The green transition at sea: new fuels and propulsion technologies

The UN's maritime organization IMO has set the goal that international shipping should be CO2-neutral by 2050 with sub-targets to reduce CO2 emissions by respectively around 20 percent in 2030 and around 70 percent in 2040. These are ambitious goals for an industry where ships typically operate for decades and where engines have traditionally run on heavy fuel oil. As a ship fitter you are part of that transition because it is ultimately you who must service the new engine types.

§Methanol as fuel

Methanol is today considered one of the most promising candidates for a green ship fuel. In 2020, the IMO already issued guidelines for the use of methyl and ethyl alcohol (methanol) as fuel in ships, and several shipping companies have since ordered ships with methanol dual-fuel engines that can run on both methanol and conventional fuel. The challenge is that methanol is still more expensive than traditional heavy fuel oil and that global green methanol production capacity is still far from the level a full transition requires.

§Ammonia – powerful, but demanding

Ammonia is another major hope because no CO2 is released during combustion itself. The first commercial ships with ammonia engines are expected to be launched in 2026. On the other hand, ammonia poses major technical and safety challenges: the substance is toxic, it is aggressive toward copper alloys, and it has a boiling point of minus 33 degrees, so it must either be stored under pressure or cooled. During combustion, NOx can also form, which must be handled with post-treatment.

• 01Methanol — liquid at ordinary temperature, already in commercial operation on several ships
• 02Ammonia – no CO2 during combustion, but toxic, aggressive toward copper and must be stored cold/under pressure
• 03LNG (liquefied natural gas) — reduces CO2 somewhat, but is still a fossil fuel
• 04Biofuels and e-fuels — can in many cases be used in existing engines with minor modifications

§The infrastructure still lags

En stor del af udfordringen er ikke selve motoren, men infrastrukturen omkring den. Bunkerfaciliteter — altså anlæg, hvor skibe kan tanke de nye brændstoffer — findes indtil videre kun i begrænset omfang i verdens havne, og det bremser, hvor hurtigt rederierne reelt kan omstille deres flåder. Det betyder, at overgangsperioden med dual-fuel-motorer, der kan køre på både gammelt og nyt brændstof, sandsynligvis bliver lang.

Uanset hvilket brændstof der vinder frem i de kommende år, er pointen for dig som skibsmontør den samme: den grundlæggende evne til at forstå og fejlfinde på et forbrændingsmotor-system er fundamentet, du bygger videre på — men du skal være indstillet på, at de tekniske detaljer og sikkerhedskrav ændrer sig i takt med, at nye teknologier vinder indpas.