Demystifying e-fuels: Explore our alternative fuels glossary

Also known as green fuels, e-fuels are liquid or gaseous fuels such as green hydrogen, green methanol, and ammonia that are produced with electricity from renewables. In sectors where direct electrification is not feasible, e-fuels allow a smooth transition from fossil to sustainable energy sources. Many e-fuels can be blended with conventional fuels and used interchangeably. Methanol, for example, can be used in existing storage systems and engines, making the transition easier and faster.

Ammonia (NH₃) is a colorless, pungent gas which becomes a liquid under pressure. When generated by renewable sources, ammonia has virtually no carbon footprint and emits no CO2, SOX, particulate matter or unburned hydrocarbons when combusted. Already widely used in industrial processes as an agricultural fertilizer, ammonia is playing an increasingly crucial role in the maritime energy transition thanks to its low production costs.

Read more about ammonia’s contribution to shipping

Find out about Everllence’s advanced two-stroke, dual-fuel ammonia engine

Green hydrogen is the simplest, most basic e-fuel. It is created by splitting water (H2O) into oxygen (O) and hydrogen (H2) using electrolysis powered by renewable energy. This hydrogen can then be used either directly as fuel for engines or as core component for the synthesis of other green fuels such as ammonia (with nitrogen), methanol, or SNG (with carbon, captured from the air, biomass or industrial plants' exhaust gases).

Methanol (CH3OH or MeOH) is a colorless, water-soluble liquid with a mild alcoholic odor. It boasts the highest hydrogen-to-carbon ratio of any liquid fuel at regular ambient conditions. As a result, it can act as a key energy carrier. Methanol is a clean-burning, cost-effective fuel, since it can be used with existing infrastructure. And when produced from biomass or synthesized from renewable energy such as solar or wind, green methanol can reduce carbon emissions by up to 95%.

Sometimes referred to as GTL diesel or FTD (Fischer–Tropsch diesel), synthetic diesel is a clean-burning liquid fuel produced by chemically transforming another hydrocarbon fuel, usually natural gas. This transformation is achieved through Gas-to-Liquid (GTL) technology which reconfigures the molecular structure of gaseous hydrocarbons into longer-chain liquid hydrocarbons suitable for diesel engines. At the heart of GTL production is the Fischer–Tropsch synthesis, a chemical process that converts syngas, a mixture of hydrogen and carbon monoxide, into synthetic diesel.

Biofuel is a diverse group made from predominantly plant-based energy sources. They should not be confused with biomass, which refers specifically to solid fuels like wood and peat or the source material (or feedstock) that biofuels are made from (such as agricultural crops and residues, animal and human waste, and food and organic refuse).

Liquid biofuels such as biodiesel, bioethanol, and hydrotreated vegetable oil (HVO), are usually made from biomass sources. For power generation applications, they can either be blended with liquid fossil fuels or can be used as a direct replacement. While liquid biofuels can be classified as renewable, they do not all have the same carbon footprint as fuels made from food crops are less sustainable than those made from organic waste.

Synthetic natural gas (SNG) encompasses various alternatives to conventional natural gas that closely mirror its composition and properties. In addition to coal, SNG can be produced from waste biomass or generated through the use of renewable energy. These production methods result in bio-SNG/biogas and e-gas/syngas, respectively. Depending on the feedstock, SNG serves as a low-carbon or potentially carbon-neutral replacement for fossil fuels. Due to its comparable composition, SNG can be blended with LNG or natural gas and utilized interchangeably across all applications. Additionally, liquefied or compressed SNG is suitable for transport and storage within the existing gas infrastructure.

VLSFO contains less than 0.5% sulfur by weight compared to up to 3.5% found in traditional high-sulfur fuel oil. This complies with the maximum sulfur content permitted in marine fuels as laid out in the International Convention for the Prevention of Pollution from Ships (MARPOL).

LNG is natural gas that has been converted to a liquid form through a cooling process, resulting in a substantially reduced volume for export, transportation, and storage. LNG is widely recognized as an effective transitional fuel for marine propulsion and power generation applications. Its use leads to lower emissions of SOX, CO2, NOX, and particulate matter when compared to traditional fuel oils.

LPG is extracted from natural gas by absorption. It is commonly used in domestic situations (cooking and heating) as well as many industrial applications. It has a high energy density and is easier to store than LNG or heavy fuel oil (HFO). LPG can contain close to zero sulfur and meets the requirements for Sulphur Emission Control Areas as well as lowering CO2 emissions.

Ethane (C2H6) is a colorless, odorless gaseous alkaline extracted from natural gas and used as fuel. When cryogenically cooled to -88.3 °C, ethane condenses to become a liquid, reducing its volume for transport and storage.