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Climate Assessment of Hydrogen Combustion Aircraft: Towards a Green Aviation Sector
... In that case, the focus was devoted to a narrow body configuration, where the fuselage was modified in order to include dorsal hydrogen lobe tanks by maintaining the original cabin size, without impacting too much the payload-range capability of the original platform, considering direct combustion of hydrogen. This strategy for generation of primary power on-board, responsible of thrust generation, is largely preferred for platforms that are larger than regional jets and commuters, as summarized in [19] and demonstrated by studies such as HyLiner 2.0 [20] and FlyZero MidSize [21], all of which feature pure hydrogen turbofan technologies. Typically, the different concepts are characterized by a conventional aircraft configuration, even if some changes are introduced to improve hydrogen storage within non-integral tanks (larger fuselage, blended shapes in fuselage-wing interface) usually positioned at the back of the plane or under the cabin floor. ...
... Reference source not found.) is considered, and the aircraft is characterized by the take-off mass and fuel mass specified in Error! Reference source not found.. A Starting with , according to [48], cockpit crew cost can be computed as in (21). ...
The commercial aviation industry is constantly evolving, driven by technological innovation and the growing demand for more efficient and environmental friendly transportation solutions. In this context, the design and development of next-generation aircraft is a crucial task, with the goal of reducing environmental impact and improving flight efficiency while continuing to ensure passenger comfort and safety. This paper aims at evaluating the technical feasibility as well as economic and environmental viability of a narrow body aircraft powered by hydrogen for direct combustion. Notably, the paper offers innovative insights regarding the update of literature models for conceptual design, in order to consider the impact of hydrogen fuel on the sizing loop at aircraft level. Moreover, it also focuses on the evaluation of operating costs for the aforementioned aircraft class, highlighting the required model updates and considerations to properly match the effect on costs of the introduction of the innovative fuel. Ultimately, a preliminary analysis of upstream sustainability of the concept, considering fuel life cycle, is provided, in order to understand the overall competitiveness, not only in terms of monetary resources but also of environmental impact, beyond the pure operating life of the airplane.
This paper presents a method to assess the key performance indicators of aircraft designed for minimum direct operating costs and aircraft designed for minimum global warming impact. The method comprises a multidisciplinary aircraft optimization algorithm capable of changing wing, engine, and mission design variables while including constraints on flight and field performance. The presented methodology uses traditional class-I methods augmented with dedicated class-II models to increase the sensitivity of the performance indicators to relevant design variables. The global warming impact is measured through the average temperature response caused by several emission species (including carbon dioxide, nitrogen oxides, and contrail formation) over a prolonged period of 100 years. The analysis routines are verified against experimental data or higher-order methods. The design algorithm is subsequently applied to a single-aisle medium-range aircraft, demonstrating that a 57% reduction in average temperature response can be achieved as compared to an aircraft optimized for minimal operating costs. This reduction is realized by flying at 7.6 km and Mach 0.60, and by lowering the engine overall pressure ratio to approximately 37. However, to compensate for the lower productivity, it is estimated that 13% more climate-optimized aircraft have to be operated for the hypothetical fleet under consideration.
Hydrogen micromix is a candidate combustion technology for hydrogen aviation gas turbines. The introduction and development of new combustion technologies always carries the risk of suffering from damaging high amplitude thermoacoustic pressure oscillations. This was a particular problem with the introduction of lean premixed combustion systems to land based power generation gas turbines.
There is limited published information on the thermoacoustic behaviour of such hydrogen micromix combustors. Diffusion flames are less prone to flashback and autoignition problems than premixed flames and conventional diffusion flames are less prone to combustion dynamics issues. However, with the high laminar flame speed of hydrogen, lean fuel air ratio (FAR) and very compact flames, the risk of combustion dynamics for micromix flames should not be neglected and a comparison of the likely thermoacoustic behaviour of micromix combustors and kerosene fueled aviation combustors would inform the early stage design of engine realistic micromix combustors.
This study develops a micromix combustor concept suitable for a modern three spool, high bypass ratio engine and derives the acoustic Flame Transfer Function (FTF) at typical engine operating conditions for top of climb, take-off, cruise, and end of runway. The FTF is derived using CFD and FTF models based on a characteristic flame delay. The relative thermoacoustic behaviour for the four conditions is assessed using a low order acoustic network code. The comparisons suggest that the risk of thermoacoustic instabilities associated with longitudinal waves at low frequencies (below 1kHz) is small, but that higher frequency longitudinal modes could be excited. The sensitivity of the combustor thermoacoustic behaviour to key combustor dimensions and characteristic time delay is also investigated and suggests that higher frequency longitudinal modes can be significantly influenced by combustion system design.
The characteristic time delay and thus FTF for a Lean Premixed Prevapourised (LPP) kerosene combustor is derived from information in the literature and the thermoacoustic behaviour of the micromix combustor relative to that of this kerosene combustor is determined using the same low order modelling approach. The comparison suggests that the micromix combustor is much less likely to produce thermoacoustic instabilities at low frequencies (below 1kHz), than the LPP combustor even though the risk in the LPP combustor is small.
It is encouraging that this simple approach used in a preliminary design suggests that the micromix combustor has lower risk at low frequency than a kerosene combustor and that the risk of higher frequency longitudinal modes can be reduced by appropriate combustion system design. However, more detailed design, more rigorous thermoacoustic analysis and experimental validation are needed to confirm this.
Aviation is an important contributor to the global economy, satisfying society’s mobility needs. It contributes to climate change through CO 2 and non-CO 2 effects, including contrail-cirrus and ozone formation. There is currently significant interest in policies, regulations and research aiming to reduce aviation’s climate impact. Here we model the effect of these measures on global warming and perform a bottom-up analysis of potential technical improvements, challenging the assumptions of the targets for the sector with a number of scenarios up to 2100. We show that although the emissions targets for aviation are in line with the overall goals of the Paris Agreement, there is a high likelihood that the climate impact of aviation will not meet these goals. Our assessment includes feasible technological advancements and the availability of sustainable aviation fuels. This conclusion is robust for several COVID-19 recovery scenarios, including changes in travel behaviour.
The price of oil has seen an unprecedented increase and the resulting demand for oil, especially from the transportation industries. The pollution emits from the vehicle has affected human health and environmental problems especially aviation industries because the emission covers much broader spectrums. Drop-in alternative fuels such as liquefied hydrogen fuel are believed to offer better engine performance and reduce the emission. An in-house computer tool, PYTHIA was used to model the performance of RB211 engine at a wide range of flight operations. Liquid hydrogen fuel will increase the thrust and the specific fuel consumption up to 63.9% reduction at higher speed. Liquid hydrogen fuel resulted in higher burning temperature which encourage the formation of NO x. At the sea level, it was found that EINOx was increased to about 5.5% when 20% blended ratio was used.
Atmospheric science: alternative aviation fuel helps mitigate the contrail climate impact Reducing soot emissions from aircraft by changing the composition of aviation fuels can effectively mitigate the climate impact of contrail cirrus. Ulrike Burkhardt and colleagues from the German Aerospace Centre use a global climate model to estimate the impacts of reduced aircraft soot emissions on properties and the climate forcing of contrail cirrus. Under the low emission condition in which the number of initial ice crystals formed from soot particles is reduced by 80%—a level of reduction that could be obtained using a blend of biofuel and conventional jet fuels—the climate impact of contrail cirrus is estimated to be reduced by 50%. The mitigation effect occurs predominantly in weather conditions that are favourable for contrail cirrus outbreaks: with the same level of reduction in the initial ice crystal number, capturing 25% of those events can reduce 30% of the climate forcing caused by contrail cirrus.
The westerly phase of the quasi-biennial oscillation (QBO) was unexpectedly disrupted by an anomalous easterly near 40 hPa (~23 km) in February 2016. At the same time, a very strong El Nino and a very low Arctic sea-ice concentration in the Barents and Kara Sea were present. Previous studies have shown that the disruption of the QBO was primarily caused by the momentum transport of the atmospheric waves in the Northern Hemisphere. Our results indicate that the tropical waves evident over the Atlantic, Africa, and the western Pacific were associated with extratropical disturbances. Moreover, we suggest that the El Nino and sea-ice anomalies in 2016 account for approximately half of the disturbances and waves based on multiple regression analysis of the observational/reanalysis data and large-ensemble experiments using an atmospheric global climate model. The El Nino and sea-ice anomalies in February 2016 were associated with the QBO disruption in 2016 through stratospheric wave anomaly. In early 2016, unprecedented behavior of the quasi-biennial oscillation (QBO), the dominant mode of stratospheric variability with a period of 22–36 months, was observed. Multiple regression analyses of the observational/reanalysis data and the large-ensemble experiments using an atmospheric climate model showed that about half of the waves were associated with the strong El Nino and the reduced Arctic sea-ice in 2016. These results suggest an importance of stratosphere-troposphere coupling process for the QBO anomaly and also for the seasonal forecasts. Similar QBO disruptions may occur more frequently in the future warm climate with the decreasing Arctic sea-ice and possible variation of the El Nino.
Aircraft-produced contrail cirrus clouds contribute to anthropogenic climate change. Observational data sets and modelling approaches have become available that clarify formation pathways close to the source aircraft and lead to estimates of the global distribution of their microphysical and optical properties. While contrail cirrus enhance the impact of natural clouds on climate, uncertainties remain regarding their properties and lifecycle. Progress in representing aircraft emissions, contrail cirrus and natural cirrus in global climate models together with tighter constraints on the sensitivity of the climate system will help judge efficiencies of and trade-offs between mitigation options.
The WeCare project (Utilizing Weather information for Climate efficient and eco efficient future aviation), an internal project of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR), aimed at finding solutions for reducing the climate impact of aviation based on an improved understanding of the atmospheric impact from aviation by making use of measurements and modeling approaches. WeCare made some important contributions to advance the scientific understanding in the area of atmospheric and air transportation research. We characterize contrail properties, show that the aircraft type significantly influences these properties, and how contrail-cirrus interacts with natural cirrus. Aviation NOx emissions lead to ozone formation and we show that the strength of the ozone enhancement varies, depending on where within a weather pattern NOx is emitted. These results, in combination with results on the effects of aerosol emissions on low cloud properties, give a revised view on the total radiative forcing of aviation. The assessment of a fleet of strut-braced wing aircraft with an open rotor is investigated and reveals the potential to significantly reduce the climate impact. Intermediate stop operations have the potential to significantly reduce fuel consumption. However, we find that, if only optimized for fuel use, they will have an increased climate impact, since non-CO2 effects compensate the reduced warming from CO2 savings. Avoiding climate sensitive regions has a large potential in reducing climate impact at relatively low costs. Taking advantage of a full 3D optimization has a much better eco-efficiency than lateral re-routings, only. The implementation of such operational measures requires many more considerations. Non-CO2 aviation effects are not considered in international agreements. We showed that climate-optimal routing could be achieved, if market-based measures were in place, which include these non-CO2 effects. An alternative measure to foster climate-optimal routing is the closing of air spaces, which are very climate-sensitive. Although less effective than an unconstrained optimization with respect to climate, it still has a significant potential to reduce the climate impact of aviation. By combining atmospheric and air Transportation research, we assess climate mitigation measures, aiming at providing information to aviation stakeholders and policy-makers to make aviation more climate compatible.
Air traffic is important to our society and guarantees mobility especially for long distances. Air traffic is also contributing to climate warming via emissions of CO2 and various non-CO2 effects, such as contrail-cirrus or increase in ozone concentrations. Here we investigate the climate impact of a future aircraft design, a multi fuel blended wing body (MF-BWB), conceptually designed within the EU-project AHEAD. We re-calculate the parameters for the contrail formation criterion, since this aircraft has very different characteristics compared to conventional technologies and show that contrail formation potentially already occurs at lower altitudes than for conventional aircraft. The geometry of the contrails, however, is similar to conventional aircraft, as detailed LES simulations show. The global contrail-cirrus coverage and related radiative forcing is investigated with a climate model including a contrail-cirrus parameterisation and shows an increase in contrail-cirrus radiative forcing compared to conventional technologies, if the number of emitted particles is equal to conventional technologies. However, there are strong indications that the AHEAD engines would have a substantial reduction in the emission of soot particles and there are strong indications that this leads to a substantial reduction in the contrail-cirrus radiative forcing. An overall climate impact assessment with a climate-chemistry response model shows that the climate impact is likely to be reduced by 20 % to 25 % compared to a future aircraft with conventional technologies. We further tested the sensitivity of this result with respect to different future scenarios for the use of bio fuels, improvements of the fuel efficiency for conventional aircraft and the impact of the number of emitted soot particles on the radiative forcing. Only the latter has the potential to significantly impact our findings and needs further investigation. Our findings show that the development of new and climate compatible aircraft designs requires the inclusion of climate impact assessments already at an early stage, i.e. pre-design level.
A moist idealized test case (MITC) for atmospheric model dynamical cores is presented. The MITC is based on the Held-Suarez (HS) test that was developed for dry simulations on a flat Earth and replaces the full physical parameterization package with a Newtonian temperature relaxation and Rayleigh damping of the low-level winds. This new variant of the HS test includes moisture and thereby sheds light on the nonlinear dynamics-physics moisture feedbacks without the complexity of full-physics parameterization packages. In particular, it adds simplified moist processes to the HS forcing to model large-scale condensation, boundary-layer mixing, and the exchange of latent and sensible heat between the atmospheric surface and an ocean-covered planet. Using a variety of dynamical cores of the National Center for Atmospheric Research (NCAR)'s Community Atmosphere Model (CAM), this paper demonstrates that the inclusion of the moist idealized physics package leads to climatic states that closely resemble aquaplanet simulations with complex physical parameterizations. This establishes that the MITC approach generates reasonable atmospheric circulations and can be used for a broad range of scientific investigations. This paper provides examples of two application areas. First, the test case reveals the characteristics of the physics-dynamics coupling technique and reproduces coupling issues seen in full-physics simulations. In particular, it is shown that sudden adjustments of the prognostic fields due to moist physics tendencies can trigger undesirable large-scale gravity waves, which can be remedied by a more gradual application of the physical forcing. Second, the moist idealized test case can be used to intercompare dynamical cores. These examples demonstrate the versatility of the MITC approach and suggestions are made for further application areas. The new moist variant of the HS test can be considered a test case of intermediate complexity.
Air traffic has an increasing influence on climate; therefore identifying mitigation options to reduce the climate impact of aviation becomes more and more important. Aviation influences climate through several climate agents, which show different dependencies on the magnitude and location of emission and the spatial and temporal impacts. Even counteracting effects can occur. Therefore, it is important to analyse all effects with high accuracy to identify mitigation potentials. However, the uncertainties in calculating the climate impact of aviation are partly large (up to a factor of about 2). In this study, we present a methodology, based on a Monte Carlo simulation of an updated non-linear climate-chemistry response model AirClim, to integrate above mentioned uncertainties in the climate assessment of mitigation options. Since mitigation options often represent small changes in emissions, we concentrate on a more generalised approach and use exemplarily different normalised global air traffic inventories to test the methodology. These inventories are identical in total emissions but differ in the spatial emission distribution. We show that using the Monte Carlo simulation and analysing relative differences between scenarios lead to a reliable assessment of mitigation potentials. In a use case we show that the presented methodology can be used to analyse even small differences between scenarios with mean flight altitude variations.
Cirrus ice clouds formed normally in the upper troposphere and contrails, shed by aircraft, impact climate and global warming due to prevailing cirrus clouds ice water content and crystal size. Space monitoring of cirrus cloud and contrails are essential in assessing the development of cirrus clouds and their interaction with contrails. Contrails monitoring is significant in assessing the effect of commercial flights to climate change which may be required to formulate climate change technology mitigation efforts. Understanding of the physical characteristics of cirrus clouds, contrails and their interactions for devising anthropogenic solutions can be facilitated by space based measurements and modeling.
Purpose – The purpose of this paper is to present a novel hybrid engine concept for a multi-fuel blended wing body (MFBWB) aircraft and assess the performance of this engine concept.
Design/methodology/approach – The proposed hybrid engine concept has several novel features which include a contra-rotating fan for implementing boundary layer ingestion, dual combustion chambers using cryogenic fuel (liquefied natural gas [LNG] or liquid hydrogen [LH2]) and kerosene in the inter-turbine burner (in flameless combustion mode) and a cooling system for bleed air cooling utilizing the cryogenic fuel. A
zero-dimensional thermodynamic model of the proposed hybrid engine is created using Gas Turbine Simulation Program to parametrically analyse the performance of various possible engine architectures. Furthermore, the chosen engine architecture is optimized at a cycle reference point using a developed in-house thermodynamic engine model coupled with genetic algorithm.
Findings – Using LH2 and kerosene, the hybrid engine can theoretically reduce CO2 emissions by around 80 per cent. Using LNG and kerosene, the CO2 emissions are reduced by more than 20 per cent as compared to the baseline engine.
Practical implications – The hybrid engine is being investigated in the AHEAD project co-sponsored by the European Commission. This unique aircraft and engine combination will enable aviation to use cryogenic fuels like LH2 or LNG, and will make aviation sustainable.
Originality/value – The MFBWB concept and the hybrid engine is a novel concept which has not yet been investigated before. The potential implications of this technology are far reaching and will shape the future development in aviation.
The growth in air transportation volume has important global environmental impacts associated with the potential for climate change. Jet aircraft emissions are deposited directly into the upper atmosphere and some of them have a greater warming effect than gases emitted closer to the surface. One of the key issues that is addressed in virtually every aero gas turbine application is emissions, particularly Nox emissions. There are different technologies for nitrogen oxide emission control in aircraft gas turbines. In this paper, we have briefly reviewed the technologies with the greatest potential to reduce Nox emissions in aero engines.
The physical and optical properties of persistent contrails were studied
with the measurements made by the Moderate Resolution Imaging
Spectroradiometer (MODIS) and the Cloud-Aerosol Lidar and Infrared
Pathfinder Satellite Observations (CALIPSO) lidar. MODIS data were used
to determine the contrail locations on the basis of their artificial
shapes easily distinguished from natural cirrus, and the so-identified
contrails were analyzed with collocated CALIPSO lidar data. Statistics
of the geography, geometry, meteorology, and optical properties are
reported for approximately 3400 persistent contrails observed over North
America, the North Atlantic Ocean, and Europe. The majority of the
detected contrails appear in ice-supersaturated air with temperatures
lower than -40°C. On average, contrails have significantly larger
backscattering coefficients and slightly higher linear depolarization
ratios (LDRs) than neighboring cirrus clouds. Depolarization tends to be
strong when ice crystals are small, and LDR is approximately 0.4-0.45
for young contrails and contrail cores. The mean LDR for the detected
contrails increases with decreasing temperature and is not strongly
dependent on the lidar pointing angle. The backscattering properties
suggest that contrails are primarily composed of small, randomly
oriented ice crystals but may also contain a few horizontally oriented
plates. Most contrails are optically thin with a mean (median) optical
thickness of approximately 0.19 (0.14); however, optically thicker
contrails do exist and tend to occur in warmer and more humid ambient
air. The mean value and range of the observed LDR data are consistent
with theoretical predictions based on a mixture of nonspherical ice
crystals randomly oriented in the atmosphere.
Aircraft induced contrails have been found to have a net warming influence on the climate
system, with strong regional dependence. Persistent linear contrails are detectable in 1 Km
thermal imagery and, using an automated Contrail Detection Algorithm (CDA), can be
identified on the basis of their different properties at the 11 and 12 μm wavelengths. The
algorithm’s ability to distinguish contrails from other linear features depends on the
sensitivity of its tuning parameters. In order to keep the number of false identifications low,
the algorithm imposes strict limits on contrail size, linearity and intensity. This paper
investigates whether including additional information (i.e. meteorological data) within the
CDA may allow for these criteria to be less rigorous, thus increasing the contrail-detection
rate, without increasing the false alarm rate.
We evaluate the response to regional and latitudinal changes in aircraft NOx emissions using several climate metrics (radiative forcing (RF), Global Warming Potential (GWP), Global Temperature change Potential (GTP)). Global chemistry transport model integrations were performed with sustained perturbations in regional aircraft and aircraft-like NOx emissions. The RF due to the resulting ozone and methane changes is then calculated. We investigate the impact of emission changes for specific geographical regions (approximating to USA, Europe, India and China) and cruise altitude emission changes in discrete latitude bands covering both hemispheres. We find that lower latitude emission changes (per Tg N) cause ozone and methane RFs that are about a factor of 6 larger than those from higher latitude emission changes. The net RF is positive for all experiments. The meridional extent of the RF is larger for low latitude emissions. GWPs for all emission changes are positive, with tropical emissions having the largest values; the sign of the GTP depends on the choice of time horizon.
The impact of black carbon (BC) aerosols on the global radiation balance is not well constrained. Here twelve global aerosol models are used to show that at least 20 % of the present uncertainty in modeled BC direct radiative forc-ing (RF) is due to diversity in the simulated vertical profile of BC mass. Results are from phases 1 and 2 of the global aerosol model intercomparison project (AeroCom). Addi-tionally, a significant fraction of the variability is shown to come from high altitudes, as, globally, more than 40 % of the total BC RF is exerted above 5 km. BC emission regions and areas with transported BC are found to have differing char-acteristics. These insights into the importance of the vertical profile of BC lead us to suggest that observational studies are needed to better characterize the global distribution of BC, including in the upper troposphere.
Simplified climate models can be used to calculate and to compare temperature response contributions from small forcings without the need for considerable computer resources. A linear climate response model using Green’s functions has been formulated to calculate radiative forcing (RF) and the global mean temperature response from aviation. The model, LinClim, can calculate aviation RF for CO2, O3, CH4, water vapour, contrails, sulphate and black carbon aerosols.
From these RFs, temperature responses may be calculated for individual effects in order to determine their relative importance by applying preliminary values for efficacies. The LinClim model is tuned to reproduce the dominant mode of its parent coupled atmosphere-ocean GCM, ECHAM4/OPYC3. LinClim is able to reproduce the IPCC (1999) 2050 aviation-related forcings.
The model is shown through some example application analyses to be a useful tool for exploring the effects of aviation on RF and temperature response.
Climate change is a challenge to society and to cope with requires assessment tools which are suitable to evaluate new technology options with respect to their impact on global climate. Here we present AirClim, a model which comprises a linearisation of atmospheric processes from the emission to radiative forcing, resulting in an estimate in near surface temperature change, which is presumed to be a reasonable indicator for climate change. The model is designed to be applicable to aircraft technology, i.e. the climate agents CO2, H2O, CH4 and O3 (latter two resulting from NOx-emissions) and contrails are taken into account. AirClim combines a number of precalculated atmospheric data with aircraft emission data to obtain the temporal evolution of atmospheric concentration changes, radiative forcing and temperature changes. These precalculated data are derived from 25 steady-state simulations for the year 2050 with the climate-chemistry model E39/C, prescribing normalised emissions of nitrogen oxides and water vapour at various atmospheric regions. The results show that strongest climate impacts (year 2100) from ozone changes occur for emissions in the tropical upper troposphere (60 mW/m2; 80 mK for 1 TgN/year emitted) and from methane changes from emissions in the middle tropical troposphere (−2.7% change in methane lifetime; –30 mK per TgN/year). For short-lived species (e.g. ozone, water vapour, methane) individual perturbation lifetimes are derived depending on the region of emission. A comparison of this linearisation approach with results from a comprehensive climate-chemistry model shows reasonable agreement with respect to concentration changes, radiative forcing, and temperature changes. For example, the total impact of a supersonic fleet on radiative forcing (mainly water vapour) is reproduced within 10%. A wide range of application is demonstrated.
The formation, growth, and composition of mixed cluster ions HSO4−AaWw and H+AaWw (A=H2SO4, W=H2O) with a up to 6 were investigated in the laboratory using a flow reactor-mass spectrometer apparatus. In the flow reactor the buffer gas (N2) pressure and temperature were kept constant at 80 hPa and 295 K, respectively, while the partial pressures of the trace gases H2SO4 and H2O and thereby also the relative humidity were varied. It was found that for small a (<5) positive ions are markedly enriched in H2O and negative ions are enriched in H2SO4 molecules. For larger a the composition of positive and negative ions becomes similar and approaches the modelled composition of a liquid AaWw droplet (respectively, for a>8 and a>15). When increasing the partial pressure of gaseous H2SO4 in the flow reactor both positive and negative ions grow via A uptake. This growth is more pronounced for negative ions where it becomes very efficient for a>8 reflecting A attachment to become faster than A detachment. We also have made model calculations indicating that for a>10 negative ion growth via A attachment occurs on nearly every collision of an A-molecule with an ion.
Current scientific knowledge on the future response of the climate system to human-induced perturbations is comprehensively captured by various model intercomparison efforts. In the preparation of the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC), intercomparisons were organized for atmosphere-ocean general circulation models (AOGCMs) and carbon cycle models, named "CMIP3" and "C4MIP", respectively. Despite their tremendous value for the scientific community and policy makers alike, there are some difficulties in interpreting the results. For example, radiative forcings were not standardized across the various AOGCM integrations and carbon cycle runs, and, in some models, key forcings were omitted. Furthermore, the AOGCM analysis of plausible emissions pathways was restricted to only three SRES scenarios. This study attempts to address these issues. We present an updated version of MAGICC, the simple carbon cycle-climate model used in past IPCC Assessment Reports with enhanced representation of time-varying climate sensitivities, carbon cycle feedbacks, aerosol forcings and ocean heat uptake characteristics. This new version, MAGICC6, is successfully calibrated against the higher complexity AOGCMs and carbon cycle models. Parameterizations of MAGICC6 are provided. The mean of the emulations presented here using MAGICC6 deviates from the mean AOGCM responses by only 2.2% on average for the SRES scenarios. This enhanced emulation skill in comparison to previous calibrations is primarily due to: making a "like-with-like comparison" using AOGCM-specific subsets of forcings; employing a new calibration procedure; as well as the fact that the updated simple climate model can now successfully emulate some of the climate-state dependent effective climate sensitivities of AOGCMs. The diagnosed effective climate sensitivity at the time of CO2 doubling for the AOGCMs is on average 2.88 °C, about 0.33 °C cooler than the mean of the reported slab ocean climate sensitivities. In the companion paper (Part 2) of this study, we examine the combined climate system and carbon cycle emulations for the complete range of IPCC SRES emissions scenarios and the new RCP pathways.
The atmospheric response to perturbations in NOx emissions from global air traffic is investigated by performing a coherent set of sensitivity experiments. The importance of cruise altitude, size of the emission perturbation and geographical distribution of emissions is systematically analyzed using two global chemistry transport models and an off-line radiative transfer model. NOx emissions from a contemporary aircraft inventory have been used to assess the impact of global air traffic on ozone and methane. In further experiments the NOx emissions are perturbed, in turn, in 16 cruise altitude bands between 5 and 15 km altitude. In the p-TOMCAT model we diagnose an annual mean ozone increase of up to 6 ppbv and a decrease in the methane lifetime of 3% due to global air traffic in 2002. Associated radiative forcings of 30 mWm−2 for ozone and −19 mWm−2 for methane are diagnosed; a simple method is used to estimate the forcing due to the methane-induced ozone change and this yields an additional −11 mWm−2. Results show that up to the tropopause, ozone production efficiency and resulting impacts increase per emitted mass of NOx with the altitude of the perturbation. Between 11 and 15 km we find that the geographical location of the NOx emissions plays a crucial role in the potential O3 impact and lifetime change of CH4. We show that changes in flight routing in this altitude range can have significant consequences for O3 and CH4 concentrations. Overall, we demonstrate a linear relationship in the atmospheric response to small emission changes which can be used to predict the importance of perturbations about the reference aircraft emissions profile, provided the geographical distribution of the emissions is not altered significantly.
It has been claimed that hydrogen aviation may still significantly contribute to global warming through jets contrails, as hydrogen jets produce more contrails than jets fueled with kerosene. The claim, based on modeling exercises, can be tested via the Covid-19 experiment. Since March 2020, air traffic has been severely disrupted because of the pandemic. This has been true especially in Australia, the hermit country where citizens have been practically prevented from leaving or returning, with international air travel dramatically reduced. Analysis of the surface temperature data about international airports and air traffic from Australia provides the opportunity to test one of the hypotheses formulated about jet contrails' contribution to global warming. It is shown as opposed to previous claims, jet contrails are not responsible for reducing the difference between the maximum and minimum daily temperatures close to airports. Compared to the last 9 months of 2019, with air traffic normal, during the last 9 months of 2020 of highly disrupted flights, the difference in between the maximum and minimum temperatures in Sydney and Melbourne airports, has not been larger, but smaller by about 1 °C. The reduction in the difference between temperatures has been also smaller in Brisbane airport, but only at about 0.22 °C. We conclude as the claim adoption of hydrogen as an aviation fuel may produce global warming through the contrails mechanism is likely wrong. The contrails effect is everything but well understood and quantified with accuracy, and poorly represented in climate models. The contrails contribution to global warming is expected to be minor, and it should not void the value of hydrogen as a future renewable fuel free of CO2 emissions.
In 2019, aviation was responsible for 2.6% of world CO2 emissions as well as additional climate impacts such as contrails. Like all industrial sectors, the aviation sector must implement measures to reduce its climate impact. This paper focuses on the simulation and evaluation of climate scenarios for air transport. For this purpose, a specific tool (CAST for “Climate and Aviation - Sustainable Trajectories”) has been developed at ISAE-SUPAERO. This tool follows a methodology for the assessment of climate impacts adapted to aviation. Firstly, models for the main levers of action, such as air traffic, aircraft energy consumption and energy decarbonization, are provided using trend projections from historical data or assumptions from the literature. Second, the evaluation of scenarios is based on aviation carbon budgets, which are also extended to non-CO2 effects using the concept of GWP*. Several scenario analyses are performed in this paper using CAST allowing different conclusions to be drawn. For instance, the modelling of the scenarios based on the more recent ATAG (Air Transport Action Group) commitments shows that aviation would consume 6.5% of the world carbon budget for +1.5 °C. Some illustrative scenarios are also proposed. By allocating 2.6% of the world carbon budget to aviation, it is shown that air transport is compatible with a +2 °C trajectory when the annual growth rate of air traffic varies between −1.8% and +2.9%, depending on the technological improvements considered. However, using the same methodology for a +1.5 °C trajectory shows that a drastic decrease in air traffic is necessary. Lastly, analyses including non-CO2 effects emphasize the importance of implementing specific strategies for mitigating contrails.
In this study, The General Electric GE90 turbofan engine is thermodynamically simulated
MATLAB in both states of using hydrocarbon fuel and hydrogen fuel at the design point
conditions. Subsequently, the genetic algorithm is used to determine the best bypass ratio and the best fan pressure ratio in order to obtain optimal performance, environmental, and economic conditions for hydrogen Turbofan, that have been obtained to be 10.2965 and 1.6111, respectively. In the end, the following are observed at the cruise altitude as a result of a change from the hydrocarbon GE90 turbofan to the optimized hydrogen GE90 turbofan: (i). The net thrust force increases by 16.27%. (ii). The thrust-specific fuel consumption decreases by 65.90%. (iii). The thermal efficiency increases by 2.65%. (iv). The propulsive efficiency remains almost unchanged with a mere decrease of 0.2% and provides adequate propulsive conditions. (v). The overall efficiency increases by 2.5%. (vi). The mass flow rate of the fuel decreases by 60.29%. (vii). The total emission of NOx reduces by 68.25% per a specified generated thrust and consumed fuel mass flow rate throughout the cruise phase of the flight cycle. Furthermore, the following are observed at the cruise altitude as a result of a change from the hydrogen GE90 turbofan to the optimized hydrogen GE90 turbofan: (i).
The emission of nitrogen oxide for every kilogram of burnt fuel decreases by 3.94%. (ii). The total emission of NOx per a specified mass flow rate of consumed fuel and generated thrust throughout the cruise phase reduces by 16.67%.
Aviation is one of the most important global economic activities in the modern world. Aviation emissions of CO2 and non-CO2 aviation effects result in changes to the climate system (Fig. 1). Both aviation CO2 and the sum of quantified non-CO2 contributions lead to surface warming. The largest contribution to anthropogenic climate change across all economic sectors comes from the increase in CO2 concentration, which is the primary cause of observed global warming in recent decades (IPCC, 2013, 2018).
The paper presents a survey of the interactive optimization cycle at Aachen University of Applied Sciences, used for the development of a new low emission Micromix combustor module for application in hydrogen fueled industrial gas turbines. During the development process, experimental and numerical methods are applied to optimize a given baseline combustor with 0.3 mm nozzles with respect to combustion efficiency, combustion stability, higher thermal power output per nozzle and reduced manufacturing complexity.
Within the described research cycle combustion and flow simulations are used in the context of parametric studies for generating optimized burner geometries and the phenomenological interpretation of the experimental results. Experimental tests, carried out on an atmospheric combustion chamber test stand provide the basis for validation of simulation results and proof of the predicted combustion characteristics under scaled down gas turbine conditions.
In the presented studies, an integration-optimized Micromix combustor with a nozzle diameter of 0.84 mm is tested at atmospheric pressure over a range of gas turbine operating conditions with hydrogen fuel. The combustor module offers an increase in the thermal power output per nozzle by approx. 390% at a significant reduced number of injectors when compared to the baseline design. This greatly benefits manufacturing complexity and the robustness of the combustion process against fuel contamination by particles.
During atmospheric testing, the optimized combustor module shows satisfactory operating behavior, combustion efficiency and pollutant emission level. Within the evaluated operating range, which correlates to gas turbine part-, full- and overload conditions, the investigated combustor module exceeds 99% combustion efficiency. The Micromix combustor achieves NOx emissions less than 2.5 ppm corrected to 15 Vol% O2 at the design point.
Based on numerical analyses and experimental low pressure testing, a full-scale gas turbine combustion chamber is derived. High pressure testing in the auxiliary power unit Honeywell/Garrett GTCP 36–300 shows stable operation during acceleration of the engine, during IDLE and during load variations between IDLE and Main Engine Start (MES) mode. Throughout the investigated operating range, the combustion chamber generates low NOx emissions under full-scale gas turbine conditions.
A radical route to soot
The chemical origin of soot is a persistent puzzle. It is clear that small hydrocarbon fragments formed in flames must aggregate into larger particles, but the initial driving force for aggregation remains a mystery. Johansson et al. combined theory and mass spectrometry to suggest a solution based on resonance-stabilized radicals (see the Perspective by Thomson and Mitra). Aromatics such as cyclopentadiene have a characteristically weak C–H bond because their cleavage produces radicals with extended spans of π-electron conjugation. Clusters thus build up through successive coupling reactions that extend conjugation in stabilized radicals of larger and larger size.
Science , this issue p. 997 ; see also p. 978
This article presents numerical simulations of the Rolls-Royce BR700 combustor operating at various realistic conditions. Emphasis is put on the prediction of soot emissions. Three-dimensional steady Reynolds-averaged Navier-Stokes (RANS) simulations were performed employing the kϵ-model for turbulence closure. Combustion is modelled by finterate chemistry and the turbulence-chemistry interactions are captured by an APDF-approach (assumed probability density function) for temperature fluctuations. The injection of the liquid fuel Jet A-1 is described by a spray model applying Lagrangian methods for spray transport and atomization. The multi-component fuel is modelled as surrogate of n-decane, iso-octane and toluene. Reaction kinetics are described by a detailed mechanism, which is optimised for Jet A-1 oxidation and accurately resolves the reaction paths up to the smallest aromatic soot precursors benzene and toluene. Heavier PAHs (Polycyclic Aromatic Hydrocarbons) are lumped to sections and hence, modelled by a sectional approach, which leads to soot nucleation. The soot particle dynamics are described by a two equation model. Due to the model’s efficiency feasible computational costs are realised. Overall, four operation points are investigated, which are take-off, climb, approach and taxi. The simulation results at the combustor exit are compared to the experimentally determined Smoke Number of the engine exhaust gas by means of empirical correlations. The comparison shows a very good agreement. In particular, the Smoke Number’s trend is predicted well with respect to the thrust of the operation points.
Cruise NOx emissions of aircraft are an important input parameter for studies investigating climate change due to their ability to alter the concentrations of certain trace gases, such as ozone, methane, and hydroxyl in the atmosphere, and to induce positive radiative forcing. Therefore, it is of importance to minimize estimation errors on NOx emitted from aircraft engines at high altitude. In this study, the cruise NOx emissions of a frequently-used narrow-bodied aircraft type operating domestic flights in Turkey, are quantified based on numerous actual flight, actual emissions and actual meteorological data. The overall average cruise NOx emissions index is found to be ∼10 g/kg fuel. In addition, newly-developed parameters of the aircraft cruise NOx footprint and NOx intensity are calculated to be 0.5 g/pa-NM and ∼60 g/NM, respectively. Regarding the effects of flight parameters on cruise NOx emissions, while there is a distinct increase in NOx parameters with an increase in aircraft mass, this may differ for altitude. The results reveal that the NOx emissions index tends to increase slightly by 1–2%, particularly above 28,000 ft, whereas NOx intensity decreases at a rate of 2.4–2.7% per 2000 ft of cruise altitude increase.
In this study, development of a new fuel flow rate model for the climbing phase of flight was achieved using a genetic algorithm (GA) method. Two modelling approaches were performed using real flight data records (FDRs) from a medium-weight transport-category aircraft. The first model considered the dependency of fuel consumption only with respect to altitude, whereas the effects of both altitude and true airspeed (TAS) were included in the second model. The proposed models are improvements on existing models because the relationship between fuel flow rate, flight altitude, and TAS can be deduced using the derived formulations. Both modelling approaches were found to provide accurate results after performing an error analysis for fuel flow rate values. It was clear that incorporating the TAS effect into the second model enhanced the accuracy of the model, but the first model was also found to be appropriate for practical usage.
This paper analyzes published works on the emission models of diesel and BD (Biodiesel) fuels. To the best our knowledge, this is the first comprehensive survey that reviews various modeling aspects of soot emitted from the combustion of diesel and BD fuels. The pros and cons of past and recent soot models,
the chronological advancement of diesel combustion chemistry, and soot modeling approaches are highlighted in this review. Soot models are divided into three main groups of empirical, semi-empirical, and detailed soot model.
Phenomenological model is also explored as a soot model which is one of the most extensively investigated soot models in recent years. Soot formation mechanism is discussed with an emphasis on their molecular structure. In a vast majority of the papers reviewed, acetylene was used as a soot precursor, and also as a reactant for soot mass growth and aromatics formation in diesel soot modeling studies. Thus, it is recommended that the formation and consumption of acetylene and aromatic compounds should be included in the diesel soot modeling. For BD, aromatic compounds are found at very low concentrations during the combustion, so the contribution of aromatic compounds to soot formation may be reduced or excluded in BD soot modeling. Unlike diesel, oxygen in BD fuels is found very important in soot oxidation, thus, formation and consumption of oxygen molecules, radicals and OH (hydroxide bonds) should be incorporated in the soot modeling as well. Finally, regardless of their structures, simple molecules such as MB (methyl butanoate) and MD (methyl decanoate) are found practical as BD surrogates in many modeling papers.
Three emissions inventories have been used with a fully Lagrangian trajectory model to calculate the stratospheric accumulation of water vapour emissions from aircraft, and the resulting radiative forcing. The annual and global-mean radiative forcing due to present-day aviation water vapour emissions has been found to be 0.9 [0.3–1.4] mW m−2. This is around a factor of three smaller than the value given in recent assessments, and the upper bound is much lower than a recently suggested 20 mW m−2 upper bound. This forcing is sensitive to the vertical distribution of emissions, and, to a lesser extent, interannual variability in meteorology. Large differences in the vertical distribution of emissions within the inventories have been identified, which result in the choice of inventory being the largest source of differences in the calculation of the radiative forcing due to the emissions.Analysis of Northern Hemisphere trajectories demonstrates that the assumption of an e-folding time is not always appropriate for stratospheric emissions. A linear model is more representative for emissions that enter the stratosphere far above the tropopause.
Journalist Peter Hoffmann, deputy bureau chief of McGraw-Hill World News in Bonn, Germany, describes worldwide scientific work toward a future hydrogen economy. He looks at the prospects of this potential fuel, at its applicability to powering everything from automobiles to airplanes, and at the principles and technologies involved in making hydrogen a viable energy alternative. He examines how and how soon nature's simplest element may become available as an energy carrier, as well as the economic conditions that will accompany its introduction and the social impact of clean hydrogen energy. 130 references, 35 figures.
Aviation alters the composition of the atmosphere globally and can thus drive climate change and ozone depletion. The last major international assessment of these impacts was made by the Intergovernmental Panel on Climate Change (IPCC) in 1999. Here, a comprehensive updated assessment of aviation is provided. Scientific advances since the 1999 assessment have reduced key uncertainties, sharpening the quantitative evaluation, yet the basic conclusions remain the same. The climate impact of aviation is driven by long-term impacts from CO2 emissions and shorter-term impacts from non-CO2 emissions and effects, which include the emissions of water vapour, particles and nitrogen oxides (NOx). The presentday
radiative forcing from aviation (2005) is estimated to be 55 mW m2 (excluding cirrus cloud
enhancement), which represents some 3.5% (range 1.3–10%, 90% likelihood range) of current anthropogenic
forcing, or 78 mW m2 including cirrus cloud enhancement, representing 4.9% of current forcing
(range 2–14%, 90% likelihood range). According to two SRES-compatible scenarios, future forcings may
increase by factors of 3–4 over 2000 levels, in 2050. The effects of aviation emissions of CO2 on global
mean surface temperature last for many hundreds of years (in common with other sources), whilst its
non-CO2 effects on temperature last for decades. Much progress has been made in the last ten years on
characterizing emissions, although major uncertainties remain over the nature of particles. Emissions of NOx result in production of ozone, a climate warming gas, and the reduction of ambient methane (a cooling effect) although the overall balance is warming, based upon current understanding. These NOx emissions from current subsonic aviation do not appear to deplete stratospheric ozone. Despite the progress made on modelling aviation’s impacts on tropospheric chemistry, there remains a significant
spread in model results. The knowledge of aviation’s impacts on cloudiness has also improved: a limited number of studies have demonstrated an increase in cirrus cloud attributable to aviation although the magnitude varies: however, these trend analyses may be impacted by satellite artefacts. The effect of aviation particles on clouds (with and without contrails) may give rise to either a positive forcing or a negative forcing: the modelling and the underlying processes are highly uncertain, although the overall effect of contrails and enhanced cloudiness is considered to be a positive forcing and could be substantial, compared with other effects. The debate over quantification of aviation impacts has also progressed towards studying potential mitigation and the technological and atmospheric tradeoffs. Current studies are still relatively immature and more work is required to determine optimal technological development paths, which is an aspect that atmospheric science has much to contribute. In terms of alternative fuels, liquid hydrogen represents a possibility and may reduce some of aviation’s impacts on climate if the fuel is produced in a carbon-neutral way: such fuel is unlikely to be utilized until a ‘hydrogen economy’ develops. The introduction of biofuels as a means of reducing CO2 impacts represents a future possibility.
However, even over and above land-use concerns and greenhouse gas budget issues, aviation fuels require strict adherence to safety standards and thus require extra processing compared with biofuels destined for other sectors, where the uptake of such fuel may be more beneficial in the first instance.
Aerodynamic contrails have been recognized for a long time although they appear sporadically. Usually one observes them under humid conditions near the ground, where they are short-lived phenomena. Aerodynamic contrails appear also at cruise levels where they may persist when the ambient atmosphere is ice supersaturated. The present paper presents a theoretical investigation of aerodynamic contrails in the upper troposphere. The required flow physics are explained and applied to a case study. Results show that the flow over aircraft wings leads to large variations of pressure and temperature. Average pressure differences between the upper and lower sides of a wing are on the order of 50 hPa, which is a quite substantial fraction of cruise-level atmospheric pressures. Adiabatic cooling exceeds 20 K about 2 m above the wing in a case study shown here. Accordingly, extremely high supersaturations (exceeding 1000%) occur for a fraction of a second. The potential consequences for the ice microphysics are discussed. Because aerodynamic contrails are independent of the formation conditions of jet contrails, they form an additional class of contrails that might be complementary because they form predominantly in layers that are too warm for jet contrail formation.
The formation of contrails (condensation trails) from aircraft exhaust has been investigated since 1919. Related studies are reviewed. The thermodynamical foundation of the Appleman threshold criterion for contrail formation has been first described by SCHMIDT in 1940. The Schmidt/Appleman criterion is reexamined, including the effects of the conversion of part of the combustion heat into kinetic energy of the motions in the wake of the aircraft causing higher threshold temperatures for contrail formation than without this conversion. The criterion is also derived including the kinetic energy of the jet plumes but this effect changes the threshold temperature only a little. The analysis is applied for a measured test case with the so-called ATTAS aircraft and for typical modern wide-body aircraft of type B747. If the aircraft would burn liquid hydrogen (liquid methane) instead of kerosene fuel, contrails would appear at typically 10 K (4.5 K) higher ambient temperatures and would be geometrically thicker and longer. However, this does not necessarily mean that such alternative fuels have a stronger impact on climate because such fuels will cause less and larger particles with smaller optical thickness and faster sedimentation.
In this paper the first numerical simulations of condensation trails (contrails) from liquid hydrogen (LH2) fueled aircraft are presented. Such aircraft produces 2.6 times more exhaust water vapor than equivalent aircraft fueled by kerosene; however, combustion of LH2 produces no aerosol particles. LH2 ice crystals, which instead form on background aerosol, are consequently 1–2 orders of magnitude fewer than in a kerosene contrail. LH2 contrails are compared to kerosene contrails for two flight altitudes, which here is equivalent to two different background temperatures. The relative humidity with respect to ice was kept constant; a value of 110% was used. It is found that LH2 contrails are optically thinner than their kerosene counterparts owing to much lower number density of ice crystals in the LH2 contrails than in the kerosene contrails but similar amounts of ice mass. The latter is controlled by ambient humidity. However, the sedimentation in the LH2 contrails is not significantly stronger than the sedimentation in the kerosene contrails although the average crystal sizes in LH2 contrails are 4–6 times larger than in the corresponding kerosene contrail. Additionally, the sensitivity of the LH2 contrail properties to variations in the background aerosol distribution is investigated. We find that by increasing the aerosol density by 4, an order of magnitude difference in mean optical thickness results; the LH2 contrail will nevertheless be optically thinner than the corresponding kerosene contrail, as the number of ice crystals that form will be fewer.
The radiative forcing of contrails is quantified for a hypothetical fleet of cryoplanes in comparison with a conventional aircraft fleet. The differences in bulk optical properties between conventional and cryoplane
contrails are determined by numerical simulations of the microphysical evolution of conventional and cryoplane contrails, under several ambient conditions. Both types of contrails contain about the same ice mass,
but the mean effective particle radius is found to be smaller by about a factor of 0.3 in conventional contrails than in cryoplane ones. Hence, in case of cryoplanes the contrail optical depth is lower, which counteracts
(with respect to radiative forcing) the effect of increased contrail cover due to the higher specific emission of water vapour. If the information gained from the microphysical simulations is translated to the framework of
a global climate model, the global mean radiative forcing of cryoplane contrails is simulated to be between about 30% lower and 30% higher compared to the radiative forcing of conventional contrails, depending
on the quantitative assumptions made for the mean particle properties and also depending on the time slice considered. Our results indicate that the effect of decreased optical depth is about the same magnitude as the
effect of increased contrail cover. Current state of knowledge does not allow a conclusive assessment whether the net radiative impact of cryoplane contrails will be smaller or larger than that of conventional contrails.
Uncertainty with respect to radiative forcing arises mainly from insufficient knowledge regarding the mean effective ice crystal radius for both conventional and, especially, cryoplane contrails.
The ice-forming activity of soot particles of various sizes has been studied in a cloud chamber under temperatures ranging from −5 to −20°C. It was found that the fraction of aerosol particles forming ice crystals was influenced by the temperature, the mean radius of aerosol particles and the degree of oxidising of the soot particle surface. It was suggested that oxidising affected the concentration of surface chemical groups that could form hydrogen bonds with water molecules. A decrease in the temperature and an increase in the radius of particles led to an increase in the number of ice crystals. Data obtained were parameterised and an expression was derived that enables the concentration of ice crystals to be calculated for conditions in a low cloud. Based on these experiments, this particular soot is a very potent source of ice nuclei. Data obtained were compared with Fletcher theory. It was shown that the theory contradicts experimental data and cannot be recommended for evaluation of the number of ice crystals in clouds. An application of the data obtained to aircraft condensation trail formation is discussed.
In this paper a new soot formation model for gas turbine combustor simulations is presented. A sectional approach for the description of Polycyclic Aromatic Hydrocarbons (PAHs) and a two-equation model for soot particle dynamics are introduced. By including the PAH chemistry the formulation becomes more general in that the soot formation is neither directly linked to the fuel nor to C2-like species, as it is the case in simpler soot models currently available for CFD applications. At the same time, the sectional approach for the PAHs keeps the required computational resources low if compared to models based on a detailed description of the PAH kinetics. These features of the new model allow an accurate yet affordable calculation of soot in complex gas turbine combustion chambers. A careful model validation will be presented for diffusion and partially premixed flames. Fuels ranging from methane to kerosene are investigated. Thus, flames with different sooting characteristics are covered. An excellent agreement with experimental data is achieved for all configurations investigated. A fundamental feature of the new model is that with a single set of constants it is able to accurately describe the soot dynamics of different fuels at different operating conditions.
This report describes the development of a three-dimensional database of aircraft fuel burn and emissions (fuel burned, NOx, CO, and hydrocarbons) from scheduled commercial aircraft for each month of 1992. The seasonal variation in aircraft emissions was calculated for selected regions (global, North America, Europe, North Atlantic, and North Pacific). A series of parametric calculations were done to quantify the possible errors introduced from making approximations necessary to calculate the global emission inventory. The effects of wind, temperature, load factor, payload, and fuel tankering on fuel burn were evaluated to identify how they might affect the accuracy of aircraft emission inventories. These emissions inventories are available for use by atmospheric scientists conducting the Atmospheric Effects of Aviation Project (AEAP) modeling studies. Fuel burned and emissions of nitrogen oxides (NOx as N02), carbon monoxide, and hydrocarbons have been calculated on a 1 degree latitude x 1 degree longitude x 1 kilometer altitude grid and delivered to NASA as electronic files.
Fuel burn of new commercial jet aircraft
- X S Zheng
Zheng, X. S., and Rutherford, D., "Fuel burn of new commercial jet aircraft: 1960 to 2019," Tech. Rep. September, The
International Council on Clean Transportation, 2020.