Advanced biofuels are produced from non-food-based raw materials such as agricultural residues, algae or wood waste. The biogenic waste and residual materials permitted in Europe are listed in the annex IX of EU Renewable Energy Directive RED II.
AKKL
The Climate-neutral aviation working Group (AKKL) was set up in autumn 2022 under the joint leadership of the Federal Ministry for Digital and Transport and the Federal Ministry for Economic Affairs and Climate Action to discuss the achievement of the Federal Government's goals towards climate-neutral aviation with a broad group of stakeholders from industry, trade unions, environmental associations, research institutes, think tanks and representatives of the federal states.
Alternative fuels
Non-fossil fuels that contribute to the reduction of emissions in the transport sector, such as biogenic or synthetic fuels.
Aromatics
Aromatics are ring-shaped organic compounds characterized by delocalized electrons. They influence the knock resistance of fuel and improve the lubricity, density and material compatibility of aviation fuels.
ASTM
Alcohol-to-jet (AtJ) is a process for producing sustainable aviation fuels. In this process, biomass containing sugar and starch is fermented into alcohol, then dehydrated and subsequently processed into kerosene.
Aviation emissions
Greenhouse gases and pollutants emitted by aircraft, including carbon dioxide, carbon monoxide, nitrogen oxides, water vapor, soot particles and sulphate. Noise is also an aviation emission.
AZEA
The Alliance for Zero Emission Aviation (AZEA) is a voluntary European initiative of private and public stakeholders initiated by the European Commission to prepare for the commercial operation of hydrogen-powered and electric aircraft.
B
BImschG
Federal Immission Control Act (BImschG) regulates the legal framework for protection against harmful environmental impacts caused by air pollution, noise, vibrations and similar processes in Germany.
Biofuel
Fuel produced from renewable raw materials or waste, e.g. bioethanol, biodiesel and biokerosene.
Blending
The blending of sustainable aviation fuels with conventional kerosene.
Book & Claim
A trading model for sustainable fuels in which buyers purchase certificates that promote the use of sustainable fuels elsewhere without using the physical fuel at their own location.
C
C14-Method
Radiocarbon method for determining the proportion of biogenic carbons in fuels.
Cap & Trade-system
A market-based system designed to reduce emissions by setting upper limits (caps) and the trading of certificates (trade).
CBAM
The Carbon Border Adjustment Mechanism (CBAM) is the EU's CO₂ border adjustment system for certain imports, such as cement.
Climate Club
An idea that goes back to Nobel Prize winner William D. Nordhaus and envisions a multinational trade agreement to promote ambitious climate protection measures.
Climate compensation system
Mechanism for offsetting CO₂ emissions through investments in climate protection projects.
Climate impact
The influence of emissions and other factors on the climate, including CO₂ and non-CO₂ effects.
Climate neutrality
State in which all climate-damaging anthropogenic emissions are offset or avoided.
CO₂
Carbon dioxide (CO₂) is a greenhouse gas that is produced, for example, when fossil fuels are burned and contributes to global warming.
CO₂-neutral
A process is CO₂-neutral if it causes no net CO₂ emissions.
CO₂-neutrality
State in which no additional CO₂ emissions are released. This can be achieved both by reducing emissions and by offsetting them. In contrast to greenhouse gas neutrality, the term only refers to CO₂.
Compensation
Measures to offset the CO₂ emissions caused by investing in climate protection projects, renewable energies or CO₂ capture and storage.
Contrail cirrus
Long-lasting ice crystal clouds that form from condensation trails in particularly cold and moist layers of air.
Contrails
Linear clouds of ice crystals that form when kerosene is burned in aircraft turbines in cold ambient air.
CORSIA
The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) is a market-based climate compensation system of the International Civil Aviation Organization (ICAO).
D
DAC
Direct Air Capture (DAC) is a technology for capturing CO₂ from the atmosphere.
Decarbonization
Shift away from energy and material use of carbon-containing resources. Complete decarbonization is not possible in all areas.
Defossilization
Shift away from the use of fossil resources. However, carbon-based technologies are still being used. One example from the aviation sector is the use of synthetic fuels produced from CO₂ and H₂.
Drop-in fuel
A fuel that can be used in existing infrastructures and engines without adaptation, e.g. synthetic kerosene.
E
E-kerosene
Synthetic kerosene produced using renewable electricity, hydrogen and CO₂. Synthetic kerosene is a sustainable alternative to fossil kerosene.
Electrolysis
Electrolysis is a process in which electric power is used to split a chemical compound, e.g. to produce hydrogen.
Electrolyzer
An electrolyzer is a technical system for carrying out electrolysis. It is also used to produce green hydrogen by breaking down water into its components using renewable electricity.
Emission certificate
Permission to emit one tonne of CO₂ within the framework of emissions trading systems, such as the European Emissions Trading System (EU ETS).
Energy carrier
Energy carriers contain or store energy. Examples are hydrogen, batteries or fossil fuels.
EU-ETS
European emissions trading system with the aim of reducing greenhouse gas emissions in the EU.
F
Fischer-Tropsch synthesis
Chemical process to produce hydrocarbons from synthesis gas (mixture of carbon monoxide and hydrogen). The process plays a major role in the search for alternatives to crude oil for the production of liquid hydrocarbons.
Flight route optimization
Adaptation of the flight route, e.g. to reduce emissions and climate-impacting effects.
G
Greenhouse gases
Gases in the atmosphere that prevent heat from being re-radiated from the earth's surface into space and thus contribute to global warming. In addition to CO₂, greenhouse gases include methane, nitrous oxide, ozone and water vapor.
H
HEFA
Hydroprocessed Esters and Fatty Acids (HEFA) is a process in which used fats and oils are converted into sustainable aviation fuel.
Hybrid power
Drive system that combines several energy sources, e.g. electric motors and combustion engines.
Hydrogen propulsion
Possible drive systems in which hydrogen could be used as an energy source, either by direct combustion in turbines or by hydrogen fuel cells.
I
IATA
The International Air Transport Association (IATA) is an international umbrella organization for airlines.
ICAO
The International Civil Aviation Organization (ICAO) is the international aviation organization that sets uniform environmental standards for international air traffic.
Intermodality
Combination of different means of transportation for efficient transport routes.
J
Jet A-1 kerosene
Standardized jet fuel used in civil aviation worldwide.
K
Kerosene
Aviation fuel produced from fossil crude oil.
Kerosene substitutes
Sustainable alternatives to fossil kerosene, such as synthetic aviation fuels or biofuels.
Kopernikus
A funding program of the Federal Ministry of Education and Research for the development of innovative solutions for the energy transition, including Power-to-X technologies.
L
LCA
Method for assessing the environmental impact of a product or service over its entire life cycle.
M
Market ramp-up
The process by which new technologies are gradually integrated into the market and scaled up.
Micro-refineries
Small, flexible refineries to produce fuels.
Mitigation strategies
Measures to reduce emissions, for example.
Monitoring systems
Monitoring emissions and compliance with environmental standards in aviation.
MtJ
Methanol-to-jet (MtJ) is a chemical process to produce aviation fuel from methanol. In this process, olefins are synthesized from methanol, then oligomerized and hydrogenated.
N
Non-CO₂ effects
Climate effects caused by emissions other than CO₂, such as contrails, water vapor, nitrogen oxides and aerosols.
Non-drop-in fuel
Fuel that cannot be used without modifications to existing infrastructure and engines.
P
PtL
Power-to-Liquid (PtL) is a process in which synthetic fuels are produced using renewable electricity, hydrogen and CO₂.
PtL-Roadmap
Strategy of the German government to significantly develop and expand the production of power-to-liquid kerosene generated from renewable electricity in Germany.
R
RCF
According to the definition in the EU Renewable Energy Directive RED II, recycled carbon fuels (RCF) are liquid and gaseous fuels derived from liquid or solid waste streams of non-renewable origin. Also included are process and waste gas streams of non-renewable origin that arise as unavoidable and unintentional by-products in industrial processes.
REACH
EU regulation on the registration and authorization of chemicals.
RED
The Renewable Energy Directive (RED) is an EU directive for the support of renewable energies at European level. It sets binding targets for the share of renewable energy for the various sectors in the member states. It also regulates the sustainability criteria for renewable fuels and the required greenhouse gas savings for biofuels.
reFuels
ReFuels are renewable fuels and include advanced biofuels, electric fuels and hydrogen.
Registration process
Procedures for the certification and approval of new fuels or technologies.
Renewable aviation fuels
Fuels that come from renewable sources and can be CO₂-neutral.
Renewable energies
Energy sources that are renewable and low-emission such as solar or wind energy.
RLCF
The Renewable and Low-Carbon Fuels Value Chain Industrial Alliance (RLCF) is an industrial alliance of the EU Commission to promote the production and supply of renewable and low-carbon fuels in the aviation and shipping sectors.
RNFBO
Renewable Fuels of Non-Biological Origin (RFNBO) are renewable fuels that are not derived from biomass. These primarily include electricity-based fuels (Power-to-X), which are produced from renewable electricity, hydrogen and carbon dioxide through electrolysis and subsequent synthesis processes.
S
SAF-Allowances
Free emissions certificates for airlines for blending sustainable aviation fuels as part of the European Emissions Trading System (EU ETS).
SPK
Synthetic paraffinic kerosene (SPK) is a type of synthetic kerosene that is used as a sustainable alternative to fossil aviation fuel. SPK can be produced from various carbon sources.
Synthetic fuels
Synthetic fuels are produced by chemical synthesis from synthesis gas (usually hydrogen and carbon monoxide or carbon dioxide). Depending on the origin of the synthesis gas, a distinction is made between electricity-based (PtL, PtG), biogenic (BtL) or fossil (GtL, CtL) fuels, which are obtained using processes such as Fischer-Tropsch or methanol synthesis.
U
Ultrafine particles
Very small particles (<0.1 nanometers), most of which are produced by combustion and affect health and the climate.
