1BiofuelBiofuel is fuel derived from living matter called biomass (usually plant matter). Examples of biofuels include but are not limited to biodiesel, ethanol, and vegetable oil.
2Blue hydrogenBlue hydrogen is produced by splitting fossil natural gas into hydrogen and CO₂ – and then capturing, storing, or reusing the CO₂ to mitigate environmental impacts. Blue hydrogen is sometimes also called low carbon hydrogen.
3Blue methanolBlue methanol is produced using blue hydrogen in combination with carbon capture technology, vastly reducing well-to-tank carbon dioxide emissions.
4BunkeringBunkering is the process of receiving oil in the ship’s tank and making sure that there is no overflow during the process. A bunker fuel is any fuel used for powering a ship.
5Carbon capture and storageThe process of trapping carbon dioxide produced by burning fossil fuels or other chemical or biological process and storing it in such a way that it is unable to affect the atmosphere.
6Carbon freeWhen energy sources are labelled carbon free, the energy is produced by a resource that generates no carbon emissions. Examples include solar and wind energy – or when speaking about fuels, hydrogen and ammonia.
7Carbon negativeIf the amount of CO₂ emissions removed during energy production is greater than the emissions released, energy is labelled carbon negative.
8Carbon neutral Energy is carbon neutral if the amount of CO₂ emissions released into the atmosphere during energy production is the same as the amount of CO₂ emissions removed from the atmosphere during the process.
9CIIThe Carbon Intensity Indicator (CII) is a measure of how efficiently a ship transports goods or passengers and is given in grams of CO2 emitted per cargo-carrying capacity and nautical mile.
10CO2 emissionsIt is a colourless, odourless and non-poisonous gas formed by combustion of carbon and in the respiration of living organisms and is considered a greenhouse gas. Carbon dioxide emissions or CO2 emissions are emissions stemming from the burning of fossil fuels and the manufacture of cement; they include carbon dioxide produced during consumption of solid, liquid, and gas fuels as well as gas flaring.
11Crude OilA mixture of hydrocarbons that exists in the liquid phase in natural underground reservoirs and remains liquid at atmospheric pressure after passing through surface-separating facilities.
12DecarbonisationDecarbonisation refers to reducing or removing CO₂ emissions for example through reducing or stopping the use of fossil fuels, switching to cleaner fuels, and using electric vehicles in transportation.
In the energy industry, decarbonisation means reducing ‘carbon intensity’ i.e., cutting or eliminating the emissions per unit of electricity generated (grams of carbon dioxide per kilowatt-hour).
Decarbonisation is needed to mitigate or reverse climate change and lowering the CO₂ levels in the atmosphere.
13Direct air captureDirect air capture (DAC) is a process that extracts CO₂ directly from the air. The captured CO₂ can then be converted to many products that normally originate from fossil materials. Currently, frontrunner DAC technology can be used for example in an office building’s ventilation to reduce CO₂ levels inside the building. In the future, DAC may be used on an industrial scale to filter excess carbon dioxide out of the air.
14Dual-fuel technologyDual-fuel technology is a system which enables diesel-engines to reduce its operation on diesel and to replace it in part with an alternative fuel. Typical alternative fuels include LPG (Autogas), CNG, LNG, biomethane, ethanol, methanol and hydrogen.
15EEXIThe Energy Efficiency eXisting ship Index (EEXI) is a short time measure introduced by IMO to reduce the greenhouse gas emissions of ships. The EEXI is a technical design related measure. Ships have to approve the attained EEXI value once in a life-time latest by the first periodical survey in 2023.
16First generation biofuelsEthanol produced from crops containing sugar and starch and biodiesel from oilseeds, are referred to as first-generation biofuels. These fuels only use a portion of the energy potentially available in the biomass.
17Fossil FuelA fossil fuel is a hydrocarbon-containing material formed underground from the remains of dead plants and animals that humans extract and burn as fuel. The main fossil fuels are coal, petroleum and natural gas, which humans extract through mining and drilling
18Future fuelsFuture fuels refer to a wide range of promising, carbon-neutral fuels, which can be used to advance decarbonisation. Future fuels include, for example, green hydrogen and hydrogen-based fuels such as synthetic methane, ammonia, and methanol, as well as bio and synthetic liquefied natural gas (LNG).
19GHGA greenhouse gas is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse gases in Earth’s atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone
20Green hydrogenGreen hydrogen is produced by splitting water via electrolysis, which produces only hydrogen and oxygen. However, the electrolysis process requires electricity. For hydrogen to be labelled green, the electricity used in production must come from renewable energy sources, like solar, wind or hydropower. Green hydrogen is sometimes also called renewable hydrogen
21Green methanolGreen methanol is a low-carbon fuel that can be made from either biomass gasification or renewable electricity and captured carbon dioxide (CO2). This is an exciting step, as the announcement could help to scale up climate-friendly methanol technology.
22Grey hydrogenMost hydrogen nowadays comes from fossil natural gas. Grey hydrogen is produced the same way as blue hydrogen: by splitting natural gas into hydrogen and CO₂. Hydrogen is called grey whenever the excess CO₂ is not captured. Grey hydrogen is sometimes also called fossil hydrogen.
23Grey methanolGrey methanol is produced from natural gas and may not significantly reduce well-to-wake carbon dioxide emissions. 
24Hydrogen blendsHydrogen blending refers to blending natural gas with hydrogen. The blend can then be used by the conventional end-users of natural gas to generate power and heat, as long as the technology itself allows it. Using hydrogen blends may require some adjustments to the technology – especially when talking about higher shares of hydrogen. At present, hydrogen blending is at a fairly early stage of development, but it is a promising option for expanding the use of hydrogen to reduce the environmental impact of natural gas.
25Hydrogen economyThe hydrogen economy is an envisioned future, in which hydrogen delivers a substantial fraction of a nation’s energy. In a hydrogen economy, hydrogen would be used both as a fuel and an energy carrier to help offset fluctuations in solar and wind power production and consumption.
26MethanisationMethanisation is a process that uses renewable electricity to combine hydrogen and CO₂, turning it into methane. Currently most of the methane used for heating, transport and power generation is fossil. Methanisation – also called Power-to-Gas – provides a carbon neutral alternative.
27NetzeroEnergy is net zero, if the CO₂ emissions generated during energy production are offset by the same amount of CO₂ elsewhere, for example through reforestation schemes, making the “net total” of emissions zero. Net zero carbon emissions are considered a synonym for carbon neutrality.
28Nitrogen Oxides (NOx) EmissionsThey refer to both nitric oxide (NO) and nitrogen dioxide (NO 2). NOx is a main constituent in the formation of ground-level ozone which causes severe respiratory problems.
29Pink hydrogenPink hydrogen is made from water via electrolysis just like green hydrogen but using nuclear energy as its source of power. Nuclear-produced pink hydrogen is sometimes also called purple hydrogen or red hydrogen.
30Power-to-X technology‘Power-to-X’ is used as an umbrella term for various emerging technology solutions for electricity conversion, energy storage, and energy reconversion, all of which use renewable electricity to produce for example synthetic fuels. Power-to-X technology essentially means turning energy into something else. For instance, renewable electricity can be turned into synthetic natural gas by combining CO₂ captured from the air and hydrogen.
31ScrubbersScrubbers are one of the primary devices that control gaseous emissions, especially acid gases. Scrubbers can also be used for heat recovery from hot gases by flue-gas condensation. They are also used for the high flows in solar, PV, or LED processes.
32Sulfur oxide (SOx) emissionsThey are main­ly due to the presence of sulfur compound in the fuel. Smoke containing sulfur oxides emitted by the combustion of marine fuel will often oxidize further, forming sulfuric acid which is a major contributor to acid rain.
33Synthetic fuels (eFuels)Synthetic fuels are not the same thing as fossil fuels, which are a finite resource. Synthetic fuels, or eFuels, are created by generating fuel from CO₂. In synthetic fuel production, CO₂ is used as a raw material for creating for example gasoline, diesel, and substitute natural gas, together with electricity from renewable sources and hydrogen.