Aviation Biofuels Research Articles

Innovation towards sustainable technologies: A socio-technical perspective on accelerating transition to aviation biofuel

The global market based measure (MBM) for international flight emissions is poised for launch in 2020, creating additional pressure for improvements of aviation environmental performance. Due to high R&D costs and long lifecycle of aircrafts, drop-in biofuels stand as a promising solution for addressing aviation's environmental sustainability. The transition to commercial aviation biofuels remains stagnant, however, despite the continuing progress made in overcoming technological and economic challenges of aviation biofuels. This paper investigates the key barriers and opportunities for biofuels transition from a comprehensive socio-technical standpoint. A multi-level perspective (MLP) system dynamics model of aviation biofuel industry is developed to investigate the adoption process. We assess the interactive mechanisms between existing regimes, landscape pressures, and niche innovations, and propose four possible scenarios of aviation biofuel adoption. From this, we provide policy recommendations and industry level strategies for accelerating the transition to aviation biofuels that balance environmental sustainability and economic benefits.

The effect of alternative fuels on gaseous and particulate matter (PM) emission performance in an auxiliary power unit (APU)

ABSTRACTThere is a growing interest in the use of alternative fuels in gas turbine engines to reduce emissions. Testing of alternative fuels is expensive when done on a large-scale gas turbine engine. In this study, a re-commissioned small gas turbine auxiliary power unit (APU) has been used to test various blends of Jet A-1, synthetic paraffinic kerosene (SPK) and diesel with as well as eight other novel fuels. A detailed analysis of performance, gaseous emissions and particulate emissions has been presented in this study. It is observed that aromatic content in general as well as the particular chemical composition of the aromatic compound plays a vital role in particulate emissions generation. SPK fuel shows substantially lower particulate emissions with respect to Jet A. However, not all the species of aromatics negatively impact particulate emissions. Gaseous emissions measured are comparable for all the fuels tested in this study.

바이오항공유의 함량 변화에 따른 점화지연특성 분석

바이오항공유의 함량 변화에 따른 점화지연특성 분석

Stakeholder signalling and strategic niche management: The case of aviation biokerosene

This paper explores a case of reputation and stakeholder management in sustainability transitions. We use the case of aviation biofuel (biokerosene) to explore the complications around signalling in strategic niche management processes. Biokerosene is currently supplied at several Scandinavian airports in a low percentage blend, either as standard or upon request, although trials suggest that modern jet engines can reliably handle much higher percentage blends. Airlines, airports and biokerosene suppliers cooperate in a process of mutual strategic positioning that supports confidence-building and market development, while at the same time being intended to encourage positive stakeholder perceptions. A key challenge for the sector, however, is that signalling biokerosene as a response to aviation-related climate emissions is complicated by mixed societal perceptions of biofuel sustainability; and the policy and material conditions for affordable, sustainable, large scale supply of biofuel are lacking. Thus while parts of the sector would like to more clearly signal the value of existing and greater biokerosene use, interrelationships between reputational risks, supply constraints and economics limit this. By bringing stakeholder management theory to strategic niche management, we present a view of the latter as in part reputationally driven, in response to the uncertain legitimacy of a technology at an early stage in its market development.

High-Performance Jet Fuels Derived from Bio-Based Alkenes by Iron-Catalyzed [2+2] Cycloaddition.

A series of high-performance cycloparaffinic fuels have been generated by [2+2] cycloaddition of the bio-derived alkenes 1-hexene, isoprene, and 1-pentene, catalyzed by a low-valent iron pyridine(diimine) complex [(Me PDI)Fe(N2 )2 (μ-N2 )] [Me PDI=N,N'-(2,6-pyridinediyldiethylidyne)bis(2,6-dimethylbenzenamine)]. Reactions with 1-pentene and 1-hexene resulted in 85 % selectivity to 1,2-cyclobutanes, and 12 % selectivity to acyclic alkenes generated by β-hydride elimination. Self-dimerization of isoprene was sluggish and generated heavier oligomer products, but cross-dimerization of isoprene with 1-hexene afforded primarily a 1,3-cyclobutane product, along with isomers of acyclic C11 mixed dimers. Hydrocarbon mixtures were hydrogenated and fractionally distilled to yield finished fuel mixtures in overall yields of 83-93 % at the multigram scale. The fuels exhibited densities ranging between 0.767 and 0.783 g mL-1 , and net heats of combustion (NHOC) of up to 120.6 kBtu gal-1 (43.8 MJ kg-1 ). These values are higher than conventional synthetic paraffinic kerosenes owing to the higher density and ring strain afforded by the cyclobutane rings. The fuel mixtures also exhibited extremely low viscosities ranging from 2.38 to 4.78 mm2 s-1 at -20 °C, due in part to the presence of the acyclic dimers. The excellent fuel properties of the product mixtures, selectivity for dimer products, high yields, and the ability to use simple bio-derived alkenes as substrates, make the [Fe]-catalyzed [2+2] cycloaddition of unactivated alkenes a compelling route to the synthesis of sustainable high-performance fuels.

Integrated catalytic conversion of waste triglycerides to liquid hydrocarbons for aviation biofuels

Deoxygenation and molecular structural modification is a critical step before the practical application of triglycerides in aviation biofuels. For low quality waste triglycerides with high viscosity, traditional way of direct hydrogenation usually has problems such as catalyst deactivation and pipe clogging. Herein, we demonstrate a facile catalytic biorefinery process for high viscosity waste triglycerides for the production of aviation biofuels via a two-step catalytic conversion. Several typical plant oils (soybean and rubber seed oils) and waste triglycerides (waste cooking and acidified plant oils) are tested, which indicate that this approach is widely applicable, and can be used to produce aviation range products, linear hydrocarbons, at high yields (55%–60%), accompanied by a diesel range fuel of 15%–40% by adjusting the operation parameters. The aviation range hydrocarbons are further catalyzed by an Ni/ZSM-5 catalyst to achieve aromatization and hydrogenation in a one-pot synthesis. Three dominant components existing in aviation fuels, including chain hydrocarbons, aromatics and cycloalkanes, can be obtained, which present the same physical-chemical properties and components as petroleum-based aviation fuels. The proportion of the three main components can be modified by the amount of molecular sieve catalyst and the initial pressure of H2, in order to meet the requirements of variable-grade aviation fuels. Overall, a catalytic refining process of decarboxylation and molecular structural modification of low quality waste triglycerides for the entire/total substitution of petroleum aviation fuels from waste triglyceride is reported.

Contributing to a European Bioenergy Trade Strategy for 2020 and Beyond

Modern bioenergy was recently called the “overlooked giant of the renewable energy field,” by Dr Fatih Birol, the IEA's Executive Director. It's latest market forecast shows that modern bioenergy will likely have the biggest growth in renewable resources between 2018 and 2023, underscoring its critical role in building a robust renewable portfolio and ensuring a more secure and sustainable energy system. Part of the recent growth of modern bioenergy was made possible by international trade of biomass for energy – which has increased strongly in the past two decades. As shown in this issue, about 2% of all bioenergy used nowadays is traded internationally - prominent examples are wood pellets, ethanol and biodiesel, which are all shipped across the globe. This trade is typically occurring between regions with an abundant supply of biomass (such as Canada, the US and Brazil), and regions with a demand for the resources to meet renewable energy targets, e.g. for electricity production or transport fuels. Biomass trade has been able to mobilize under-utilized biomass resources in many parts of the world, often also enabling local use as well once the supply chains are in place. But biomass trade has also been facing a number of challenges: logistic chains need to be set up and optimized, biomass markets are often still in their infancy due to a lack of fungible products, and international sustainability governance frameworks have to be implemented and monitored. This special issue bundles key insights from two major projects who have looked at these challenges in detail. The main aim of the BioTrade2020plus project was to provide guidelines for the development of a European Bioenergy Trade Strategy for 2020 and beyond. It contributed to strategies to ensure that imported biomass feedstock is sustainably sourced and used in an efficient way, while avoiding distortion of other markets. The work carried out included an analysis of the sustainability risks of current and future lignocellulosic biomass and bioenergy carriers for potential sourcing regions, such as the US, Ukraine, Brazil, Eastern Africa, Colombia and Indonesia. The BioTrade2020plus was supported by the Intelligent Energy for Europe Programme of the European Commission. IEA Bioenergy Task 40, part of the IEA Bioenergy Technology Collaboration Programme, has been looking at biomass trade related issues since 2004, publishing amongst others market overviews of e.g. wood pellets, waste wood, wood chips and liquid biofuels, investigating the performance of logistic chains, and working on different ways to ensure the development of sustainable biomass supply chains. The contributions to this special issue show amongst others that there are substantial volumes of sustainable biomass that may still be mobilized in the years to come, but this will require significant efforts. Practical challenges ahead include further developing cost-efficient logistic chains to mobilize difficult resources such as sugarcane straw or empty fruit bunches, and at the same time further improving the GHG performance of supply chains to meet the new ambitious sustainability targets as set under the Renewable Energy Directive 2. More fundamentally, trade of biomass commodities needs to be part of the strategy to integrate bioenergy in the circular bioeconomy, making sure that trade and deployment of bioenergy go hand in hand with achieving SDGs and other policy goals. Looking ahead, it is likely that biomass trade will further increase, driven by new demand, e.g. for biorefineries, to produce biobased chemicals and fuels for the maritime and aviation sectors, but also to replace coal for electricity production in e.g. East Asia. Possibly, this will also mean new ways of trading biomass commodities – the first signs of emerging trade of e.g. aviation biofuels and biomethane are already visible. Long-term forecasts by integrated assessment models show that by 2050, globally-traded biomass volumes might (have to) increase to a size similar to the current trade of fossil fuels in order to make supply and demand meet. But such scenarios can only unfold if they are supported by a wide range of stakeholders and if the challenges sketched above are met. With this special issue, we hope to make a contribution laying out options how this can be achieved. Author: Martin Junginger Contact: H.M.Junginger@uu.nl

Hydrodeoxygenation and hydrocracking of microalgae biodiesel to produce jet biofuel over H3PW12O40-Ni/hierarchical mesoporous zeolite Y catalyst

To improve jet biofuel quality with increased iso-alkane content, a bi-functional catalyst with strong acidity was proposed to promote hydrodeoxygenation and hydrocracking of microalgae biodiesel through loading heteropoly acid H3PW12O40 (HPW) on Ni-based hierarchical mesoporous zeolite Y (meso-Y). It was found by quantum chemistry calculation that hydrodeoxygenation process of microalgae biodiesel was inclined to the decarboxylation pathway other than the decarbonylation pathway, because the total enthalpy of pentadecane and byproducts obtained through decarboxylation of methyl palmitate (C16:0) was lower by 187.7 kJ/mol than that through decarbonylation. The selectivities of hydrocracking products with odd carbons (2n − 1, n = 5, 6, 7, 8) were higher than those with even carbons (2n), because the covalent bonds hydrocracked to remove even carbons were 0.001–0.149% longer in bond length and 0.012–1.697% lower in bond order than those hydrocracked to remove odd carbons. The experimental results of hydrodeoxygenation and hydrocracking conversion of microalgae biodiesel into jet biofuel carried out in a fixed bed reaction system agreed well with the quantum chemistry calculation results. The BET surface area of 10% Ni/meso-Y catalyst loaded with 4% HPW decreased by 14.3% to 453.9 m2/g, but its strong acid density increased by 30.6% to 1.62 mmol/g. Accordingly, the selectivity of jet biofuel in liquid products converted from microalgae biodiesel at 255 °C and 2 MPa hydrogen increased to 63.1%, in which iso-alkane selectivity markedly increased to 20.5% and arene selectivity was reasonable at 11.1%.

Production of jet fuel and green diesel range biohydrocarbons by hydroprocessing of soybean oil over niobium phosphate catalyst

Drop-in biofuels are non-oxygenated biofuels composed by biohydrocarbons produced from different biomass. These drop-in biofuels (biogasoline, bio jet-fuel and green diesel) show a great importance due to their properties similar to those observed for fossil fuels. Lipids are one of the most important raw material used for deoxygenation reactions over special catalysts. In this work, niobium phosphate was investigated as catalyst in the production of drop-in biofuels from soybean oil, using mild experimental conditions. The performance of niobium phosphate was evaluated under different reaction time (3–5 h), catalyst amount (0–25%) and temperature (300–350 °C), using 10 bar H2. The composition of the liquid products was determined by gas chromatography coupled with mass spectrometry, and characterized by infrared spectroscopy. The optimization process led to high yields of hydrocarbons in the range of C9–C17. About 62% of bio-jet fuel, 40% of green diesel, and 18% of gasoline range hydrocarbons were obtained in a single reaction step. Their composition included mainly linear and branched alkanes as well as aromatics compounds. The pathways for the involved reactions are discussed.

Greenhouse gas abatement optimal deployment of biofuels from crops in Germany

The optimal role of biofuels from energy crops for greenhouse gas (GHG) abatement in the German transport sectors is investigated under different progressive long-term scenarios, from a set arable land area corresponding to current use. The sectors included are land passenger and goods transport, shipping and aviation. The GHG abatement from the same land area can be increased by a factor of five through switching to higher yielding biofuel options. Silage maize based biomethane and wood based Synthetic Natural Gas (SNG), in either gaseous or liquefied form are the options with the highest GHG abatement potential per arable land unit, and thus markets where such fuels are an option should be prioritised. Sector fuel restrictions combined with fuel yields resulted in the land passenger sector to be the first priority for maximising GHG abatement, followed by land goods transport, shipping and finally aviation. Only when the previous sectors have been covered by renewable options do the following become relevant and thus a large transition is required before aviation biofuels or any liquid advanced biofuel become the climate optimal use of biomass. Applying admixture quotas to sub-sectors yields a lower GHG abatement than an optimal strategy.

Competitive conversion pathways of methyl palmitate to produce jet biofuel over Ni/desilicated meso-Y zeolite catalyst

To clarify the conversion mechanism of methyl palmitate (C16:0) to produce jet biofuel over Ni/desilicated meso-Y zeolite catalyst, quantum chemistry calculation and verification experiments were conducted to evaluate three proposed competitive reaction pathways, in which hydrodecarboxylation pathway was more feasible than hydrogenolysis and decarboxylation pathways. It was found that overall enthalpy change to produce pentadecane (−130.2 kJ/mol) in hydrodecarboxylation pathway was lower than that to produce palmitic acid (−90.1 kJ/mol) in hydrogenolysis pathway and that to produce hexadecane (−68.6 kJ/mol) in decarboxylation pathway. The experimental results of hydrodeoxygenation and hydrocracking conversion of methyl palmitate into jet biofuel were consistent with quantum chemistry calculation, when conventional Y zeolite was modified into hierarchical mesoporous Y zeolite catalyst by desilication with NaOH and then loading Ni nanoparticles. The jet biofuel product selectivity reached a peak (64.8%) with reasonable composition distributions, when Ni/meso-Y zeolite was desilicated with 0.4 M NaOH to promote BET surface area (554.9 m2/g) and specific pore volume (0.340 cm3/g) with 2–10 nm mesopores. The relative content of pentadecane in liquid products was always higher than those of palmitic acid and hexadecane over Ni/meso-Y zeolite catalysts desilicated with various concentrations of NaOH. The main compositions of gas phase by-products in hydrodeoxygenation and hydrocracking conversion were CH4 with selectivity up to 25.2% and CO2 with selectivity of ∼10%, which agreed well with quantum chemistry calculation results.

Preparation of Palm Fatty Acid Distillate (PFAD) As Raw Material for Bio Aviation Fuel Production

Nowadays, aviation sector became one of the most important transportation in the world. The demand in this sector has increased rapidly over the last 10 years. Unfortunately, the increase of the demand leads to an increase of fuel consumption and CO2 emission in the aviation’s sector. Bio-based aviation fuel is believed to be one of the solution for the reduction of CO2 emission in the aviation’s sector. Palm Fatty Acid Distillate (PFAD) which is a by product of palm oil refinery, contains a high amount of free fatty acids. The free fatty acids contained in the PFAD are able to be converted into straight hydrocarbon chain through decarboxylation process. This thesis conducted 3 different experiments to find out the best decarboxylation reaction’s condition to convert the FFA into straight chain hydrocarbons over an activated carbon catalyst. The experiments compared the results between the experiment with different reaction’s conditions and the presence of solvent in the reaction. The results have shown that the third experiment, which used heptane as solvent and hydrogen in argon gas as reaction’s environment, has the best reaction’s condition among others. Experiment 3 has converted 77.07% of the FFA, while experiment 2 and 1 only converted 58.37% and 16.30% respectively.

Exploring the emergence of a biojet fuel supply chain in Brazil: An agent‐based modeling approach

AbstractThe aviation industry accounts for more than 2% of global CO2 emissions. Biojet fuel is expected to make an essential contribution to the decarbonization of the aviation sector. Brazil is seen as a key player in developing sustainable aviation biofuels owing to its long‐standing experience with biofuels. Nevertheless, a clear understanding of what policies may be conducive to the emergence of a biojet fuel supply chain is lacking. We extended a spatially explicit agent‐based model to explore the emergence of a biojet fuel supply chain from the existing sugarcane–ethanol supply chain. The model accounts for new policies (feed‐in tariff and capital investment subsidy) and new considerations into the decision making about production and investment in processing capacity. We found that in a tax‐free gasoline regime, a feed‐in tariff above 3 R$/L stimulates the production of biojet fuel. At higher levels of gasoline taxation (i.e., 2.46 R$/L), however, any feed‐in tariff is insufficient to ensure the production of biojet fuel. Thus, at these levels of gasoline taxation, it is needed to introduce regulations on the production of biojet fuel to ensure its production. Given the current debate about the future direction of the biofuel policy in Brazil, we recommend further research into the effect of market mechanisms based on greenhouse gas emissions on the emergence of a Brazilian biojet fuel supply chain.

Evaluation of Brassica carinata meal on ruminant metabolism and apparent total tract digestibility of nutrients in beef steers1,2.

Brassica carinata is a new oilseed crop with the potential of producing high-quality jet biofuel. A high-protein meal (~40% crude protein) is obtained as a byproduct of hexane-solvent oil extraction; however, limited research is available on the use of this meal as a protein supplement for beef cattle. A duplicated 4 × 4 Latin square design was used to determine the effects of supplementation with B. carinata meal on ruminal fermentation, digestibility, and blood metabolites in beef cattle consuming bahiagrass hay (Paspalum notatum Flüggé), compared with frequently used protein supplements. Eight Angus crossbred steers (473 ± 119 kg initial BW) were randomly allocated to 8 pens, over 4 periods of 28-d each. Within period, steers were assigned to 1 of 4 treatments: 1) 1.62 kg/d cottonseed meal (CSM); 2) 2.15 kg/d dry distillers grains plus solubles (DDGS); 3) 1.39 kg/d B. carinata meal pellets (BCM); or 4) 1.17 kg/d soybean meal (SBM), supplemented daily, on an isonitrogenous basis. Steers had ad libitum access to bahiagrass hay and water. Intake was measured using the GrowSafe system. Following a 14-d adaptation, feed and fecal samples were collected to determine apparent total tract nutrient digestibility using indigestible NDF as an internal marker. Blood and ruminal fluid samples were collected before providing the protein supplements and then every 3 h, during a 24-h period, to analyze urea nitrogen (PUN) and glucose in plasma, as well as ruminal pH, ammonia nitrogen (NH3-N), and VFA concentrations. Data were analyzed using PROC MIXED of SAS with repeated measures. Model included the fixed effects of treatment, time, treatment × time, square, and period, and the random effects of steer(square) and steer(treatment). No effect of treatment (P > 0.05) was observed for pH, NH3-N, or glucose concentration. An effect of treatment (P < 0.01) was observed for PUN, with steers receiving SBM having greater concentrations. A treatment × time interaction was observed (P < 0.05) for total VFA concentration, acetate to propionate ratio, and molar proportions of acetate, propionate, butyrate, and valerate. Steers consuming SBM had greater molar proportions of branched-chain VFA (P < 0.01) compared with CSM and DDGS. There was no effect of treatment (P > 0.05) on intake or apparent total tract digestibility of nutrients. Brassica carinata performed similarly to commonly used protein supplements indicating its viability as a protein supplement for beef cattle.

Genetic parameters and simultaneous selection for adaptability and stability of macaw palm

Macaw palm is a potential raw material for biodiesel production due to its high oil yield that being able used as aviation biofuels. However, the species is still under domestication in Brazil, which requires accurate selection strategies to obtain superior genotypes. This work aimed to estimate genetic parameters and select macaw palm progenies for yield, adaptability, and stability, via mixed models. Fifteen half-sib progenies of macaw palm were evaluated at the juvenile stage, considering a randomized block design, with five replications and three plants per plot, spaced at 5 x 5 m. The following traits were evaluated: plant height, canopy projection in the row, canopy projection between rows, stem diameter, and fruit yield. The genetic parameters were estimated by the mixed models' methodology (REML/BLUP). The selection of the promising genotypes was based on the HMRPGV method and consisted of three strategies: i) mean performance in all environments (without interaction effect), ii) performance of genotypes in each environment with the mean of the effect of interaction, both based on the predicted genetic value, and (iii) simultaneous selection for yield, stability (HMGV), and adaptability (RPGV). Heritability estimates indicated the possibility of the successful selection of promising genotypes. Progenies CPAC-012, CPAC-01, CPAC-05, CPAC-03, Accession-280, CPAC-07, and EPAMIG-1 stood out, considering simultaneous selection for yield, stability, and adaptability. The statistics HMGV, RPGV, and HMRPGV presented the same genotype ordering and therefore are promising methodologies for the selection of macaw palm genotypes.

Airport management perspectives on aviation biofuels: drivers, barriers, and policy requirements in the US Pacific Northwest

This study explores perspectives of airport management on aviation biofuels in the Pacific Northwest of the USA by administering an online survey of airport managers in FAA certified airports in the region. Respondents provided their opinions on factors important for sustainable aviation fuel (SAF) development in the Pacific Northwest, including perceptions of various potential drivers and barriers to scale-up in the region. Most respondents indicated that policy certainty to attract capital, higher oil prices, and technology breakthroughs are required for a viable industry, and they also indicated that government intervention is important to ensure successful adoption and implementation. Respondents indicated that aviation biofuel tax credits, a system to issue and trade sustainable biofuel certificates, and fuel sustainability certification criteria are required policies/protocol to ensure viability. We suggest that a regional approach to examining barriers, drivers, and policy requirements provides more nuanced perspectives regarding key SAF development and scale-up issues.

Airport management perspectives on aviation biofuels: drivers, barriers, and policy requirements in the US Pacific Northwest

Airport management perspectives on aviation biofuels: drivers, barriers, and policy requirements in the US Pacific Northwest

What factors predict a consumer's support of environmental sustainability in aviation A multi-model analysis

Environmental sustainability remains a focal point of current research in the aviation industry. The purpose of the current study was to create four statistical models which could predict the types of factors that would indicate a consumer's support for the use of sustainable products in the aviation industry. Four models were proposed: overall support for sustainability in aviation, support for the use of aviation biofuels, support of sustainable construction materials in aviation, and support of sustainable aviation manufacturing. The study used an overall sample of 514 participants who were randomly divided into two separate datasets. The first dataset was used to produce the regression equations and the second dataset was used to assess model fit. The results produced four valid models with the amount of variance explained ranging from 29.0% to 41.1%. Perceived value of sustainability was found to be a significant predictor in all four models.

Impacts of prescribed fires and benefits from their reduction for air quality, health, and visibility in the Pacific Northwest of the United States

ABSTRACTUsing a WRF-SMOKE-CMAQ modeling framework, we investigate the impacts of smoke from prescribed fires on model performance, regional and loc al air quality, health impacts, and visibility in protected natural environments using three different prescribed fire emission scenarios: 100% fire, no fire, and 30% fire. The 30% fire case reflects a 70% reduction in fire activities due to harvesting of logging residues for use as a feedstock for a potential aviation biofuel supply chain. Overall model performance improves for several performance metrics when fire emissions are included, especially for organic carbon, irrespective of the model goals and criteria used. This effect on model performance is more pronounced for the rural and remote IMPROVE sites for organic carbon and total PM2.5. A reduction in prescribed fire emissions (30% fire case) results in significant improvement in air quality in areas in western Oregon, northern Idaho, and western Montana, where most prescribed fires occur. Prescribed burning contributes to visibility impairment, and a relatively large portion of protected class I areas will benefit from a reduced emission scenario. For the haziest 20% days, prescribed burning is an important source of visibility impairment, and approximately 50% of IMPROVE sites in the model domain show a significant improvement in visibility for the reduced fire case. Using BenMAP, a health impact assessment tool, we show that several hundred additional deaths, several thousand upper and lower respiratory symptom cases, several hundred bronchitis cases, and more than 35,000 workday losses can be attributed to prescribed fires, and these health impacts decrease by 25–30% when a 30% fire emission scenario is considered.Implications: This study assesses the potential regional and local air quality, public health, and visibility impacts from prescribed burning activities, as well as benefits that can be achieved by a potential reduction in emissions for a scenario where biomass is harvested for conversion to biofuel. As prescribed burning activities become more frequent, they can be more detrimental for air quality and health. Forest residue-based biofuel industry can be source of cleaner fuel with co-benefits of improved air quality, reduction in health impacts, and improved visibility.

Considerations on GHG emissions and energy balances of promising aviation biofuel pathways

This article presents results of a European Commission Joint Research Centre study to analyse the Greenhouse Gas (GHG) emissions and energy efficiency of various options for alternative aviation fuels. Interest in alternative aviation fuels is growing, as the sector seeks viable options to reduce increasing GHG emissions. For biofuels non-biogenic emissions arise from cultivation, harvesting and transport of the feedstock, as well as from their conversion into biofuel. It is important to consider whether any emissions reductions benefits are justified by the energy efficiency of each alternative. This article is focussed on American Society for Testing and Materials (ASTM) certifiable alternative drop-in biojet fuels [1], i.e. non-fossil hydrocarbon fuels which have (i) the same chemical structure and (ii) can be blended with conventional jet fuels, (iii) can use the same jet fuel supply infrastructure, and (iv) do not require modification of the aircraft. The results indicate that the biofuels studied tended to exhibit lower GHG than conventional jet fuels although indirect effects or existing uses of materials were not included in this study. Some biofuels performed better at reducing GHG than others (for example biofuels from wastes and residues). A large and important effect on emissions is seen due to land type used for cultivation and whether methane capture is used for certain pathways. GHG savings results vary due to the Life Cycle Analysis (LCA) methodology chosen for dealing with emissions and co-products. Certain pathways are notably more energy intensive than others and strong GHG reduction does not always coincide with high energy efficiency. An overview of industry initiatives and critical EU legislation relating to aviation biofuels is given. The insights from this work are expected to be of use for decision-makers considering investment options in this sector.