Search Results (9)

Sustainable aviation fuels (SAFs) are currently considered a key element in the decarbonization of the aviation sector, offering a feasible solution to reduce life cycle greenhouse gas emissions without requiring fundamental changes in aircraft or infrastructure. This article provides a comprehensive overview of the current state of SAFs, including their classification, production technologies, economic aspects, and environmental performance. The analysis covers both currently certified SAF pathways, such as HEFA and FT-SPK, and emerging technologies like alcohol-to-jet and power-to-liquid, assessing their technological maturity, feedstock availability, and scalability. Economic challenges related to high production costs, investment risks, and policy dependencies are discussed, alongside potential mechanisms to support market deployment. Furthermore, the article reviews SAFs’ emission performance, including CO₂ and non-CO₂ effects, based on existing life cycle assessment (LCA) studies, with an emphasis on variability caused by feedstock type and production method. The findings highlight that, while SAFs can significantly reduce aviation-related emissions compared to fossil jet fuels, the magnitude of benefits depends strongly on supply chain design and sustainability criteria. There are various certified pathways for SAF production, as well as new technologies that can further contribute to the development of the industry. Properly selected biomass sources and production technologies can reduce greenhouse gas emissions by more than 70% compared to conventional fuels. The implementation of SAFs faces obstacles related to cost, infrastructure, and regulations, which hinder its widespread adoption. The study concludes that although SAFs represent a promising pathway for aviation climate mitigation, substantial scaling efforts, regulatory support, and continued technological innovation are essential to achieve their full potential. Full article

As aviation is a rapidly growing sector, many actions must be taken to significantly reduce the emission of harmful gases such as CO₂, CO, HC, NOx, and particulate matter (PM). One accessible solution is the use of drop-in sustainable aviation fuels (SAFs), which do not require any changes in the engine or infrastructure construction. The aim of this research was to analyze changes in non-volatile particulate matter (nvPM) emissions for SAF blends compared to Jet A-1 using a miniature jet engine, as there is still limited research on particulate matter emissions from miniature engines, especially for SAFs. This study focuses on non-volatile particle emissions from HEFA-SPK fuel, with comprehensive analyses of particle number and particulate mass-emission indices, as well as number-based and volume-based particle-size distribution (PSD). The tests were conducted on the miniature GTM 400 engine, which was specially designed for SAF testing. The tested fuels were 30/70%v and 50/50%v blends of HEFA-SPK/Jet A-1, as well as neat Jet A-1 as a reference fuel. The results showed that the use of 50%v HEFA-SPK can reduce non-volatile particulate mass emissions up to 59% at low engine loads, and non-volatile particle number emissions by up to 56% at maximum thrust, compared to Jet A-1. Full article

The production of sustainable aviation fuel (SAF) has gained more attention in recent years due to the initiative to implement new technologies to improve the decarbonization of the energy and transport industry, especially the aviation sector, in different countries. In Mexico, the production of SAF has been promoted as a sustainable initiative to boost the agro-industrial sector, the nation’s self-sufficiency, and compliance with national and international CO₂ emission reduction goals. Nowadays, there are two technologies with a high level of technological readiness ready to be implemented as a solution to produce SAF, which are hydrotreating esters and fatty acids (HEFA) and Alcohol to Jet (ATJ). These technologies use biomass as a source of feedstock and are described as possible sustainable solutions to reduce the CO₂ emissions from conventional aviation fuels. This work analyses the feasibility of implementing these two technologies as a strategy to promote the use of SAF in Mexico from the biomass available in the country based on a techno-economic analysis and a life cycle assessment of each technology. Based on this study on SAF production, a return on investment of 10.2% for HEFA-SPK technology and 13.7% for ATJ-SPK technology was obtained. Full article

An expected increase in the demand for aviation transport service will result in the deterioration of the environment and human health, respectively, due to extra greenhouse gas (GHG) emissions. Concerns from EU institutions about the issue have led to legislation initiatives and, later, to development of Regulation (EU) 2023/2405 for the reduction of GHG emissions via the substitution of fossil kerosene with an increasing share of sustainable components. Hydroprocessed esters and fatty acids (HEFAs) are the most commercially acceptable sustainable alternative but their influence on aviation fuel properties needs to be further evaluated in terms of all required and extended properties, as per ASTM D1655. The main properties, together with the rarely reported upon existent gum, water separation, corrosion, and the electrical conductivity of HEFAs and their blends with fossil kerosene were quantitatively evaluated in this study. For every increase of 10% (v/v) of HEFAs, the following fuel properties improve: the freezing point decreases by 1.3 °C, the smoke point increases by an average of 3 mm, and the specific net energy increases by 0.08 MJ/kg. The acidity of HEFAs are an order of magnitude higher than that of conventional aviation fuel and, thus, close to the limit. The existent gum of the studied SAF is higher than that of fossil kerosene due to, most probably, the presence of non-evaporated residual material. Full article

Sustainable aviation fuel (SAF) is anticipated to have a significant impact on decarbonizing the aviation industry owing to its ability to be seamlessly incorporated into the current aviation infrastructure. This paper analyzes the potential of meeting the proposed SAF targets set by the ReFuelEU initiative. The approved SAF production pathways according to ASTM D7566 using renewable bio-based feedstocks were defined and analyzed. Moreover, a detailed matrix for comparison was used to provide an overview of the current state of those pathways. The analysis has shown that hydroprocessed esters of fatty acids (HEFA), alcohol to jet (ATJ), and Fischer–Tropsch (FT-SPK) are the most promising pathways in the foreseeable future due to their high technology readiness and fuel levels. HEFA is the most mature and affordable pathway; therefore, it is expected to form the backbone of the industry and stimulate the market in the short term despite its low sustainability credentials, limited feedstock, and geopolitical implications. On the other hand, FT-SPK can utilize various feedstocks and has the lowest greenhouse gas emissions with around 7.7 to 12.2 gCO₂e/MJ compared to the conventional jet fuel baseline of 89 gCO₂e/MJ. Overall, the EU has enough sustainable feedstocks to meet the short-term SAF targets using the current technologies. In the long term, the reliability and availability of biomass feedstocks are expected to diminish, leading to a projected deficit of 1.35 Mt in SAF production from bio-based feedstocks. Consequently, a further policy framework is needed to divert more biomass from other sectors toward SAF production. Moreover, a significant investment in R&D is necessary to improve process efficiencies and push new technologies such as power-to-liquid toward commercial operation. Full article

Recently, soybean production almost doubled in Brazil, reaching 122 million tonnes, and it is expected to increase even more. Brazil is the world’s largest producer and is primarily an exporter. From a sustainability point of view, soy production has been strongly criticized mainly in relation to deforestation, albeit for indirect effects. Soybean oil is a potential feedstock for the production of bio-jet fuels, which needs to be sustainable according to international criteria (sustainable aviation fuels—SAF). This paper aims to estimate the areas still available for soy expansion in Brazil, considering conditions that would allow the production of SAF. We used the SAFmaps platform, a geospatial database with information on the most promising bioenergy crops for SAF and their supply chains. Just by displacing pastures and observing a set of constraints, the total area available for expansion was estimated at 192.8 thousand km², of which 43% is of high suitability. These areas are concentrated in the Center-West region. Assuming a vertical supply chain, the results of the case studies of SAF production indicate potential feasibility, but some hypotheses considered are optimistic. Moreover, the results indicate that there can be sustainable production of soybean oil and contribution to the production of SAF. Full article

An accelerating global energy demand, paired with the harmful environmental effects of fossil fuels, has triggered the search for alternative, renewable energy sources. Biofuels are arguably a potential renewable energy source in the transportation industry as they can be used within current infrastructures and require less technological advances than other renewable alternatives, such as electric vehicles and nuclear power. The literature suggests biofuels can negatively impact food security and production; however, this is dependent on the type of feedstock used in biofuel production. Advanced biofuels, derived from inedible biomass, are heavily favoured but require further research and development to reach their full commercial potential. Replacing fossil fuels by biofuels can substantially reduce particulate matter (PM), carbon monoxide (CO) emissions, but simultaneously increase emissions of nitrogen oxides (NO_x), acetaldehyde (CH₃CHO) and peroxyacetyl nitrate (PAN), resulting in debates concerning the way biofuels should be implemented. The potential biofuel blends (FT-SPK, HEFA-SPK, ATJ-SPK and HFS-SIP) and their use as an alternative to kerosene-type fuels in the aviation industry have also been assessed. Although these fuels are currently more costly than conventional aviation fuels, possible reduction in production costs has been reported as a potential solution. A preliminary study shows that i-butanol emissions (1.8 Tg/year) as a biofuel can increase ozone levels by up to 6% in the upper troposphere, highlighting a potential climate impact. However, a larger number of studies will be needed to assess the practicalities and associated cost of using the biofuel in existing vehicles, particularly in terms of identifying any modifications to existing engine infrastructure, the impact of biofuel emissions, and their chemistry on the climate and human health, to fully determine their suitability as a potential renewable energy source. Full article

For international civil aviation to be able to significantly reduce its greenhouse gas (GHG) emissions, the use of Sustainable Aviation Fuels (SAF) needs to be made feasible. This paper presents the results of an assessment of the feasibility of production of SAF in Brazil, considering three certified routes, based on the dedicated production of eucalyptus, soy, sugarcane and corn. The results presented here refer to the production of biomass in selected locations, aiming to reduce GHG emissions and minimise production costs. Considering that the opportunity costs of feedstocks were not observed, the minimum selling price (MSP) of SAF in the reference case was estimated at 13.4 EUR·GJ⁻¹ for the production based on soybean oil (HEFA-SPK route), 21.0 EUR·GJ⁻¹ for the production based on ethanol from sugarcane and corn (ATJ-SPK) and 32.0 EUR·GJ⁻¹ from eucalyptus (FT-SPK). These values refer to SAF’s nth industrial plant and biomass costs that are compatible with the current agricultural yields in Brazil but which are also the highest. The MSP results are relatively low compared to the estimates available in the literature, but they do not show the strict economic viability of SAFs in the short- to medium-term, mainly because of the low prices of fossil fuels. Full article

Limited alternative fuels for a CO₂-neutral aviation sector have already been ASTM certified; synthetic paraffinic kerosene from hydrotreated esters and fatty acids (HEFA-SPK) is one of these—a sustainable aviation fuel. With the hypothesis to improve the greenhouse gas (GHG) balance of a HEFA plant by realizing the required hydrogen supply via electrolysis—power to gas (PTG)—an exemplary SynBioPTx approach is investigated in a comprehensive feasibility study, which is, regarding this comparatively new approach, a novelty in its extent. About 10 scenarios are analysed by technical, environmental, and economic aspects. Within the alternative scenarios on feedstocks, electricity supply, necessary hydrogen supply, and different main products are analysed. For different plant designs of the hybrid refinery, mass and energy balances are elaborated, along with the results of the technical assessment. As a result of this environmental assessment, the attainment of at least 50% GHG mitigation might be possible. GHG highly depends on the renewability grade of the hydrogen provision as well as on the used feedstock. One important conclusion of this economic assessment is that total fuel production costs of 1295 to 1800 EUR t⁻¹ are much higher than current market prices for jet fuel. The scenario in which hydrogen is produced by steam reforming of internally produced naphtha proves to be the best combination of highly reduced GHG emissions and low HEFA-SPK production costs. Full article