AVL Focus - Issue 2025

Alternative Fuels Take Center Stage

Ships powered by large internal combustion engines are

responsible for about 2 to 3 % of global energy-related CO2

emissions. In July 2023, the IMO’s Marine Environment Pro-

tection Committee therefore adopted a revised greenhouse

gas (GHG) strategy with ambitious targets: By 2050, net-zero

emissions shall be achieved.

One way to achieve these goals is through the widespread

use of alternative fuels, especially those that are carbon-free.

Ammonia is one of the most intensively studied options. It is

carbon-free and can be processed on board without directly

producing GHG emissions. If produced by electrolysis with

Achieving IMO CO2 Targets

Converting Traditional

­Engines to Alternative

Fuels for Maritime

­Decarbonization

The maritime sector must cut its carbon footprint to meet the

International Maritime Organization’s (IMO) net-zero targets for 2050.

Converting conventional engines to run on alternative fuels such as

ammonia offers a promising path. AVL demonstrates how innovative

combustion concepts and proven methodologies can accelerate this

transition.

renewable power sources, the well-to-wake emissions over

the whole supply chain are at the same low level (100 gCO2/

kWh-GWP100) as e-methane, e-methanol, and e-hydrogen.

Ammonia is attractive not only because of its zero direct GHG

emissions but also due to its favorable storage properties

compared to hydrogen. In addition, ammonia – mainly pro-

duced from fossil resources today – is already a commonly

traded commodity and available at many seaports through

existing infrastructure.

Investigating Three Combustion Concepts

In this context, AVL has recently investigated different ammo-

nia combustion concepts for high-speed internal combustion

Early combustion

in a diesel-ignited

ammonia engine

with high-pressure

fuel injection

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