting the SAF industry and achieving China’s carbon peak and carbon neutrality goals. This article first projects the future SAF demand in China for the coming decades. Using SAF demand data as an input, this article employs the TOPSIS analysis method to comprehensively evaluate the suitability of four SAF production technology pathways at different stages of development in China, which are Hydroprocessed Esters and Fatty Acids (HEFA), Alcohol-to-Jet (AtJ), Natural Gas + Fischer–Tropsch Synthesis (G + FT), and Power-to-Liquid (PtL). The research results reveal the following trends: HEFA-based processes are the most suitable technology pathways for China in the near term; the G + FT route, based on energy crops, appears the most likely to support civil aviation needs in the medium to long term. In the long run, the PtL route holds significant potential, especially with the decreasing costs of green electricity, advancements in carbon capture, utilization, and storage (CCUS) technology, and improvements in SAF synthesis methods. In the final section of this article, we provide recommendations to drive the development of the SAF industry in China.

Different Hydrocarbon Types in Jet Fuel as Determined by GCxGC/FID - An Alternative Method to D2425

The ASTM D2425 Standard Test Method for the determination of different hydrocarbon types in middle distillates by using mass spectrometry is a required test for the certification of various sustainable (not petroleum derived) aviation fuels according to ASTM D7566. However, recent studies show that the D2425 method updated in 2019 does not provide accurate results for a synthetic paraffinic kerosene (SPK) made from hydroprocessed esters and fatty acids (HEFA). A promising alternative to the D2425 method for the analysis of different hydrocarbon types in both conventional jet fuel (Jet A-1) and SPK-HEFA type sustainable aviation fuel is presented here. The new method is based on GCxGC/FID technology. The performance of the new method is demonstrated by a validation study, which suggests that the GCxGC/FID method is rugged and selective, and it can be used to accurately quantify 12 different hydrocarbon types with a wide content range in both conventional Jet A-1 and SPK-HEFA type sustainable aviation fuel samples.

Recent Advances on Alternative Aviation Fuels/Pathways: A Critical Review

The Paris Agreement’s objectives related to climate change put aviation under great pressure and environmental inspection. In particular, the aviation industry is committed to achieving a 50% reduction in CO2 emissions by 2050 compared to 2005 levels. A shift to alternative aviation fuels seems imperative. The International Air Transport Association (IATA) has identified the production of drop-in sustainable liquid fuels (SAFs) as the most promising strategy, at least short term, to reduce the environmental impact of the sector. Within this review, a critical summary of the current alternative aviation fuels/pathways is presented and a comparative analysis of the dominant technologies is performed considering techno-economic assessment, environmental evaluation, and future projections. The impact of the ‘ReFuelEU Aviation’ initiative on the current dominant policies and market incentives is assessed. Hydroprocessed esters and fatty acids (HEFA), Fischer–Tropsch (FT) synthesis, alcohol-to-jet (AtJ) conversion, and e-fuel pathways are put under the microscope. A wide range of potential fuel selling prices (0.81–5.00 EUR/L) was observed due to the presence of multiple routes, while some pathways seem able to secure more than 90% emission savings compared to the fossil jet reference. The accelerated scale-up of SAF production is a reasonable demand for the aviation industry. The establishment of a sustainable scale-up framework and the alignment of all of the involved aviation stakeholders is an immediate challenge.

Production of transportation fuels via hydrotreating of scrap tires pyrolysis oil

The hydrotreating of scrap tires pyrolysis oil over commercial Ni-Mo/Al2O3 catalyst was researched for the best processing scheme allowing the production of high-quality alternative transportation fuels components of gasoline, jet, diesel, and marine fuel. Despite the initial high content of olefins, aromatics, sulfur, and nitrogen in pyrolysis oil, fuel components obtained by redistillation after the hydrotreating at 360 °C and 10 MPa met the majority of standard fuel specifications. Although the octane number of the naphtha fraction was lower, this fraction can be used as acomponent of the gasoline pool directly or after the catalytic reforming. Kerosene fraction can be utilized as jet fuel after the additional mild hydrotreatment or blending with hydroprocessed esters and fatty acids (HEFA) to decrease aromatics content. Diesel fraction can be blended with hydrotreated vegetable oils (HVO) to fulfill the density and cetane index specification. The bottom residue can be utilized as a low-sulfur fuel oil component in marine transportation.

Sustainable aviation fuels must control induced land use change: an integrated assessment modelling exercise for Brazil

Bio-sustainable aviation fuels (bio-SAFs) are an important pillar of the aviation sector decarbonisation strategy in the mid-term. Here we assess the induced Land-Use Change (LUC) implications of producing bio-SAFs in Brazil under different assumptions of forest conservation governance. We evaluate four bio-SAF routes via two main pathways: the Alcohol-to-Jet (ATJ) and the Hydroprocessed Esters and Fatty Acids (HEFA) syntheses. We chose the most promising agriculture-based feedstocks to produce bio-SAFs in all five macro-regions of Brazil, including sugarcane and maize ethanol to jet and palm and macaw HEFA routes. To this end, we calculated future projections of air transport demand in Brazil and used the Brazilian Land Use and Energy Systems integrated assessment model to estimate LUC greenhouse gas (GHG) emissions within five different levels of bio-SAF blends (10% to 50% of total aviation fuel demand) for each bio-SAFs evaluated. Estimated cumulated emissions vary widely, ranging from a carbon sequestration of −286.8 gCO2e.MJ−1 for a 10% blend of maize ATJ under a controlled deforestation scenario to a release of 15.0 gCO2e.MJ−1 for a 40% blend of high productivity macaw oil HEFA considering historical deforestation rates in the country. Results are highly sensitive to deforestation rate parameters, volume of bio-SAFs produced, the type of feedstock used, and methodological assumptions. Negative LUC GHG emissions were found under controlled deforestation assumptions and in low blends of bio-SAFs for maize and sugarcane ATJ routes. Under historical deforestation rates, the LUC GHG emissions are higher. Bio-SAF can be beneficial to reduce GHG emissions if effective land conservation policies are implemented. Therefore, large-scale bio-SAF production from sugar crops in Brazil may play an important role in the decarbonisation of the aviation sector if coupled with successful strategies to control deforestation. Additionally, when imposing bio-SAF demand, other biofuels demand reduces under the model optimal solution due to land restrictions.

Microfluidic-assisted toxicity studies of jet fuels on environmental microorganisms – Towards new lab-on-a-chip sensing applications

In this paper, a lab-on-a-chip (LOC) for cellular studies with software-enhanced metrological parametrisation of toxin-to-cell effects on-chip is shown. A special design of LOC is proposed herein whose performance prior to use was confirmed utilising numerical simulations based on a laminar exhaust microflow module. Model microorganisms – Euglena gracilis – were used as a bioindicator to evaluate the toxicity of jet fuels, i.e. Jet A-1 and Jet A-1 + HEFA (Hydroprocessed Esters and Fatty Acids). Apart from the biological results that show notable cell degradation for both of the fuels after 20 min of exhaust exposure (e.g. mobility decrease by 80 % and 100 % for Jet A-1 and Jet A-1 + HEFA), interesting outcomes were also obtained in an exhaust gas chromatography analysis, being in strong correlation with the observed euglena colony behaviour. The major focus was put herein on the concentration of VOCs (Volatile Organic Compounds) and BTEX (Benzene, Toluene, Ethylbenzene and Xylene isomers). Although the sum of volatile hydrocarbon compounds in the exhaust gas decreased due to the addition of HEFA-type hydrocarbons to the fuel, the concentration of the most toxic, BTEX group, was increased about two times compared to the standard Jet A-1. On that basis, our preliminary tests show that further research in this regard is required, in the context of both the toxin-to-cell impact and its direct correlation with the fuel composition.

Uncertainty in life cycle greenhouse gas emissions of sustainable aviation fuels from vegetable oils

Sustainable aviation fuel (SAF) is one of the most promising short-to medium-term term options to mitigate greenhouse gas (GHG) emissions from aviation. Life cycle assessment (LCA) is commonly used to estimate GHG emissions from SAF in comparison to fossil kerosene. While there are several studies reporting the GHG emissions from SAF, uncertainty in the results is not always addressed in a comprehensive way.In this work, GHG emissions of hydroprocessed esters and fatty acids (HEFA) fuels derived from jatropha (Jatropha curcas), pennycress (Thlaspi arvense), castor (Ricinus communis), energy tobacco (Nicotiana tabacum, Solaris) and Salicornia (Salicornia bigelovii) oils were estimated. A stochastic methodology was employed where parametric uncertainty was propagated using Monte Carlo simulations. Uncertainty due to methodological choices was incorporated through scenario analyses. Emissions from direct land use change (DLUC) and the associated uncertainty were assessed under the IPCC Tier 1 approach by considering alternative land use transitions per feedstock.Analyzed HEFA pathways provide GHG emissions benefits (34–65%) in comparison to fossil kerosene when DLUC emissions are not considered. Parametric uncertainty yields up to 26% deviation from the median well-to-wake GHG emissions. Changing the allocation choice for the oil extraction step, from the base assumption of energy-based allocation to mass- or market-based, can impact the results by up to 46%. DLUC is a more significant source of uncertainty than both parametric uncertainty and allocation assumptions in the analysis. DLUC emissions negate any GHG savings from HEFA fuels if forests or natural shrublands are lost.

Cumulative Impact of Federal and State Policy on Minimum Selling Price of Sustainable Aviation Fuel

With jet fuel consumption projected to more than double by 2050, dramatic expansion of sustainable aviation fuel (SAF) use will be essential to meeting the aviation industry goal of achieving carbon neutrality in the same time frame. However, to date, the SAF price has, in part, been responsible for the lack of widespread adoption signaling the need for strong and stable policy. Multiple pathways have been developed and received ASTM approval to convert a variety of feedstocks into SAF, each with strengths and weaknesses that vary with conversion technology, feedstock, and production location. To assist researchers and governments in understanding the role of policy on fuel pricing, a set of harmonized, techno-economic analyses (TEAs) were developed to assess three ASTM-qualified production pathways: hydroprocessed esters and fatty acids (HEFAs), alcohol to jet (ATJ), and Fischer–Tropsch (FT), with multiple feedstock options. These decision support tools were used to assess the minimum selling price (MSP) for fuel distillates. Both mature (nth) plants and first of a kind (pioneer plants) were assessed using TEAs. Existing and proposed U.S. incentives, at both the federal and state levels, were integrated into the tools to determine the impact on the MSP. Considering the existing federal policies, analysis indicated that HEFAs could achieve a SAF price that would be competitive to conventional fuels when using waste lipid feedstocks, making this the most viable near-term option. However, this feedstock for HEFAs is limited and unlikely to support the production of large quantities of SAF. After stacking federal and state programs, SAF produced using FT with municipal solid waste (MSW) has the lowest MSP, although FT forest residuals, FT agricultural residues, ATJ corn ethanol, and HEFAs using second crop oilseeds all approach the historical range of traditional jet fuel prices for nth plants. Pioneer plants are viable for only ATJ corn ethanol; however, FT-MSW is approaching price parity.

Techno-economic Analysis and Life-Cycle Analysis of Renewable Diesel Fuels Produced with Waste Feedstocks

Wet waste feedstocks represent an important category of resources that could be utilized to produce biofuels. Diversion of the wet waste resources from going through conventional waste management practices to utilization as feedstocks for energy production also benefits from avoided cost and pollutant emissions of waste management and disposal. This study investigates the economic and environmental implications of producing bioblendstocks for mixing controlled compression ignition engines from two waste-to-fuel pathways: hydroprocessed esters and fatty acids (HEFA) from yellow grease and swine manure hydrothermal liquefaction (HTL) followed by biocrude upgrading. Detailed process models were developed for both pathways, which informed the techno-economic analysis and life-cycle analysis. Conventional swine manure management practice was also modeled in detail as the business-as-usual scenario for the swine manure HTL pathway. The estimated minimum fuel selling prices were $1.22/gasoline liter equivalent (GLE) and $0.94/GLE for the yellow grease to HEFA and swine manure HTL pathways, respectively. The life-cycle greenhouse gas (GHG) emissions of the two pathways were 11.2 and −33.3 g of CO2e/MJ, respectively, for the yellow grease to HEFA and swine manure HTL pathways. The credits of avoided emissions from conventional swine manure management were the main reason for the negative GHG emissions of the swine manure HTL pathway. The marginal GHG emissions abatement costs were estimated to be $116–$270/tonne CO2e and $5–$103/tonne CO2e for the yellow grease HEFA and swine manure HTL pathways, respectively, for a diesel price ranging between $0.5/GLE and $0.9/GLE. Since the yellow grease HEFA pathway is already commercialized, it can benefit from the $200/tonne carbon credit in the California Low Carbon Fuel Standard market, which could help the yellow grease HEFA pathway to achieve near-zero marginal GHG emissions abatement cost.

Quantitative Policy Analysis for Sustainable Aviation Fuel Production Technologies

This paper quantifies the impact of different policy options on the economic viability of sustainable aviation fuel (SAF) production technologies. The pathways considered include isobutanol to jet from corn grain, hydroprocessed esters and fatty acids (HEFA) from inedible fats and oils, HEFA from palm fatty acid distillate, synthesized iso-paraffins from sugarcane, Fischer-Tropsch (FT) gasification and synthesis from municipal solid waste, and micro FT from wood residues. The policies considered include feedstock subsidies, capital grants, output based incentives, and two policies intended to reduce project risk. Stochastic techno-economic analysis models are used to quantify the policies’ impact on project net present value and minimum selling price of the middle distillate fuel products. None of the technology pathways studied are found to be financially viable without policy aid. The median total policy costs required for economic viability range from 35 to 337 million USD per production facility, or 0.07–0.71 USD/liter. Our results indicate that the cumulative impact of multiple policies, similar in magnitude to analogous real-world fuel policies, could result in economically viable SAF production.

Biojet fuel production from oleaginous crop residues: thermoeconomic, life cycle and flight performance analysis

This study assesses an integrated biorefinery model's efficiency for biojet fuel production as Jet A1 blending component through the Alcohol-to-Jet (ATJ) and Hydroprocessed Esters and Fatty Acids (HEFA) thermochemical routes, employing lignocellulosic biomass from oleaginous crops. The ATJ process involved cellulosic ethanol production through steam explosion hydrolysis, simultaneous saccharification and co-fermentation. The anhydrous ethanol was sequentially dehydrated, oligomerized, and hydrotreated. On the other hand, the HEFA process upgraded vegetable oil from residues and fatty acid distillates. The vegetable oil was thermally hydrolyzed, decarboxylated and hydrotreated. The models were simulated in AspenPlus® v.11, achieving a specific biojet fuel production of 48 wt% for the ATJ and 87 wt% for the HEFA. In both cases, a biojet fuel mixture primarily composed of C9 to C12 isoalkanes was produced. The minimum selling price ranged between 1.01 €/kg to 1.43 €/kg. The studied routes were evaluated through exergetic and thermoeconomic analyses for optimizing. The life cycle assessment was carried out in SimaPro® v.9.0. The estimated net GHG emissions were 75 gCO2eq/MJ for the ATJ and 18 gCO2eq/MJ for the HEFA; nevertheless, significant improvements were achieved from by-product displacement credits. In both cases, the GHG emissions are under those from petroleum-derived Jet A1 production. Finally, the physico-chemical properties fulfilled the ASTM D7566 specifications, and the calculated payload vs range showed a better performance for an intermediate-range flight.

Analysis of the EU Secondary Biomass Availability and Conversion Processes to Produce Advanced Biofuels: Use of Existing Databases for Assessing a Metric Evaluation for the 2025 Perspective

Nowadays in Europe, the production of advanced biofuels represents a very important objective, given the strong interest in increasing sustainability throughout the transport sector. Production and availability of advanced biofuels are cited as a relevant issue in the most important international actions, such as the Sustainable Development Goals in UN Agenda 2030, EU RED II, and EU Mission Innovation 4, to cite a few of them. However, an important aspect to be considered is the prediction of feedstocks availability to produce advanced biofuel. The first aim of this paper is to assess the availability of European agricultural residues, forestry residues, and biogenic wastes in 2025. The data were collected through a deep review on open FAOSTAT and EUROSTAT databases and then elaborated by the authors. The analysis focuses on the fraction of feedstocks that can be used for advanced biofuels production, i.e., incorporating specific information on sustainable management practices, competitive uses, and environmental risks to preserve soil quality. An autoregressive model is developed to predict future availability, while also considering corrections due to the current pandemic. The results suggest that several European countries could produce enough sustainable advanced feedstocks to meet the European binding target. In particular, France, Germany, and Romania will have high production of agricultural feedstocks; while Austria, Finland, and Sweden will be rich of forestry residues; finally, Italy, France, and United Kingdom will have the highest availability of wastes. To complete the picture, a proper metric is introduced, aiming at generating a technology ranking of the examined alternative fuels, in terms of several relevant parameters such as biomass availability, Technology Readiness Level (TRL), quality of the biofuel, and costs. This analysis allows us to compare advanced biofuels and first-generation biofuels, whose utilization can impact the food market, while also contributing to the increase in the indirect land use change (ILUC). Although the first-generation biofuels remain the most common choice, the renewable (or green) diesel, pyrolysis bio-oil, green jet fuel, and the second-generation bioethanol are promising for different applications in the transport sector. Hydrotreated Vegetable Oils (HVO), Hydroprocessed Esters and Fatty Acids (HEFA), Anaerobic Digestion (AD), and transesterification from vegetable oil represent the most widespread and mature technologies. Thus, it seems mandatory that the transport sector will rely more and more on such fuels in the future. For such reason, a specific support for advanced biomass collection, as well as specific programs for conversion technologies development, are strongly suggested.

Combustion kinetics of alternative jet fuels, Part-I: Experimental flow reactor study

A comprehensive collection of technical aviation fuels enabled an experimental and numerical study on detailed combustion chemistry and pollutant formation presented in a series of 3 interlinking parts. Part-I: Experimental Flow Reactor Study focuses on the characterization of 42 technical jet fuels and provides experimental speciation data for model development presented in Part-II: Model and Surrogate Strategy. Model validation based on the presented technical fuels here is presented in Part-III: Model Application on Technical Jet Fuels.The fuels investigated in this study cover a broad range of approved SAFs (Sustainable Aviation Fuels), candidates for approval, and technical products outside the present ASTM-D7566 specification and is completed by reference fuels (ASTM-D1655). This includes SAF components such as HEFA (Hydroprocessed Esters and Fatty Acids), ATJ (Alcohol-To-Jet), SIP (Synthesized Iso-Paraffins), and Fischer-Tropsch-products as well as their blends.A systematic investigation of the soot precursor chemistry by analyzing the influence of the complex chemical fuel composition on the intermediate species pool is presented. The experimental set-up consists of an atmospheric flow reactor with coupled molecular-beam mass spectrometer (MBMS). Quantitative evolution of combustion reaction intermediates is recorded for fuel-rich (Φ = 1.2) and fuel-lean (Φ = 0.8) conditions at intermediate temperatures up to 1200 K including small intermediate species (e.g. ethylene, butene) and soot precursor species (e.g. benzene, naphthalene, phenanthrene).A general systematic dependency of the soot precursor concentration on the degree of unsaturation (Index of Hydrogen Deficiency) or the hydrogen content, respectively, is demonstrated. Furthermore, larger soot precursor concentrations depend on the naphthalene content of the fuel.

Process simulation and techno-economic assessment of Salicornia sp. based jet fuel refinery through Hermetia illucens sugars-to-lipids conversion and HEFA route

Succulent halophyte Salicornia sp. was characterized to evaluate its suitability for biorefinery, as soil salinization is seen as a major agricultural issue and the demand for biofuel is increasing. Green fractionation of biomass approach was chosen, with liquid and solid fractions of the biomass considered separately. Soxhlet extractions were used to separate different biochemical groups from the pulp, and the lignocellulosic residue was hydrothermally pretreated, enzymatically hydrolyzed, mixed with an existing agricultural feedstock, and fed to black soldier fly larvae (BSFL) for sugars-to-lipids conversion. The ASTM approved route of hydroprocessed esters and fatty acids (HEFA) was applied using in silico study of processing BSFL lipids to sustainable jet fuel, using SuperPro Designer and Aspen HYSYS. Simulations and techno-economic assessment showed, with the applied process routes, inputs and production rates, the biorefinery process will be profitable in 7 years, with a biomass input flow rate of over 60 ton h−1Salicornia sp. with decreasing payback time as the biomass input flow rate increases. Therefore, Salicornia sp. feedstock and sugars-to-lipids conversion method for biorefinery and liquid fuel production can function as a feasible biorefinery process with a normalized CO2-e reduction of HEFA-SPK of 95.5% compared to similar fossil fuels.

Performance and Emissions of a Microturbine and Turbofan Powered by Alternative Fuels

Alternative fuels containing biocomponents produced in various technologies are introduced in aviation to reduce its carbon footprint but there is little data describing their impact on the performance and emissions of engines. The purpose of the work is to compare the performance and gas emissions produced from two different jet engines—the GTM-140 microturbine and the full-size DGEN380 turbofan, powered by blends of Jet A-1 and one of two biocomponents: (1) Alcohol-to-Jet (ATJ) and (2) Hydroprocessed Esters and Fatty Acids (HEFA) produced from used cooking oil (UCO) in various concentrations. The acquired data will be used to develop an engine emissivity model to predict gas emissions. Blends of the mineral fuel with synthetic components were prepared in various concentrations, and their physicochemical parameters were examined in the laboratory. Measurements of emissions from both engines were carried out in selected operating points using the Semtech DS gaseous analyzer and the EEPS spectrometer. The impact of tested blends on engine operating parameters is limited, and their use does not carry the risk of a significant decrease in aircraft performance or increase in fuel consumption. Increasing the content of biocomponents causes a noticeable rise in the emission of CO and slight increase for some other gasses (HC and NOx), which should not, however, worsen the working conditions of the ground personnel. This implies that there are no contraindications against using tested blends for fuelling gas-turbine engines.

Strategic assessment of sustainable aviation fuel production technologies: Yield improvement and cost reduction opportunities

The aviation industry has been studying strategies to produce sustainable aviation fuels (SAF) for over ten years. Our objective is to conduct detailed techno-economic analyses (TEA) of six SAF production technologies and to develop a simplified cost estimation method. Triglyceride based Hydroprocessed esters and fatty acids (HEFA) was compared against five lignocellulose-based technologies using standardized criteria. TEA was conducted to determine minimum fuel selling price (MFSP). The base case annual product capacity was fixed at 60 million liters of total fuel, for which SAF MFSPs ranged from 0.88 to 3.86 $ L−1 of fuel. Triglyceride-based HEFA had the best economic performance. Although triglycerides are more expensive than lignocellulose, HEFA is still a very competitive technology due to its high fuel yield (86–91% of feedstock) and low MFSP. Lignocellulosic-based technologies have lower fuel yields (9–23% of feedstock) due to high oxygen content of initial feedstock, resulting in higher fuel cost per unit of fuel. In order to reach a market fuel price, SAF yields from lignocellulosic materials needs to achieve an estimated value of 60%. Such yields are only possible if carbon efficiencies are close to 100%. Therefore, efforts are needed to avoid the removal of oxygen as CO2. Based on these considerations, a new scheme is proposed for SAF production that could result in yields near those needed to achieve cost targets. This proposed integrated biomass/natural gas hybridized concepts to produce inexpensive SAFs should be thoroughly investigated in future work.

Comparison of three different analytical protocols for 2019 updated D2425 method for renewable jet fuel product certification analysis

ASTM standard specification D7566 covers the manufacture of synthetic aviation turbine fuel components and their blends with conventional Jet fuel (Jet A or Jet A-1). One of the components is renewable jet fuel (RJF) which is synthetic paraffinic kerosene (SPK) made from hydroprocessed esters and fatty acids (HEFA). The specification D7566 dictates property requirements for the SPK-HEFA, including concentration limits for selected hydrocarbon types (paraffins, cycloparaffins, and aromatics), which are analyzed by using the mass spectrometry (MS) based standard method D2425. The most recent update for D2425 released in 2019 includes the synthetic hydrocarbon sample type (e.g., SPK-HEFA) and defines various analytical procedures for the analysis. Notably, the procedures differ considerably from each other, and the experimental conditions are not defined in details. This leads to laboratories setting up analytical schemes for D2425 that are likely to differ from each other, which may result in variation in the quality of the results obtained in different laboratories.In the present study, the performances of D2425 analytical protocols set up by three laboratories were tested in certification analysis (D7566) of SPK-HEFA type RJF. The tested analytical protocols were proven to comply with the requirements of the 2019 version of the D2425 standard. Furthermore, the precisions of the protocols did not differ significantly from each other. However, a significant bias was found for the results obtained for cycloparaffins and aromatics. Further, considerable differences were found in the bias values between the laboratories. Based on the results of this study, the guidelines of the 2019 updated D2425 standard may result in setting up an analytical protocol for D2425 which may not be optimal for RJF certification.